Space Briefs
Deep Impact comet hunter
mission comes to an end
After almost 9 years in space that included an unprecedented July 4th impact
and subsequent flyby of a comet, an additional comet flyby, and the return of
approximately 500,000 images of celestial objects, NASA’s Deep Impact mission
has ended.
The project team at NASA’s Jet Propulsion Laboratory in Pasadena, Calif., has
reluctantly pronounced the mission at an end after being unable to communicate
with the spacecraft for over a month. The last communication with the probe was
Aug. 8. Deep Impact was history’s most traveled comet research mission, going
about 4.7 billion miles (7.58 billion kilometers).
“Deep Impact has been a fantastic, long-lasting spacecraft that has produced
far more data than we had planned,” said Mike A’Hearn, the Deep Impact principal
investigator at the University of Maryland in College Park. “It has revolutionized our
understanding of comets and their activity.”
Deep Impact successfully completed its original bold mission of six months in
2005 to investigate both the surface and interior composition of a comet, and a
subsequent extended mission of another comet flyby and observations of planets
around other stars that lasted from July 2007 to December 2010. Since then, the
spacecraft has been continually used as a space-borne planetary observatory to
capture images and other scientific data on several targets of opportunity with its
telescopes and instrumentation.
Launched in January 2005, the spacecraft first traveled about 268 million miles
(431 million kilometers) to the vicinity of comet Tempel 1. On July 3, 2005, the
spacecraft deployed an impactor into the path of comet to essentially be run
over by its nucleus on July 4. This caused material from below the comet’s surface
to be blasted out into space where it could be examined by the telescopes and
instrumentation of the flyby spacecraft. Sixteen days after that comet encounter,
the Deep Impact team placed the spacecraft on a trajectory to fly back past Earth
in late December 2007 to put it on course to encounter another comet, Hartley 2
in November 2010.
“Six months after launch, this spacecraft had already completed its planned
mission to study comet Tempel 1,” said Tim Larson, project manager of Deep
Impact at JPL. “But the science team kept finding interesting things to do, and
through the ingenuity of our mission team and navigators and support of NASA’s
Discovery Program, this spacecraft kept it up for more than eight years, producing
amazing results all along the way.”
The spacecraft’s extended mission culminated in the successful flyby of comet
Hartley 2 in 2010. Along the way, it also observed six different stars to confirm the
motion of planets orbiting them, and took images and data of Earth, the Moon
and Mars. These data helped to confirm the existence of water on the moon, and
attempted to confirm the methane signature in the atmosphere of Mars.
In January 2012, Deep Impact performed imaging and accessed the composition
of distant comet C/2009 P1 (Garradd). It took images of comet ISON this year and
collected early images of ISON in June.
After losing contact with the spacecraft last month, mission controllers spent
several weeks trying to uplink commands to reactivate its onboard systems.
“Despite this unexpected final curtain call, Deep Impact already achieved much
more than ever was envisioned,” said Lindley Johnson, the Discovery Program
Executive at NASA Headquarters, and the Program Executive for the mission since
a year before it launched. “Deep Impact has completely overturned what we
thought we knew about comets and also provided a treasure trove of additional
planetary science that will be the source data of research for years to come.”
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