Deep Impact succumbs to 'HAL bug' as glitch messes with antenna

NASA has stopped trying to contact Deep Impact, the comet-pronging probe that in 2005 dropped an “impactor” the size of a coffee table onto comet Tempel-1.

The space agency's explanation for the decision will be familiar to anyone that has read or watched 2001: A Space Odyssey: a software glitch means the spacecraft can't point its antenna at Earth.

Deep Impact was launched in January 2005 and later that year gave the USA a nice birthday present by demonstrating its ability to drop stuff onto comets on the nation's July 4th birthday. The mission produced the notion that Tempel 1 was “fluffy”, inasmuch as it was rather less dense than expected and may consist of loosely-bound chunks of matter rather than a single big lump of stuff.

NASA's original mission plan called for the probe to become space junk not long afterwards, but the craft's instruments were still working so it was decided to carry on poking around the cosmos for other interesting objects. Deep Impact therefore added the moniker “EPOXI”, a handle that reflected its two new missions: the Extrasolar Planet Observations and Characterization (EPOCh) and a flyby of comet Hartley 2 called the Deep Impact Extended Investigation (DIXI).

EPOCh went rather well: the craft peered at six remote solar systems and helped to confirm the presence of exoplanets and provided more information about their orbits. DIXI also did the business, yielding useful information about ratios of carbon-dioxide ice to carbon-monoxide ice.

Deep Impact was still doing useful things early this year, when it captured images of comet ISON. Russian astroboffins spotted ISON in 2012 and it was quickly identified as having come from the Oort Cloud.

But in August the craft stopped responding to radio commands. NASA says analysis “has uncovered a potential problem with computer time tagging that could have led to loss of control for Deep Impact's orientation.”

“That would then affect the positioning of its radio antennas, making communication difficult”.

The Reg has no idea what the antenna is called, but on the off-chance it's the AE-35 unit it seems safe to keep one's eyes on Jupiter and stocking up on sun screen.

NASA bods are sad about Deep Impact's demise, but given the craft performed for seven years longer than intended they're happy to cut their losses.

To put the feat of seven years of extra operations into perspective, consider that the private robo-capsule sent to the international space station last week, Orbital Sciences Corp's Cygnus, developed a glitch after just four days aloft. The capsule is expected to make its rendezvous with the ISS later this week. ®