Image: Trench
A wide-angle view taken by the Opportunity rover's hazard avoidance camera last month shows a trench dug in Martian dirt. Some scientists say the rover tracks suggest that the soil contains brine, with permafrost beneath the surface.
By Senior Space Writer
updated 3/1/2004 8:06:44 PM ET 2004-03-02T01:06:44

Evidence that suggests Mars was once a water-rich world is mounting as scientists scrutinize data from the Opportunity rover, Opportunity, busily at work in a small crater at Meridiani Planum. That information may well be leading to a biological bombshell of a finding that the Red Planet has been, and could well be now, an extraterrestrial home for life.

There is a palpable buzz here at the Jet Propulsion Laboratory that something wonderful is about to happen in the exploration of Mars.

There is no doubt that the Opportunity Mars rover is relaying a mother lode of geological data. Using an array of tools carried by the golfcart-sized robot — from spectrometers, a rock grinder, cameras and powerful microscopic imager — scientists are carefully piecing together a compelling historical portrait of a wet and wild world.

Where Opportunity now roves, some scientists here suggest, could have been underneath a huge ocean or lake. But what has truly been uncovered by the robot at Meridiani Planum is under judicious and tight-lipped review.

Those findings and their implications are headed for a major press conference on Tuesday.

It is clear that Opportunity's Earth-to-Mars hole in one — bouncing into a small crater complete with rock outcrop — has also proven to be a scientific bull’s-eye. The robot is wheeling about the crater that is 70 feet (22 meters) across and 10 feet (3 meters) deep.

It is also apparent that there is a backlog of scientific measurements that Mars rover scientists working Opportunity have pocketed and kept close to their lab coats.

For one, the rover found the site laden with hematite — a mineral that typically, but not always — forms in the presence of water. Then there are the puzzling spherules found in the soil and embedded in rock. They too might be water-related, but also could be produced by the actions of a meteor impact or a spewing volcano.

A few spheres have been sliced in half and their insides imaged. Patches of these spherules, or "berries" as some call them, have undergone spectrometer exam to discern their mineral and chemical makeup. Close-up photos of soil and rock have also shown threadlike features and even an oddly shaped object that looks like Rotini pasta.

Brew of dissolved salts
There is speculation that the soil underneath the wheels of both Spirit and Opportunity rovers contains small amounts of water mixed with salt in a brine. That brew of dissolved salts keeps the mixture well below the freezing point of pure water, permitting it to exist in liquid form.

Opportunity has revisited select spots in the outcrop, drawn there, in part, to look for cross-beds — sedimentary deposits that are formed in beach, river and sand-dune environments. Using its rock abrasion tool, the rover has carried out several cleaning and grinding sessions on exposed rock outcrop.

Cross-beds are patterns of curving lines or traces found within the strata of sandstone and other sedimentary rocks. Cross-bedding indicates the general direction and force of the wind or water that originally laid down the sediments.

Right around the corner
Opportunity's research is a "work in progress," said Ray Arvidson, deputy principal investigator for the Mars Exploration Rover project from Washington University in St. Louis. Data is being gathered to present "a coherent story," he said during a press briefing last Thursday.

"That story is right around the corner," Arvidson told "But we need to finish this work in progress, finish the set of experiments, get the data down from the spacecraft, processed and analyzed. Then I think that the story will be known."

Arvidson said multiple working hypotheses are still at play. Water is involved, but only in some of the hypotheses. Until coordinated experiments on the outcrop are completed, what the right hypothesis is remains unknown, he added.

Severing the umbilical cord
Mars exploration using the rovers has allowed on-the-spot "discovery-driven science," said Albert Haldeman, deputy project scientist for the rover missions. He likened the Mars robot work now under way to deep-ocean research using remotely operated submersibles.

"It turns out that the best way to explore rocks (on Mars) is go look at craters. Mobility buys us the ability to do that. It was the right fit for looking at rocks," Haldeman told "The discovery from the microscopic imager and seeing those spherules … and finding a larger population of spherules and seeing them in the rocks and the outcrop … that progression of discovery influences our thinking."

Haldeman said the next step will be severing the umbilical cord between Opportunity and the crater it's exploring. The robot would wheel itself out of that site and onto the expansive terrain of Meridiani Planum.

"That umbilical cord — that's hard to break. It's more than even just a tension within the science team," Haldeman said.

Tantalizing hints
Scientists are carefully analyzing the rock data gleaned by the Opportunity rover. "We really want to understand that we've got those figured out right," Haldeman said. Up to now they have offered some "tantalizing hints," he said, that speak to a possible relationship with water.

Piecing together the story of what Opportunity has found involves great care and deliberation, Haldeman said, based on a wide range of viewpoints and levels of expertise. "We want to be cautious," he explained.

More to the point, the science output from Mars must withstand scrutiny by experts outside the rover investigation teams.

"There are lots of geologists out there who are looking at these pictures, and they are starting to drool," Haldeman said. "The American taxpayer that spent $800 million on this deserves a thorough analysis."

Slippery slope leading to life
One scientist eagerly awaiting the news from Mars, particularly from Opportunity, is Gilbert Levin. He is chairman of the board and executive officer for science of Spherix Inc. in Beltsville, Md.

Levin is a former Viking Mars lander investigator. He has long argued that his 1976 Viking Labeled Release life detection experiment, known as LR, found living microorganisms in the soil of Mars.

In 1997, Levin reported that simple laws of physics require water to occur as a liquid on the surface of Mars. Subsequent experiments and research have bolstered this view, he said, and reaffirms his Viking LR data regarding microbial life on Mars.

Levin detailed his Mars views in a Space.comphone interview and via email.

"It's hard to image why such bulletproof evidence was denied for such a long time, and why those so vigorously denying it never did so by meeting the science, but merely by brushing it away," Levin said.

"Of course, now that it must be acknowledged by all that there is liquid water on the surface of Mars," Levin added, "this starts those denying the validity of the Mars LR data down the slippery slope leading to life."

Mars mud
Levin points to Opportunity imagery that offers evidence of standing liquid water and running water on a cold Mars. 

Other images show the rover tracks clearly are being made in "mud," with water being pressed out of that material, Levin said. "That water promptly freezes, and you can see reflecting ice. That's clearly ice. It could be nothing else," he said, "and the source is the water that came out of the mud."

Image: Spherules
JPL / NASA / Cornell / USGS
Ground-down spherules appear as black circles in this microscopic image of Martian rock that has been subjected to a drilling from Opportunity's rock abrasion tool.
As for the spherical objects found at the Opportunity site, Levin has a thought.

"I wonder on Mars if it can rain upwards," he said. The idea is that subsurface water comes up through the soils and then freezes when it gets to the surface.

"Maybe these little spherules form just like raindrops form up above," Levin explained.

Levin said that brine on Mars is a code word for liquid water. He senses that great care is being taken by rover scientists because the liquid water issue starts the road to life.

"That's the monument that they are afraid to erect without real due process," Levin concluded.

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