New Gamma-Ray Space Telescope to Launch

The observatory’s other instrument, the GBM, will work in tandem with the LAT to determine the source of the gamma rays. While the LAT can cover one-fifth of the sky, the GBM can view the entire sky. When it picks up a bright gamma-ray burst, the GBM will immediately send a signal to the LAT to observe that portion of the sky. The GBM contains 12 flat-disk detectors made of sodium iodide. When struck by a gamma ray, they produce a faint but detectable flash of light. Astronomers can then use triangulation to determine where in the sky the flash came from.

Gamma-ray bursts won’t be the only phenomena GLAST tracks. It may also play a role in figuring out the nature of the mysterious dark matter that physicists say makes up 22 percent of the universe. One popular theory on dark matter is that it is made of as-yet-undetected particles. Astrophysicists have postulated that these alleged particles interact weakly with their environment but can interact with one another to produce gamma rays in an energy range that GLAST can detect. ”If GLAST can find evidence of such particles, it would provide an astrophysical measurement that would complement direct searches for new particles being conducted at particle accelerators like Fermilab and the Large Hadron Collider,” says David Thompson, a physicist with the NASA Goddard Space Flight Center and the deputy project scientist for GLAST.

Other intriguing phenomena that GLAST will look for include odd objects called blazars, which are jets of extremely energetic radiation emitted from the centers of some galaxies. ”These highly variable jets are seen across the electromagnetic spectrum, from radio to gamma ray, and the relationship in time and intensity between different parts of the spectrum is a key diagnostic of how these jets are formed and how they work,” says Thompson.

GLAST is expected to help answer some questions left behind by its predecessor observatory, but it’s just as likely to generate new questions. ”We know that over half the sources seen by the previous high-energy gamma-ray telescope [Compton] remain mysteries. In solving those mysteries, GLAST has a high potential for discovery. My greatest hope is that GLAST will provide surprises. That is an exciting prospect,” says Thompson.