Fermi Gamma-ray Space Telescope

Infobox Space telescope
name = Fermi Gamma-ray Space Telescope (GLAST)


caption = Artist's conception of the GLAST satellite
organization = NASA, the United States Department of Energy, and government agencies in France, Germany, Italy, Japan, and Sweden.
major_contractors = General Dynamics
alt_names =
nssdc_id =
location =
orbit_type =
height = 550 km (340 mi)
period = about 95 minutes
velocity =
accel_gravity =
launch_date = 2008-06-11 at 16:05 GMT
launch_location = pad B at Cape Canaveral Air Force Station Launch Complex 17
launch_vehicle = Delta II 7920-H rocket
wavelength = gamma ray
mass =
style =
diameter =
area =
focal_length =
instrument_1_name = Large Area Telescope (LAT)
instrument_1_characteristics = telescope
instrument_2_name = GLAST Burst Monitor (GBM)
instrument_2_characteristics =
website = http://glast.gsfc.nasa.gov/The Fermi Gamma-ray Space Telescope (formerly named the Gamma-ray Large Area Space Telescope, or 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 GLAST, the GLAST Burst Monitor (GBM), is being used to study gamma ray bursts. [cite web |url=http://www.nasa.gov/mission_pages/GLAST/news/glast_gbm.html |title=NASA's GLAST Burst Monitor Team Hard at Work Fine-Tuning Instrument and Operations |publisher=NASA |date=2008-07-28]

GLAST was launched 2008-06-11 at 16:05 GMT 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. [cite web | url = http://glast.stanford.edu/ | title = An Astro-Particle Physics Partnership Exploring the High Energy Universe - List of funders | publisher = SLAC | accessmonthday = August 9 | accessyear = 2007] NASA announced 2008-02-08 that it was seeking a new name that would, "capture the excitement of GLAST's mission and call attention to gamma-ray and high-energy astronomy." [cite web | url = http://science.nasa.gov/headlines/y2008/08feb_namethattelescope.htm | title = Name that Space Telescope! | date = 2008-02-08 | publisher = NASA]

Overview

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General Dynamics Advanced Information Systems (formerly Spectrum Astro) in Gilbert, Arizona designed and built the spacecraft that carries the instruments. It will travel in a low, circular orbit with a period of about 95 minutes. Its normal mode of operation will maintain 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.

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.

Data from the instruments will be available to the public through the GLAST Science Support Center web site. Software for analyzing the data will also be available. Scientists with plans for research will be able to apply to the Guest Investigator program.

NASA's Alan Stern, associate administrator for Science at NASA Headquarters, launched a public competition 2008-02-07, closing 2008-03-31, 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." [cite web |url=http://www.nasa.gov/home/hqnews/2008/feb/HQ_08036_GLAST.html |title=NASA Calls for Suggestions to Re-Name Future Telescope Mission |publisher=NASA |date=2008-02-07 |accessdate=2008-02-10]

On 2008-08-26, GLAST was renamed the "Fermi Gamma-ray Space Telescope" in honor of Enrico Fermi, a pioneer in high-energy physics.cite web |url=http://science.nasa.gov/headlines/y2008/26aug_firstlight.htm |title=First Light for the Fermi Space Telescope |publisher=NASA |date=2008-08-26]

Mission

The key scientific objectives of the GLAST mission are: [cite web | url = http://glast.stanford.edu/mission.html | title = The Mission | publisher = SLAC | accessmonthday = August 9 | accessyear = 2007]
*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 (eg. 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] .

NASA designed the mission with a five-year lifetime, with a goal of ten years of operations. [cite web | url = http://glast.gsfc.nasa.gov/public/ | title = The GLAST Mission - GLAST Overview, mission length | publisher = NASA | accessmonthday = August 9 | accessyear = 2007]

Mission Status

Prelaunch

On 2008-03-04 the spacecraft arrived at the Astrotech payload processing facility in Titusville, Florida. [cite web |url=http://www.nasa.gov/centers/kennedy/news/releases/2008/release-20080304.html |title=GLAST Spacecraft Arrives in Florida to Prepare for Launch |publisher=NASA] On 2008-06-04, after several previous delays, launch status was retargeted for June 11 at the earliest, [cite web |url=http://www.spaceflightnow.com/tracking/index.html |title=Spaceflight Now - Tracking Station - Worldwide launch schedule |accessdate=2008-06-04 |format= |work= ] [cite web |url=http://www.nasa.gov/mission_pages/GLAST/main/index.html|title=GLAST Mission Coverage - Latest News|accessdate=2008-06-04 |format= |work= ] the last delays resulting from the need to replace the Flight Termination System batteries.cite web |url=http://www.nasa.gov/centers/kennedy/launchingrockets/status/2008/elvstatus-20080606.html |title=NASA - Expendable Launch Vehicle Status Report |accessdate=2008-06-09 |publisher=NASA |date=2008-06-06 ] The launch window extended from 11:45 a.m. until 1:40 p.m. EDT (15:45-17:40 GMT) daily, until 2008-08-07.

Launch

Launch occurred successfully on

Orbit

GLAST resides in a low-earth circular orbit at an altitude of convert|550|km|mi|abbr=on, and at an inclination of 28.5 degrees. [cite web | url = http://glast.gsfc.nasa.gov/public/ | title = The GLAST Mission - GLAST Overview, orbital information | publisher = NASA | accessmonthday = August 9 | accessyear= 2007]

oftware modifications

GLAST received some minor modifications to its computer software 2008-06-23.

LAT/GBM computers operational

Computers operating both the LAT and GBM (see below) and most of the LAT's components were turned on, 2008-06-24. The LAT high voltage was turned on, 2008-06-25, and it began detecting high-energy particles from space, but minor adjustments were still needed to calibrate the instrument. The GBM high voltage was also turned on, 2008-06-25, but the GBM was still requiring one more week of testing/calibrations before searching for gamma ray bursts.

ky Survey Mode

GLAST was expected to have switched to "sky survey mode" on 2008-06-26 so as to begin sweeping its field of view over the entire sky every three hours (every two orbits).

GLAST Science Packages

After presenting an overview of the GLAST instrumentation and goals, Jennifer Carson of the Stanford Linear Accelerator Center concludes that the primary goals "are all achievable with the all-sky scanning mode of observing."cite web |url=http://arxiv.org/pdf/astro-ph/0610960 | title=GLAST: physics goals and instrument status |last=Carson |first=Jennifer]

GBM

GBM is an acronym for GLAST Burst Monitor; the GBM 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," says Charles Meegan of NASA's Marshall Space Flight Center. [cite web |url=http://science.nasa.gov/headlines/y2008/11jun_glast2.htm |title=GLAST Off! |publisher=NASA]

GBM Participating Institutions

US Team Institution

*NASA's Marshall Space Flight Center

German Team Institution

*Max Planck Institut für Extraterrestrische Physik

LAT

LAT is an acronym for Large Area Telescope; the 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 microstrips, 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 may be a bigger and better successor to the EGRET instrumenton 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 the Stanford Linear Accelerator Center (SLAC).

LAT Participating Institutions

US Team Institutions

*Stanford University, Physics Department, GLAST group & Hansen Experimental Physics Laboratory
*Stanford Linear Accelerator Center, Particle Astrophysics group
*NASA Goddard Space Flight Center, Astrophysics Science Division
*U.S. Naval Research Laboratory, High Energy Space Environment (HESE) branch
*Ohio State University, Physics Department
*University of California, Santa Cruz, Physics Department
*Sonoma State University, Department of Physics & Astronomy
*University of Washington
*Texas A&M University-Kingsville

Japanese Team Institutions

*Japan GLAST Collaboration
*University of Tokyo
*Tokyo Institute of Technology
*Institute for Cosmic-Ray Research
*Institute for Space and Astronautical Science
*Hiroshima University

Italian Team Institutions

*Instituto Nazionale di Fisica Nucleare (INFN)
*Italian Space Agency
*Istituto di Fisica Cosmica, Milano, CNR
*INFN and University of Bari
*INFN and University of Padova
*INFN and University of Perugia
*INFN and University of Pisa
*INFN and University of Rome Tor Vergata
*INFN and University of Trieste
*INFN and University of Udine

French Team Institutions

*Service d'Astrophysique, CEA DAPNIA, CEA Saclay
*Centre National d'Études Spatiales
*Institut National de Physique Nucléaire et de Physique des Particules, IN2P3
*Laboratoire Leprince-Ringuet de l'École Polytechnique
*Centre d'Études nucléaires de Bordeaux Gradignan
*Laboratoire de Physique Théorique et Astroparticules, Montpellier

wedish Team Institutions

*Royal Institute of Technology
*Stockholm University

Education and public outreach

Education and public outreach are important components of the GLAST project. The main GLAST 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 GLAST education and outreach resources at Sonoma State University.

References

External links

* [http://glast.gsfc.nasa.gov/ NASA website for GLAST]
* [http://solarsystem.nasa.gov/missions/profile.cfm?MCode=GLAST GLAST Mission Profile] by [http://solarsystem.nasa.gov NASA's Solar System Exploration]
* [http://www-glast.stanford.edu/ Stanford University GLAST website (LAT)]
* [http://glast.sonoma.edu/ Sonoma State University GLAST website]
* NASA Education and Public Outreach Group at Sonoma State University
* [http://gammaray.msfc.nasa.gov/gbm/ GBM website at Marshall Space Flight Center]
* [http://www-glast.sonoma.edu/ GLAST public outreach and education website]
* [http://glast.gsfc.nasa.gov/ssc/ GLAST Science Support Center]
* [http://www.symmetrymagazine.org/cms/?pid=1000260 "GLAST into space" article in "symmetry" magazine]
* [http://www.sciam.com/article.cfm?id=window-on-the-extreme-universe "Window on the Extreme Universe" article in "Scientific American", Dec. 2007 issue. Note: full article on website requires subscription.]