WASHINGTON, Sept. 20 (Xinhua) -- U.S. space agency NASA on Friday announced an end to the eight-year Deep Impact mission that included an unprecedented impact, comet flybys and the return of approximately 500,000 images of celestial objects.
The project team at NASA's Jet Propulsion Laboratory (JPL) gave up on the Deep Impact after being unable to communicate with the spacecraft for more than a month. The last communication with the probe was on Aug. 8.
Deep Impact was most traveled comet research mission in history, going about 4.7 billion miles (7.58 billion km).
"Deep Impact has been a fantastic, long-lasting spacecraft that has produced far more data than we had planned," Mike A'Hearn, Deep Impact principal investigator at the University of Maryland said in a statement. "It has revolutionized our understanding of comets and their activity."
Launched in January 2005, the spacecraft first made worldwide headlines on July 4, 2005, when it released a refrigerator-sized impactor to collide spectacularly with comet Tempel 1, giving scientists their first-ever view of pristine material from inside a comet.
"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 a successful flyby of comet Hartley 2 on Nov. 4, 2010. Along the way, it also observed six different stars to confirm the motion of planets orbiting them, and took images and data of the 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, NASA said.
But last month, mission controllers lost contact and could not reactivate its onboard systems.
Although the exact cause of the loss is not known, it might be related to computer time tagging problem that makes communication difficult, as well as Deep Impact's solar arrays, which would in turn prevent the spacecraft from getting power and allow cold temperatures to ruin onboard equipment, essentially freezing its battery and propulsion systems, according to NASA.
"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," Johnson added.