Scientists Get New View of Mars Landscape
In a surprise-filled day of looking at new pictures from Mars, the Pathfinder spacecraft scientists at the Jet Propulsion Laboratory learned Monday what any child discovers sitting on a parent’s shoulders to view a parade: Things look very different from six feet up.
After Pathfinder’s camera sprang to its full height from its coiled, ground-level position, what seemed to be boulders only the day before revealed themselves as 1-foot-high rocks. “What a change!” said Peter Smith, a scientist for the spacecraft’s camera, called Imager for Mars Pathfinder, or IMP. “Yesterday we thought [they were] huge!”
With its new adult-size perspective, the camera also found what appeared to be salt left by ancient puddles--suggesting that perhaps standing water once graced the Red Planet and offered a habitat for life. These crusty mineral deposits might be evidence that at least some water stagnated long enough to evaporate and leave behind crusts like dried concrete, said geologist Michael Malin.
Equally enticing, Pathfinder appears to have landed at the edge of an ancient river channel. IMP’s 3-D eyes discerned deep ridges and valleys rolling off into the distance, a sign that at one time a river (or at least water in some form) ran through the terrain. Larger hillsides in the distance were layered with what looked like mud lines left when water recedes from flooded houses.
Although Pathfinder geologists selected the spacecraft landing site, the Ares Vallis, because it appeared to be an ancient flood plain, the new images erased any doubts. In fact, the water appears to have gushed forth at a rate equal to the flood that filled the Mediterranean Sea, said Malin, a consultant to the mission. Water probably flowed from horizon to horizon, he said, making the floods this spring in the Midwest seem like a small leak by comparison.
The floods, which geologists speculate took place a billion or so years ago, interest scientists primarily because they sweep different kinds of rocks together in one place. No standing water could have existed on Mars so recently. However, some of the rocks carried to Ares Vallis by the flood may bear evidence of even more ancient, and quieter, waters.
As IMP surveyed its surroundings, the 1-foot-high, six-wheeled rover named Sojourner spent the night with its spectral analyzer snout “nestled up against” a knobby rock named Barnacle Bill. In black-and-white photos sent back to Earth, the rock and the rover appeared to be kissing, said project scientist Matthew Golombek.
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While IMP took pictures of the rover, Sojourner’s camera took pictures of the lander--like two tourists at Niagara Falls. Images of the Pathfinder mother ship, which landed on the Fourth of July encased in giant air bags, showed the spacecraft surrounded by huge, billowing mountains of material. Such images will help engineers plan for future missions.
Researchers also retrieved images in several colors from IMP’s 12-filter camera. Colors not only make prettier pictures, said astronomer/geologist James Bell of Cornell University, but tell volumes about the kinds of minerals in the rocks.
The ubiquitous red tint of Mars, for example, suggests iron oxide--the result of iron rusting. Although the entire surface of Mars appears to be rusting like an old car, some rocks are relatively free of the fine red powder, and researchers would love to know why.
Mars holds ample lessons for Earth on climate change. About 4 billion years ago, scientists speculate, Mars was a blue world like Earth, with temperatures and atmosphere that could sustain liquid water. Today, it is a parched, barren landscape. Researchers don’t know why.
One obstacle to answering these questions any time soon, ironically, is the overwhelming success of the mission so far. Scientists are drowning in data, pulling down more than 50 megabytes--about the same amount of data on 36 floppy disks--each night.
“We’re finding more and more surprises as we look in detail,” said Golombek, adding that scientists simply hadn’t had time to look at, much less digest, the flood of bits streaming via radio beam from Pathfinder to NASA’s deep space antennas in Madrid. “We are so awash in all of these new things.”
Much more is still to come. Researchers are studying the tire tracks that Sojourner made when it “pirouetted” around to snuggle up to Barnacle Bill, said Smith. The rover also fishtailed like a skidding car as it came down the ramp from Pathfinder, digging troughs in the fine, powdery soil and exposing rocks underneath.
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Within the next few days, Sojourner will be heading toward its next target--a large bear-shaped rock named Yogi by the scientists. In future weeks, it will try to stick its Alpha X-ray Proton Spectrometer nose into one of the “puddles” to see if it’s really made of salt.
Researchers decided not to release results of Sojourner’s first-day investigations of the Martian soil because the signal was too noisy, said Golombek. The “noise” that plagues scientific instruments is not normally the kind you can hear, but more like the bright light of the sun that drowns out the stars during the day.
Once Sojourner cools down from its 300-million-mile, seven-month journey from Earth, its signal should be easier to hear. But because it rolled onto the cold Martian surface later than planned, it is still rather warm, said JPL geologist Bob Anderson. The readings from Barnacle Bill--due to be presented today--should be much clearer, he said.
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Mars Mysteries
Images from Mars show a field littered with rocks and boulders with twin peaks on the horizon. Scientists describe it as an exciting location, that offers evidence a flood did indeed wash over the area eons ago.
