Looking for Gamma-Ray Bursts

Next to the big bang itself, gamma-ray bursts (GRBs)which take place nearly every dayare the largest explosions in the universe, releasing as much energy as a billion trillion suns. You would think scientists would have something that large and that frequent figured out by now. But because GRBs usually take place billions of light-years from the earth, no one really knows what causes them as yet. In hopes of answering that question, though, an international team plans on launching a new, washing machinesize satellite, called HETE-2, from the Pacific Kwajalein Atoll in the Marshall Islands this Saturday.

From its final perch 600 kilometers above Earth, HETE-2, the successor to the HETE satellite lost during its own launch in 1996, promises to give astronomers far more information than the Burst and Transient Source Experiment (BATSE) aboard the Compton Gamma Ray Observatory, deorbited in June. "The magic of HETE-2 is that it not only detects a large sample of these bursts, but it also will relay the accurate location of each burst in real time to ground-based optical and radio observatories," says George T. Ricker of M.I.T.'s Center for Space Research, where the satellite was built. Ricker is also the Principal Investigator for the 20-person team.

The plan is this: within seconds of detecting a burst, the satellite calculates the coordinates of the event and sends that information to a receiving station. To minimize the distance and time involved, the team has set up 12 such stations around the planet. The station then transmits the data to the control center at M.I.T., where the satellite was built, and it is immediately forwarded on to the GRB Coordinate Distribution Network at the Goddard Space Flight Center for distribution on the Internet. They guess that this entire relay race will get the data to astronomers at large within 10 to 20 secondsplenty of time for ground-based and orbiting telescopes to take a look and potentially catch a burst in the act.