Rovers Continue Martian Missions

May 24, 2005
Opportunity's left front wheel. Image credit: NASA/JPL

NASA's Mars rover Opportunity is trying to escape from a sand trap, while its twin, Spirit, has been busy finding new clues to a wet and violent early Martian history.
"Spirit has finally found the kind of geology you can really sink your teeth into," said Dr. Steve Squyres of Cornell University, Ithaca, N.Y. He is principal investigator for the Mars rovers' science instruments. According to Squyres, multiple layers of rock in the hills Spirit is exploring suggest successive deposits of water-altered explosive debris.

Image: Opportunity's left front wheel. Image credit: NASA/JPL. Here is the movie.
NASA's Mars Exploration Rovers' discovery of evidence of past water on Mars was the top scientific "Breakthrough of the Year," according to the journal Science.

Spirit, inside Mars' Gusev Crater, had to share the spotlight with the drama provided by Opportunity on the Martian Meridiani plains. The rover has been hindered by soft sand for nearly three weeks. Traction is difficult in the ripple-shaped dune of windblown dust and sand Opportunity drove into on April 26. Since it began trying to get out, the rover has advanced only 11 inches. Without the slippage caused by the rover's wheels spinning in the soft sand, Opportunity could have driven 157 feet.

"If Opportunity gets free, its next task will be examining the site to give the rover team a better understanding of how this ripple differs from dozens Opportunity easily crossed," said Jim Erickson. He is project manager for the Mars Exploration Rover Project at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

The rovers have worked under harsh Martian conditions longer than expected. They have been studying geology on opposite sides of Mars for more than a year since successfully completing their three-month primary missions. Shortly after landing in January 2004, Opportunity found layered bedrock bearing geological evidence of a shallow ancient sea. More than one year later, Spirit found extensive layered bedrock, after driving more than two miles and climbing into the "Columbia Hills."

Squyres said, "In the last few weeks, we have gone from a state of confusion about the geology of the Columbia Hills to having real stratigraphic sequence and a powerful working hypothesis for the history of these layers."

For several months, Spirit climbed a flank of Husband Hill, the tallest in the range. The slope closely matched the angle of underlying rock layers, which made the layering difficult to detect. Spirit reached an intermediate destination, dubbed "Larry's Lookout," then continued uphill and looked back. "That was the critical moment, when it all began falling into place," Squyres said. "Looking back downhill, you can see the layering, and it suddenly starts to makes sense."

Spirit has been examining rocks in a series of outcrops called Methuselah, Jibsheet and Larry's Lookout. Some of the rocks contain the mineral Ilmenite, not found previously by Spirit. "Ilmenite is a titanium-iron oxide formed during crystallization of magma," said Dr. Dick Morris, a rover science-team member at NASA's Johnson Space Center, Houston. "Its occurrence is evidence for diversity in the volcanic rocks in the Gusev region."

Rocks from different layers share compositional traits, high in titanium, and low in chromium, which suggests a shared origin. However, the degree to which minerals in rocks have been chemically altered by exposure to water or other processes varies greatly from outcrop to outcrop. The textures also vary. At Methuselah, rocks have thin laminations revealed by Spirit's microscopic imager. At Jibsheet, they are built of bulbous grains packed together. At Larry's Lookout, the rocks are massive, with little fine-scale structure.

"Our best hypothesis is we're looking at a stack of ash or debris that was explosively erupted from volcanoes and settled down in different ways," Squyres said. "We can't fully rule out the possibility the debris was generated in impact explosions instead of volcanic ones. But we can say, once upon a time, Gusev was a pretty violent place. Big, explosive events were happening, and there was a lot of water around," he explained.

Source: NASA

Explore further: NASA team lays plans to observe new worlds

add to favorites email to friend print save as pdf

Related Stories

Curiosity spots a heavy metal meteorite

Jul 16, 2014

Talk about heavy metal! This shiny, lumpy rock spotted by NASA's Curiosity rover is likely made mostly of iron—and came from outer space! It's an iron meteorite, similar to ones found in years past by Curiosity's ...

Opportunity peers out from 'Pillinger Point'

Jun 17, 2014

NASA's decade old Opportunity rover has reached a long sought after region of aluminum-rich clay mineral outcrops at a new Endeavour crater ridge now "named 'Pillinger Point' after Colin Pillinger the Principal ...

NASA rover gains Martian vista from ridgeline

May 20, 2014

The rim surrounding Endeavour Crater on Mars recedes southward, then sweeps around to the east in a vista obtained by NASA's Mars Exploration Rover Opportunity. The view is from high on the south end of the ...

With 10 years as Martians, rovers unveil true grit

Jan 20, 2014

In the 10th year of a 90-day warranty, the Mars rover Opportunity begins its second decade of exploration and still traverses the oxidized terrain to answer crucial questions of cosmic exploration.

Recommended for you

Satellite galaxies put astronomers in a spin

5 hours ago

An international team of researchers, led by astronomers at the Observatoire Astronomique de Strasbourg (CNRS/Université de Strasbourg), has studied 380 galaxies and shown that their small satellite galaxies almost always ...

Video: The diversity of habitable zones and the planets

5 hours ago

The field of exoplanets has rapidly expanded from the exclusivity of exoplanet detection to include exoplanet characterization. A key step towards this characterization is the determination of which planets occupy the Habitable ...

User comments : 0