The hobbled Spirit rover, stuck in a tricky patch of Martian soil, is whiling away the hours with a little stargazing. From its stationary post in an area known as Troy, the rover has been turning its cameras to the skies to act as an ad hoc observatory on Mars, as noted by Universe Today.

Planetary scientist Mark Lemmon of Texas A&M University, the member of the rover team who is leading the effort, tells ScientificAmerican.com that Spirit has been observing stars and planets for about two weeks.

But it is a different kind of observation than that on Earth. "Images of stars are useful not for the astronomy but for the atmospheric information," Lemmon says. "Astronomers on Earth use multiple observations to cancel out the Earth's atmospheric effects and leave information on the target. We cancel out the information on the target to learn about Mars's atmosphere."

Spirit's tiny cameras are hardly purpose-built for sky observation. As such, astronomy from Spirit and its more able-bodied twin, Opportunity, don't "compete with their ability to do what they were designed for," Lemmon says. "But at least we can use the excess power we have to good purpose."

Photo from Spirit's Navigation Camera: NASA