Dec 17, 2010 07:57 GMT  ·  By

From its perch 241 kilometers (150 miles) above the surface of the planet, the Mars Reconnaissance Orbiter (MRO) is helping mission controllers decide where to point the Mars Exploration Rover (MER) Opportunity first. The robot is trying to reach the distant Endeavor crater.

Obtaining as many clues about past Martian environments as possible is the main mission that the robot has, yet it's not easy getting around on the Red Planet, or determining from the surface what areas are more suited for further exploration.

And this is precisely where MRO comes in. The spacecraft has an excellent vantage point from orbit, and also the instruments that allow it to conduct remote sensing studies of the planetary surface.

For example, its Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument is perfectly capable of mapping mineral distribution in the Endeavor crater, which has been Opportunity's target for years.

Using the maps the orbiter produces, the NASA Jet Propulsion Laboratory (JPL) team that controls the rover can establish the best path the machine needs to follow in order to shorten travel time and boost scientific return at the same time.

“This is the first time mineral detections from orbit are being used in tactical decisions about where to drive on Mars,” explains CRISM co-investigator Ray Arvidson.

The expert, who is also the MER deputy principal investigator for both Opportunity and Spirit, is based at the Washington University in St. Louis.

“We used to have a disconnect between the scale of identifying minerals from orbit and what missions on the surface could examine,” adds expert Janice Bishop, who is based at the NASA Ames Research Center (ARC), in Moffett Field, California.

“Now, rovers are driving farther and orbital footprints are getting smaller,” adds the CRISM team member, who also holds an appointment at the SETI Institute of Mountain View, California.

This orbiter-rover collaboration is already beginning to yield its first results. Opportunity is currently investigating Santa Maria, a 90-meter (300-foot) crater that the MRO identified as containing mineral-trapped water.

Over the next few weeks, the rover will analyze the formation extensively, in a bid to confirm the orbital readings. It will then relay its data to the MRO, which will forward it to mission controllers.

But the fact that spacecraft on the ground and in orbit can collaborate like this also has additional benefits, such as for example conducting validation studies.

In Earth's orbit, the European Space Agency's (ESA) SMOS satellite measures soil moisture and ocean salinity. But ground crews are also conducting similar measurements at certain locations.

This helps them remain at ease that the satellite is indeed collecting valid data. This has never been done on another planet before, but Mars is most likely to be the first to receive such special treatment.