Fermi Gamma-ray Space Telescope

Dolores Beasley
Headquarters, Washington, DC
(Phone: 202/358-1753)

Nancy Neal
Goddard Space Flight Center, Greenbelt, Md.
(Phone: 301/286-0039)

October 9, 2000 - RELEASE: 00-123


A new gamma ray burst mission, the High-Energy Transient Explorer (HETE-2), made its entrance into space this morning at 1:38 a.m. EDT from the Kwajalein Missile Range in the Marshall Islands.

HETE-2 was deployed by an L-1011 aircraft and carried into orbit by a Hybrid Pegasus expendable launch vehicle. The spacecraft separated from the Pegasus rocket approximately 12 minutes after launch. The launch was delayed 48 hours to repair a spacecraft ground support cable.

"Gamma ray bursts are stupendous explosions. They are the most energetic events since the Big Bang, yet one occurs about once a day somewhere in the sky," said Dr. George R. Ricker from the Massachusetts Institute of Technology (MIT) in Cambridge, Mass., HETE-2 principal investigator. "The successful launch of HETE-2 means that for the first time we can locate with pinpoint accuracy hundreds of these bursts. Also, HETE-2's ability to relay the accurate location of each burst in real-time to space- and ground-based optical and radio observatories will surely revolutionize this exciting new area of high energy astrophysics."

Controllers at NASA's Kennedy Space, Fla. managed launch countdown. Spacecraft operations will be managed by the MIT. NASA's Goddard Space Flight Center, Greenbelt, Md. provides project oversight.

Gamma ray bursts are a mystery to scientists, and very little is known about their fundamental origin. HETE-2 will embark upon a gamma ray burst fact-finding mission during the four years it is slated to operate. In addition to detecting hundreds of bursts during its mission, it will provide detailed information on the location and light characteristics of many of these bursts.

Within seconds of a burst, HETE-2 will be able to calculate a precise location for that burst. On the ground, a dedicated network of 12 listen-only burst alert stations will relay the data to the MIT control center. From there, information will be transmitted to the Gamma Ray Burst Coordinate Distribution Network at the Goddard Space Flight Center, which can send the information to other observatories worldwide in 10-20 seconds, significantly faster than previously possible. HETE-2 will allow astronomers to see a burst while it is still occurring and allow scientists to study its development at various wavelengths.

The spacecraft carries three main instruments and is supported by a computer network that transmits data to other observatories. The French Gamma Telescope (FREGATE), built by CESR, will detect gamma ray bursts and very bright (higher energy) X-ray transients. The Wide-Field X-ray Monitor (WXM), built by RIKEN and Los Alamos National Laboratory, detects photons slightly lower in energy than the FREGATE does. The WXM therefore will detect fewer gamma ray bursts than FREGATE, but because of its superior resolution, will be able to locate the FREGATE-detected bursts to within 10 arc minutes (an area of sky about equal to 1/10 the size of the full Moon). The Soft X-Ray Camera (SXC), built by MIT, covers the lowest energy band of the three instruments. It also provides the best angular resolution, resulting in a location accuracy of about 10 arc seconds, more than an order of magnitude finer than any previous GRB instrument.

HETE-2 is a collaboration between NASA; MIT; Los Alamos National Laboratory, New Mexico; France's Centre National d'Etudes Spatiales (CNES), Centre d'Etude Spatiale des Rayonnements (CESR), and Ecole Nationale Superieure de l'Aeronautique et de l'Espace (Sup'Aero); and Japan's Institute of Physical and Chemical Research (RIKEN). The science team includes members from the University of California (Berkeley and Santa Cruz) and the University of Chicago.

More information on the HETE-2 mission can be found at: