Indian rocket launches Italian space telescope
BY STEPHEN CLARK
Posted: April 23, 2007
An Italian gamma ray observatory hitched a ride to space aboard an Indian rocket today, beginning a three-year mission to survey the sky in a search for faraway sources of the Universe's most energetic form of light.
The 776-pound craft separated from the four-stage PSLV booster about 23 minutes after launch. The rocket was targeting an orbit approximately 342 miles high with an inclination of 2.5 degrees, according to Indian officials.
An avionics package was housed inside a dual-payload adapter to test advanced computer, navigation and telemetry systems, but the equipment remained attached to the rocket's fourth stage.
The rocket flew without the six standard solid rocket boosters attached around the base of the launcher - a first for the PSLV. Today's launch was the 11th flight of the PSLV since its 1993 debut.
The mission was the first commercial launch conducted by India's space program. Earlier PSLV missions launched small foreign spacecraft, but today was the first time a paying customer's satellite filled the role of a primary payload.
Paid for by the Italian Space Agency, AGILE's array of scientific
instruments will detect high-energy emissions from the most far-flung
regions of the Universe.
The combination of gamma ray and X-ray detectors will give scientists a unique tool to perform synchronized observations in both energy bands.
The AGILE instrument is the most compact and low-power science payload ever developed in high energy astrophysics, officials said.
The science package will provide data continuity to build upon discoveries made by NASA's Compton Gamma Ray Observatory. Part of the U.S. space agency's Great Observatories program, the satellite was deliberately crashed into Earth's atmosphere in 2000 due to fears of an uncontrolled reentry.
AGILE science data will also help astronomers lay the foundation for GLAST, a follow-on NASA mission scheduled to launch in December with more advanced gamma ray detection instruments. Gamma ray sources identified by AGILE could become the first science targets for GLAST.
AGILE covers an energy bandwidth not observed since the end of Compton's mission. Other recent gamma ray telescopes have mostly focused on lower energy bands, according to the AGILE science team.
The instrument will observe both fleeting gamma ray emissions such as gamma ray bursts and solar flares, and steady sources like galactic nuclei and pulsars, the rapidly spinning collapsed remnants of dead stars
The spacecraft can quickly detect and respond to sudden events like gamma
ray bursts. AGILE's science team will immediately send information on such
events to both ground- and space-based telescopes for complementary
observations. Scientists expect at least one gamma ray burst per month
will be detected by AGILE.
AGILE will send the alerts back to Earth through the ORBCOMM communications satellite constellation when the satellite is not linked to a ground station.
The AGILE instrument can survey up to one-quarter of the sky at a time, which surpasses the field of view of any previous gamma ray research mission.
The wide field of view will give scientists a better opportunity to simultaneously look for unidentified gamma ray bursts and observe multiple known targets such as supernova remnants and objects near the center of the Milky Way galaxy.
The craft's payload is also about twice as sensitive to gamma ray waves than the Energetic Gamma Ray Experiment Telescope, Compton's primary instrument.
EGRET, which weighed more than 4,000 pounds on the ground, was much larger than the entire science payload aboard AGILE. The craft's instrument weighs less than 300 pounds on Earth.
AGILE will be pressed into service late this summer after a few months of tests.