How to Mine Martian Water
The confirmation of Martian water ice by the Phoenix Mars Lander may hint at the planet?s potential for supporting life or at least human life.
NASA scientists have quietly developed technologies such as microwave beams for future explorers to extract water from the moon or Mars, even as the Phoenix team focuses on finding out more about the Martian climate and history of water.
"If there is an outpost, there's a need for water, and we don't want to bring water from Earth," said Edwin Ethridge, a materials scientist at NASA's Marshall Space Flight Center in Huntsville, Ala.
Water could provide more than just an extraterrestrial drink: the right equipment could break down water for oxygen and even fuel for a human mission. That could lighten the load and cost of any future mission heading for the moon or Mars.
Mining with microwaves
Ethridge spends most of his time working on the Ares rockets slated to return NASA astronauts to the moon. So perhaps it's no surprise that he devotes his spare moments to tinkering with a device that can beam microwaves down to help extract underground water ice.
"One of the chief advantages of microwaves is that it will penetrate the soil, and so would greatly minimize if not eliminate requirement to dig," Ethridge told SPACE.com.
Eliminating the need to dig would also reduce the chance for dust to cause problems with astronauts and their equipment. Microwaves could also work better on the moon given its near-vacuum environment and super-insulating lunar dust.
Ethridge worked with colleague Bill Kaukler, also at NASA Marshall and a materials scientist at the University of Alabama in Huntsville, to run demonstration tests on simulated lunar permafrost. They found that they could remove 98 percent of water ice through sublimation, or converting the frozen water directly into a gas, and could also capture 99 percent of the extracted water.
Shaken, not stirred
Recent missions have shown that any water found on the moon or Mars will likely remain locked away in ice, whether on the surface or underground. Adjusting the frequency of microwaves can allow them to penetrate deeper to reach any such frozen reservoirs.
The use of water-mining technology during the planned moon missions could serve as a "test bed for Mars and any other extraterrestrial body that has water," Ethridge noted.
No one has uncovered solid evidence of water ice on the moon yet, but lunar orbiters have detected concentrations of hydrogen at the poles that strongly suggest the presence of untapped ice. A study earlier this year also confirmed the presence of water inside ancient moon samples brought back by Apollo astronauts.
"At the poles, there are craters that have been permanently shadowed for billions of years," Ethridge said. Many lunar scientists suspect that water ice survives in those permanently shadowed regions away from sunlight.
No one has to wonder that about Mars, where the Phoenix Mars Lander directly detected water ice after scraping away at the polar surface. Mars orbiters have also detected concentrations of hydrogen on the red planet, all the way from the poles to near the equator.
"It absolutely amazed me about Mars that they just had to scratch the surface and found water ice that is stable," Ethridge said.
Drink your (Mars) milkshake?
There could be an ocean of frozen water under Phoenix, but tapping it would still require energy resources that a Mars mission might not have.
"As far as humans go, if you want to form a colony on Mars or establish a station, you'd want to dig a well and pump liquid up from the surface," said Peter Smith, the principal investigator leading the Phoenix Mars Lander mission at the University of Arizona in Tucson.
Liquid water would much more easily enable any human mission, but remains an elusive and perhaps unlikely find. Phoenix still needs to run further tests on its water ice sample.
"We're trying to figure out its past," Smith noted. "Our job is to figure out if this ice has melted and gone through a liquid phase."
Squeezing out the drops
Meanwhile, Ethridge continues to plow ahead with his study to make the microwave extraction process more efficient. He and Kaukler hope to shrink the energy requirements for their current 1 kilowatt system.
"One of the early landers on the moon probably won't have that power," Ethridge pointed out. "We're working on a smaller power type demonstration."
Most scientists agree that the current Martian climate remains too cold for water to exist in liquid form. Still, some hold out the chance for flowing water somewhere underground, perhaps in the form of hot springs.
"I think that's the big discovery yet to be made that's going to enable humans to go to Mars and sink a well," Smith said.
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