Countering contamination for Mars spacesuits

Jun 16, 2011 By Jeremy Hsu
Countering contamination for Mars spacesuits
Aouda.X, a spacesuit mockup, was tested with the Long Term Medical Survey System (LTMS) in Mars-like terrain of Spain's Rio Tinto in April 2011. Credit: ESA

To search for life on Mars, future astronauts would naturally want to step outside their living habitat for a walk. But the spacesuits keeping them alive might also carry Earth microbes or ingredients of life that could contaminate the red planet and complicate the search for extraterrestrial life.

That danger has driven scientists to simulate the contamination risks. Tiny fluorescent tracers stood in for microbes during mock Mars missions with simulators in the San Rafael desert of Utah. Simply shining a on the spacesuits allowed the researchers to detect levels of contamination based on the fluorescent response.

Such tests may help ensure that contamination risks do not "endanger the entire science of searching for life on Mars," according to Gernot Groemer, president of the Austrian Space Forum and lead researcher on the contamination experiments.

"As long as we have no clue about the potential contamination vectors, we would jeopardize the pristine [quality] of the samples," Groemer said.

Beyond contamination risks, Groemer and his international team also considered how a spacesuit might rid itself of the Martian dust that might carry such contamination. The experiments took place during the Austrian Space Forum's PolAres program that runs from 2007-2012.

Turn on the glow

Scientists have used L.I.F.E. (laser-induced fluorescence emission) techniques to search for microbes locked in the ice of Antarctica. They have also used L.I.F.E. to simulate how rovers might search for on Mars during tests in Death Valley, according to Michael Storrie-Lombardi, an who heads the Kinohi Institute in California.

Tiny spherical crystals, called microspherules, glow a fluorescent orange when a green laser pointer shines on them. Researchers used the the crystals to simulate possible contamination by microbes during Mars simulations in the Utah desert. The left image shows a soil sample, while the right shows the same sample under a laser beam. Microspherules show up as white dots in the right panel. Credit: Groemer et al.

"The technique can be implemented with a laser pointer and an iPhone," Storrie-Lombardi explained. "At present, once the system is calibrated, it takes only a few seconds to process the raw data if the target is an unknown field sample."

But the latest experiments represent the first time L.I.F.E. has simulated possible contamination during a Mars mission with human astronauts.

If the laser pointers reveal a fluorescent glow, pocket digital cameras capture the images and a laptop compares the fluorescent signatures with those belonging to known organic or inorganic molecules. The latest Mars simulations only needed green laser pointers to identify the presence of the tiny bead-like crystals that served as fluorescent tracers.

The method might not only detect "forward" contamination of Mars by Earth material, but also pick up on "backward" contamination of astronauts or their spacesuits by Mars material. The Mars simulations showed that about 60 to 405 bacteria per centimeter squared could gather on a clean spacesuit within minutes.

Bust the dust

Detecting contamination may prove easier than guarding against it. can ride along with the Martian dust that would cling to spacesuits due to the electrostatic forces between dust grains. Vibration equipment failed to shake off the tiny dust particles during the Mars simulation.

Instead, future astronauts on Mars might have to step inside an airlock, plug the spacesuit into a high-voltage connector, and push a button. The electric charge could levitate the remaining dust off the suit so that an air jet might blow the dust away like cigarette smoke, Groemer told Astrobiology Magazine.

Spacesuit testing in Death Valley could help us reach for the stars. Credit: Dan Duriscoe / U.S. National Park Service

Such "dust-buster" technology could also have the side benefit of protecting astronauts from breathing in inside their living habitat.

Still, scientists worry most about the risk of Earth material contaminating Martian samples.

"The challenge is that if we find something astrobiologically or geochemically stunning on Mars we really have to be sure it is indigenous and not a hitchhiker," Storrie-Lombardi said.

Of robots and spacesuits

Conducting scientific field tests in a bulky spacesuit can be difficult. In this image, Margarita Marinova tries to operate a Geiger counter while wearing a spacesuit in Antarctica. Credit: Jon Rask

Future robotic rovers may use the same fluorescent detection methods to focus on searching for extraterrestrial ingredients of life.

The ExoMars rover, slated for launch in 2018, may carry along a panoramic camera. Several of the camera's filters could detect the fluorescent signatures from the most common polycyclic aromatic hydrocarbons found in Mars meteorites. Such molecules may have served as a key building block for life on Earth.

"We have already published a simulation study for such an experiment and a laser prototype has passed initial ESA engineering review," Storrie-Lombardi said.

Scientists also hope to continue studying possible contamination risks with the Aouda.X spacesuit simulator used in the simulations. The 99-pound (45-kg) suit gives users the sensation of jogging inside a full SCUBA diving suit.

The constant hum of the life support system reminds spacesuit users that they are wearing a "living" machine designed to help keep them alive, according to Groemer.

"You feel like a turtle in its shell; safe and protected against the environment," Groemer said. "And no matter how many EVA (extra-vehicular activity) hours you have experienced, you get the sense of doing something extraordinary with a strong sense of purpose and dedication."

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Peteri
3 / 5 (2) Jun 16, 2011
Until we have used robotic explorers to provide definitive proof that there's no native (microbial) life on Mars, we should refrain from any costly manned missions to the planet.

To prematurely send humans to the only other terrestrial planet in our solar system which might harbour extra-terrestrial life and risk contamination of its near pristine environment with terrestrial organisms would be an unforgivable act of vandalism.

Don't get me wrong - I am all for the manned exploration of Mars in the long term. However, no bio-containment system is 100% foolproof and the bacteria and fungi accompanying human explorers are bound to be inadvertently released into the Martian environment either by accident or by carelessness.

The fact that early Martian probes were not 100% sterile is hopefully not going to have any widespread impact as the number of bacterial or fungal spores present would be relatively small. But humans, on the other hand, are teeming with microbial life!
Scientist_Steve
1 / 5 (1) Jun 16, 2011
@Peteri
I hear ya. Although in my mind the biggest concern of ours shouldn't necessarily be contamination with OUR microbial life (except that it would inhibit the search for ET), as much as the potential to bring back extraterrestial microbes to our own planet unknowingly.
Sinister1811
1 / 5 (6) Jun 17, 2011
@Peteri - I think it's highly unlikely that any microbes are present on Mars. Think about it - if there are microbes living in the soil, or whatever, why wouldn't those microbes have eventually evolved to colonize every aspect of the planet like they have done on the Earth? Why wouldn't those micro-organisms have eventually clumped together and evolved into multi-cellular organisms? Not only is there no proof of life on Mars, there isn't any detectable signature of it. Unless microbes only recently have established themselves on Mars. They might have survived the ride, when we sent rovers there.
Peteri
5 / 5 (2) Jun 17, 2011
Sinister1811: I suspect that in the early history of Mars, when it had a thicker atmosphere and abundant surface water, microbial life - had it evolved - would have been widespread.

As the planet's interior cooled, lost its magnetic field and consequently lost most of the solar energy retaining atmosphere, water became trapped as deep permafrost. The conditions under which even the hardiest of extremophile-type microbial life could survive became increasingly restricted to a subsurface environment.

Subsurface life on Mars could still be holding out in liquid water layers where the residual heat from the interior of Mars warms the permafrost. That would be why we have so far not detected life on the harsh sterilised surface.

Life on earth was microbial for 3 Byrs before multicellular life evolved ~700 Myrs ago - the latter requiring oxygen, something that had been gradually generated by photosynthetic bacteria over 1-2 Byrs. On Mars time ran out before this could ever happen.
EWH
4 / 5 (2) Jun 17, 2011
Actually Viking did get a positive result on one of its tests for life. Unfortunately it was later learned that martian soil contains perchlorate, which would both explain the positive result while at the same time confounding the test for organic molecules, making its negative result meaningless. Water existed on Mars, and still does below the surface.

Methane has been detected by later missions and it may well be a sign of continued subsurface life.

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