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NASA loses contact with veteran comet probe

Paul Sutherland, Feature writer
Sep 6, 2013, 7:00 UTC

Sen—NASA controllers have lost contact with a veteran spaceprobe as it was heading for a final rendezvous with one of our Solar System’s smaller inhabitants.

The Deep Impact mission, which has already made close-up studies of two comets, and observations of two more, was last heard from on 8 August. Attempts to communicate with it since have failed.

NASA say they know what the problem is, though they have not officially revealed its cause, and discussions are being held to decide how to get the spacecraft to respond once more.

However, according to Nature’s news blog, a software communications glitch reset the probe’s computer and the craft is now spinning out of control. There is a race against time to restore contact because, if the solar panels are turned away from the Sun for too long, Deep Impact will lose all power and die.

The drama was disclosed in a short status update on the website for the Deep Impact mission, which was launched from Cape Canaveral, Florida, on 12 January, 2005.

While en route to an asteroid that is considered a potential threat to Earth, the probe has been making long-distance observations of incoming Comet ISON which could become a bright object in our skies later this year.

The NASA update read: “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.”

Comets Tempel 1 and Hartley 2Images of the missile hitting Tempel 1 (left) and gas jets from Hartley 2. Credit: NASA/JPL

Deep Impact made space headlines on 4 July, 2005, when it fired a fridge-sized missile at a comet called Tempel 1, producing Independence Day fireworks and blasting a large crater in the comet’s icy head, or nucleus.

The explosion, with the force of 4.5 tons of TNT, was recorded by a camera on board the probe but was much brighter than expected and the flare was observed back on Earth and by space telescopes and other probes including ESA’s Rosetta.

More than five years later, on 4 November, 2010, the probe flew close by another peanut-shaped comet, called Hartley 2, and recorded spectacular images of its head sprouting jets of gas as it was warmed by the rays of the Sun.

That new mission, renamed EPOXI to cover its new twin goals of observing a second comet and also studying extrasolar planets with its on-board instruments, was originally intended in 2007 to be a flyby of Comet 85P/Boethin. However, when attempts were made to locate the comet to check its orbit, it could not be found and may have disintegrated.

Comet ISON

A mini movie of Comet ISON taken by Deep Impact on
17 
and 18 January. Credit: NASA/JPL/UMD

Following the Hartley 2 encounter, there was not enough fuel left on board to visit any more comets. But engineers decided they could reach a Near Earth Asteroid labelled 2002 GT. A series of manoeuvres were executed to send it for a rendezvous in 2020.

The probe went on to make a series of observations of Comet Garradd (C/2009 P1) in February-April of 2012 and was able to measure its rotation and the relative abundances of gases in the coma surrounding its head.

Observations of Comet ISON began on 17 January and showed that its brightness was varying on a timescale of hours. The comet was unobservable from the probe from early March until early July, but fresh images were due to be received during the latest observing window.