There’s some weird stuff out there in the remote reaches of the universe, things that we humans have only caught occasional glimpses of, or things whose existence we’ve only guessed at. But astrophysicists hope they’ll be able to aim a telescope deep into those dark corners by sometime next week, if all goes well with the launch of the $690 million orbital telescope tomorrow.
The Gamma-Ray Large Area Space Telescope (GLAST), which has been cleared for launch, will scan the skies for gamma rays, the highest-energy form of radiation on the electromagnetic spectrum, and will then try to identify their origins. That’s when it will get really weird and wonderful.
Researchers expect to detect gamma rays from pulsars, a form of extremely dense neutron star which spins around, sending out a beam of radiation that periodically sweeps past Earth like a lighthouse beacon. They’ll also be looking for gamma-ray bursts, which were first detected in the 1960s when American scientists were using satellites to look for signs of Soviet nuclear tests; instead, they found strange radiation blasts coming from space.
To this day [gamma-ray bursts] remain one of the greatest mysteries of modern astronomy. Despite lasting only a few milliseconds to several minutes, they are the brightest gamma-ray phenomena known, outshining all other sources of gamma rays combined. “An individual [gamma-ray burst] can release in a matter of seconds the same amount of energy that our Sun will radiate over its 10-billion-year lifetime,” says GLAST Deputy Project Scientist Neil Gehrels of NASA’s Goddard Space Flight Center in Greenbelt, Md [NASA].
Astrophysicists think there are several sources of gamma-ray bursts, all very dramatic. Smaller bursts may come from the merging of two neutron stars, while larger bursts may be produced when a massive star collapses into a black hole at the end of its life, sending shock waves throughout the universe.
Going even farther into uncharted territory, researchers hope to gain a better understanding of dark matter, the mysterious substance that is believed to make up 70 percent of matter in the universe. No one has seen the stuff directly. Its presence was initially inferred from its gravitational effects on galaxies: Without it, galaxies would fly apart.
The leading candidate for dark matter is thought to belong to a class of particles dubbed WIMPs, for weakly interacting massive particles. Theories predict that when two of these particles meet, they annihilate each other in a burst of energy detectable as gamma rays. The energy the gamma rays carry allows physicists to calculate the WIMPs’ masses. Dark matter candidates fall into a mass range that would yield gamma rays GLAST is designed to detect [Christian Science Monitor].
The GLAST telescope is the brainchild of both astrophysicists and particle physicists, who are equally interested in the strange behavior of cosmic particles; the project is a collaboration between NASA, the U.S. Department of Energy, and many international partners.
The launch has been delayed several times because of issues with the Delta II rocket that will carry it to orbit, but NASA says the odds are good that it will have a successful takeoff from Kennedy Space Center tomorrow, with weather now the only unknown. The mission is expected to last five years, but could continue for many years beyond that with a little luck.
Image: NASA/Jim Grossmann
