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Fermi Gamma-ray Space Telescope
NamesGamma-ray Large Area Space Telescope
Mission typeGamma-ray telescope
OperatorNASA / U.S. Department of Energy
with significant contributions by CNES, DLR, ISA, JAXA, and SNSB
COSPAR ID2008-029A
SATCAT no.33053
Websitefermi.gsfc.nasa.gov/
Mission durationPlanned: 5-10 years
Elapsed: 16 years, 4 months and 28 days
Orbits completed36496[1]
Spacecraft properties
ManufacturerGeneral Dynamics
Start of mission
Launch date11 June 2008, 16:05 UTC (2008-06-11UTC16:05Z)
RocketDelta II 7920-H #333
Launch siteCape Canaveral SLC-17B
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Semi-major axis6,916.16 km (4,297.50 mi)[1]
Eccentricity0.0012564[1]
Perigee altitude536 km (333 mi)[1]
Apogee altitude553 km (344 mi)[1]
Inclination25.58 degrees[1]
Period95.40 minutes[1]
RAAN189.97 degrees[1]
Argument of perigee256.57 degrees[1]
Mean anomaly15.09 degrees[1]
Mean motion15.09[1]
Velocity7.59 km/s (27,300 km/h; 17,000 mph)[1]
Epoch24 January 2015, 17:45:50 UTC[1]

The Fermi Gamma-ray Space Telescope (FGST[2]), formerly called the Gamma-ray Large Area Space Telescope (GLAST), is a space observatory being used to perform gamma-ray astronomy observations from low Earth orbit. Its main instrument is the Large Area Telescope (LAT), with which astronomers mostly intend to perform an all-sky survey studying astrophysical and cosmological phenomena such as active galactic nuclei, pulsars, other high-energy sources and dark matter. Another instrument aboard Fermi, the Gamma-ray Burst Monitor (GBM; formerly GLAST Burst Monitor), is being used to study gamma-ray bursts.[3]

Fermi was launched on 11 June 2008 at 16:05 UTC aboard a Delta II 7920-H rocket. The mission is a joint venture of NASA, the United States Department of Energy, and government agencies in France, Germany, Italy, Japan, and Sweden.[4]


Mission Overview

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Fermi is one of NASA's facility-class missions.(NEED REF) It consists of a spacecraft bus (provided by Spectrum Astro, later General Dynamics Advanced Information Systems, now Orbital Sciences), and two scientific instruments, the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). The LAT is an imaging gamma-ray detector (a pair-conversion instrument) which detects photons with energy from about 20 million to about 300 billion electron volts (20 MeV to 300 GeV),[5] with a field of view of about 20% of the sky; it may be thought of as a sequel to the EGRET instrument on the Compton gamma ray observatory. The GBM consists of 14 scintillation detectors (twelve sodium iodide crystals for the 8 keV to 1 MeV range and two bismuth germanate crystals with sensitivity from 150 keV to 30 MeV), and can detect gamma-ray bursts in that energy range across the whole of the sky not occluded by the Earth.

What is Fermi?

Gamma-ray Burst Monitor (GBM)

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SECTION NEEDS REWORK!! The Gamma-ray Burst Monitor (GBM) (formerly GLAST Burst Monitor) detects sudden flares of gamma-rays produced by gamma ray bursts and solar flares. Its scintillators are on the sides of the spacecraft to view all of the sky which is not blocked by the Earth. The design is optimized for good resolution in time and photon energy.

"Gamma-ray bursts are so bright we can see them from billions of light years away, which means they occurred billions of years ago, and we see them as they looked then," stated Charles Meegan of NASA's Marshall Space Flight Center.[6]

The Gamma-ray Burst Monitor has detected gamma rays from positrons generated in powerful thunderstorms.[7]

Large Area Telescope (LAT)

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The Large Area Telescope (LAT) detects individual gamma rays using technology similar to that used in terrestrial particle accelerators. Photons 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. Several countries produced the components of the LAT, who then sent the components for assembly at SLAC National Accelerator Laboratory. SLAC also hosts the LAT Instrument Science Operations Center, which supports the operation of the LAT during the Fermi mission for the LAT scientific collaboration and for NASA.


Background

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INPUT NEEDED!! Fermi was selected for mission development in 199x as part of NASA's XXXX call for proposals. etc..ect... Can we say anything about using same bus as Swift to reduce costs?

Mission Design & Development

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NASA designed the mission with a five-year lifetime, with a goal of ten years of operations.[8] After presenting an overview of the Fermi instrumentation and goals, Jennifer Carson of SLAC National Accelerator Laboratory concluded that the primary goals were "all achievable with the all-sky scanning mode of observing".[9]

The key scientific objectives of the Fermi mission have been described as:[10]

  • To understand the mechanisms of particle acceleration in active galactic nuclei (AGN), pulsars, and supernova remnants (SNR).
  • Resolve the gamma-ray sky: unidentified sources and diffuse emission.
  • Determine the high-energy behavior of gamma-ray bursts and transients.
  • Probe dark matter (e.g. by looking for an excess of gamma rays from the center of the Milky Way) and early Universe.
  • Search for evaporating primordial micro black holes (MBH) from their presumed gamma burst signatures [Hawking Radiation component].

General Dynamics Advanced Information Systems (formerly Spectrum Astro and now Orbital Sciences) in Gilbert, Arizona designed and built the spacecraft that carries the instruments. It travels in a low, circular orbit with a period of about 95 minutes. Its normal mode of operation maintains its orientation so that the instruments will look away from the Earth, with a "rocking" motion to equalize the coverage of the sky. The view of the instruments will sweep out across most of the sky about 16 times per day. The spacecraft can also maintain an orientation that points to a chosen target.

 
Fermi at completion of integration and testing, with solar arrays in place

Integration & Testing

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Both science instruments underwent environmental testing, including vibration, vacuum, and high and low temperatures to ensure that they can withstand the stresses of launch and continue to operate in space. They were integrated with the spacecraft at the General Dynamics ASCENT facility in Gilbert, Arizona.[11] The observatory underwent environmental testing at the United States Naval Research Laboratory in Washington, DC.[12]

Launch & Activation

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GLAST launch aboard a Delta II rocket, 11 June 2008.

On 4 March 2008 the spacecraft arrived at the Astrotech payload processing facility in Titusville, Florida.[13] On 4 June 2008, after several previous delays, launch status was retargeted for 11 June at the earliest,[14][15] the last delays resulting from the need to replace the Flight Termination System batteries.[16] The launch window extended from 11:45 a.m. until 1:40 p.m. EDT (15:45-17:40 GMT) daily, until 7 August 2008.[16]

 
GLAST launch as pictured by a space-based infrared sensor, looking down at the Earth.

Launch occurred successfully on 11 June 2008 at 16:05, and the spacecraft separated from the carrier rocket about 75 minutes later. The spacecraft departed from pad B at Cape Canaveral Air Force Station Space Launch Complex 17 aboard a Delta 7920H-10C rocket.

The observatory activation was completed on 24 June 2008 when both the LAT and GBM instruments were turned on. The LAT high voltage was enabled on 25 June, and it began detecting high-energy particles from space, but minor adjustments were still needed to calibrate the instrument. The LAT began collecting usable science data on 28 June.[17] The LAT's first light image was released publicly on 26 August 2008,[18] revealing the first science result from the mission, as the blazar 3C 454.3 was in the process of a major flaring episode.[19][20] The GBM high voltage was also turned on 25 June, but the GBM still required one more week of testing/calibrations before searching for gamma-ray bursts.[21]

GLAST Renamed Fermi Gamma-ray Space Telescope

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Fermi gained its new name in 2008: On 26 August 2008, GLAST was renamed the "Fermi Gamma-ray Space Telescope" in honor of Enrico Fermi, a pioneer in high-energy physics.[22]

NASA's Alan Stern, associate administrator for Science at NASA Headquarters, launched a public competition 7 February 2008, closing 31 March 2008, to rename GLAST in a way that would "capture the excitement of GLAST's mission and call attention to gamma-ray and high-energy astronomy ... something memorable to commemorate this spectacular new astronomy mission ... a name that is catchy, easy to say and will help make the satellite and its mission a topic of dinner table and classroom discussion".[23][24]


Mission Status

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Fermi resides in a low-earth circular orbit at an altitude of 550 km (340 mi), and at an inclination of 28.5 degrees.[25] The observatory began operating in "sky survey mode" on 26 June 2008 as it begin sweeping its field of view over the entire sky every three hours (every two orbits).

Safehold Events

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INPUT NEEDED!! Describe the two safehold events, including dates and resolutions.

Collision avoided

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On 30 April 2013, NASA revealed that the telescope had narrowly avoided a collision a year earlier with a defunct Cold War-era Soviet spy satellite, Kosmos 1805, in April 2012. Orbital predictions several days earlier indicated that the two satellites were expected to occupy the same point in space within 30 milliseconds of each other. On 3 April, telescope operators decided to stow the satellite's high-gain parabolic antenna, rotate the solar panels out of the way and to fire Fermi's rocket thrusters for one second to move it out of the way. Even though the thrusters had been idle since the telescope had been placed in orbit nearly five years earlier, they worked correctly and disaster was thus avoided.[26]

Extended mission 2013-2018

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ADD LINK TO 5-YEAR VIDEO! In August 2013 Fermi started its 5 year mission extension.[27]


Public Data Set

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Data from the instruments are available to the public through the Fermi Science Support Center web site. Software for analyzing the data is also available.

INPUT NEEDED!! Add discussion of the rapid release of data and the public availability of the science tools. Add information about the GI program. Add information about the GI-funded multiwavelength programs

Public Outreach

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Education and public outreach are important components of the Fermi project. The main Fermi education and public outreach website at http://glast.sonoma.edu offers gateways to resources for students, educators, scientists, and the public. NASA's Education and Public Outreach (E/PO) group operates the Fermi education and outreach resources at Sonoma State University.

INPUT NEEDED!! Add information about the Einstein Fellows program.


Key Science Results

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Fermi is an all-sky observer with a large energy range, and so it contributes to a wide range of science topics. In its 2000 Decadal Survey, the National Academies of Sciences ranked this mission as a top priority.[28] Many new possibilities and discoveries are anticipated to emerge from this single mission and greatly expand our view of the Universe.[28][29]

Extragalactic Science

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Gamma-ray Bursts

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Greatest GRB Energy Release

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In September 2008, the gamma-ray burst GRB 080916C in the constellation Carina was recorded by the Fermi telescope. This burst is notable as having “the largest apparent energy release yet measured”.[30] The explosion had the power of about 9,000 ordinary supernovae, and the relativistic jet of material ejected in the blast must have moved at a minimum of 99.9999% the speed of light. Overall, GRB 080916C had "the greatest total energy, the fastest motions, and the highest-energy initial emissions" ever seen.[31]

GRB 130427A

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Before and after in 100+ MeV light

On 27 April 2013, Fermi detected GRB 130427A, a gamma-ray burst with one of the highest energy outputs yet recorded.[32] This included detection of a gamma-ray over 94 billion electron volts (GeV).[32] This broke Fermi's previous record detection, by over three times the amount.[32]

Blazars & Active Galaxies

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Add a discussion of the huge data set being generated in support of blazar science.

Gamma-ray Background Radiation

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Main article: Gamma-ray burst progenitors

In March 2010 it was announced that active galactic nuclei are not responsible for most gamma-ray background radiation.[33] Though active galactic nuclei do produce some of the gamma-ray radiation detected here on Earth, less than 30% originates from these sources. The search now is to locate the sources for the remaining 70% or so of all gamma-rays detected. Possibilities include star forming galaxies, galactic mergers, and yet-to-be explained dark matter interactions.


Galactic Science

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Gamma-ray & X-ray Bubbles

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In November 2010, it was announced two gamma-ray & X-ray bubbles were detected around Earth's galaxy, the Milky Way.[34] The bubbles, dubbed the "Fermi Bubbles," extend about 25 thousand light years distant above and below the center of the galaxy.[34] The galaxy's diffuse gamma-ray fog hampered prior observations, but the discovery team led by D. Finkbeiner, building on research by G. Dobler, worked around this problem.[34]

 
X-ray/gamma-ray bubbles of Earth's Galaxy, the Milky Way. (Art)
Using data from NASA's Fermi Gamma-ray Space Telescope, scientists have discovered a gigantic, mysterious structure in our galaxy. This never-before-seen feature looks like a pair of bubbles extending above and below our galaxy's center.

Pulsars

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Fermi's first major discovery came when the space telescope detected a pulsar in the CTA 1 supernova remnant that appeared to emit radiation in the gamma ray bands only, a first for its kind.[35] This new pulsar sweeps the Earth every 316.86 milliseconds and is about 4,600 light years away.[36]

Fermi discovers youngest millisecond pulsar.
 
Gamma-ray pulsars detected by the Fermi Gamma-ray Space Telescope.

Cosmic Rays & Supernova Remnants

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In February 2010,[37] it was announced that Fermi-LAT had determined that supernova remnants act as enormous accelerators for cosmic particles. This determination fulfills one of the stated missions for this project.[38]

Gamma-ray Novae

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Solar and Planetary Science

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Add a paragraph about solar flares and gamma rays from the moon.

Highest-Energy Light Ever Seen from the Sun

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In early 2012, Fermi observed the highest energy light ever seen in a solar eruption.[39]

At the flare's peak, the LAT detected gamma rays with two billion times the energy of visible light, or about four billion electron volts (GeV), easily setting a record for the highest-energy light ever detected during or immediately after a solar flare

— NASA[39]

Terrestrial Gamma-ray Flashes

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The Fermi observatory has observed and detected numerous terrestrial gamma-ray flashes and discovered that such flashes can produce 100 trillion positrons, far more than scientists had previously expected.[7]


Fundamental Physics

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Add a discussion of Dark Matter Searches. Add a discussion of poitron/electron papers. Add a discussion of testing relativity and the foaminess of space.


Unexpected Discoveries

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Brief paragraph stating that the Fermi Bubbles, antimatter from thunderstorms, and gamma rays from stellar novae are all examples of unexpected discoveries made by Fermi.


Awards & Prizes

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Rossi Prize

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The 2011 Bruno Rossi Prize was awarded to Bill Atwood, Peter Michelson and the Fermi LAT team "for enabling, through the development of the Large Area Telescope, new insights into neutron stars, supernova remnants, cosmic rays, binary systems, active galactic nuclei and gamma-ray bursts."[40]

Participating Institutions

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US team institutions
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Austrian team institution
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German team institutions
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Japanese team institutions
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Icelandic team institutions
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Italian team institutions
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French team institutions
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Spanish team institution
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Swedish team institutions
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References

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  1. ^ a b c d e f g h i j k l m "GLAST Satellite details 2008-029A NORAD 33053". N2YO. 24 January 2015. Retrieved 25 January 2015.
  2. ^ Stanford University: "FGST" is a now common acronym.
  3. ^ "NASA's GLAST Burst Monitor Team Hard at Work Fine-Tuning Instrument and Operations". NASA. 28 July 2008.
  4. ^ "An Astro-Particle Physics Partnership Exploring the High Energy Universe - List of funders". SLAC. Retrieved 9 August 2007.
  5. ^ Harrington, J. D.; Harris, David; Cominsky, Lynn (26 August 2008). "NASA Renames Observatory for Fermi, Reveals Entire Gamma-Ray Sky". NASA. Release no. 08-214. Retrieved 27 October 2014.
  6. ^ "GLAST Off!". NASA.
  7. ^ a b NASA's Fermi Catches Thunderstorms Hurling Antimatter into Space
  8. ^ "The GLAST Mission: GLAST Overview, mission length". NASA. Retrieved 9 August 2007.
  9. ^ Carson, Jennifer (2007). "GLAST: physics goals and instrument status". Journal of Physics: Conference Series. 60: 115–118. arXiv:astro-ph/0610960. Bibcode:2007JPhCS..60..115C. doi:10.1088/1742-6596/60/1/020.
  10. ^ "The Mission". SLAC. Retrieved 9 August 2007.
  11. ^ "NASA's GLAST Mission One Step Closer to Launch". Goddard Space Flight Center.
  12. ^ "NASA's GLAST Satellite Arrives at Naval Research Lab for Testing". Goddard Space Flight Center.
  13. ^ "GLAST Spacecraft Arrives in Florida to Prepare for Launch". NASA.
  14. ^ "Spaceflight Now – Tracking Station — Worldwide launch schedule". Retrieved 4 June 2008.
  15. ^ "GLAST Mission: Coverage Latest News". Retrieved 4 June 2008.
  16. ^ a b "NASA - Expendable Launch Vehicle Status Report". NASA. 6 June 2008. Retrieved 9 June 2008.
  17. ^ "GLAST-LAT detection of extraordinary gamma-ray activity in 3C 454.3". The Astronomer's Telegram.
  18. ^ "NASA Teleconference to Announce GLAST New Name, First Light Findings". NASA. {{cite web}}: Cite has empty unknown parameter: |1= (help)
  19. ^ "NASA's GLAST Burst Monitor Team Hard at Work Fine-Tuning Instrument and Operations". NASA's Marshall Space Flight Center.
  20. ^ "First Light from Space Telescope Reveals Gamma-Ray Sky". Scientific American.
  21. ^ "NASA's GLAST Burst Monitor Team Hard at Work Fine-Tuning Instrument and Operations". NASA's Marshall Space Flight Center.
  22. ^ "First Light for the Fermi Space Telescope". NASA. 26 August 2008.
  23. ^ "NASA Calls for Suggestions to Re-Name Future Telescope Mission". NASA. 7 February 2008. Retrieved 10 February 2008.
  24. ^ "Name that Space Telescope!". NASA. 8 February 2008.
  25. ^ "The GLAST Mission: GLAST Overview, orbital information". NASA. Retrieved 9 August 2007.
  26. ^ The Day NASA's Fermi Dodged a 1.5-ton Bullet
  27. ^ Mission extension
  28. ^ a b "NASA - Q&A ON THE GLAST MISSION". Nasa: Fermi Gamma-ray Space Telescope. NASA. 28 August 2008. Retrieved 29 April 2009.
  29. ^ See also Nasa - Fermi Science and NASA - Scientists Predict Major Discoveries for GLAST.
  30. ^ The Fermi LAT and Fermi GBM Collaborations (2009). "Fermi Observations of High-Energy Gamma-Ray Emission from GRB 080916C". Science. 323 (922): 1688–1693. Bibcode:2009Sci...323.1688A. doi:10.1126/science.1169101. PMID 19228997.
  31. ^ "Most Extreme Gamma-ray Blast Ever, Seen By Fermi Gamma-ray Telescope". Science Daily. 19 February 2009. Retrieved 13 January 2010.
  32. ^ a b c ASA's Fermi, Swift See 'Shockingly Bright' Burst 05.03.13
  33. ^ NASA’s Fermi Probes “Dragons” of the Gamma-ray Sky, NASA
  34. ^ a b c Astronomers find giant, previously unseen structure in our galaxy (November 9, 2010) - E! Science News
  35. ^ Fermi Telescope Makes First Big Discovery: Gamma Ray Pulsar. Universe Today. Retrieved on 16 November 2010.
  36. ^ Cosmos Online - New kind of pulsar discovered
  37. ^ NASA’s Fermi Closes on Source of Cosmic Rays, NASA
  38. ^ Cosmic Rays and Supernova Remnants, NASA
  39. ^ a b NASA's Fermi Detects the Highest-Energy Light From a Solar Flare 06.11.12
  40. ^ "Astronomers Honored for Excellence by the American Astronomical Society".
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