Those “never say ‘die’” Mars Exploration Rovers — NASA’s Spirit and Opportunity — continue to chalk up scientific discoveries on opposite sides of the red planet.

Looming large on the horizon for the Opportunity rover at Meridiani Planum is Victoria Crater — a grand bit of territory that is roughly 800 meters in diameter. That is about six times wider than Endurance Crater, a feature Opportunity previously surveyed for several months in 2004, gathering data on rock layers there that were affected by water a long, long time ago.

“We are closing in. … We’ve got only about a kilometer to go now,” Steve Squyres, lead scientist for the dual Mars exploration rovers at Cornell University in Ithaca, N.Y., said May 19.

“Feel free to work out your own guess at an estimated time of arrival based on our recent progress … but I’m not making any predictions. Mars has fooled us too many times before,” Squyres said.

Pushing across Meridiani Planum has not been easy for Opportunity. The landscape is one of rolling ripples of sand and splashes of outcrop rock. “We’re pushing as hard as we can with a very old rover,” Squyres added. “We’ll get there when and if we get there.”

Once there, Squyres said the plan is to approach that feature much as they did Endurance Crater. “[We’ll] start by taking images from several points along the rim to get the lay of the land … and then see if there’s a place where we can enter the crater safely,” Squyres said. “There’s no guarantee that we’ll be able to get in, of course, but we’re not driving all this way just for the view.”

William Farrand, a research scientist at the Space Science Institute in Boulder, Colo., also is anxious for the exploration of Victoria Crater to begin. He is a member of the Mars Exploration Rover science team.

“The rover has been making good progress towards Victoria Crater. So — knock on wood — it should get there perhaps as early as late July,” Farrand said.

Farrand noted the views at that feature are sure to be spectacular. But the real payoff, he added, will be the opportunity to check out the exposures of outcrop that the science team is expecting to see on the inner walls of Victoria Crater.

“Opportunity’s mission has been all about reading the story contained within the layered rocks that lie just below the surface of Meridiani Planum,” Farrand advised. “We got about 40 to 50 centimeters of outcrop at Eagle Crater [at the start of its roving] and then 7 meters at Endurance Crater.”

However, at Victoria, it looks like there’s a deeper story there.

Images taken from Mars orbit suggest there might be close to 20 meters of outcrop exposed within the walls of Victoria Crater, Farrand said.

It is still not clear whether rover scientists will be able to get into the crater to do the type of detailed, on-the-spot analysis they were able to do within the inner rim of Endurance Crater. But Farrand said that by utilizing Opportunity’s Panoramic Camera and Mini-Thermal Emission Spectrometer, researchers should be able to do some tremendous remote sensing at that locale.


On the other side of Mars in Gusev Crater, Opportunity’s sister rover Spirit is gathering science data too. Spirit, however, is in need of a little dental work.

The grinding teeth on Spirit’s robot arm-mounted rock abrasion tool have worn away after exposing interiors of five times more rock targets than its design goal of three rocks. The tool still has useful wire bristles for brushing targets.

“Spirit has been very busy lately, taking an enormous panorama that we call the McMurdo Pan,” Squyres said . The robot is doing lots of work with its robot arm –officially labeled, in mechanical jargon, as the Instrument Deployment Device .

Spirit has been positioned in such a way that its solar panels can help the machine endure several months of martian winter.

The power on Spirit is good, Squyres said, noting that projections of the rover’s overall health suggest the vehicle will make it through the martian winter and be able to keep doing science the whole time.

“One thing about staying in one place for a long time is that it enables lots of interesting science that just isn’t possible when you’re always moving. We’re taking advantage of that now with Spirit,” Squyres explained.

Spirit and Opportunity are churning out travelogue-like photos of their respective treks over Mars. The eyes of the robots — their camera systems — are capturing a wide range of scenery along the way.

“All of the cameras continue to work remarkably well and are continuing to acquire beautiful images,” said astronomer Jim Bell, the Panoramic camera (Pancam) payload element lead for the Mars Exploration Rovers at Cornell University. “They have proven to be extremely robust to the extreme conditions on the martian surface … large temperature swings, fine dust everywhere, large cosmic ray flux,” he said.

Since the twin rovers independently landed on Mars in January 2004, Spirit’s cameras have taken about 82,000 pictures. Opportunity has taken about 71,500 pictures — for a total down-linked image data volume of about 19 gigabytes. Of these, 54,400 and 49,500 are the high-resolution Pancam images, respectively, Bell said.

“At Meridiani, once we get to Victoria Crater in June or July, we are obviously looking forward to remarkable views of the interior,” Bell said, and to help identify possible routes to explore even deeper exposures of sedimentary outcrop rocks.

“At Gusev, we are hunkered down for the winter now, obtaining detailed chemical measurements on reachable rocks and soils and acquiring the gigantic 360-degree McMurdo panorama with little or no compression in all [camera] filters from our winter haven parking spot,” Bell said.

Up there on Mars, Bell concluded, “the missions just keep rocking on. “