Night Moves: Spirit Mars Rover Turns Astronomer
Picture snapped by Spirit shows the Sun hanging low on the landscape. Thanks to the robot?s high power levels, operators have begun making nighttime observations. Image
Credit: NASA/JPL

High atop Husband Hill within Gusev crater, the Spirit Mars rover is performing nighttime astronomical duties.

From its "top of the world" vantage point, Spirit has snagged images of the two Mars moons--Phobos and Deimos. The robot is also assessing weather features in the dark of the night on Mars. Other nighttime duties are being discussed, such as charting meteor showers on the red planet.

"We're actually shunting some power during the daytime. So we'd much rather use that power to do some science instead of shunting it out as waste heat," said Jim Bell, an Associate Professor in the Cornell University Astronomy Department in Ithaca, New York.

Bell is lead scientist for the Panoramic Camera color imaging system carried by the dual Mars robots: Spirit and Opportunity.

Moons in view

Having so much power has allowed group controllers to task Spirit to execute nighttime observing campaigns, Bell told

While each rover is equipped with a Panoramic Camera--or PanCam--the devices are not telescopes. "Still, we can do some pretty good astronomy," Bell said.

Spirit has been able to snap shots of both Phobos and Deimos together. "We're killing two birds with one stone by selecting times when those two moons pass each other in the sky. That does frequently happen...every couple of nights," Bell said.

Bell said that, by taking the nighttime photos, a better understanding of where those two moons are in their respective orbits becomes possible.

"We're getting some good orbital refinement on the positions of the satellites," Bell added. "They haven't been monitored by astronomers since the late 1980s."

In addition, by using color filters on Spirit, colors of the two martian moons can be ascertained, Bell noted.

Weather service

Spirit has also gazed longingly up into nighttime sky for meteorological purposes.

"We're looking for any evidence of clouds forming at night, or fog, or haze," Bell said. To do this job, nighttime shots are being taken using the backdrop of stars--as well as Phobos and Deimos--to help pin down atmospheric phenomena.

As the two moons slip by overhead, Spirit is getting a spectacular view.

Deimos looks pretty much like a star, far away. But Phobos is an eyeful, Bell observed.

"You can clearly see that Phobos is an oblong, potato-shaped object in the sky. It's not as big as the full moon, but it is still pretty decent in size," Bell said. A soon-to-be-released image will show features on the surface of Phobos, he said, "and this is with not much better than human eye resolution!"

In fact, Phobos is so close and large enough, a person standing on Mars, within a few minutes, would notice the moon moving, Bell said.

Shower times

Thanks to the rover's power levels, Bell said that a proposal is being made to use Spirit to observe meteor showers this fall.

Just like here on Earth, the red planet also sweeps through areas of space laden with comet debris. Scientists want to evaluate the flux of these small particles streaming into the martian atmosphere.

"There are models that predict certain rates of meteors, and like on Earth, there are shower times," Bell said. Spirit's nighttime powers should help record that shower activity, he said.