Tiny rock-eating microbes could minepreciousextraterrestrial resources from Mars and pave the way for the firsthumancolonists. Just don't expect them to transform the Red Planet's surfaceinto anew Earth on a short deadline, researchers say.
One of the most promising planetarycolonizers comes in theform of cyanobacteria. The ancient bacteria helped createahabitable Earth with oxygen at least 2.5 billion years ago,and have sincecolonized practically every possible environment while relying uponphotosynthesis to convert sunlight into energy.
Cyanobacteria and other rock-dwellingmicrobes also haveproven that they can survive the hard vacuum of space aboard facilitiessuch asEurope's BIOPAN exposure platform and the International Space Station'sEXPOSEplatform. Only the harshspace radiation in low Earth-orbit presents alife-threatening problem forthe hardy organisms.
"They?re quite capable of toleratingextremeconditions," said Charles Cockell, a geomicrobiologist at The OpenUniversity in the UK. "But we were surprised at their abilities totolerate some conditions such as vacuum."
Fortunately, cyanobacteria won't haveto endure quite suchharsh conditions on Mars.
Mining extraterrestrial rocks
We already use microbes to helpextract materials on Earth,including over 25 percent of the world's copper supply. Microbes couldserve asimilar purpose on other planets to mine resources, save on rocket fuelneededto launch such resources from Earth, and perhaps make a human base moreself-sustaining, Cockell said. [Gallery:Future Mars Bases]
He and a colleague, KarenOlsson-Francis, first wanted tosee how well cyanobacteria could deal with rocks found on the Moon andMars.They tested several types of cyanobacteria for a study detailed in theAugustissue of the journal Planetary and Space Science.
A microbe known as Anabaenacylindrica stood out asthe clear winner on all different rock types, including those with bothhighand low silica content. It also survived up to 28 days of exposure todryconditions under the Mars scenario.
But the silica content in the rocksmade a big difference inthe growth rates of all the cyanobacteria types ? rhyolite rock withhighersilica content slowed growth significantly. The high silica contentalsohampered the ability of the microbes to break down the rock and releaseusefulelements or nutrients.
Still, the microbes did fine breakingdown basaltic rocksimilar to volcanic rock on the moon and Mars, as well as anorthositerocksimilar to lunar regolith. That suggests cyanobacteria could work wellalongsideplants for in-situ resource utilization on extraterrestrial surfaces.
"Humanity has been completely linkedinto the microbialworld, so it?s logical we would continue that relationship withmicrobes as wego into space," Cockell said. "The question is how we can mostproductively optimize them going into space."
Surviving the surface
Cockell pointed out other waysmicrobes can help open upspace as a new frontier, in a review for the August issue of TrendsinMicrobiology
Some microbes can make oxidized ironfrom reduced iron inpyrite ore, and also create sulfuric acid that further breaks downrock. Oneacid-loving, iron-oxidizing microbe proved capable of perhaps usingmaterialfrom a Murchison meteorite, according to a 2009 study by Gronstal andcolleagues.
Microbes might even help deal withthe menace of lunar dustor Martiandust storms to humans and robots alike. A 2008 study by Liuand colleaguesshowed how artificially seeding the desert sands of Inner Mongolia withcyanobacteria created a strong crust within 15 days. Such crusts alsoprovedcapable of surviving wind that reached speeds of almost 33 feet persecond (10meters per second).
Researchers also have begunexperimenting with microbialfuel cells that might someday help produce methane fuel from carbondioxide andhydrogen on the Martian surface.
But none of this marvelous microbialactivity would likely takeplace under exposed surface conditions on the moon or Mars. Instead,themicrobes would do their work inside protected bioreactors or similarfacilities,Cockell explained.
"I suspect you could use them undergreenhouseconditions,? Cockell said. He added that some slow-growing varieties ofcyanobacteria had trouble even under optimal lab conditions.
Changing the surface
That word of warning may seem to puta damper on hopes thatmicrobes could become the vanguard for transforming Mars into a lushgreen andblue planet. But researchers still have tried to envision how microbescouldhelp terraformthe Red Planet.
Humans might first need to push Marsinto a state known asecopoesis. Geoengineering might help raise the surface temperature by60degrees C so that liquid water can exist once more on the Martiansurface, aswell as thicken the atmosphere and reduce the amount of ultravioletradiationand cosmic rays that reach the surface.
But Cockell remained cautious aboutthe likelihood thatmicrobes could make Mars habitable for humans in a relatively shortperiod oftime.
"Terraforming is more difficultbecause you?re tryingto change planetary conditions on a short timescale," Cockell pointedout."It took hundreds of millions of years to do it on Earth."
That doesn't mean humans might notengineer a super-varietyof microbe that might do the trick down the line, Cockell said. But hisinterest remains focused on the more practical application ofharvestingresources, and continuing to test how well different microbes deal withthewide variety of extraterrestrial rocks.
Another exciting possibility mayarise from how wellmicrobes cooperate together on doing their job.
"One thing we really don?t understandis whether we canuse a community of organisms to improve extraction from rocks," Cockellsaid.