Radiation astronomy/Satellites Radiation astronomy satellites may be designed and built for detection in one particular radiation astronomy or for many. Some have been built for more than one purpose or for a different purpose entirely.
This is an artist's rendering of the Interstellar Boundary Explorer (IBEX) satellite. Credit: NASA/Goddard Space Flight Center Conceptual Image Lab.
To place sensors (or detectors) above the Earth’s atmosphere
is often a necessity for radiation astronomy
. “The sensors at once lose the basic advantage of both radio and optical telescopes, a rigid, well-surveyed foundation upon a well-behaved earth.”
“The source locations, therefore, reflect uncertainties in both the sensor data and in vehicle aspect.”
Computer rendering shows the Deep Impact space probe after separation of the impactor. Credit: NASA/JPL.
"The Moon is generally anhydrous, yet the Deep Impact spacecraft found the entire surface to be hydrated during some portions of the day. Hydroxyl (OH) and water (H2
O) absorptions in the near infrared were strongest near the North Pole and are consistent with <0.5 weight percent H2
Artist's concept shows SOHO. Credit: Cgruda
The Solar and Heliospheric Observatory (SOHO) is a spacecraft built by a European industrial consortium led by Matra Marconi Space (now Astrium) that was launched on a Lockheed Martin Atlas II AS launch vehicle on December 2, 1995 to study the Sun. SOHO has also discovered over 3,000 comets.
It began normal operations in May 1996. It is a joint project of international cooperation between the European Space Agency (ESA) and NASA. Originally planned as a two-year mission, SOHO
continues to operate after over 20 years in space: the mission is extended until the end of 2020 with a likely extension until 2022.
GOLF, MDI, and VIRGO are used for helioseismology:
- Global Oscillations at Low Frequencies which measures velocity variations of the whole solar disk to explore the core of the Sun.
- Michelson Doppler Imager which measures velocity and magnetic fields in the photosphere to learn about the convection zone which forms the outer layer of the interior of the Sun and about the magnetic fields which control the structure of the corona. The MDI is the biggest producer of data by far on SOHO. In fact, two of SOHO's virtual channels are named after MDI, VC2 (MDI-M) carries MDI magnetogram data, and VC3 (MDI-H) carries MDI Helioseismology data. MDI has not been used for scientific observation since 2011, because it was superseded by the Solar Dynamics Observatory's Helioseismic and Magnetic Imager.
- Variability of solar IRradiance and Gravity Oscillations which measures oscillations and solar constant both of the whole solar disk and at low resolution, again exploring the core of the Sun.
Active galactic nuclei
Exosat dedicated control room was in Darmstadt 1983. Credit: European Space Agency.
European X-ray Observatory Satellite (EXOSAT), originally named HELOS, was an X-ray telescope operational from May 1983 until April 1986. Credit: NASA.
The European X-ray Observatory Satellite (EXOSAT), originally named HELOS, was an X-ray telescope operational from May 1983 until April 1986 and in that time made 1780 observations in the X-ray band of most classes of astronomical object including active galactic nuclei, stellar coronae, cataclysmic variables, white dwarfs, X-ray binaries, clusters of galaxies, and supernova remnants.
This European Space Agency (ESA) satellite for direct-pointing and lunar-occultation observation of X-ray sources beyond the solar system was launched into a highly eccentric orbit (apogee 200,000 km, perigee 500 km) almost perpendicular to that of the moon on May 26, 1983. The instrumentation includes two low-energy imaging telescopes (LEIT) with Wolter I X-ray optics (for the 0.04-2 keV energy range), a medium-energy experiment using Ar/CO2
detectors (for 1.5-50 keV), a Xe/He gas scintillation spectrometer (GSPC) (covering 2-80 keV), and a reprogrammable onboard data-processing computer. Exosat was capable of observing an object (in the direct-pointing mode) for up to 80 hours and of locating sources to within at least 10 arcsec with the LEIT and about 2 arcsec with GSPC.
"Thirty-four years ago, on 26 May 1983, ESA’s Exosat satellite was launched by a Thor-Delta rocket from Vandenburg Airforce Base, California, USA, and was taken over by mission controllers at ESOC, the European Space Operations Centre, Darmstadt, Germany."
"Designed to observe and detect high-energy sources, Exosat was the first ESA mission to study the Universe at X-ray wavelengths, and one of the first uncrewed satellites to feature an on-board computer."
"By placing the satellite in an elliptical orbit, mission teams were able to operate the instruments for 76 hours of each revolution."
"In its three-year life, the mission observed a wide variety of objects, including active galactic nuclei, X-ray binary systems, supernova remnants and clusters of galaxies."
"The results that Exosat obtained were very useful to scientists, and led to several new discoveries. The most important of these was probably the discovery of quasi-periodic oscillations in low-mass X-ray binary stars and X-ray pulsars, a phenomenon unknown before Exosat. All the data that Exosat retrieved are still available for study, and are still leading to new discoveries."
Aqua (EOS PM-1, 2002-022A) was launched on 4 May 2002 from Vandenberg AFB Space Launch Complex 2W. Credit: NASA.
Aqua carries six state-of-the-art instruments in a near-polar low-Earth orbit. Credit: NASA.
"Aqua [...] is a NASA Earth Science satellite mission named for the large amount of information that the mission is collecting about the Earth's water cycle, including evaporation from the oceans, water vapor in the atmosphere, clouds, precipitation, soil moisture, sea ice, land ice, and snow cover on the land and ice. Additional variables also being measured by Aqua include radiative energy fluxes, aerosols, vegetation cover on the land, phytoplankton and dissolved organic matter in the oceans, and air, land, and water temperatures."
"It continues transmitting high-quality data from four of its six instruments, AIRS [Atmospheric Infrared Sounder], AMSU [Advanced Microwave Sounding Unit], CERES [Clouds and the Earth's Radiant Energy System], and MODIS [Moderate Resolution Imaging Spectroradiometer], and reduced quality data from a fifth instrument, AMSR-E [Advanced Microwave Scanning Radiometer-EOS]. The sixth Aqua instrument, HSB [Humidity Sounder for Brazil — VHF band], collected approximately nine months of high quality data but failed in February 2003."
"Aqua follows a kind of polar orbit known as a Sun-synchronous orbit, which means it crosses the equator at the same local time during each pass. Aqua’s orbit ascends from south to north during the daylight hours, crosses near the North Pole, circles around Earth’s nighttime side, and crosses near the South Pole to return to the daytime side."
ER-2 tail number 809, is one of two Airborne Science ER-2s used as science platforms by Dryden. Credit: NASA/Jim Ross.
"ER-2 tail number 809, is one of two Airborne Science ER-2s used as science platforms by Dryden. The aircraft are platforms for a variety of high-altitude science missions flown over various parts of the world. They are also used for earth science and atmospheric sensor research and development, satellite calibration and data validation."
"The ER-2s are capable of carrying a maximum payload of 2,600 pounds of experiments in a nose bay, the main equipment bay behind the cockpit, two wing-mounted superpods and small underbody and trailing edges. Most ER-2 missions last about six hours with ranges of about 2,200 nautical miles. The aircraft typically fly at altitudes above 65,000 feet. On November 19, 1998, the ER-2 set a world record for medium weight aircraft reaching an altitude of 68,700 feet."
"The aircraft is 63 feet long, with a wingspan of 104 feet. The top of the vertical tail is 16 feet above ground when the aircraft is on the bicycle-type landing gear. Cruising speeds are 410 knots, or 467 miles per hour, at altitude. A single General Electric F118 turbofan engine rated at 17,000 pounds thrust powers the ER-2."
The "Swarm" satellites have been flying around Earth since Fall of 2013. Credit: Christoph Seidler, ESA/DTU.
Depiction shows where the molten iron jet is moving - in the outer core. Credit: ESA.
"Three [Swarm] satellites of the European Space Agency (ESA) have measured the magnetic field of Earth more precisely than ever before."
A "kind of "jet stream" - a fast-flowing river of liquid iron [depicted with an artist's impression in the image on the left] is surging westwards under Alaska and Siberia."
"The moving mass of metal has been inferred from measurements made by Europe’s Swarm satellites. [...] the jet is the best explanation for the patches of concentrated field strength that the satellites observe in the northern hemisphere."
The International Monitoring Platform (IMP) 8 is the last in a series of ten IMP missions with the primary objective to perform detailed and near-continuous observations of the Sun/Earth environment (solar wind monitoring, measuring the plasma/field environment of the magnetosheath and the magnetotail). Credit: NASA.
"IMP-8 is a NASA/GSFC mission - also known by the names of Explorer 50, and IMP-J (COSPAR designation: 73-078A). IMP-8 is the last in a series of ten IMP missions with the primary objective to perform detailed and near-continuous observations of the Sun/Earth environment (solar wind monitoring, measuring the plasma/field environment of the magnetosheath and the magnetotail). The IMP-8 mission is part of NASA's Sun-Earth Connections research program."
Instruments on-board for measuring alpha particles included the Charged Particle Measurement Experiment (CPME), the Cosmic Ray Nuclei Experiment (CRNE or CHE), and the Energetic Particle Experiment (EPE).
"The [Charged Particle Measurement Experiment] instrument is a solid-state telescope [...] measuring fluxes of protons in 11 energy channels between 0.29 and 140 MeV, and alpha particles in 6 channels between 0.64 and 52 MeV/n. Time resolution for the measurement cycle is 10.24 s."
"The CPME has two major components, the PET (Proton-Electron Telescope) and five thin-window Geiger-Mueller (GM) tubes. The PET measures and identifies electrons, protons, alpha particles, M-nuclei, and Fe-group nuclei. The GM array measures both solar X-rays and the more intense galactic X-ray sources."
"Energetic protons [P] (0.39–440 MeV), alpha particles [α] (0.59–52 MeV/nucleon), and medium nuclei [M] (carbon, nitrogen, and oxygen; 0.7–8.8 MeV/nucleon) have been observed with the Charged Particle Measurement Experiment (CPME) aboard the Interplanetary Monitoring Platform 8 (IMP 8) spacecraft from 1973 to ."
Alpha particle maxima Cycle 20 1700, Cycle 21 2700, Cycle 22 3300, Cycle 23 4100 particles/cm2
"The [Chicago] instrument is also referred to as CRNE (Cosmic Ray Nuclei Experiment). The instrument (mass=7.4 kg) consists of a pair of solid-state telescopes. The main telescope measures nuclei in the energy range of 10 to 100's of MeV/n, and electrons in the range of about 2 to about 25 MeV. The second telescope measures protons and alpha particles in the 0.5-1.8 MeV/n range. The charge resolution improved by using curved detectors."
"The objective [of the Goddard Medium Energy experiment] was to measure fluxes as a functions of energy and to make elemental identification for protons, alpha particles and heavier ions from < 1 MeV/nucleon to >400 MeV/nucleon as well as to measure the flux of relativistic electrons between 3 and 18 MeV."
An artists' depiction shows the OSIRIS-REx spacecraft. Credit: National Aeronautics and Space Administration (NASA) / Goddard Space Flight Center (GSFC) / University of Arizona / Lockheed Martin.
Asteroid Bennu imaged by the OSIRIS-REx probe on arrival 3 December 2018. Credit: NASA/Goddard/University of Arizona.
OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is a NASA asteroid-study and sample-return mission.
The material returned is expected to enable scientists to learn more about the formation and evolution of the Solar System, its initial stages of planet formation, and the source of organic compounds that led to the abiogenesis (formation of life) on Earth.
OSIRIS-REx was launched on 8 September 2016, flew past Earth on 22 September 2017, and rendezvoused with 101955 Bennu
on 3 December 2018.
It spent the next several months analyzing the surface to find a suitable site from which to extract a sample. On 20 October 2020, OSIRIS-REx touched down on Bennu
and successfully collected a sample.
Though some of the sample escaped when the flap that should have closed the sampler head was jammed open by larger rocks, NASA is confident that they were able to retain between 400 g and over 1 kg of sample material, well in excess of the 60 g (2.1 oz) minimum target mass.
"The spacecraft grabbed so much of the asteroid Bennu
, its sample-collection device got jammed. Now the material is safe and sound."
"The spacecraft will deliver the pristine material from asteroid Bennu
back to Earth in 2023."
OSIRIS-REx is expected to return with its sample to Earth on 24 September 2023.
This is an exploded diagram of the European Space Agency's Gaia spacecraft for astrometry. Credit: ESA.
This image of the Milky Way galaxy has depicted onto it the various targets and experimental regions for the ESA Gaia spacecraft. Credit: ESA.
An image from an animation has the Gaia spacecraft spinning slowly (four revolutions per day) to sweep its two telescopes across the entire celestial sphere. Credit: ESA - C. Carreau.
"Gaia [NSSDC/COSPAR ID: 2013-074A] is a European Space Agency astronomy mission whose primary goals are to: (1) measure the positions and velocity of approximately one billion stars; (2) determine the brightness, temperature, composition, and motion through space of those stars; and, (3) create a three-dimensional map of the Milky Way galaxy."
At left is an image of the Milky Way galaxy depicted onto it the various targets and experimental regions for the ESA Gaia spacecraft.
"Repeatedly scanning the sky, Gaia will observe each of the billion stars an average of 70 times each over the five years. It will measure the position and key physical properties of each star, including its brightness, temperature and chemical composition."
At lower left is an image from an animation that has the Gaia spacecraft spinning slowly (four revolutions per day) to sweep its two telescopes across the entire celestial sphere.
The image shows the Upper Atmosphere Research Satellite. Credit: NASA/GSFC.
"The Upper Atmosphere Research Satellite (UARS) is a NASA program aimed at improving our knowledge of the physical and chemical processes controlling the stratosphere, mesosphere, and lower thermosphere, emphasizing those levels that are known to be particularly susceptible to change by human activities. The spacecraft was launched by the Space Shuttle Discovery on September 12, 1991, into a near-circular orbit at 585 km altitude and 57° inclination. Measurements include vertical profiles of temperature, many trace gases, and horizontal wind velocities, as well as solar energy inputs. Many of the limb-scanning instruments can measure to as high as 80° latitude, providing near-global coverage."
This image shows the IBEX (photo cells forward) being surrounded by its protective nose cone. Credit: NASA (John F. Kennedy Space Center).
"The sensors on the IBEX spacecraft are able to detect energetic neutral atoms (ENAs) at a variety of energy levels."
The satellite's payload consists of two energetic neutral atom (ENA) imagers, IBEX-Hi and IBEX-Lo. Each of these sensors consists of a collimator that limits their fields-of-view, a conversion surface to convert neutral hydrogen and oxygen into ions, an electrostatic analyzer (ESA) to suppress ultraviolet light and to select ions of a specific energy range, and a detector to count particles and identify the type of each ion.
"IBEX–Lo can detect particles with energies ranging from 10 electron–volts to 2,000 electron–volts (0.01 keV to 2 keV) in 8 separate energy bands. IBEX–Hi can detect particles with energies ranging from 300 electron–volts to 6,000 electron–volts (.3 keV to 6 keV) in 6 separate energy bands. ... Looking across the entire sky, interactions occurring at the edge of our Solar System produce ENAs at different energy levels and in different amounts, depending on the process."
This is a spacecraft diagram of WMAP. Credit: NASA.
This is a diagram of Explorer 66, the COBE spacecraft. Credit: NASA.
"The Wilkinson Microwave Anisotropy Probe (WMAP) is a Medium-class Explorer (MIDEX) mission designed to elucidate cosmology by producing full-sky maps of the cosmic microwave background (CMB) anisotropy."
The Cosmic Background Explorer (COBE) has aboard a differential microwave radiometer (DMR) labeled in the diagram at left.
The super pressure balloons flown by the NASA program are essentially very large pressure vessels. Credit: NASA Official: David L. Pierce, Curator: Brandon Wright.
This seven-million-cubic-foot super-pressure balloon is the largest single-cell, super-pressure, fully-sealed balloon ever flown. Credit: NASA.
The Ultra Long Duration Balloon (ULDB) Project is developing new composite materials and a new balloon design, a standard gondola including power, global telemetry/command and an altitude control system. The ULDB is seeking to improve mission control and operations and the integration of scientific instruments. It is the potential for longer duration flights that has been the driver for the resurgence of interest in balloons by the scientific community. In recent years, the manned global ballooning attempts have called attention to the difficulty of achieving “longer”.
"High altitude balloons are an inexpensive means of getting payloads to the brink of space [The first test shown in the image on the left] was launched from McMurdo Station in Antarctica. The balloon reached a float altitude of more than 111,000 feet and maintained it for the entire 11 days of flight. [...] The flight tested the durability and functionality of the scientific balloon’s novel globe-shaped design and the unique lightweight and thin polyethylene film. It launched on December 28, 2008 and returned on January 8, 2009."
"The University of Hawaii Manoa’s Antarctic Impulsive Transient Antenna launched December 21, 2008, and is still aloft. Its radio telescope is searching for indirect evidence of extremely high-energy neutrino particles possibly coming from outside our Milky Way galaxy."
This auroral image was taken from the International Space Station. Credit: NASA.
The image is taken from the ISS and shows aurora above the ocean off Australia. Credit: Unknown, or unstated.
This view of the Aurora Australis, or Southern Lights, which was photographed by an astronaut aboard Space Shuttle Discovery (STS-39) in 1991, shows a spiked band of red and green aurora above the Earth's Limb. Credit: NASA.
NASA and the CSA created a network of satellites for THEMIS. Credit: NASA/Goddard Space Flight Center Conceptual Image Lab.
Both images on the right was shot from the International Space Station on or about 13 July 2012 and in 2014, respectively going down the page. Note that lights are blurred across the image rather than top to bottom in the first image.
"This view [on the left] of the Aurora Australis, or Southern Lights, which was photographed by an astronaut aboard Space Shuttle Discovery (STS-39) in 1991, shows a spiked band of red and green aurora above the Earth's Limb. Calculated to be at altitudes ranging from 80 - 120 km (approx. 50-80 miles), the auroral light shown is due to the "excitation" of atomic oxygen in the upper atmosphere by charged particles (electrons) streaming down from the magnetosphere above."
To study macroscale interactions during substorms, NASA and the Canadian Space Agency (CSA) created a network of satellites shown in the image on the lower left for “Time History of Events and Macroscale Interactions during Substorms" (THEMIS).
This diagram shows the mounting of PAMELA on the Resurs-DK1 satellite. Credit: -=HyPeRzOnD=-
as modified by Aldebaran66
The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics
(PAMELA) is an operational cosmic ray research module attached to the Resurs-DK1
commercial Earth observation satellite. PAMELA is the first satellite-based experiment dedicated to the detection of cosmic rays, with a particular focus on their antimatter component, in the form of positrons and antiprotons. Other objectives include long-term monitoring of the solar modulation of cosmic rays, measurements of energetic particles from the Sun, high-energy particles in Earth's magnetosphere and Jovian electrons.
The instrument is built around a permanent magnet spectrometer with a silicon microstrip tracker that provides rigidity and dE/dx information. At its bottom is a silicon-tungsten imaging calorimeter, a neutron detector and a shower tail scintillator to perform lepton/hadron discrimination. A Time of Flight (ToF), made of three layers of plastic scintillators, is used to measure the beta and charge of the particle. An anticounter system made of scintillators surrounding the apparatus is used to reject false triggers and albedo particles during off-line analysis.
The Fermi Gamma-ray Space Telescope sits on its payload attachment fitting. Credit: NASA/Kim Shiflett.
"The Large Area Telescope (LAT) is a pair-conversion gamma-ray telescope onboard the Fermi Gamma-ray Space Telescope satellite. It has been used to measure the combined [cosmic-ray] CR electron and positron spectrum from 7 GeV to 1 TeV [20, 21]. The LAT does not have a magnet for charge separation. However, as pioneered by  and , the geomagnetic field can also be used to separate the two species without an onboard magnet. Müller and Tang  used the difference in geomagnetic cutoff for positrons and electrons from the east and west to determine the positron fraction between 10 GeV and 20 GeV. As reported below, we used the shadow imposed by the Earth and its offset direction for electrons and positrons due to the geomagnetic field, to separately measure the spectra of CR electrons and positrons from 20 GeV to 200 GeV. In this energy range, the 68% containment radius of the LAT point-spread function is 0.1° or better and the energy resolution is 8% or better."
"The Large Area Telescope (LAT) detects individual gamma rays using technology similar to that used in terrestrial particle accelerators
hit thin metal sheets, converting to electron-positron pairs, via a process known as pair production
. These charged particles pass through interleaved layers of silicon microstrip detectors
, causing ionization
which produce detectable tiny pulses of electric charge. Researchers can combine information from several layers of this tracker to determine the path of the particles. After passing through the tracker, the particles enter the calorimeter
, which consists of a stack of caesium iodide scintillator
crystals to measure the total energy of the particles. The LAT's field of view is large, about 20% of the sky. The resolution of its images is modest by astronomical standards, a few arc minutes for the highest-energy photons and about 3 degrees at 100 MeV. The LAT is a bigger and better successor to the EGRET
instrument on NASA's Compton Gamma Ray Observatory
satellite in the 1990s.
Artist's impression shows the Mars Reconnaissance Orbiter spacecraft. Credit: NASA.
This is a natural color image by the HiRISE camera on the Mars Reconnaissance Orbiter. Credit: NASA/JPL/University of Arizona.
On the left is an image in natural color by the HiRISE camera of Cerberus Fossae Graben showing exposed blue material.
The Pioneer Venus Orbiter was inserted into an elliptical orbit around Venus on December 4, 1978. Credit: NASA.
Imaged is the cloud structure in the Venusian atmosphere in 1979, revealed by ultraviolet observations by Pioneer Venus Orbiter. Credit: NASA.
In visual astronomy
almost no variation or detail can be seen in the clouds. The surface is obscured by a thick blanket of clouds. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. It has thick clouds of sulfur dioxide. There are lower and middle cloud layers. The thick clouds consisting mainly of sulfur dioxide and sulfuric acid droplets.
These clouds reflect and scatter about 90% of the sunlight that falls on them back into space, and prevent visual observation of the Venusian surface. The permanent cloud cover means that although Venus is closer than Earth to the Sun, the Venusian surface is not as well lit.
Strong 300 km/h winds at the cloud tops circle the planet about every four to five earth days.
Venusian winds move at up to 60 times the speed of the planet's rotation, while Earth's fastest winds are only 10% to 20% rotation speed.
This is an exploded view of the Juno spacecraft. Credit: NASA.
The diagram shows where the instruments aboard Juno are attached. Credit: NASA / Jet Propulsion Laboratory.
An artist's impression of Juno near Jupiter. Credit: NASA/JPL.
"Juno [NSSDC/COSPAR ID: 2011-040A] is also carrying a colour camera, promising Earthlings "the first detailed glimpse of Jupiter's poles"."
"The Juno mission was launched on 05 August 2011 to study Jupiter from polar orbit for approximately one year beginning in 2016. The primary scientific objectives of the mission are to collect data to investigate: (1) the formation and origin of Jupiter's atmosphere and the potential migration of planets through the measurement of Jupiter's global abundance of oxygen (water) and nitrogen (ammonia); (2) variations in Jupiter's deep atmosphere related to meteorology, composition, temperature profiles, cloud opacity, and atmospheric dynamics; (3) the fine structure of Jupiter's magnetic field, providing information on its internal structure and the nature of the dynamo; (4) the gravity field and distribution of mass inside the planet; and (5) Jupiter's three-dimensional polar magnetosphere and aurorae. Juno carries eight experiments to achieve these objectives."
"The spacecraft is built around a hexagonal cylinder bus measuring 3.5 m in diameter by 3.5 m high. Three solar panel wings extend from alternate sides of the hexagon giving a total diameter of approximately 20 m. A high gain antenna is mounted on top of the bus, with instruments mounted on the deck and propellant, oxygen, and pressurant tanks mounted within. At the center of the top deck is a 0.8 x 0.8 x 0.6 m titanium "vault" which houses the spacecraft avionics and critical systems to protect them from the severe jovian radiation environment. The vault has a mass of 150 kg and walls up to over a cm in thickness. Power is provided by ultra triple junction GaAs solar cells, covered with thick glass for radiation shielding, which are grouped into 11 solar panels, four on two of the wings and three on the other. (The end of the third wing is a boom structure holding science instruments.) The solar panels will produce a total of 18 kW at Earth and 400 W initially at Jupiter. The science payload comprises ten instruments: the Jovian Auroral Distributions Experiment (JADE), the Jupiter Energetic-particle Detector Instrument (JEDI), the Ultraviolet Spectrograph (UVS), the JunoCam, the Jovian Infrared Auroral Mapper (JIRAM), the Plasma Waves Instrument (Waves), the Microwave radiometer (MWR), the Fluxgate Magnetometer (FGM), the Advanced Stellar Compass (ASC), the Scalar Helium Magnetometer (SHM), and the Gravity Science experiment."
This is a 3D model of the Rosetta Spacecraft. The individual scientific payloads are highlighted in different colours. Credit: IanShazell
For elongated dust particles in cometary comas an investigation is performed at 535.0 nm (green) and 627.4 nm (red) peak transmission wavelengths of the Rosetta spacecraft
's OSIRIS Wide Angle Camera broadband green and red filters, respectively.
"In the green, the polarization of the pure silicate composition qualitatively appears a better fit to the shape of the observed polarization curves".
"[B]ut they are characterized by a high albedo."
The silicates used to model the cometary coma dust are olivene (Mg-rich is green) and the pyroxene, enstatite.
Anomalous cosmic rays
A mechanism is suggested for anomalous cosmic rays (ACRs) of the acceleration of pick-up ions at the solar wind termination shock. Credit: Eric R. Christian.
Artist's representation shows the Advanced Composition Explorer (ACE). Credit: NASA.
"While interstellar plasma is kept outside the heliosphere by an interplanetary magnetic field, the interstellar neutral gas flows through the solar system like an interstellar wind, at a speed of 25 km/sec. When closer to the Sun, these atoms undergo the loss of one electron in photo-ionization or by charge exchange. Photo-ionization is when an electron is knocked off by a solar ultra-violet photon, and charge exchange involves giving up an electron to an ionized solar wind atom. Once these particles are charged, the Sun's magnetic field picks them up and carries them outward to the solar wind termination shock. They are called pickup ions during this part of their trip."
"The ions repeatedly collide with the termination shock, gaining energy in the process. This continues until they escape from the shock and diffuse toward the inner heliosphere. Those that are accelerated are then known as anomalous cosmic rays."
"ACRs [may] represent a sample of the very local interstellar medium. They are not thought to have experienced such violent processes as GCRs, and they have a lower speed and energy. ACRs include large quantities of helium, oxygen, neon, and other elements with high ionization potentials, that is, they require a great deal of energy to ionize, or form ions. ACRs are a tool for studying the movement of energetic particles within the solar system, for learning the general properties of the heliosphere, and for studying the nature of interstellar material itself."
During solar activity minima (low or no sunspots), the Solar Isotope Spectrometer (SIS) measures the isotopes of low-energy cosmic rays from the Galaxy and isotopes of the anomalous cosmic ray component, which originates in the nearby interstellar medium.
Extragalactic cosmic rays
"In this study, the temporal variation of the speckle values on Sentinel 1 satellite images were compared with the cosmic ray intensity/count data, to analyze the effects which may occur in the electromagnetic wave signals or electronic system. Sentinel 1 Synthetic Aperture Radar (SAR) images nearby to the cosmic ray stations and acquired between January 2015 and December 2019 were processed. The median values of the differences between speckle filtered and original image were calculated on Google Earth Engine Platform per month. The monthly median “noise” values were compared with the cosmic ray intensity/count data acquired from the stations. Eight selected stations’ data show that there are significant correlations between cosmic ray intensities and the speckle amounts."
"Cosmic rays are various atomic and subatomic particles that continuously enter the Earth’s atmosphere from the Sun and outside of the Solar System and reach the Earth . They are studied in two groups as primary and secondary cosmic rays. Primary cosmic rays are energetic particles that reach the Earth’s atmosphere and consist of approximately 83% protons, 13% alpha particles, 1% nuclei with atomic number >2 and 3% electrons . As cosmic rays pass through the atmosphere, they interact with atoms and molecules in the atmosphere, thus producing lower energy particles. These particles with lower energy reaching the ground are secondary cosmic rays. Cosmic rays are also divided into three categories: Galactic Cosmic Rays (GCR) coming from outside the solar system; Solar Energetic Particles, which are defined as high-energy particles emitted by Solar Explosions or coronal mass ejections (CMEs); and Extragalactic Cosmic Rays, which flow into the Solar System from beyond the Milky Way galaxy. Cosmic rays have high enough energy to affect the electronic circuit components and optical materials of satellites. They can cause signal attenuation, deterioration of GPS calibration, complete loss of the signal, incorrect operations, equipment damage and thus undesirable effects on communication and image acquisition ."
"The amount of speckle on radar images was compared with the cosmic ray intensity for all test areas. The analysis results showed a similar trend for the whole dataset (speckle and cosmic ray intensity) and significant positive correlation values which vary between 0.62 and 0.78. Both similar trends and high positive correlations show that cosmic rays interact within the CCD sensors on the satellite and some pixels are oversaturated. Because these particles have very high energy, they can penetrate inside the electronics of the instrument and produce some additional noise in the measurements. Thus, we may conclude that the amount of the difference between measurements is directly related to the number of cosmic rays interacting with the satellite or the observed area".
Galactic cosmic rays
Pioneer 10 on its kick motor prior to encapsulation before launch. Credit: NASA Ames Resarch Center (NASA-ARC).
The charged particle instrument (CPI) is used to detect cosmic rays in the solar system. Credit: NASA.
The cosmic-ray telescope collects data on the composition of the cosmic ray particles and their energy ranges. Credit: NASA.
The launch of Pioneer 10 aboard an Atlas/Centaur
vehicle. Credit: NASA Ames Resarch Center (NASA-ARC).
This diagram shows the interplanetary trajectory for Pioneer 10. Credit: NASA.
"In 1972, the return of the galactic cosmic rays in the inner solar system to solar minimum conditions and the launch of Pioneer 10 toward Jupiter coincided to make possible the measurements of the low-energy cosmic-ray charge spectra during solar quiet times."
"Recent measurements using the Goddard-University of New Hampshire cosmic-ray telescope on the Pioneer 10
spacecraft have revealed an anomalous spectrum of nitrogen and oxygen nuclei relative to other nuclei such as He and C, in the energy range 3-30 MeV per nucleon."
"To eliminate [the solar cosmic-ray background] a very careful selection of times must be made to assure that solar cosmic rays are not obviously present [by] requiring that the 10-20 MeV proton intensity measured on the same experiment be essentially at background level."
Primary cosmic rays
This is an image of HEAO 3. Credit: William Mahoney, NASA/JPL.
The HEAO 3 French-Danish C-2 experiment measured the relative composition of the isotopes of the primary cosmic rays between beryllium and iron (Z from 4 to 26) and the elemental abundances up to tin (Z=50). Cerenkov counters and hodoscopes
, together with the Earth's magnetic field, formed a spectrometer. They determined charge and mass of cosmic rays to a precision of 10% for the most abundant elements over the momentum range from 2 to 25 GeV/c (c=speed of light).
The purpose of the HEAO 3 C-3 experiment was to measure the charge spectrum of cosmic-ray nuclei over the nuclear charge (Z) range from 17 to 120, in the energy interval 0.3 to 10 GeV/nucleon; to characterize cosmic ray sources; processes of nucleosynthesis, and propagation modes.
dependence of the escape length of cosmic rays in the galaxy has been derived in the framework of the leaky box model from the measured values of the B/C ratio."
For an interstellar medium "composed of 90% H and 10% He, [with a density of 0.3 atoms cm-3
] and using the most recently measured cross sections (Webber, 1989; Ferrando et al., 1988b), the escape length has been found equal to 34βR-0.6
for rigidities R
above 4.4 GV, and 14β
below. ... where R
are the interstellar values of the rigidity and the ratio of the velocity of the particle to the velocity of light."
Secondary cosmic rays
In this image, the Alpha Magnetic Spectrometer-2 (AMS-02) is visible at center left on top of the starboard truss of the International Space Station. Credit: STS-134 crew member and NASA.
The Alpha Magnetic Spectrometer is designed to search for various types of unusual matter by measuring cosmic rays.
About 1,000 cosmic rays are recorded by the instrument per second, generating about one GB/sec
of data. This data is filtered and compressed to about 300 KB/sec for download to the operation centre POCC at CERN. In July 2012, it was reported that AMS-02 had observed over 18 billion cosmic rays.
"As cosmic rays pass through the atmosphere, they interact with atoms and molecules in the atmosphere, thus producing lower energy particles. These particles with lower energy reaching the ground are secondary cosmic rays."
Solar cosmic rays
A technician stands next to one of the twin Helios spacecraft during testing. Credit: NASA/Max Planck.
Trajectory of the Helio space probes is diagrammed. Credit: NASA.
and Helios 2
are a pair of probes launched into heliocentric orbit for the purpose of studying solar processes. The probes are notable for having set a maximum speed record among spacecraft at 252,792 km/h
(157,078 mi/h or 43.63 mi/s or 70.22 km/s or 0.000234c). Helios 2 flew three million kilometers closer to the Sun than Helios 1, achieving perihelion on 17 April 1976 at a record distance of 0.29 AU (or 43.432 million kilometers),
slightly inside the orbit of Mercury
. Helios 2 was sent into orbit 13 months after the launch of Helios 1. The probes are no longer functional but still remain in their elliptical orbit around the Sun. On board, each probe carried an instrument for cosmic radiation investigation (the CRI) for measuring protons, electrons, and X-rays to determine the distribution of cosmic rays.
Ultra-high-energy cosmic rays
Lomonosov satellite measured fluorescence light radiated by EAS (Extensive Air Showers) of Ultra High Energy Cosmic Rays (UHECR) in the Earth atmosphere. Credit: Pline
The objective of the mission is the observation of gamma-ray bursts, high-energy cosmic rays and transient phenomena in the Earth's upper atmosphere.
The spacecraft is equipped with seven scientific instruments,
including the Tracking Ultraviolet Set Up system
) designed to measure fluorescence light radiated by EAS (Extensive Air Showers) of Ultra High Energy Cosmic Rays (UHECR) in the Earth atmosphere as well as for transients' studies within UV-range. This was the first space based instrument dedicated to these phenomena. The TUS-project started in 2001.
This image depicts the GPM Core Observatory satellite orbiting Earth, with several other satellites from the GPM Constellation in the background. Credit: NASA.
"The Global Precipitation Measurement (GPM) mission is an international network of satellites [shown in the image at right] that provide the next-generation global observations of rain and snow. Building upon the success of the Tropical Rainfall Measuring Mission (TRMM), the GPM concept centers on the deployment of a “Core” satellite carrying an advanced radar / radiometer system to measure precipitation from space and serve as a reference standard to unify precipitation measurements from a constellation of research and operational satellites. Through improved measurements of precipitation globally, the GPM mission will help to advance our understanding of Earth's water and energy cycle, improve forecasting of extreme events that cause natural hazards and disasters, and extend current capabilities in using accurate and timely information of precipitation to directly benefit society. GPM, initiated by NASA and the Japan Aerospace Exploration Agency (JAXA) as a global successor to TRMM, comprises a consortium of international space agencies, including the Centre National d’Études Spatiales (CNES), the Indian Space Research Organization (ISRO), the National Oceanic and Atmospheric Administration (NOAA), the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT), and others."
The launch occurred on February 28, 2014 at 3:37am JST on the first attempt.
This is a photograph of one of the two STEREO spacecraft. Credit: NASA.
This is an artist depiction of Stardust during the 'burn-to-depletion' phase which ended the mission on March 24, 2011. Credit: NASA/JPL.
In January 1986, the Voyager 2
spacecraft flew by Uranus at a minimal distance of 107,100 km
providing the first close-up images and spectra of its atmosphere. They generally confirmed that the atmosphere was made of mainly hydrogen and helium with around 2% methane.
The atmosphere appeared highly transparent and lacking thick stratospheric and tropospheric hazes. Only a limited number of discrete clouds were observed.
To produce 3D images of the Sun, the STEREO spacecraft [at right] take images in red and cyan.
To produce 3D images of Comet Wild 2, the Stardust spcecraft at right takes images in red and cyan.
This tree diagram shows the relationship between types and classification of most common particle detectors. Credit: Wdcf
Artist impression shows the Rossi X-ray Timing Explorer (RXTE). Credit: GDK
This is an image of a real X-ray detector. The instrument is called the Proportional Counter Array and it is on the Rossi X-ray Timing Explorer
(RXTE) satellite. Credit: NASA.
Radiation detectors provide a signal that is converted to an electric current. The device is designed so that the current provided is proportional to the characteristics of the incident radiation.
There are detectors that provide a change in substance as the signal and these may be automated to provide an electric current or quantified proportional to the amount of new substance.
Transition Region And Coronal Explorer (TRACE) is shown in artist's impression. Credit: NASA.
The image shows solar coronal loops observed by the Transition Region And Coronal Explorer (TRACE), 171 Å filter. Credit: TRACE/NASA.
The image shows the cooling post-flare arcade (rotated by -90 degrees so that north is to the right) 6h after the flare (at 00:11 UT on September 8. Credit: TRACE/NASA.
"Almost as soon as Active Region 10808 rotated onto the solar disk, it spawned a major X17 flare. TRACE was pointed at the other edge of the Sun at the time, but was repointed 6 hours after the flare started. The image on the left shows the cooling post-flare arcade (rotated by -90 degrees so that north is to the right) 6h after the flare (at 00:11 UT on September 8); the loop tops still glow so brightly that the diffraction pattern repeats them on diagonals away from the brightest spots. Some 18h after the flare, the arcade is still glowing, as seen in the image on the right (at 11:42 UT on September 8). In such big flares, magnetic loops generally light up successively higher in the corona, as can be seen here too: the second image shows loops that are significantly higher than those seen in the first. Note also that the image on the right also contains a much smaller version of the cooling arcade in a small, very bright loop low over the polarity inversion line of the region."
The image shows the Spitzer Space Telescope prior to launch. Credit: NASA/JPL/Caltech.
"The Spitzer Space Telescope [imaged at the right] is a space-borne, cryogenically-cooled infrared observatory capable of studying objects ranging from our Solar System to the distant reaches of the Universe. Spitzer is the final element in NASA's Great Observatories Program, and an important scientific and technical cornerstone of the Astronomical Search for Origins Program."
The telescope specifications are 85 cm diameter (33.5 Inches), f/12 lightweight Beryllium, cooled to less 5.5 K.
Its wavelength range is 3 - 180 µm.
This is an image of the Energetic Particles Detector (EPD) aboard the Galileo Orbiter. Credit: NASA.
The Energetic Particles Detector (EPD) aboard the Galileo Orbiter
is designed to measure the numbers and energies of electrons whose energies exceed about 20 keV
. The EPD can also measure the direction of travel of electrons. The EPD uses silicon solid state detectors and a time-of-flight
detector system to measure changes in the energetic electron population at Jupiter as a function of position and time.
"[The] two bi-directional, solid-state detector telescopes [are] mounted on a platform which [is] rotated by a stepper motor into one of eight positions. This rotation of the platform, combined with the spinning of the orbiter in a plane perpendicular to the platform rotation, [permits] a 4-pi [or 4π] steradian coverage of incoming [electrons]. The forward (0 degree) ends of the two telescopes [have] an unobstructed view over the [4π] sphere or [can] be positioned behind a shield which not only [prevents] the entrance of incoming radiation, but [contains] a source, thus allowing background corrections and in-flight calibrations to be made. ... The 0 degree end of the [Low-Energy Magnetospheric Measurements System] LEMMS [uses] magnetic deflection to separate incoming electrons and ions. The 180 degree end [uses] absorbers in combination with the detectors to provide measurements of higher-energy electrons ... The LEMMS [provides] measurements of electrons from 15 keV to greater than 11 MeV ... in 32 rate channels."
Himawari-8 and 9 (“sunflower”) are Geostationary Meteorological Satellites. Credit: Japanese Meteorological Agency and Mitsubishi Electric.
The bolide is captured by the Himawari 8 operated by the Japan Meteorological Agency. Credit: Himawari 8 satellite operated by the Japan Meteorological Agency.
Cause was a 10-14-meter (32-45-foot) asteroid
Impact energy: 173 kiloton
Radiated energy: 130 TJ
The Kamchatka bolide was a meteor that exploded in an air burst off the east coast of the Kamchatka Peninsula in eastern Russia on 18 December 2018.
At around midday, local time,
an asteroid roughly 10 meters in diameter entered the atmosphere at a speed of 32.0 kilometres per second (72,000 mph), with a TNT equivalent energy of 173 kilotons, more than 10 times the energy of the Little Boy bomb dropped on Hiroshima in 1945.
The object entered at a steep angle of 7 degrees, close to the zenith, terminating in an air burst at an altitude of around 16 miles (26 km).
"The main instrument of the Himawari-8 and 9 spacecraft is the Advanced Himawari Imager – a multispectral imaging payload developed by Exelis. It covers 16 spectral channels from the visible spectrum into the infrared wavelengths marking a major increase in channels compared to heritage instruments."
Image shows the MetOp-A & -B spacecraft, two separate identical satellites, with transparent background. Credit: NASA.
The first atmospheric contributions by Metop-A were made by the Global Ozone Monitoring Experiment-2 (GOME-2), a scanning spectrometer on board the satellite. GOME-2, designed by German Aerospace Center (DLR) and developed by SELEX Galileo as the successor of European Remote-Sensing Satellite (ERS-2)'s GOME (1995), provided coverage of most areas of planet Earth measuring the atmospheric ozone, the distribution of surface ultraviolet radiation, and the amount of nitrogen dioxide (NO2
In addition, sun-induced chlorophyll fluorescence, a proxy for gross primary production, can be observed using the GOME-2 instrument.
The GOME-2 instrument provides a second source of ozone observations that supplement data from the SBUV/2 ozone instruments on the NOAA-18 and NOAA-19 satellites, which are part of the IJPS.
The primary instrument for observations was the Large Area Counter (LAC). Credit: NASA.
Some "60 spectra of 27 Seyfert galaxies [were observed] with the Ginga
Large Area proportional Counter (LAC). The 2-10 keV continuum is found to be compatible with previous spectral surveys, but a spectral flattening, or 'hard tail', is evident above 10 keV. Excess absorption over the Galactic column density is found in around half of the soures, with an equivalent hydrogen column density NH
. Spectral features are found to be common, with all but two of the sources showing evidence for an iron K𝛂 emission line. The mean energy of the line, at around 6.4 keV, indicates an origin via fluorescence in near-neutral material."
The pre-launch mounting of the AGILE satellite before being loaded aboard the PSLV C8 rocket is shown. Credit: A. Morselli.
(Astro‐rivelatore Gamma a Immagini LEggero
) is an X-ray and Gamma ray astronomical satellite of the Italian Space Agency
(ASI). The AGILE mission is to observe Gamma-Ray sources in the universe. AGILE’s instrumentation combines a gamma-ray imager (GRID) (sensitive in the energy range 30 MeV-50 GeV), a hard X-ray imager and monitor: Super-AGILE (sensitive in the range 18-60 KeV), a calorimeter (sensitive in the range 350 KeV-100 MeV) (MCAL), and an anticoincidence system (AC), based on plastic scintillator. AGILE was successfully launched on [April 23,] 2007.
Hard gamma rays
The first half of the payload fairing is ready to be moved around NASA's Gamma-Ray Large Area Space Telescope, or GLAST, within the mobile service tower on Launch Pad 17-B at Cape Canaveral Air Force Station. Credit: NASA/Jim Grossmann.
Emergence of IC 310 is captured in a series of images. Credit: A. Neronov et al. and NASA/DOE/LAT collaboration.
"Fermi's Large Area Telescope (LAT) scans the entire sky every three hours, continually deepening its portrait of the sky in gamma rays, the most energetic form of light. While the energy of visible light falls between about 2 and 3 electron volts, the LAT detects gamma rays with energies ranging from 20 million to more than 300 billion electron volts (GeV)."
"At higher energies, gamma rays are rare. Above 10 GeV, even Fermi's LAT detects only one gamma ray every four months from some sources."
"Any object producing gamma rays at these energies is undergoing extraordinary astrophysical processes. More than half of the 496 sources [the Fermi hard-source list] in the new census are active galaxies, where matter falling into a supermassive black hole powers jets that spray out particles at nearly the speed of light."
"One example is the well-known radio galaxy NGC 1275 [above left], which is a bright, isolated source below 10 GeV. At higher energies it fades appreciably and another nearby source begins to appear. Above 100 GeV, NGC 1275 becomes undetectable by Fermi, while the new source, the radio galaxy IC 310, shines brightly."
"The catalog serves as an important roadmap for ground-based facilities called Atmospheric Cherenkov Telescopes, which have amassed about 130 gamma-ray sources with energies above 100 GeV. They include the Major Atmospheric Gamma Imaging Cherenkov telescope (MAGIC) on La Palma in the Canary Islands, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) in Arizona, and the High Energy Stereoscopic System (H.E.S.S.) in Namibia."
Soft gamma rays
The Compton Gamma Ray Observatory (CGRO) is deployed in 1991. Credit: NASA/Ken Cameron.
A view of 4C 71.07 from observations by the Burst and Transient Source Experiment. Credit: Mike McCollough, USRA.
On the right is a "view of 4C 71.07 from observations by the Burst and Transient Source Experiment. This helped convince scientists that they were studying data from the quasar and not some other source in the neighborhood."
"Angela [Malizia] has now discovered this quasar in soft gamma rays."
"It is also known as QSO 0836+710, a quasar or quasi-stellar object that emits baffling amounts of radio energy. (The numbers actually designate the same place in the sky: 71.07 is its declination, and 0836+710 is right ascension and declination.)"
"It's basically the nucleus of a galaxy that is showing extraordinary activity."
"What BATSE has discovered is that it can be a soft gamma-ray source."
"This makes it the faintest and most distant object to be observed in soft gamma rays. 4C 71.07 has already been observed in gamma rays by the Energetic Gamma Ray Telescope (EGRET) also aboard the Compton Gamma Ray Observatory."
"In the case of 4C 71.07, it's the brightest AGN seen above 20,000 electron volts (20 keV). Its average flux (the amount of radiation reaching our telescopes) is about 13 milliCrabs, or 13/1,000ths as much as the Crab Nebula, a standard candle in astrophysics."
This image shows the narrow angle camera (NAC) of Cassini's Imaging Science Subsystem (ISS). Credit: NASA/JPL.
This image shows the wide angle camera (WAC) of Cassini's Imaging Science Subsystem (ISS). Credit: NASA/JPL.
The image shows Dawn prior to encapsulation at its launch pad on July 1, 2007. Credit: NASA/Amanda Diller.
The Cassini Orbiter
spacecraft that is in orbit around Saturn has two science telescopes observing in the green. The Imaging Science Subsystem (ISS) has a narrow angle camera (NAC) and a wide angle camera (WAC). The NAC uses a reflecting telescope and the WAC uses a refractor. The NAC on Cassini has a green filter centered at 568 nanometers. The WAC has a 567 nm centroid.
Overall the camera observes a wavelength range of 200-1100 nm and has 24 filters [on two wheels] with a 6.0 microradians per pixel angular resolution.
The wide angle camera detects a wavelength range from 380-1100 nm using 18 filters [on two wheels] and has a 60 microradians per pixel angular resolution.
"The Visual and Infrared Mapping Spectrometer (VIMS) is a pair of imaging grating spectrometers designed to measure reflected and emitted radiation from atmospheres, rings, and surfaces over wavelengths from 0.35 to 5.1 micrometers to determine their compositions, temperatures, and structures. ... The visible channel (VIMS-V) is an opto-mechanical assembly designed to produce multispectral images in the visible range. It consists of a Shafer telescope, a holographic spectrometer grating, and a silicon CCD area array focal plane detector cooled to its required temperature by a passive radiator. The VIMS-V will be configured as a "pushbroom" imager, which means that the optical instrument's IFOV is an entire line of pixels. This is scanned over the scene with a single-axis scanning mirror to produce a series of contiguous rows, which together form a two-dimensional image. ... The visible channel has 96 channels covering the wavelength range from 0.35 to 1.07 µm."
The Hubble Space Telescope has used three cameras to capture green images: the wide field planetary camera 1 (PC-1), the wide field planetary camera 2 (PC-2), and the wide field camera 3 (WCF3).
The Galileo spacecraft uses a 559 nm green filter.
The Rosetta Spacecraft has two instruments aboard that use green astronomy: the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) and the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS).
For OSIRIS, the "camera system has a narrow-angle lens (700 mm) and a wide-angle lens (140 mm), with a 2048x2048 pixel [charge-coupled device] CCD chip."
The Visible and IR spectrometer is able to make pictures of the core in the IR and also search for IR spectra of molecules in the coma. The detection is done by a mercury cadmium teluride array for IR and with a CCD chip for the Visible range. ... improved versions were used for Dawn and Venus express.
spacecraft has onboard a framing camera (FC) with a refractive optical system and an 8-position filter wheel of a panchromatic (clear filter) and seven narrow band filters. The visual and infrared spectrometer (VIR) has an array of HgCdTe photodiodes cooled to about 70K spans the spectrum from 0.95 to 5.0 µm.
The green filter aboard Dawn
in the FC has a central wavelength of 555 nm.
The VIR on Dawn
has a green filter centered at 563 nm.
: The V
amera is a wide-angle, multi-channel CCD
. The VMC is designed for global imaging of the planet.
It operates in the visible, ultraviolet, and near infrared spectral ranges, and maps surface brightness distribution searching for volcanic activity, monitoring airglow
, studying the distribution of unknown ultraviolet absorbing phenomenon at the cloud-tops, and making other science observations.
: The "V
isible and I
pectrometer" (VIRTIS) is an imaging spectrometer that observes in the near-ultraviolet, visible, and infrared
parts of the electromagnetic spectrum
. It will analyze all layers of the atmosphere, surface temperature and surface/atmosphere interaction phenomena.
Artist's concept shows the GPM Core Observatory. Credit: NASA.
The Global Precipitation Measurement project provides global precipitation maps to assist researchers in improving the forecasting of extreme events, studying global climate, and adding to current capabilities for using such satellite data to benefit society.
The GPM Core Observatory was assembled and tested at Goddard Space Flight Center, and launched from Tanegashima Space Center, Japan, on a Mitsubishi Heavy Industries H-IIA rocket, on February 28, 2014 at 3:37am JST on the first attempt.
This is the Herschel Space Observatory. Credit: NASA.
The European Space Agency's Herschel Space Observatory has aboard the Photodetector Array Camera and Spectrometer (PACS). "The camera operates in three bands centred on 70, 100, and 160 μm, respectively, and the spectrometer covers the wavelength range between 51 and 220 μm."
Infrared Space Observatory (ISO) was a European Space Agency orbiting infrared observatory. Credit: European Space Agency.
The ISO was designed to study infrared light at wavelengths of 2.5 to 240 micrometers and operated from 1995 to 1998.
The SPIRIT-III instrument is aboard the orbiting Midcourse Space Experiment satellite. Credit: U.S. Air Force.
The mid-infrared image of the Moon was taken during a 1996 lunar eclipse by the SPIRIT-III instrument aboard the orbiting Midcourse Space Experiment satellite. Credit: DCATT Team, MSX Project, BMDO (Ballistic Missile Defense Organization of the US DoD).
"The mid-infrared image of the Moon [at left] was taken during a 1996 lunar eclipse by the SPIRIT-III instrument aboard the orbiting Midcourse Space Experiment satellite. At these wavelengths, MSX was able to characterize the thermal (heat) distribution of the lunar surface during the eclipse. The brightest regions are the warmest, and the darkest areas are the coolest. The well-known crater Tycho is the bright object to the south of center. Numerous other craters are also seen as bright spots, indicating that their temperature is higher than in the surrounding dark mare. The Moon is geologically inactive for the most part, and any temperature differences are a result primarily of variations in solar heating (rather than volcanoes, for example). The Moon lacks an atmosphere to moderate temperatures, which can vary from 130 degrees Celsius (265 degrees Fahrenheit) in the sun to -110 degrees Celcius (-170 degrees Fahrenheit) in the shade."
Model shows Sentinel 2 satellite. Credit: Rama
The Sentinel-2 satellites each carry a single multi-spectral instrument (MSI) with 13 spectral channels in the visible/near infrared (VNIR) and short wave infrared spectral range (SWIR). Within the 13 bands, the 10 meter spatial resolution allows for continued collaboration with the Spot 5 and Landsat 8 missions, with the core focus being land classification.
Designed and built by Airbus Defense and Space in France, the MSI imager uses a push-broom concept and its design has been driven by the large 290 km (180 mi) swath requirements together with the high geometrical and spectral performance required of the measurements.
It has a 150 mm (6 in) aperture and a three-mirror anastigmat design with a focal length of about 600 mm (24 in); the instantaneous field of view is about 21° by 3.5°.
The mirrors are rectangular and made of silicon carbide, a similar technology to those on the Gaia
mission. The system also employs a shutter mechanism preventing direct illumination of the instrument by the sun, which is also used in the calibration of the instrument.
Out of all the different civic optical earth observation missions, Sentinel-2 is the first to have the ability to show three bands in the red edge.
The radiometric resolution is 12 bit with brightness intensity ranging from 0-4095.
Spectral bands for the Sentinel-2 sensors
Sentinel 5 is an Earth observation satellite in continuity of observations with Envisat.
Sentinel 5 is the first mission of the Copernicus Programme dedicated to monitoring air pollution with its instrument called Tropomi built on a hexagonal Astrobus L 250 satellite bus equipped with S- and X-band communication antennas, three foldable solar panels generating 1500 watts and hydrazine thrusters for orbital station-keeping.
Tropomi is taking measurements every second covering an area of approximately 2600 km wide and 7 km long in a resolution of 7 x 7 km, where light is separated into different wavelengths using grating spectrometers and then measured with four different detectors for respective spectral bands: UV spectrometer 270-320 nm, the visible light spectrometer 310-500 nm, NIR 675-775 nm, and SWIR 2305-2385 nm.
World map showing frequency of lightning strikes, in flashes per km² per year (equal-area projection), from combined 1995–2003 data from the Optical Transient Detector and 1998–2003 data from the Lightning Imaging Sensor. Credit: Citynoise
This drawing shows the location of the CERES instrument on the TRMM satellite. Credit:NASA
CERES and the Lightning Imaging Sensor are two Earth Observation System instruments which were added to the primary TRMM payload to complement the goals of the mission.
Lightning is more than ground-to-cloud electron transfer.
"Cloud flashes sometimes have visible channels that extend out into the air around the storm (cloud-to-air or CA), but do not strike the ground. The terms sheet lightning or intra-cloud lightning (IC) refers to lightning embedded within a cloud that lights up as a sheet of luminosity during the flash. A related term, heat lightning, is lightning or lightning-induced illumination that is too far away for thunder to be heard. Lightning can also travel from cloud-to-cloud (CC). Spider lightning refers to long, horizontally traveling flashes often seen on the underside of stratiform clouds."
"Large thunderstorms are capable of producing other kinds of electrical phenomena called transient luminous events (TLEs) that occur high in the atmosphere. They are rarely observed visually and not well understood. The most common TLEs include red sprites, blue jets, and elves."
North and South Auroras Aren't Mirrored: This series of near-simultaneous auroras were observed between 11:24 am and 12:10 pm Universal Time. Credit: NASA.
Diagram shows the Polar spacecraft and its instruments. Credit: NASA.
This perspective view of the IMAGE observatory shows an octagonal shape spacecraft covered with arrays of dual-junction, high-efficiency gallium-arsenide solar cells. Credit: NASA.
An auroral oval
is a permanent region of luminescence 15 to 25 degrees in latitude from the magnetic poles and 5 to 20 degrees wide.
"This series of near-simultaneous auroras [on the left] were observed between 11:24 am and 12:10 pm Universal Time (6:24am and 7:10am ET) on October 23, 2002. Observations were made of the northern (left) and southern (right) hemispheres by IMAGE and Polar satellites, respectively. White dots indicate the geographic poles. Analysis of the spacecraft images showed how the auroras shift depending on the "tilt" of the Earth's magnetic field toward the sun and conditions in the solar wind. The "12" at the top indicates noon (the direction toward the sun), and "0" at the bottom indicates midnight, (the direction away from the sun). Likewise, the "6" indicates dawn or morning side of the Earth, while "18" indicates dusk or evening side of the Earth, thus placing the auroras on a 24 hour clock face."
"Looking at the auroras from space, they look like almost circular bands of light around the North and South Poles."
"From spacecraft observations made in October, 2002, scientists noticed that these circular bands of aurora shift in opposite directions to each other depending on the orientation of the sun's magnetic field, which travels toward the Earth with the solar wind flow. They also noted that the auroras shift in opposite directions to each other depending on how far the Earth's northern magnetic pole is leaning toward the sun."
"What was most surprising was that both the northern and southern auroral ovals were leaning toward the dawn (morning) side of the Earth for this event."
"This is the first analysis to use simultaneous observations of the whole aurora in both the northern and southern hemispheres to track their locations."
The MISSE are usually loaded on the outside of International Space Station. The inset image shows where. Credit: NASA.
"Space is considered an environment — an extreme environment, filled with entities that can be harmful to spacecraft."
"In space, there are several environmental threats that can harm materials used to create spacecraft. These threats include ultraviolet rays and x-rays from the sun; solar wind particle radiation; thermal cycling (hot and cold cycles); space particles (micrometeoroids and debris); and atomic oxygen."
"Since 2001, NASA and its partners have operated a series of flight experiments called Materials International Space Station Experiment, or MISSE. The objective of MISSE is to test the stability and durability of materials and devices in the space environment."
"PECs [Passive Experiment Containers], which are attached to the exterior of the International Space Station, are about 2-feet by 2-feet and hold a variety of materials samples and devices whose reactions in space are of interest."
"The PECs are positioned in either a ram/wake orientation or in a zenith/nadir orientation. The ram orientation is the direction in which the space station is traveling, and the wake orientation faces the direction traveled. The zenith orientation faces away from Earth into space, while the nadir orientation faces straight down to Earth. Each orientation exposes the samples to different space environmental factors."
The Planck telescope was launched in 2009 to observe the Cosmic Microwave Background Radiation. Credit: ESA.
The COBE is launched into Earth orbit on November 18, 1989. The WMAP is launched on June 30, 2001, into orbit at the Lagrange 2 location. Both satellites have aboard detectors designed to perform microwave astronomy, as these are limited to only the microwave band.
The Gravity Recovery and Climate Experiment (GRACE) "mission uses a microwave ranging system to accurately measure changes in the speed and distance between two identical spacecraft flying in a polar orbit about 220 kilometers (140 mi) apart, 500 kilometers (310 mi) above Earth. The ranging system is sensitive enough to detect separation changes as small as 10 micrometres (approximately one-tenth the width of a human hair) over a distance of 220 kilometers.
As the twin GRACE satellites circle the globe 15 times a day, they sense minute variations in Earth's gravitational pull. When the first satellite passes over a region of slightly stronger gravity, a gravity anomaly, it is pulled slightly ahead of the trailing satellite. This causes the distance between the satellites to increase. The first spacecraft then passes the anomaly, and slows down again; meanwhile the following spacecraft accelerates, then decelerates over the same point.
"The basic scientific goal of the Planck mission is to measure [cosmic microwave background] CMB anisotropies at all angular scales larger than 10 arcminutes over the entire sky with a precision of ~2 parts per million. The model payload consists of a 1.5 meter off-axis telescope with two focal plane arrays of detectors sharing the focal plane. Low frequencies will be covered by 56 tuned radio receivers sensitive to 30-100 GHz, while high frequencies will be covered by 56 bolometers sensitive to 100-850 GHz."
This is an artist's impression of AIM above the Earth. Credit: NASA.
The clean room is used to keep particulate matter from short-circuiting AIM satellite sensitive systems. Credit: NASA.
"The scientific purpose of the Aeronomy of Ice in the Mesosphere (AIM, [NSSDC/COSPAR ID: 2007-015A]) mission is focused on the study of Polar Mesospheric Clouds (PMCs) that form about 50 miles [60 km] above the Earth's surface in summer and mostly in the polar regions. The overall goal is to resolve why PMCs form and why they vary."
"AIM will measure PMCs and the thermal, chemical and dynamical environment in which they form. This will allow the connection to be made between these clouds and the meteorology of the polar mesosphere. This connection is important because a significant variability in the yearly number of noctilucent ("glow in the dark") clouds (NLCs), one manifestation of PMCs, has been suggested as an indicator of global change."
"The AIM scientific objectives will be achieved by measuring near simultaneous PMC abundances, PMC spatial distributions, cloud particle size distributions, gravity wave activity, cosmic dust influx to the atmosphere needed to study the role of these particles as nucleation sites and precise, vertical profile measurements of temperature, H2
O, OH, CH4
, NO, and aerosols. AIM carries three instruments: an infrared solar occultation differential absorption radiometer, ... (Solar Occultation for Ice Experiment, SOFIE); a panoramic ultraviolet imager (Cloud Imaging and particle Size Experiment, CIPS); and, an in-situ dust detector (Cosmic Dust Experiment, CDE)".
"The solar occultation for ice experiment (SOFIE) is an infrared radiometer experiment that uses a differential absorption technique in solar occultation (sunrise and sunset). SOFIE measures absorption of sunlight in eight spectral regions between 0.25 and 5.3 mm. The specific wavelengths are chosen to provide altitude profiles of temperature, polar mesospheric clouds (PMCs), water vapor, Carbon Dioxide, Methane, Nitric Oxide, Ozone and aerosol absorption."
"The cloud imaging and particle size experiment (CIPS) is a UV panoramic imager that uses intensified CCD cameras to image the Polar Mesospheric Clouds (PMC) latitude versus longitude distribution. It provides nadir imaging with a 120 degrees by 80 degrees field of view (1140 by 960 km) with at least 3 km spatial resolution at 83 km. CIPS observes the backscattered radiance from PMCs (near 82 km altitude) to derive the morphology of PMCs and the cloud particle sizes. Rayleigh scattering from the background near 50 km altitude is used to measure gravity wave activity. Multiple exposures of individual cloud elements provide a measurement of the scattering phase function and detect spatial scales ~2 km. The Ultraviolet bandpass (265 plus or minus 5 nm) maximizes cloud contrast."
"The cosmic dust experiment (CDE) is an in-situ dust detector that measures the influx of dust particles into the upper atmosphere (the PMC region). The CDE is mounted on the zenith side of the spacecraft, with a very wide field of view looking away from the Earth."
Artist's view shows the ISEE-1 spacecraft in orbit. Credit: NASA.
"Energetic neutral atoms (ENA), emitted from the magnetosphere with energies of ∼50 keV, have been measured with solid-state detectors on the IMP 7/8 and ISEE 1 spacecraft. The ENA are produced when singly charged trapped ions collide with the exospheric neutral hydrogen geocorona and the energetic ions are neutralized by charge exchange."
"The IMAGE mission ... High Energy Neutral Atom imager (HENA) ... images [ENAs] at energies between 10 and 60 keV/nucleon [to] reveal the distribution and the evolution of energetic [ions, including protons] as they are injected into the ring current during geomagnetic storms, drift about the Earth on both open and closed drift paths, and decay through charge exchange to pre‐storm levels."
This is a computer-generated image of the Extreme Universe Space Observatory (EUSO) as part of the Japanese Experiment Module (JEM) on the International Space Station (ISS). Credit: JEM-EUSO, Angela Olinto.
The Extreme Universe Space Observatory
) is the first Space mission concept devoted to the investigation of cosmic rays and neutrinos of extreme energy
(E > 5×
eV). Using the Earth's atmosphere as a giant detector, the detection is performed by looking at the streak of fluorescence
produced when such a particle interacts with the Earth's atmosphere.
Lunar Prospector orbiter has the magnetometer mounted on the boom-end facing toward the viewer. Credit: NASA.
The neutron spectrometer (NS) aboard the Lunar Prospector
is designed to detect minute amounts of water ice which [are] believed to exist on the Moon. It [is] capable of detecting water ice at a level of less than 0.01%. The neutron spectrometer [is] a thin cylinder at the end of one of the three radial Lunar Prospector science booms. The instrument [has] a surface resolution of 150 km. The neutron spectrometer consisted of two canisters each containing helium-3 and an energy counter. Any neutrons colliding with the helium atoms give an energy signature which can be detected and counted. One of the canisters [is] wrapped in cadmium
, and one in tin
. The cadmium screens out thermal (low energy or slow-moving) neutrons, while the tin does not. Thermal neutrons are cosmic-ray
-generated neutrons which have lost much of their energy in collisions with hydrogen atoms. Differences in the counts between the two canisters indicate the number of thermal neutrons detected, which in turn indicates the amount of hydrogen on the Moon's crust at a given location. Large quantities of hydrogen would likely be due to the presence of water.
Artist's rendering shows Hisaki in orbit around the Earth
. Credit: Nesnad
HST/STIS image of Jupiter's northern polar region is overlain by Hisaki UV winow. Credit: Chihiro Tao, Tomoki Kimura, Sarah V. Badman, Nicolas André, Fuminori Tsuchiya, Go Murakami, Kazuo Yoshioka, Ichiro Yoshikawa, Atsushi Yamazaki, Masaki Fujimoto.
"Quasi-continuous observations over 40 min of every 106 min Hisaki orbit were conducted from December 2013 to April 2014 [of Jupiter's northern polar region]. In addition, Hubble Space Telescope (HST) observations were also carried out during the first half of January 2014."
On the left is a Hubble Space Telescope (HST) image in the ultraviolet of Jupiter's North pole auroral ring, "(a) HST/STIS image of Jupiter‟s northern polar region, the position of the STIS slit (white vertical line) for spectrum observation on 2 January 2014, and Hisaki/EXCEED [Extreme Ultraviolet Spectroscope for Exospheric Dynamics] auroral aperture (area bounded by red lines), (b) auroral spectra taken by HST/STIS integrated over the slit (black) and Hisaki/EXCEED (red)".
"[G]ray hatched regions correspond to the H Lyman and He emission lines from geocorona. Absorption cross section for the methane is overplotted by blue line referring to the right-hand axis."
"EXCEED provides continuous auroral spectra covering the wavelength range over 80–148 nm from the whole northern polar region. The auroral electron energy is estimated using a hydrocarbon color ratio adopted for the wavelength range of EXCEED, and the emission power in the long wavelength range 138.5–144.8 nm is used as an indicator of total emitted power before hydrocarbon absorption and auroral electron energy flux."
The Hubble Space Telescope is seen from the departing Space Shuttle Atlantis, flying Servicing Mission 4 (STS-125), the fifth and final human spaceflight to visit the observatory. Credit: Ruffnax (Crew of STS-125).
Polishing of Hubble's primary mirror begins at Perkin-Elmer corporation, Danbury, Connecticut, March 1979. The engineer pictured is Dr. Martin Yellin, an optical engineer working for Perkin-Elmer on the project.
This diagram is an exploded view of the HST. Credit: AndrewBuck
Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared. Hubble's Ultra-Deep Field
image, for instance, is the most detailed visible-light image ever made of the universe's most distant objects. Hubble is the only telescope designed to be serviced in space by astronauts. Optically, the HST is a Cassegrain reflector
of Ritchey-Chrétien design
, as are most large professional telescopes. This design, with two hyperbolic mirrors, is known for good imaging performance over a wide field of view, with the disadvantage that the mirrors have shapes that are hard to fabricate and test. The mirror and optical systems of the telescope determine the final performance, and they were designed to exacting specifications.
Optical telescopes typically have mirrors polished to an accuracy
of about a tenth of the wavelength
of visible light
, but the Space Telescope was to be used for observations from the visible through the ultraviolet (shorter wavelengths) and was specified to be diffraction limited
to take full advantage of the space environment. Therefore its mirror needed to be polished to an accuracy of 10 nanometers
, or about 1/65 of the wavelength of red light.
On the long wavelength end, the OTA was not designed with optimum IR performance in mind — for example, the mirrors are kept at stable (and warm, about 15 °C) temperatures by heaters. This limits Hubble's performance as an infrared telescope.
The HST is an optical astronomy telescope that incorporated a set of 48 filters isolating spectral lines of particular astrophysical interest. The instrument contained eight charge-coupled device (CCD) chips divided between two cameras, each using four CCDs. The "wide field camera" (WFC) covered a large angular field at the expense of resolution, while the "planetary camera" (PC) took images at a longer effective focal length than the WF chips, giving it a greater magnification.
The GHRS was a spectrograph
designed to operate in the ultraviolet. It was built by the Goddard Space Flight Center and could achieve a spectral resolution
Also optimized for ultraviolet observations were the FOC and FOS, which were capable of the highest spatial resolution of any instruments on Hubble. Rather than CCDs these three instruments used photon
-counting digicons as their detectors. ... The final instrument was the HSP, designed and built at the University of Wisconsin–Madison
. It was optimized for visible and ultraviolet light observations of variable stars
and other astronomical objects varying in brightness. It could take up to 100,000 measurements per second with a photometric
accuracy of about 2% or better.
HST's guidance system can also be used as a scientific instrument. Its three Fine Guidance Sensors
(FGS) are primarily used to keep the telescope accurately pointed during an observation, but can also be used to carry out extremely accurate astrometry
; measurements accurate to within 0.0003 arcseconds have been achieved.
This is a pre-launch image of LandSat 7. Credit: NASA.
This figure shows the major components in two views of the Landsat 8 spacecraft (without solar arrays). Credit: NASA, USGS.
This view of the deployed LDCM spacecraft shows the calibration ports of the TIRS and OLI instruments. Credit: NASA/GSFC.
This is a block diagram of the OLI illustrating the calibration subsystem in front of the telescope. Credit: NASA, BATC.
These images are two orientations for a schematic view of the TIRS instrument internal assembly. Credit: NASA.
The image is a cutaway view of the Scene Select Mechanism (SSM) of the TIRS. Credit: NASA.
LandSat 7 is one of the most recent of the LandSat series of Earth observing satellites. It produced an orange astronomy image of the Namib Desert.
Landsat 8 is a "collaboration between NASA and the US Geological Survey to obtain measurements of the Earth's radiation in the visible, near-infrared, short wave infrared, and thermal infrared."
The satellite is referred to as the Landsat Data Continuity Mission (LDCM).
"The LDCM spacecraft uses a nadir-pointing three-axis stabilized platform (zero momentum biased) ... The ADCS (Attitude Determination and Control Subsystem) employs six reaction wheels and three torque rods as actuators. Attitude is sensed with three precision star trackers (2 of 3 star trackers are active), a redundant SIRU (Scalable Inertial Reference Unit), twelve coarse sun sensors, redundant GPS receivers (Viceroy), and two TAMs (Three Axis Magnetometers)."
"Attitude control error (3σ): ≤ 30 µrad; Attitude knowledge error (3σ): ≤ 46 µrad; Attitude knowledge stability (3σ): ≤ 0.12 µrad in 2.5 seconds; ≤ 1.45 µrad in 30 seconds; [and] Slew time: 180º any axis: ≤ 14 minutes, including settling; 15º roll: ≤ 4.5 minutes, including settling."
The "spacecraft pointing capability [allows] the calibration of the OLI using the sun (roughly weekly), the moon (monthly), stars (during commissioning) and the Earth (at 90° from normal orientation, a.k.a., side slither) quarterly. The solar calibration [is] used for OLI absolute and relative calibration, the moon for trending the stability of the OLI response, the stars [are] used for Line of Sight determination and the side slither [is] an alternate OLI and relative gain determination methodology."
"C&DH (Command & Data Handling) subsystem: The C&DH subsystem uses a standard cPCI backplane RAD750 CPU. The MIL-STD-1553B data bus is used for onboard ADCS, C&DH functions and instrument communications. The SSR (Solid State Recorder) provides a storage capacity of 4 Tbit @ BOL and 3.1 Tbit @ EOL. The C&DH subsystem provides the mission data interfaces between instruments, the SSR, and the X-band transmitter. The C&DH subsystem consists of an IEM (Integrated Electronics Module), a PIE (Payload Interface Electronics), the SSR, and two OCXO (Oven Controlled Crystal Oscillators)."
"TCS (Thermal Control Subsystem): The TCS uses standard Kapton etched-foil strip heaters. In general, a passive, cold-biased system is used for the spacecraft. Multi-layer insulation on spacecraft and payload as required. A deep space view is provided for the instrument radiators."
"EPS (Electric Power Subsystem): The EPS consists of a single deployable solar array with single-axis articulation capability and with a stepping gimbal. Triple-junction solar cells are being used providing a power of 4300 W @ EOL. The NiH2
battery has a capacity of 125 Ah. Use of unregulated 22-36 V power bus."
"The onboard propulsion subsystem provides a total velocity change of ΔV = 334 m/s using eight 22 N thrusters for insertion error correction, altitude adjustments, attitude recovery, EOL disposal, and other operational maintenance as necessary."
"RF communications: Earth coverage antennas are being used for all data links. The X-band downlink uses lossless compression and spectral filtering. The payload data rate is 440 Mbit/s. The X-band RF system consists of the X-band transmitter, TWTA (Travelling Wave Tube Amplifier), DSN (Deep Space Network) filter, and an ECA (Earth Coverage Antenna). The serial data output is set at 440.825 Mbit/s and is up-converted to 8200.5 MHz. The TWTA amplifies the signal such that the output of the DSN filter is 62 W. The DSN filter maintains the signal’s spectral compliance. An ECA provides nadir full simultaneous coverage, utilizing 120º half-power beamwidth, for all in view ground sites below the spacecraft's current position with no gimbal or actuation system. The system is designed to handle up to 35 separate ground contacts per day as forecasted by the DRC-16 (Design Reference Case-16)."
The second image at left is a view of the deployed LDCM spacecraft showing the calibration ports of the TIRS and OLI instruments.
The Operational Land Imager (OLI) is multispectral and of moderate resolution. "An edge response slope is ... specified for the image date from each [of nine] spectral band. The edge response is defined as the normalized response of the image data to a sharp edge as expressed in a Level 1R VDP (Validation Data Product). An edge response slope of 0.027 is required for bands 1 through 7, a slope of 0.054 is required for the panchromatic band, band 8, and a slope of 0.006 for the cirrus band, band 9."
The nine bands are
- New Deep Blue 433-453 nm,
- Blue 450-515 nm,
- Green 525-600 nm,
- Red 630-680 nm,
- NIR 845-885 nm,
- SWIR 2 1560-1660 nm,
- SWIR 3 2100-2300 nm,
- PAN 500-680 nm (for image sharpening), and
- SWIR 1360-1390 nm.
"The OLI calibration subsystem [at lower right] consists of two solar diffusers (a working and a pristine), and a shutter. When positioned so that the sun enters the solar lightshade, the diffusers reflect light diffusely into the instruments aperture and provide a full system full aperture calibration. The shutter, when closed, provides a dark reference. In addition, two stim lamp assemblies are located at the front aperture stop. Each lamp assembly contains three lamps (per redundant configuration) that are operated at constant current and monitored by a silicon photodiode. The lamp signal goes through the full telescope system. Additionally, the OLI focal plane [includes] masked HgCdTe detectors, that is, detectors that [are] blocked from seeing the Earth’s radiance"
The Thermal Infrared Sensor (TIRS) "is a QWIP (Quantum Well Infrared Photodetector) based instrument intended to supplement the observations of the OLI instrument. The TIRS instrument is a TIR (Thermal Infrared) imager operating in the pushbroom mode with two IR channels: 10.8 µm and 12 µm. The two spectral bands are achieved through interference filters that cover the FPA (Focal Plane Assembly)."
"The imaging telescope [for the TIRS] is a 4-element refractive lens system. A scene select mechanism (SSM) rotates a scene mirror (SM) to change the field of regard from a nadir Earth view to either an on-board blackbody calibrator or a deep space view. The blackbody is a full aperture calibrator whose temperature may be varied from 270 to 330 K."
At lowest left are two orientations for a schematic view of the TIRS instrument internal assembly. "The scene select mechanism rotates the field of regard from the Earth view to either the space view or to the on-board calibrator. The right side provides some detail of optical system showing the 4-element lens, a cut-away view of the [Scene Mirror] SM and the thermal strap connecting the [Focal Plane Assembly] FPA to the cryocooler cold tip."
At lowest right is a cutaway view of the Scene Select Mechanism (SSM) of the TIRS. The SSM ... is a single axis, direct drive mechanism which rotates a 207 mm scene mirror from the nadir science position to the 2 calibration positions twice per orbit. It provides pointing knowledge and stability to ~10 µradians. The SSM can be driven in either direction for unlimited rotations. The rotating mirror is dynamically balanced over the spin axis, and does not require launch locking."
"The design of the SSM is straightforward; it is a single axis rotational mechanism. The operational cadence [is] to hold the scene mirror stationary for ~40 minutes staring at nadir, rotate 120º to the space view aperture and stare for 30 seconds, rotate 120º to the internal blackbody and stare for 30 seconds and then rotate the mirror to the back to nadir. Then the entire process [starts] again. The mechanism [operates] all of the time, or [has] a 100% duty cycle. Since LDCM/TIRS [is] in a highly-inclined polar orbit, the general idea [is] to calibrate twice per orbit while over the poles."
Artist's impression shows the Parasol satellite in orbit above Earth. Credit: Ill. D. Ducros, CNES.
Radiation astronomy results from Parasol show world-wide intensity variations from aerosols at 865 nm. Credit: LOA/CARE, CNES.
a “man-made apparatus designed to be placed in orbit around a celestial body, generally to relay information, data etc. to Earth”
is called a satellite
Ideally, a radiation satellite has a detector or sensor system aboard for each of the many types of radiation the probe is likely to encounter. These systems are balanced against support requirements to optimize the probes performance.
Satellites often spin at a fairly constant rate to allow each detector access to the targets. Spinning may give the detector system stability.
Supplying power, usually in the form of electricity, often comes from photocells. Interplanetary and interstellar craft need other sources such as radionuclides in high concentration.
Parasol (Polarization & Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar) was launched from Centre Spatial Guyanais (CSG) northwest of Kourou, French Guiana, on 18 December 2004 by an Ariane 5 G+.
« C’est un instrument qui sert à mesurer la direction et la polarisation de la lumière réfléchie par l’atmosphère dans diverses longueurs d’onde. »
On the left are the intensity results for aerosols detected at 865 nm from March 2005 to February 2010.
This is an exploded view of the INTEGRAL spacecraft. Credit: ESA/Medialab.
"[P]ositron astronomy results ... have been obtained using the INTEGRAL
The positrons are not directly observed by the INTEGRAL space telescope, but "the 511 keV positron annihilation emission is".
Wind is the first of NASA's Global Geospace Science program. Credit: NASA.
"The ... solar proton flare on 20 April 1998 at W 90° and S 43° (9:38 UT) was measured by the GOES-9-satellite (Solar Geophysical Data 1998), as well as by other experiments on WIND ... and GEOTAIL. Protons were accelerated up to energies > 110 MeV and are therefore able to hit the surface of Mercury."
This is an artist's impression of the Mars Express orbiter over Mars. Credit: ESA.
Numerous airborne and spacecraft radars have mapped the entire planet, for various purposes. One example is the Shuttle Radar Topography Mission
, which mapped the entire Earth at 30 m resolution.
The Mars Express
mission carries a ground-penetrating radar.
An artist's view of the Van Allen Probes spacecraft constellation is illustrated. Credit: JHU/APL.
The diagram shows one of the Van Allen Probes with various components and subsystems labeled. Credit: JHU/APL.
"The Radiation Belt Storm Probes [RBSP, NSSDC/COSPAR ID: 2012-046A, now the Van Allen Probes] mission is part of NASA's Living With a Star Geospace program to explore fundamental processes that operate throughout the solar system, in particular those that generate hazardous space weather effects near the Earth and phenomena that could affect solar system exploration. RBSP is designed to help understand the sun's influence on the Earth and near-Earth space by studying the planet's radiation belts on various scales of space and time. Understanding the radiation belt environment and its variability has extremely important practical applications in the areas of spacecraft operations, spacecraft and spacecraft system design, mission planning, and astronaut safety."
"The mission's science objectives are to: (1) discover which processes, singly or in combination, accelerate and transport radiation belt electrons and ions and under what conditions; (2) understand and quantify the loss of radiation belt electrons and determine the balance between competing acceleration and loss processes; and, (3) understand how the radiation belts change in the context of geomagnetic storms."
"The Energetic Particle, Composition and Thermal Plasma Suite (ECT) ... directly [measures] near-Earth space radiation particles to understand the physical processes that control the acceleration, global distribution, and variability of radiation belt electrons and ions. The objectives of the experiment are to: (1) determine the physical processes that produce radiation belt enhancements; (2) ascertain the dominant mechanisms for relativistic electron loss; (3) determine how the intter magnetospheric plasma environment controls radiation belt acceleration and loss; and, (4) develop empirical and physical models for understanding and predicting radiation belt space weather effects. In order to accomplishments these goals, ECT consists of three instruments: the Magnetic Electron Ion Spectrometer (MagEIS), the Helium Oxygen Proton Electron electrostatic analyzer (HOPE), and the Relativistic Electron Proton Telescope (REPT)."
"The Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) is intended to determine how space weather creates the so-called "storm-time ring current" around the Earth and ascertain how that ring current supplies and supports the creation of radiation populations. The investigation [measures] the ring current pressure distribution, needed to understand how the inner magnetosphere changes during geomagnetic storms and how that environment supplies and support the acceration and loss processes involved in creating and sustaining hazardous radiation particle populations. The experiments objectives are to: (1) understand the effects of the ring current and other storm phenomena on radiation electrons and ions; (2) examine how and why the ring current and associated phenomena vary during storms; and, (3) support the development and validation of specification models of the radiation belts for solar cycle time scales."
"The Relativistic Proton Spectrometer (RPS) [measures] inner radiation belt protons with energies from 50 MeV-2 GeV. Such protons are known to pose a number of hazards to humans and spacecraft, including total ionizing dose, displacement damage, single event effects, and nuclear activation. The objectives of the investigation are to: (1) support the development of a new AP9/AE9 standard radiation model for spacecraft design; (2) to develop and test the model for RBSP data in general and RPS specifically; and, (3) to provide standardized worst-case specifications for dose rate, internal and deep dielectric chargins, and surface charging."
At left is a diagram of one of the Van Allen Probes labeling various subsystems including the ECT.
This is an artist's impression of Explorer 49 in orbit above the Moon. Credit: NASA.
[is] a 328 kilogram satellite launched on June 10, 1973 for longwave
radio astronomy research. It had four 230-meter long X-shaped antenna elements, which made it one of the largest spacecraft ever built. ... Explorer 49
was placed into lunar orbit to provide radio astronomical measurements of the planets, the sun, and the galaxy over the frequency range of 25 kHz to 13.1 MHz.
This image shows Mariner 10. Credit: NASA.
This is Mercury in real colors, processed from clear and blue filtered Mariner 10 images. Credit: Images processed by Ricardo Nunes.
Mariner 10, at right, made a true color image of Mercury that shows its reddish color.
"The equipment consisted of two spherical (150 mm diameter) Cassegrain telescopes with eight filters, each attached to a GEC 1 inch vidicon tube camera (1500 mm focal length and 0.5 degree field of view) for narrow-angle photography. An auxiliary optical system mounted on each camera provided wide-angle (62 mm focal length, 11 x 14 degree field of view) photography by moving a mirror on a filter wheel to a position in the optical path. Exposure time ranged from 3 ms to 12 s, and each camera took a picture every 42 s. The TV picture consisted of 700 scan lines with 832 picture elements per line, which were digitally coded into eight-bit words for transmission. There were eight filter wheel positions: (1) wide-angle image relay mirror; (2) blue bandpass; (3) UV polarizing; (4) minus UV high pass; (5) clear; (6) UV bandpass; (7) defocusing lens (for calibration); and, (8) yellow bandpass."
"A higher-reflectance [HR], relatively red material occurs [on Mercury] as a distinct class of smooth plains [P] that were likely emplaced volcanically; a lower-reflectance material with a lesser spectral slope may represent a distinct crustal component enriched in opaque minerals, possibly more common at depth."
"The distinctively red smooth plains (HRP) appear to be large-scale volcanic deposits stratigraphically equivalent to the lunar maria (20), and their spectral properties (steeper spectral slope) are consistent with magma depleted in opaque materials. The large areal extent (>106
) of the Caloris HRP is inconsistent with the hypothesis that volcanism was probably shallow and local (10); rather, such volcanism was likely a product of extensive partial melting of the upper mantle."
"Despite the dearth of ferrous iron in silicates, Mercury's surface nonetheless darkens and reddens with time like that of the Moon. This darkening and reddening has been interpreted to be the result of production of nanophase iron (e.g., Pieters et al., 2000; Hapke, 2001), which could be derived from an opaque phase in the crustal material or from delivery by micrometeorite impacts (Noble and Pieters, 2003). On the Moon, deposits that are brighter and redder than the average Moon spectrum appear to be lower in iron (e.g., highland material); deposits that are darker and redder than average are higher in iron (e.g., low-Ti mare material) (Lucey et al., 1995)."
This oblique astronaut photograph from the International Space Station (ISS) captures a white-to-grey ash
and steam plume extending westwards from the Soufriere Hills volcano. Credit: NASA Expedition 21 crew.
This is a computer generated model of the Lunar Atmosphere and Dust Environment Explorer (LADEE). Credit: NASA.
Oblique images such as the one at right are taken by astronauts looking out from the International Space Station (ISS) at an angle, rather than looking straight downward toward the Earth
(a perspective called a nadir
view), as is common with most remotely sensed data from satellites
. An oblique view gives the scene a more three-dimension quality
, and provides a look at the vertical structure of the volcanic plume.
"The Lunar Atmosphere and Dust Environment Explorer (LADEE, at left) launched 07 September 2013 at 03:27 UT (06 September 11:27 EDT) on a Minotaur-V from Wallops Flight Facility. LADEE is designed to characterize the tenuous lunar atmosphere and dust environment from orbit. The scientific objectives of the mission are:(1) determine the global density, composition, and time variability of the fragile lunar atmosphere; and, (2) determine the size, charge, and spatial distribution of electrostatically transported dust grains and assess their likely effects on lunar exploration and lunar-based astronomy. Further objectives are to determine if the Apollo astronaut sightings of diffuse emission at 10s of km above the surface were Na glow or dust and document the dust impactor environment (size-frequency) to help guide design engineering for outpost and future robotic missions."
"The orbiter will carry a Neutral Mass Spectrometer (NMS), an Ultraviolet/Visible Spectrometer (UVS), and a Lunar Dust Experiment (LDEX)."
"The NMS is a quadrupole mass spectrometer designed ot detect species up to 150 amu and will look for CH4
, S, O, Si, Kr, Xe, Fe, Al, Ti, Mg, OH, and H2
O. The UVS will detect Al, Ca, Fe, K, Li, Na, Si, T, Ba, Mg, H2
O, and O and will monitor the dust composition. The LDEX is an impact ionization dust detector designed to measure particles down to 0.3 microns at the spacecraft altitude. The LLCD is a test of a high data-rate optical (laser) communications system."
This is a schematic of the various experiments aboard the Gamma-ray Observatory. Credit: NASA/JPL.
The Imaging Compton Telescope (COMPTEL) utilizes the Compton Effect and two layers of gamma-ray detectors. Credit: NASA.
For cosmic gamma-ray events, the experiment required two nearly simultaneous interactions, in a set of front and rear scintillators. Gamma rays would Compton scatter
in a forward detector module, where the interaction energy E1
, given to the recoil electron was measured, while the Compton scattered photon would then be caught in one of a second layer of scintillators to the rear, where its total energy, E2
, would be measured. From these two energies, E1
, the Compton scattering angle, angle θ, can be determined, along with the total energy, E1 + E2
, of the incident photon. The positions of the interactions, in both the front and rear scintillators, was also measured. The vector
, connecting the two interaction points determined a direction to the sky, and the angle θ about this direction, defined a cone about V
on which the source of the photon must lie, and a corresponding "event circle" on the sky.
"COMPTEL's upper layer of detectors are filled with a liquid scintillator which scatters an incoming gamma-ray photon according to the Compton Effect. This photon is then absorbed by NaI crystals in the lower detectors. The instrument records the time, location, and energy of the events in each layer of detectors which makes it possible to determine the direction and energy of the original gamma-ray photon and reconstruct an image and energy spectrum of the source."
This is an artist's impression of Aquarius above the Earth's atmosphere. Credit: NASA.
The diagram shows the many natural sources, besides salinity, that contribute to the microwave radiation at L-band frequencies (approximately 1 gigahertz). Credit: NASA.
"Many natural sources, besides salinity, contribute to the microwave radiation at L-band frequencies (approximately 1 gigahertz) measured by satellites. Correcting the influence of these natural sources is a key to obtaining Aquarius’ accurate salinity measurements."
"Aquarius is dedicated to making precise measurements of ocean salinity over months and years, providing important new information for climate studies. It will produce monthly maps of the surface salinity of the global ocean with a 93-mile (150-kilometer) resolution and an accuracy of 0.2 practical salinity units, which is equal to about one-eighth teaspoon of salt in a gallon of water. (Practical salinity is a scale used to describe the concentration of dissolved salts in seawater, nearly equivalent to parts per thousand.) The mission is to make these measurements continuously for at least three years."
"The radiometers on Aquarius measure the microwave emissions from the sea surface at 1.4 gigahertz in the L-band portion of the electromagnetic spectrum. This energy, which is measured as an equivalent temperature called the "brightness temperature" in Kelvin, has a direct correlation to surface salinity."
The Submillimeter Wave Astronomy Satellite "is a NASA Small Explorer Project (SMEX)".
The Submillimeter Wave Astronomy Satellite "is a NASA Small Explorer Project (SMEX) designed to study the chemical composition of interstellar gas clouds."
AMS-02 is a RICH detector for analyzing cosmic rays. Credit: NASA.
A full-disk multiwavelength extreme ultraviolet image of the sun taken by SDO on March 30, 2010. Credit: NASA/Goddard/SDO AIA Team.
A full-disk multiwavelength extreme ultraviolet image of the sun taken by SDO on March 30, 2010. Credit: NASA/Goddard/SDO AIA Team.
"A full-disk multiwavelength extreme ultraviolet image of the sun [was] taken by SDO on March 30, 2010. False colors trace different gas temperatures. Reds are relatively cool (about 60,000 Kelvin, or 107,540 F); blues and greens are hotter (greater than 1 million Kelvin, or 1,799,540 F)."
"Some of the images from the spacecraft show never-before-seen detail of material streaming outward and away from sunspots. Others show extreme close-ups of activity on the sun’s surface. The spacecraft also has made the first high-resolution measurements of solar flares in a broad range of extreme ultraviolet wavelengths."
"The Extreme Ultraviolet Variability Experiment measures fluctuations in the sun’s radiant emissions. These emissions have a direct and powerful effect on Earth’s upper atmosphere -- heating it, puffing it up, and breaking apart atoms and molecules."
The Far Ultraviolet Spectroscopic Explorer is shown in a pre-launch clean room. Credit: NASA.
This image shows how the Earth glows in the ultraviolet. Credit: John W. Young, Apollo 16 lunar landing mission, NASA.
"The Far Ultraviolet Spectroscopic Explorer
) ... detected light in the far ultraviolet portion of the electromagnetic spectrum, between 90.5-119.5 nanometres
, which is mostly unobservable by other telescopes. Its primary mission was to characterize universal deuterium
in an effort to learn about the stellar processing times of deuterium left over from the Big Bang
. ... [T]he ... telescope comprises four individual mirrors. Each of the four mirrors is a 39-by-35 cm (15.4-by-13.8 in) off-axis parabola. Two mirror segments are coated with silicon carbide
for reflectivity at the shortest ultraviolet wavelengths, and two mirror segments are coated with lithium fluoride
that reflects better at longer wavelengths. ... Each mirror has a corresponding astigmatism
-ruled diffraction grating
, each one on a curved substrate so as to produce four 1.65 m (5.4 ft) Rowland
. The dispersed ultraviolet light is detected by two microchannel plate
intensified double delay-line detectors, whose surfaces are curved to match the curvature of the focal plane.
"This unusual false-color image [at left] shows how the Earth glows in ultraviolet (UV) light. The Far UV Camera/Spectrograph deployed and left on the Moon by the crew of Apollo 16 captured this image. The part of the Earth facing the Sun reflects much UV light and bands of UV emission are also apparent on the side facing away from the Sun. These bands are the result of aurora caused by charged particles given off by the Sun. They spiral towards the Earth along Earth's magnetic field lines."
"An artificially reproduced color enhancement [at right] of a ten-minute far-ultraviolet exposure of Earth, taken with a filter which blocks the glow caused by atomic hydrogen but which transmits the glow caused by atomic oxygen and molecular nitrogen. Note that airglow emission bands are visible on the night side of Earth, one roughly centered between the two polar auroral zones and one at an angle to this extending northward toward the sunlit side of Earth. The UV camera was operated by astronaut John W. Young on the Apollo 16 lunar landing mission."
The Wisconsin Experiment Package had eleven different telescopes for ultraviolet observations. Credit: NASA.
"Spectra of Venus (~35 Å resolution) and Jupiter (~50 Å resolution) were obtain using objective grating spectrographs in the 2300-3700 Å wavelength range. The geometric reflectivity of Jupiter, as a function of wavelength, lies in the range 0.15 to 0.25; that of Venus, 0.08 to 0.40."
The "Wisconsin equipment package contained seven telescopes [on OAO 2 at right] designed to make spectrophotometric measurements of selected celestial objects in the ultraviolet longward of 1050 A [105.0 nm]; a set of four stellar photoelectric photometers located behind 8-in. telescopes; a nebular photoelectric photometer located at the prime focus of a 16-in. telescope; and a set of two objective grating spectrometers. The stellar photometers were each located behind a filter wheel containing three filter passbands, a calibration source, and a dark slide. The filter passbands ranged from 1180 to 1370 A with effective wavelength 1330 A, and from 3810 to 4670 A with effective wavelength 4250 A. [...] The nebular photometer was located behind a six-position filter wheel providing passbands from 1930 to 2230 A (effective wavelength 2130 A) to 3050 to 3570 A (effective wavelength 3330 A,) as well as a calibration slide and a dark slide. [...] Spectrometer 1 covered the wavelength range from 1800 to 3800 A in 100 steps with resolutions of 20 or 200 A (switchable). The slit width of 20 A corresponded to 2 arc-min projected on the sky, and the slit height corresponded to 8 arc-min. Spectrometer 2 covered the wavelength range from 1050 to 2000 A in 100 steps with resolutions of 10 or 100 A. The slit width of 10 A corresponded to 2 arc-min projected onto the sky, and the slit height corresponded to 8 arc-min."
This composite image shows Z Camelopardalis, or Z Cam, a double-star system featuring a collapsed, dead star, called a white dwarf, and a companion star, as well as a ghostly shell around the system. Credit: NASA/JPL-Caltech/M. Seibert(OCIW)/T. Pyle(SSC)/R. Hurt(SSC).
The Galaxy Evolution Explorer (GALEX) was an orbiting ultraviolet space telescope which was launched on April 28, 2003 and operated until early 2012 (decommissioned in June 2013). Credit: NASA.
"This composite image [on the right] shows Z Camelopardalis, or Z Cam, a double-star system featuring a collapsed, dead star, called a white dwarf, and a companion star, as well as a ghostly shell around the system. The massive shell provides evidence of lingering material ejected during and swept up by a powerful classical nova explosion that occurred probably a few thousand years ago."
"The image combines data gathered from the far-ultraviolet and near-ultraviolet detectors on NASA's Galaxy Evolution Explorer on Jan. 25, 2004. The orbiting observatory first began imaging Z Cam in 2003."
"Z Cam is the largest white object in the image, located near the center. Parts of the shell are seen as a lobe-like, wispy, yellowish feature below and to the right of Z Cam, and as two large, whitish, perpendicular lines on the left."
"Z Cam was one of the first known recurrent dwarf nova, meaning it erupts in a series of small, "hiccup-like" blasts, unlike classical novae, which undergo a massive explosion."
The "huge shell around Z Cam [...] it could only be explained as the remnant of a full-blown classical nova explosion. This finding provides the first evidence that some binary systems undergo both types of explosions. Previously, a link between the two types of novae had been predicted, but there was no evidence to support the theory."
"The faint bluish streak in the bottom right corner of the image is ultraviolet light reflected by dust that may or may not be related to Z Cam."
"The yellow objects are strong near-ultraviolet emitters; blue features have strong far-ultraviolet emission; and white objects have nearly equal amounts of near-ultraviolet and far-ultraviolet emission."
This is a NASA photograph of one of the two identical Voyager space probes Voyager 1 and Voyager 2 launched in 1977. Credit: NASA.
The image shows the spectral range for the violet filter of Voyager 1 and Voyager 2. Credit: Xession
The scan platform of Voyager 1 and 2 comprises: the Infrared Interferometer Spectrometer (IRIS) (largest camera at right) in the image at left; the Ultraviolet Spectrometer (UVS) to the right of the UVS; the two Imaging Science Subsystem (ISS) vidicon cameras to the left of the UVS; and the Photopolarimeter System (PPS) barely visible under the ISS.
At right is an image of the spectral range of the Violet filter (50 to 400 nm)
on the Imaging Science System aboard the Voyager 1 and Voyager 2 Spacecraft, as defined by the instrument descriptions of the Narrow Angle Camera and Wide Angle Camera.
Aurora Borealis is photographed by NASA astronaut Donald R. Pettit. Credit: NASA.
An STS-134 crew member on the space shuttle Endeavor photographed the International Space Station
shown at right. The photograph was taken after the station and shuttle began their post-undocking relative separation.
At right is a natural color photograph of the Aurora Borealis
or northern lights and the Manicouagan Impact Crater reservoir
(foreground) in Quebec, Canada. They are featured in this photograph taken by astronaut Donald R. Pettit, Expedition Six NASA ISS science officer, on board the International Space Station (ISS).
The Third Orbiting Solar Observatory, OSO 3, carried a hard X-ray experiment (7.7 to 210 keV) and an MIT gamma-ray instrument (>50 MeV), besides a complement of solar physics instruments. Credit: HEASARC Director: Dr. Alan P. Smale HEASARC Associate Director: Dr. Roger Brissenden Responsible NASA Official: Phil Newman Web Curator: Meredith Gibb.
The third Orbiting Solar Observatory (OSO 3) was launched on March 8, 1967 into a nearly circular orbit of mean altitude 550 km, inclined at 33° to the equatorial plane, deactivated on June 28, 1968, followed by reentry on April 4, 1982. Its XRT consisted of a continuously spinning wheel (1.7 s period) in which the hard X-ray experiment was mounted with a radial view. The XRT assembly was a single thin NaI(Tl) scintillation crystal plus phototube enclosed in a howitzer-shaped CsI(Tl) anti-coincidence shield. The energy resolution was 45% at 30 keV. The instrument operated from 7.7 to 210 keV with 6 channels. OSO-3 obtained extensive observations of solar flares, the diffuse component of cosmic X-rays, and the observation of a single flare episode from Scorpius X-1, the first observation of an extrasolar X-ray source by an observatory satellite. Among the extrasolar X-ray sources OSO 3 observed were Luyten 726-8 (UV Ceti), YZ CMi, EV Lacertae, and GJ 388 (AD Leo), yielding upper soft X-ray detection limits on flares from these sources.
Artist's rendering, from NASA, of the European Space Agency's XMM-Newton spacecraft, shows its in-flight configuration. Credit: National Aeronautics and Space Administration (NASA).
This is an XMM Newton image of the Gemini gamma-ray source. Credit: P.A. Caraveo (INAF/IASF), Milan and ESA.
From 0.1 nm to 0.01 nm (about 12 to 120 keV) [are] hard X-rays.
Geminga may be a sort of neutron star: the decaying core of a massive star that exploded as a supernova
about 300,000 years ago.
This nearby explosion may be responsible for the low density of the interstellar medium
in the immediate vicinity of the Solar System
. This low-density area is known as the Local Bubble.
Possible evidence for this includes findings by the Arecibo Observatory
that local micrometre-sized interstellar meteor particles appear to originate from its direction.
"Geminga is a very weak neutron star and the pulsar next to us, which almost only emits extremely hard gamma-rays, but no radio waves. ... Some thousand years ago our Sun entered this [Local Bubble] several hundred light-years big area, which is nearly dust-free."
Artist's impression shows the Hinode spacecraft (then known as Solar-B) in orbit Credit: NASA/GSFC/C. Meaney.
The Sun in the soft X-rays as seen by the Hinode
X-ray Telescope (XRT) on October 15, 2009. Credit: Joseph B. Gurman, Facility Scientist, Solar Data Analysis Center, ISAS/JAXA and NASA.
From 10 to 0.1 nanometers (nm) (about 0.12 to 12 keV) they are classified as soft x-rays.
On the right is a soft X-ray image in the titanium-polyimide ("Ti_poly") filter from the Hinode X-Ray Telescope (XRT) obtained at: 2009/10/15 18:03 UTC.
"The primary filter for the sigmoid observations was the “thin-aluminum/polyimide” (or “Al/poly”) filter, imaging plasmas with temperature of roughly 2–5 MK in the active region."
Super soft X-rays
The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space telescope launched aboard the Space Shuttle Columbia during STS-93 by NASA on July 23, 1999. Credit: NASA/CXC/NGST.
The first detection of Pluto in X-rays has been made using NASA's Chandra X-ray Observatory in conjunction with observations from NASA's New Horizons spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Center/Chandra X-Ray Center.
Super soft X-ray source "SSXSs are in most cases only detected below 0.5 keV".
There are three SSXSs with bolometric luminosity of ~1038
erg/s that are novae: GQ Mus (BB, MW), V1974 Cyg (WD, MW), and Nova LMC 1995 (WD).
"Apparently, as of 1999 the orbital period of Nova LMC 1995 if a binary was not known."
U Sco, a recurrent nova as of 1999 unobserved by ROSAT, is a WD (74-76 eV), Lbol
~ (8-60) x 1036
erg/s, with an orbital period of 1.2306 d.
"[S]uper-soft X-rays [are] between 0.12 and 2.0 keV."
The image on the right contains counts from super soft X-rays.
"The first detection of Pluto in X-rays has been made using NASA's Chandra X-ray Observatory in conjunction with observations from NASA's New Horizons spacecraft."
"There is a significant difference in scale between the optical and X-ray images. New Horizons made a close flyby of Pluto but Chandra is located near the Earth, so the level of detail visible in the two images is very different. The Chandra image is 180,000 miles across at the distance of Pluto, but the planet is only 1,500 miles across. Pluto is detected in the X-ray image as a point source, showing the sharpest level of detail available for Chandra or any other X-ray observatory."
"Detecting X-rays from Pluto is a somewhat surprising result given that Pluto - a cold, rocky world without a magnetic field - has no natural mechanism for emitting X-rays. However, scientists knew from previous observations of comets that the interaction between the gases surrounding such planetary bodies and the solar wind - the constant streams of charged particles from the sun that speed throughout the solar system -- can create X-rays."
"The immediate mystery is that Chandra's readings on the brightness of the X-rays are much higher than expected from the solar wind interacting with Pluto's atmosphere. The Chandra detection is also surprising since New Horizons discovered Pluto's atmosphere was much more stable than the rapidly escaping, "comet-like" atmosphere that many scientists expected before the spacecraft flew past in July 2015. In fact, New Horizons found that Pluto's interaction with the solar wind is much more like the interaction of the solar wind with Mars, than with a comet. While Pluto is releasing enough gas from its atmosphere to make the observed X-rays, there isn't enough solar wind flowing directly at Pluto at its great distance from the Sun to make them according to certain theoretical models."
Ultra soft X-rays
SAS 3 spacecraft as it might have appeared deployed on orbit. The nominal spin axis, or +z axis, points to the upper right, with the RMC and one star tracker for attitude determination. The remaining instruments and a second star tracker point out of the image towards the viewer. The four solar panels charged batteries during orbit day. Credit: NASA.
The Small Astronomy Satellite 3
, also known as SAS-C
before launch) was a NASA X-ray astronomy
It functioned from May 7, 1975 to April 1979. It covered the X-ray range with four experiments on board. The satellite, built by the Johns Hopkins University Applied Physics Laboratory (APL), was proposed and operated by MIT's Center for Space Research (CSR). It was launched on a Scout vehicle from the Italian San Marco launch platform near Mombasa, Kenya, into a low-Earth, nearly equatorial orbit. It was also known as Explorer 53, as part of NASA's Explorer program.
Ultra-soft X-rays are also known as grenz-rays (GRs).
"Ultra soft X-ray spectra [are] in the range 60-250 eV".
This is an artist's rendering of the Terra spacecraft. Credit: NASA/JPL.
Composite images of the Sahara, a large yellow feature on Earth in the northern third of Africa, are mostly from the MODIS imager on board the Terra satellite.
The use of satellites should provide ten times the information as sounding rockets or balloons.
A control group for a radiation satellite would contain
- a radiation astronomy telescope,
- a two-way communication system,
- a positional locator,
- an orientation propulsion system, and
- power supplies and energy sources for all components.
A control group for radiation astronomy satellites may include an ideal or rigorously stable orbit so that the satellite observes the radiation at or to a much higher resolution than an Earth-based ground-level observatory is capable of.
- ↑ 1.0 1.1 Gerald A. Ouellette (June 1967). "Development of a Catalogue of Galactic X-Ray Sources". The Astronomical Journal 72 (5): 597-600. doi:10.1086/110278.
- ↑ Jessica M. Sunshine, Tony L. Farnham, Lori M. Feaga, Olivier Groussin, Frédéric Merlin, Ralph E. Milliken, Michael F. A’Hearn (23 Oct 2009). "Temporal and spatial variability of lunar hydration as observed by the Deep Impact spacecraft". Science 326 (5952): 565-568. doi:10.1126/science.1179788. https://science.sciencemag.org/content/326/5952/565.abstract. Retrieved 8 June 2021.
- ↑ "3,000th Comet Spotted by Solar and Heliospheric Observatory (SOHO)". NASA. Retrieved 2015-09-15. (2,703 discoveries as of 21 April 2014)
- ↑ Green light for continued operations of ESA science missions
- ↑ GOLF
- ↑ MDI
- ↑ "MDI Web Page". soi.stanford.edu. Retrieved 2019-01-16.
- ↑ VIRGO
- ↑ HA Hoff (August 1983). "EXOSAT - The new extrasolar X-ray observatory". Journal of the British Interplanetary Society (Space Chronicle)36 (8): 363–7. https://web.archive.org/web/20120829162441/http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=TRD&recid=A8339971AH&q=&uid=788028604&setcookie=yes.
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Chang, Kenneth (5 September 2016). "NASA aims at an asteroid holding clues to the Solar system's roots". The New York Times. Retrieved 6 September 2016.
Corum, Jonathan (8 September 2016). "NASA launches the Osiris-Rex spacecraft to asteroid Bennu". The New York Times. Retrieved 9 September 2016.
Chang, Kenneth (8 September 2016). "The Osiris-Rex spacecraft begins chasing an asteroid". The New York Times. Retrieved 9 September 2016.
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- ↑ Fireball and Bolide Reports (JPL)
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