Ceilidh

Michael Zey
olution images ever taken while looking at a rock on another planet. Scientists are studying this area, which measures 3 centimeters (1.2 inches) across, for clues about how the rock formed. The image was created by merging five separate images taken at varying distances from the target by the microscopic imager, an instrument located on the Mars Exploration Rover Opportunity's instrument deployment device, or 'arm.' B&W ONLY NO SALES REUTERS/NASA/JPL/Cornell/USGS

LOS ANGELES (Reuters) - NASA (news - web sites)'s two rovers played martian tourists this week, stopping to take pictures of places they may want to revisit, before moving on at record breaking pace to other sites of possible interest, scientists said on Thursday.

The rover Spirit, which landed Jan. 3 in the massive Gusev Crater, broke its own driving distance record on Thursday, moving 80 feet in two hours and 48 minutes -- a cracking pace of just under 6 inches a minute -- while approaching a group of rocks nicknamed "Stone Council."

Engineers at NASA's Jet Propulsion Laboratory in Pasadena, California, gradually have allowed the golf cart-sized rover to use an autopilot feature that allows Spirit to drive faster and further and to navigate around hazards.

On Friday, Spirit's 40th day on Mars, scientists planned to order the rover to drive a short distance to Stone Council and use instruments on its robotic arm to take photos and soil samples.

Spirit is slowly working its way toward a feature nicknamed Bonneville Crater 1,115 feet away from its lander. It has driven 190 feet in the last three days, taking soil samples and photographs along the way, mission technical leader Art Thompson said on Thursday.

Other than a temporary problem with an antenna earlier in the week that engineers quickly remedied, Spirit has suffered "absolutely no adverse effects from its earlier memory problems," Thompson told a press briefing at JPL.

The rover stopped communicating with its handlers at NASA's Jet Propulsion Laboratory in Pasadena for about a week in January after its memory became overloaded. Since its return to good health, Spirit has performed flawlessly, Thompson said.

"I am very pleased to report that we have two very busy rovers on the surface of Mars," he said.

OPPORTUNITY CRUISES

Half a planet away, the rover Opportunity cruised an outcrop of bedrock in the wall of the small crater where it landed near the planet's equator, Thompson said.

Since it landed on the flat expanse of the Meridiani Planum on Jan. 24, Opportunity has traveled more than 43 feet from its lander, stopping at four spots of scientific interest to take microscopic and spectrographic images of the soil, Thompson said.

Engineers programming the rover's daily drives have had difficulty accounting for the way the rover's six wheels slip in the fine-grained sand as it climbs the wall of the crater to take scientific samples.

"We have since corrected the way we drive ... now when we attempt to drive up the slope we overdrive and when we ... drive down we underdrive," Thompson said.

After surveying the outcrop, Opportunity will return to spots of interest to perform more detailed observations of the soil, and will eventually climb out of the crater.

In the coming days, Opportunity will drive to a hematite-rich area nicknamed "Sand Patch," where it will dig a trench with its wheels and take subsoil samples, Thompson said.

Both rovers have used their mini-thermal emission spectrometer, which senses infrared spectra, to observe rapid temperature swings in the planet's lower atmosphere, science team member Don Banfield said on Thursday.

Scientists hope to mate the rovers' ground-level temperature observations with those of a Mars orbiter to refine models of the planet's wind patterns, in part to make landing on the wind-swept planet safer.

"We've been talking a lot about water on Mars in the past but wind is currently the important agent of change on Mars," Banfield said.

PHOTO This sharp, high-resolution image shows a rock target dubbed 'Robert E,' on a rock called Stone Mountain at Meridiani Planum, Mars, taken by the Opportunity Rover and released by NASA (news - web sites) Febraury 12, 2004. It is one of the highest-resolution images ever taken while looking at a rock on another planet. Scientists are studying this area, which measures 3 centimeters (1.2 inches) across, for clues about how the rock formed. The image was created by merging five separate images taken at varying distances from the target by the microscopic imager, an instrument located on the Mars Exploration Rover Opportunity's instrument deployment device, or 'arm.' B&W ONLY NO SALES REUTERS/NASA/JPL/Cornell/USGS