Planetary Society | Emily Lakdawalla | 2013 Sep 04
A terse update on the status of the aging Deep Impact spacecraft was posted on the mission website this morning:
We have not received any of our expected observations of comet ISON due to a spacecraft problem. Communication with the spacecraft was lost some time between August 11 and August 14 (we only talk to the spacecraft about once per week). The last communication was on August 8. After considerable effort, the team on August 30 determined the cause of the problem. The team is now trying to determine how best to try to recover communication.
As long as controllers are communicating with a spacecraft, there is hope. When they are not in communication with a spacecraft, that's pretty scary. Good luck to the Deep Impact team on recovering the spacecraft for a future comet or asteroid encounter. It's a great little mission.
No Images of Comet ISON from Deep Impact/EPOXI Spacecraft Due to Communication Loss
Universe Today | Nancy Atkinson | 2013 Sep 04
In a Spin? NASA Loses Contact with Comet Chaser
Discovery News | Ian O'Neill | 2013 Sep 10
Team Attempts to Restore Communications
NASA | Solar System Exploration | 2013 Sep 10
Ground controllers have been unable to communicate with NASA's long-lived Deep Impact spacecraft. Last communication with the spacecraft was on Aug. 8, 2013. Deep Impact mission controllers will continue to uplink commands in an attempt to reestablish communications with the spacecraft.
Mission controllers postulate that there was an anomaly generated by the spacecraft's software which left the vehicle's computers in a condition where they are continuously rebooting themselves. If this is the case, the computers would not continue to command the vehicle's thrusters to fire and hold attitude. Lack of attitude hold makes attempts to reestablish communications more difficult because the orientation of the spacecraft's antennas is unknown. It also brings into question the vehicle's electrical power status, as the spacecraft derives its power from a solar array that is fixed, with its cells pointing in one direction.
Deep Impact is history's most traveled deep-space comet hunter. It successfully completed its original mission and a subsequent extended mission.
Launched in January 2005, the spacecraft traveled about 268 million miles (431 million kilometers) to the vicinity of comet Tempel 1. On July 3, 2005, the spacecraft deployed an impactor, which was essentially "run over" by the nucleus of Tempel 1 on July 4. Sixteen days after the comet encounter, the Deep Impact team placed the spacecraft on a trajectory to fly past Earth in late December 2007. The extended mission of the Deep Impact spacecraft culminated in the successful flyby of comet Hartley 2 on Nov. 4, 2010. In January of 2012, the spacecraft performed, from a distance, an imaging campaign of comet C/2009 P1 (Garradd), and in 2013, an imaging campaign of comet ISON.
To date, Deep Impact has traveled about 4.7 billion miles (7.58 billion kilometers) in space.