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 AGILE satellite flew
into orbit on top of India's Polar Satellite Launch Vehicle. Liftoff was at
1000 GMT (6:00 a.m. EDT) from the Satish Dhawan Space Center at Sriharikota on
India's eastern coast.
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.
AGILE carries a gamma ray
imager, an X-ray detector, and a device called a mini-calorimeter to hunt for transient
events such as gamma ray bursts, the most powerful explosions in 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.
The bursts, which usually
last just several minutes, are mysterious explosions scattered throughout the
Universe. AGILE will be able to send alerts with burst coordinates to other
observatories within seconds of the initial event, according to the mission's
science team.
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.
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