Gearing Up to Harvest Mars' Water Resource
Wed Jun 19, 8:39 AM ET
By Leonard David
Senior Space Writer, SPACE.com
The surprising signal from Mars Odyssey is that oceans of ice lie in wait just under the surface of the Red Planet.
Scientists have found Martian terrain that is hydrogen-rich, an indicator of water ice. The most abundant reservoirs of that near-surface water stretch from the planet's poles to within about 50 degrees of the equator.
The amount of hydrogen detected is huge. So much so that one brimming bucket of ice-rich polar soil, when heated, can yield more than half a bucket of water.
That's big news for Mars water reclamation experts. As a watering hole to sustain an expeditionary crew, Mars must now be approached with an eye on how to tap into the invaluable resource. Scientists and engineers have begun charting how this watery commodity can nourish the human drive to distant Mars.
"It's a huge windfall," said Larry Clark, manager of the Spacecraft Technology Development Laboratory at Lockheed Martin Astronautics near Denver, Colorado. "We were expecting water…but having so much is incredible," he said.
For over eight years, Clark has been hard at work on a host of in-situ resource utilization (ISRU) techniques. Last month, work on a special chamber was finished. Buckets of Mars ice and soil, as well as lunar surface simulant -- samples that mimic Moon or Mars surface materials -- can be heated and cooled inside the environmentally controlled vacuum chamber.
The Odyssey data changes all the planning, Clark told SPACE.com.
"For example, we had planned for ISRU missions where we'd have to bring our own hydrogen. That's not needed anymore," Clark said. However, the water ice that is there for the picking still requires hard work. In fact, using a pick might be one tool of choice.
"Rather than loosely bound soil holding a small percentage of water…now it's going to be more like a consistency of an ice cube with dirt…like a dirty ice cube. Ice is hard stuff to scrape up," Clark said. How to handle the volume of Mars turf while removing the water needs more thought too. "Now there's 50 times as much," he added.
"The thought of taking a bucket full of stuff and just melting it…it just didn't occur to us before. We just didn't think we had that much water," Clark said.
Clark sees on-the-move equipment using big-toothed gears to bite into and grind up Mars' surface. Material is then fed into a pressurized vessel, warmed up to reach a liquid stage. The water is filtered and likely needs pushing through purifiers to remove chemical contaminants.
"I see a simple device, nothing exotic. The trick is to make it lightweight and power efficient. It will boil down to energy, that is, how much energy you can afford to pour into the equipment. You're going to be changing the states of water. That's a power-intensive process on any planet," Clark emphasized.
A water conversion depot on Mars would be busily used. All types of exploration vehicles would pull up to the pump.
Putting foresight aside, Clark said that there remain need-to-know nuggets of important information.
For one, what about the dynamics of the water level. Is it permanently there? Does it rise and fall with the seasons? Is the depth of water steady throughout the Martian year?
"If we scrape off an acre of water," Clark said, "could a crew go back to that same spot the following month or year and get more?"
Still, Mars as a watershed of a world is alluring.
"I don't think people realize the impact it could have if you really started to exploit those resources," Clark said. "We should start using this valuable resource as soon as possible," he said.
Need for liquids
Several soon-to-be-launched spacecraft should help researchers satisfy their need for liquids on Mars.
Now being prepped for blastoff are NASA ( news - web sites)'s twin Mars Exploration Rovers. They will depart Earth between May 30 and July 14, 2003, arriving on Mars in January and February of the following year. Then, in 2005, NASA plans to launch a powerful scientific orbiter, the Mars Reconnaissance Orbiter. This probe will train cameras and other high-tech gear on Mars, surveying the planet at new scales for tantalizing hints of water.
NASA is also mulling over Mars Scout ideas for launch in 2007 and subsequent years.
Numbers of Scout proposals are now under review. A handful of concepts were awarded study money last year. Those funds don't guarantee any one of them will be picked, but do suggest a range of innovative ways to dig into Mars for telltale signs of water.
Among the Scout schemes that got the nod for further study:
Yet the Mars divining rod award may go to Europe.
The European Space Agency is readying Mars Express, both an orbiter and lander mission. It's set for liftoff on a Russian Soyuz-Fregat booster in May 2003.
As a scientific water diviner, Mars Express totes along a sub-surface sounding radar jointly developed by Italy and the United States. Also, the British-built Beagle 2 lander will be released around December 25 of next year, heading for a Mars touchdown. This compact lander carries an exquisite instrument package, including a robotic arm to study Martian geochemistry and exobiology on the surface and below.
Nobody knows for sure just how hard removing the ice from the Martian subsurface might be.
It could be in the form of cement-like permafrost. That might mean a lot of chipping and drilling, rather than scoops of water ice.
More data is needed, said William Boynton, principal investigator for Odyssey's gamma ray spectrometer suite at the University of Arizona, Tucson.
This group of sensors includes a neutron spectrometer, built by Los Alamos National Laboratory, and the device that is measuring Mars for water ice. The neutron spectrometer data are supported by simultaneous measurements taken by Mars Odyssey's gamma ray spectrometer.
"We need a lander in the polar areas to know for sure," Boynton said. "If it were just formed as frost condensation, then one would expect it to be easy to dig, but if the ice is as massive as our data suggest, then it could be difficult," he told SPACE.com.
It's a bad memory, but there has already been one on-the-surface shot at knowing first hand the extent and depth of available water ice.
The Mars Polar Lander might have performed such a duty. Unfortunately, on December 3, 1999, the NASA craft disappeared on touchdown. The probe's targeted landing site was Mars' southern polar layered terrain, some 620 miles (1,000 kilometers) from the planet's South Pole.
Replete with robotic arm, a successful Mars Polar Lander would have studied the seasonal advance and retreat of the South polar ice cap, looking for clues to the climatic history of Mars.
Full of surprises
William Boynton was a key member of the Mars Polar Lander science team.
"With Mars Polar Lander we would have learned a lot more about the nature of the ice, but we would have learned about in just one spot. We would not have known if we just got lucky, or if there was ice everywhere. This is why we really need both landers and orbiters to understand what is the nature of the ice," Boynton said.
Is it possible that pockets of water ice - away from the polar areas - might be found in the future, say in equatorial landing areas used by incoming Mars crews?
"It would not be expected, since we know it is warm enough near the equator for ice to evaporate," said
"But it is hard to say. Mars is full of surprises. We never expected to find this much ice so close to the surface. It's possible there is ice beneath the surface and it is just evaporating so slowly it hasn't gone away yet," Boynton said.
"The ice is where we thought it would be…that is, near the polar regions," said Chris McKay, space scientist at the NASA Ames Research Center near San Francisco, California. "That might make it hard to access by humans from a Mars base, which is likely to be sited near equatorial for power and launch reasons," he said.
McKay said, however, that there are some "spots" of blue in Odyssey's neutron spectrometer data near the equator. "If these are ground ice, then those are appealing as Mars exploration crew sites. Even if these are just regions where the ground is rich in bound water, this might prove very interesting and useful," he said.
Then there's always one hot prospect.
If hot spots are "unmarsed", a landing party may only need to poke a hose down subsurface and snake into an aquifer.
Pure or dirty water?
"We do not know much about the near-surface ice," said Jeffrey Taylor, Hawai'i Institute of Geophysics and Planetology space geologist at the University of Hawaii in Honolulu. If that ice formed solely by the interaction of atmosphere and Martian surface, he added, "it might be pretty pure, like rainwater is on Earth."
On the other hand, Taylor said, if the ice came from ground water that had interacted with rock -- especially hot rocks -- deposits would be full of elements and, therefore, the ice might need purification, he said.
Sending a Mars spacecraft capable of drilling down a few feet, outfitted with devices that appraise the composition of the water, would be a good next step, Taylor said. "If it's pure, an atmospheric source is likely. If it's dirty, then maybe a more complicated history [of the ice] is more probable," he said.
Even frozen ground water, however, could be fairly pure in places, Taylor said. In briny water, the first ice to form is more pure than subsequent ice, he said.
In using near surface ice that's pure, Mars explorers would find the resource easy to extract by melting and filtering. "The fact that it's so close to the surface would mean humans could excavate it relatively easily with small backhoes or front-end loaders. Assuming they can get them to Mars," Taylor said.
The first human visitors to Mars will likely not have adequate power nor all the excavation tools needed, Taylor said. It's a matter of time scale. Settlements of the future will require more energy and other massive tools for settlement to take place, he said.
Not everybody ties water ice to moving in day for Mars expeditionary crews.
The Mars Odyssey surveillance greatly enhances the prospect of discovering non-terrestrial life, said Bob Park of the American Physical Society (APS) and physicist at the University of Maryland in College Park, Maryland.
But Park said that taping "frozen mud" beneath the polar surface of Mars for on-the-spot utilization by humans is suspect, a questionable use fanned by media hype.
"The search for life to which we have no genetic link is surely the most exciting quest in science. But the Mars lobby sees the mud as a source of drinking water for astronauts, and rocket fuel for the return trip," Park said.
"But, you might ask, is it a practical idea? Alas, the hydrogen found by Odyssey is in the polar regions. Elsewhere, things look pretty dry," Park said. "Even in the polar regions the water is a foot or two below the surface and it's in the form of frozen mud, maybe 20 percent water. So where does the media get hold of these ideas? They must be coming from the Mars lobby, which is dedicated to underestimating the difficulty," he scoffed.
"We now face a deadline: explore Mars before astronauts contaminate it. If they rely on water as a source of fuel, it should be easy," Park said.
Park notes that these views are his own, not necessarily shared by the American Physical Society or the University, "but they should be," he points out on his "What's New" column on the APS web site.
Mars Odyssey's discovery "represents a very important resource for human explorers," said leading advocate for a humans-to-Mars project, Robert Zubrin, President of the Mars Society, based in Indian Hills, Colorado.
Located so close to the surface, Mars ice reserves should be accessible, Zubrin said. "It is true that it may not be pure, but it could be desalinated or distilled, as required," he said.
"It is of course also true that the water is of great scientific interest. It may contain the frozen remains of Martian microorganisms," Zubrin told SPAC.com.
Zubrin said by combining the water with known resources of carbon dioxide and nitrogen from the atmosphere, plants could thrive on Mars, rocket fuel and oxidizer produced, and plastics and fabrics could be manufactured. In addition, chemical reductants obtained would make it relatively straightforward to produce iron. Also, but with more difficulty, silicon, aluminum, and other metals can be produced from Martian rocks, he said.
Mars crews can live off the land using available water and atmospheric resources, Zubrin said. Doing so drives down the cost a humans-to-Mars program. "It will be possible to send human missions to Mars at much lower cost than would otherwise be possible. Expeditions will be able to make much of what they need on Mars, instead of shipping them at great cost from the Earth," Zubrin said.
"The same resources that make Mars interesting will also make it accessible," Zubrin concluded.
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