Deep Impact on the Fritz

The up-close comet mission is currently out of control. 

The Deep Impact spacecraft is having problems. On September 3rd mission principal investigator Michael 
A’Hearn (University of Maryland) reported that the team had lost communication with the spacecraft sometime between August 11th and August 14th — it's unclear exactly when, as the team only links up with the craft about once a week. The last communication was August 8th.


The Jet Propulsion Laboratory announced yesterday that the problem appears to be a software glitch that reset Deep Impact’s computers into a constant reboot mode. Without computers to control its thrusters, the craft can’t hold still, and the team doesn’t know its current orientation. That makes reestablishing communication hard: it’s tricky broadcasting to antennas when you don’t know which ones are pointing at you. 

There’s also the problem of power. Deep Impact’s solar cells aim in one direction, and if they’re not facing the Sun, the craft won’t be able to recharge its batteries. A dead craft can’t be communicated with, regardless of orientation. 

Deep Impact is a long-lived interplanetary mission. It jettisoned a projectile that Comet 9P/Tempel 1 “ran over” on Independence Day in 2005, excavating material and allowing scientists to study the comet’s composition. The spacecraft was subsequently recommissioned to a dual mission called EPOXI (short for EPOCH and DIXI, both of which are also acronyms) to investigate comets and exoplanets. In 2010 the craft swept past Comet 103P/Hartley 2, taking fantastic images of the individual jets of gas and dust on the comet’s surface.

Right now the spacecraft was supposed to be observing Comet ISON, which has been the recipient (or victim?) of much fanfare this year. Deep Impact’s pre-perihelion observing window extended from early July to early September, but because of the glitch the team has missed out on about half of that window.