Archive for martian conditions

Genome Hunters Go after Martian DNA

Two high-profile entrepreneurs say they want to put a DNA sequencing machine on the surface of Mars in a bid to prove the existence of extraterrestrial life.

In what could become a race for the first extraterrestrial genome, researcher J. Craig Venter said Tuesday that his Maryland academic institute and company, Sythentic Genomics, would develop a machine capable of sequencing and beaming back DNA data from Mars.

Separately, Jonathan Rothberg, founder of Ion Torrent, a DNA sequencing company, is collaborating on an effort to adapt his company’s “Personal Genome Machine” for Martian conditions.

<!–

Story continues below

–>


“We want to make sure an Ion Torrent goes to Mars,” Rothberg told Technology Review.

Although neither team yet has a berth on Mars rocket, their plans reflect the belief that the simplest way to prove there is life on Mars is to send a DNA sequencing machine to the planet.

“There will be DNA life forms there,” Venter predicted Tuesday in New York, where he was speaking at the Wired Health Conference.

Venter said researchers working with him have already begun tests at a Mars-like test site in the Mojave Desert. Their goal, he said, is to demonstrate a machine capable of autonomously isolating microbes from soil, sequencing their DNA, and then transmitting the information to a remote computer, as would be required on an unmanned Mars mission. (Hear his comments in this video, starting at 00:11:01). Heather Kowalski, a spokeswoman for Venter, confirmed the existence of the project, but also said the prototype system was “not yet 100 percent robotic.”

Meanwhile, Rothberg’s Personal Genome Machine is being adapted for Martian conditions as part of a NASA-funded project at Harvard and MIT called SET-G, or “the search for extra-terrestrial genomes.”

Christopher Carr, an MIT research scientist involved in the effort, says his lab is working to shrink Ion Torrent’s machine from 30 kilograms down to just 3 kilograms so that it can fit on a NASA rover. Other tests, already conducted, have determined how well the device can withstand the heavy radiation it would encounter on the way to Mars.

NASA, whose Curiosity rover landed on Mars in August, won’t send another rover mission to the planet before at least 2018 (see “The Mars Rover Curiosity Marks a Technological Triumph“), and there’s no guarantee a DNA sequencing device would go aboard. “The hard thing about getting to Mars is hitting the NASA specifications,” says George Church, a Harvard University researcher and a senior member of the SET-G team. “[Venter] isn’t ahead of anyone else.”

Many scientists are lobbying NASA for what’s called a “sample return” mission–one that would make a round trip, bringing back soil and rocks for analysis. However, taking a DNA sequencing machine to Mars could be a better way to search for life.

“The reason to take a device all the way to Mars, and not bring back the sample, is because of contamination. No one would believe you,” says Tessi Kanavarioti, a chemist who carried out early theoretical work on Martian biology and was involved in studying rocks brought back from the moon in the 1970s. Sequencing machines are so sensitive that if a single Earth germ landed on the sample returned from Mars, it might ruin the experiment.

Martian chronicler: A micro-fluidic device developed at MIT designed to automatically run DNA experiments on other planets.
Credit: Christopher Carr | MIT

Looking for DNA on Mars won’t be easy. A robot would have to scoop up soil and prepare a sample automatically. The sequencing machine would need to work in cold temperatures and in a very thin atmosphere made mostly of CO2.Martian genes might also be different from those in the bodies of terrestrial animals, perhaps being made up of different chemical building blocks.

“This will work only if the DNA on Mars is exactly the same in its fundamental structure as on Earth,” says Steven Benner, president of the Foundation for Applied Molecular Evolution in Gainesville, Florida. He says he’s skeptical that will be the case. “It is very unlikely that Terran DNA is the only structure able to support Darwinian evolution.”

Discovering and sequencing extraterrestrial life would be an immense scientific prize. Sequencing could reveal whether life evolved in similar ways on both Earth and Mars or, perhaps, moved between the planets. During a series of massive space collisions around 4 billion years ago, the two bodies exchanged about a billion tons of rocks and debris.

So far, NASA researchers have looked for traces of water on Mars—a prerequisite for life as we know it—as well as indirect signs that life might have existed there many eons ago. Since DNA molecules don’t survive more than a million years, even on Earth, anyone sending a DNA sequencer to Mars has to believe that living microorganisms will be found there now.

“The current NASA approach is to look for past life. Many people are reticent to talk about extant life,” says Carr. “We are sticking out necks out a little bit, but we want to take that leap.”

Life probably can’t survive on the Martian surface due to radiation, but it could exist under a meter or more of soil, where it would be protected. On Earth, for instance, living microorganisms are found several kilometers beneath the ground.

Carr calls sending a DNA sequencer to Mars a “high risk, high payoff” experiment. While it might find nothing, if DNA were discovered, that would provide nearly irrefutable proof of extraterrestrial life.

The slim odds apparently appeal to both Venter and Rothberg, two of biotechnology’s biggest showmen. A decade ago, Venter gave academic researchers heartburn with his privately-financed effort to sequence the human genome. Rothberg, also a media celebrity, has made news by sequencing the DNA of notables like James Watson, as well as of Neanderthals.

“We want our name out there. [Mars] is a corporate opportunity, but we think our technology is faster and better, too,” says Rothberg.

In an email, Venter’s spokeswoman downplayed the idea of any competition to discover extraterrestrial DNA first. “[I] wouldn’t say there is any race” to go after Martian life, Kowalski says. ”Yes [the] idea is that we would do it, but that certainly doesn’t preclude anyone else from doing it,” she said.

Venter also said it might be feasible in the future to reconstruct Martian organisms in a super-secure laboratory on Earth, using just their DNA sequence. The idea would be to use the DNA data to rebuild their genomes, then inject those into an artificial cell of some kind. It’s an idea he calls the “biological teleporter.”

“People are worried about the Andromeda strain,” says Venter. “We can rebuild the Martians in a P-4 spacesuit lab, instead of having them land in the ocean.”

Article source: http://www.technologyreview.com/news/429662/genome-hunters-go-after-martian-dna/

Tags: , , , , , , <BR/>

Microbe Risk When Rover Wheels Hit Martian Dirt


Earth microbes trying to make it to Mars must survive sterilization in NASA’s clean rooms, harsh cosmic rays during months of space travel, and the Red Planet’s unforgiving surface environment. But any bacteria that successfully hitchhike aboard the wheels of NASA’s Mars Science Laboratory mission in 2012 might manage to scratch out a brief existence on the martian surface.

The finding comes from a study that examined how the new high-tech landing technique of the Mars Science Laboratory (MSL) may affect the risk of contaminating Mars. The mission will use both a parachute and downward-firing thruster rockets to slow its descent so that its “sky crane” can lower the SUV-sized Curiosity rover onto the surface — a direct touchdown that may give microbes a brief chance to experience life on Mars.
That translates into a higher risk of contamination when compared to some past Mars rover missions, said Andrew C. Schuerger, a microbiologist at the University of Florida and the Space Life Sciences Lab at NASA’s Kennedy Space Center in Florida. But he added that microbes still face tough odds for surviving space travel and martian conditions.

“Although this paper suggests we could be transferring bacteria to martian surface, we don’t know for certain yet,” Schuerger said. “We could very well be losing most due to the exposure to vacuum in space, cosmic rays and hard radiation. Even if cells are present on a rover wheel at launch, they might be dead by the time they get to Mars.”

Standing still

Schuerger and his colleague, Krystal Kerney, wanted to find out whether the wheels of Mars rovers past and future could contaminate the martian surface. They ran two experiments simulating the contamination possibilities for MSL versus the Mars Pathfinder mission of 1997 and the Mars Exploration Rovers (MER) that landed on the red planet in 2004.

The Mars Pathfinder rover, called Sojourner, sat on a landing platform for 2 martian days before rolling onto the surface. The twin MER rovers, Spirit and Opportunity, sat on their landing platforms for 12 and 7 martian days, respectively. Each martian day is just a little over 24 hours.

In the recent study, researchers simulated a Mars rover sitting on a landing platform for 1, 3 and 6 hours while being exposed to martian levels of ultraviolet (UV) rays. Even such short amounts of time killed between 81 percent and 96.6 percent of the Bacillus subtilis bacteria used in the experiment.

“We did very short UV exposures, and even there we see 96 percent [of bacteria killed] over 6 hours,” Schuerger told Astrobiology Magazine. “That’s a very dramatic and a very positive sign that a rover wheel which sits on a platform, like MER did, has a much better chance of being sterilized prior to roll-off than a direct to ground system.”

The number of survivors would likely have dropped to practically zero if the experiment had run for 7 or 12 days, Schuerger said.

Rolling in the dirt

By contrast, the second experiment simulated how a rover wheel in the future MSL mission would immediately come into contact with the martian surface. When the contaminated rover wheel rolled over the simulated surface, about 31.7 percent of the surface samples ended up showing bacterial growth.

But the contamination level dropped by 50 percent after 24 hours of exposure to simulated Mars conditions, such as UV radiation, low pressure, low temperature and high levels of carbon dioxide. The results pointed once again to the harshness of the martian surface environment for Earth life.

The second experiment doesn’t say anything definitive about the real risk of contamination, Schuerger warned. For instance, it didn’t test whether having multiple wheels rolling over the same surface area could bury microbes from the first wheel beneath the martian surface. It also didn’t simulate the weight of the SUV-sized Curiosity rover that could mash even more microbes into the ground.

On the other hand, the researchers contaminated the rover wheels with perhaps 100,000 times more bacteria compared to what would realistically exist during any of the Mars rover missions. Some Mars rovers get sterilized three or four times, Schuerger said. He added that the journey through space may kill 75 percent of whatever survived after launch.

The next test

What the experiments do suggest is that just having the Curiosity rover sit still for a number of days could help kill off much of the bacteria clinging to its wheels. But the researchers still have questions to answer.
“We need to repeat these experiments with much longer time exposures to martian conditions to see if we can get to a rover wheel completely sterilized sitting on a landing pad,” Schuerger explained. “We also need to see if 7 or 8 martian days would essentially get to zero amount of survivors, even if we accidentally transferred bacterial spores to the surface.”

Such contamination experiments could be done more easily once humans establish a Mars colony and can work alongside their robotic rovers, Schuerger said. But for now, he will have to make do with small Mars simulation chambers on Earth.

The study was detailed in the June 2011 issue of journal Astrobiology.

Article source: http://www.astrobio.net/index.php?option=com_exclusive&task=detail&id=4196

Tags: , , , , , <BR/>