A Bizarre New Mars

Summary (Jan 25, 2004): Initial color images from Meridiani, Opportunity's landing site in a flat, volcanic plain, suggest fine-grain soil and the first bedrock ever seen on Mars. The significance of bedrock to geologists can be compared to a history book of the planet, with its binding still ordering the pages to be read. This differs from the scattered page order that other site geology may have offered, because crater impacts and surface flows transport those materials.

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A Bizarre New Mars

Pasadena, Sol 1, Opportunity mission

By Henry Bortman

Opportunity site at Meridiani Planum, a volcanic plain on the opposite side of Mars from Spirit's Gusev crater. Click for large view.
Credit: NASA/JPL

Shortly after 1:00 am PST on Sunday morning, Opportunity sent back a stunning series of images from its new home in Meridiani Planum. The photos not only confirmed that the rover was safe and healthy on the martian surface, but revealed a bizarre landscape unlike any other previously seen on Mars.

See Opportunity image gallery and slideshow

The landscape is flat looking out toward the horizon, although there are small hilly bumps, or hummocks, in the distance. Up close, the surface appears pebbly, but it was easily compressed and smoothed by the lander's airbags.

There is a sizable craggy rock outcrop directly in front of the rover, which is likely to be an early target for the rover's first traverse. By studying the material in the outcrop, scientists will be able to learn unequivocally the geologic history of a specific location on Mars.

Rock Abrasion Tool (RAT), a diamond cutter for removing surface layers from rocks. On the rover's Instrument Deployment Device, or IDD, are four key diagnostic instruments-the RAT, Mossbauer and APXS spectrometer for chemical and elemental determinations and microscopic imager. Meridiani is predicted to have less rock-dust to clear than most previous landing sites. Bottom mosaic shows four perspectives on the Meridiani site. Click lower image to enlarge. Squyres: "I'm thrilled with the landing site. The thing about the Meridiani region is it's very homogeneous over a very large area, so once you get down safe and sound, you kinda can't miss."
Credit: NASA/JPL

"This is the first bedrock outcrop ever seen on Mars," said Steve Squyres, principal investigator for the Mars Exporation Rovers. Bedrock, he said, is geologically significant because "you know where it came from.

"One of the problems that we always had at the Viking sites, at the Pathfinder site, and that we're having at Gusev right now, is that we've got these little loose rocks sitting on the surface. Where did they come from and how did they get there? Are they ejecta from out of a crater? If so, where's the crater? Were they brought in by a flood? If so, from how far upstream?

"These rocks grew up right in this neighborhood. This is where they came from."

The lure of Meridiani Planum is a mineral called hematite, a form of iron oxide. Squyres discussed the different ways that hematite can form - many of them involve water - and how the science team plans to learn about the processes that formed the hematite in Meridiani.

"There's lots of different ways you can make hematite. One is you can have these massive deposits like you form in deep-standing liquid water bodies. Then you'd expect to see the hematite uniformly through the rock".

"Another is something hydrothermal. So suppose you got hot water percolating through rocks, through cracks, and you precipitate the hematite, and we see it in veins, in fractures running through the rock. That tells a different story".

Descent image (DIMES) as Opportunity was about one mile altitude. The large 150 meter crater is a likely driving target, perhaps a half-mile away. The dark spot in the sun glare left of the large crater is the shadow of the parachute. The lander is in a 20 meter crater perhaps near the center.
Credit: NASA/JPL

"You can form hematite as coatings on the outside of rocks, just by a thin film of liquid water. So suppose we see a hematite-bearing rock, we RAT it, we look underneath and there's no hematite. That's a coating".

"I can't tell you that this is a place where there was ever water. You can take a magnetite-bearing lava and you can oxidize it at high temperature - you get hematite, no water involved."

"The way you tell [how the hematite formed] is by asking yourself what other minerals are present. It's those other minerals, the configuration in which you find it".

"So I don't know what we're going to see. I really don't know. This was a tantalizing place to check, and we're going to check it out. And what we see is what we see. You can't go into this expecting Mars to conform to your wishes. That's asking too much of Mars. You go there and you get what Mars gives you."

And after seeing Opportunity's first photographs, Squyres was quite happy, indeed, with what Mars has given him. "This is exactly what it looked like in my wildest dreams," he said. "And they were pretty wild."

Related Web Pages

Two for Two: Opportunity Lands
Water Signs
Microscopic Imager
Gusev Crater
Pancam- Surveying the Martian Scene
Mössbauer spectrometer
Alpha Proton X-ray Spectrometer
Mars Rover: The Owner's Manual
NASA's RATs Go Roving on Mars
Reverse Robotic Origami
Scientists Home in on Opportunity's Location

Note: Mars Life

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Sunday, January 25, 2004