Craig Venter helped crack the human genome, created the first synthetic cell and has scoured the sea for novel genomes. Now he has set his sights on Mars.
As first reported, earlier this week at the in New York, in order to sequence the genome of alien life that may be there. He鈥檚 not the first to suggest doing this. Do any of these missions stand a chance?
How will Venter鈥檚 scheme work?
In short, he wants to send machinery to Mars that can robotically sift through Martian soil to isolate any microbes it contains, sequence their DNA and then beam the digitised results back to Earth. These would be used to create a synthetic version of the Martian genome, which could then be used to recreate Martian life on Earth 鈥� all without having to deal with the difficulties of actually bringing the sample back.
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How far along are the plans?
Venter has been scooping DNA from seawater for a number of years, with some interesting results. At Wired Health, he said that similar technologies are beginning to be tested at a Mars-like site in the Mojave Desert in California, as a prelude to a Martian mission. The next planned landing is NASA鈥檚 InSight mission, scheduled to launch in 2016.
Assuming we can get a gene sequencer to Mars, what are the chances that it will discover life in the soil?
Venter is unequivocal: 鈥淭here will be DNA life forms there,鈥� he said at the conference. NASA鈥檚 1976 Viking mission failed to find any evidence that there are or ever were 鈥� but some dispute that. Even if Mars鈥� surface is barren, though, recent surprising discoveries of life deep below Earth鈥檚 surface 鈥� some of it apparently surviving independently of the sun鈥檚 energy 鈥� suggest that Mars鈥檚 rocky interior might contain life.
Venter is certain that subsurface is the best place to seek DNA on Mars: 鈥淟ife discovery will have to wait until we can drill beyond the surface.鈥� On Earth, life goes a long way down 鈥� to at least 3.6 kilometres.
What about past life?
This month鈥檚 discovery of an ancient riverbed on Mars has certainly got astrobiologists excited. The find, by NASA鈥檚 Curiosity rover, suggests habitable environments once existed on the planet. However, the river probably dried up several billion years ago, according to the Curiosity team 鈥� too long for any DNA from that era to have survived.
Earlier this month, biologists established that DNA has a half-life 鈥� it breaks down at a roughly predictable rate. Even if conditions are ideal for its preservation, measurable quantities should all but have disappeared 1.5 million years after an organism鈥檚 death.
So are extinct Martians out of the hunt?
No. A team at the Massachusetts Institute of Technology is also building a sequencer called (Search for Extraterrestrial Genomes), that will search for DNA or RNA from past or present life. 鈥淲e鈥檇 be looking for something that鈥檚 alive or recently dead,鈥� says team member 鈥� although he is using 鈥渞ecently鈥� in the geological sense, so could go back as far as a million years. The team has been working on the device for about seven years.
The current incarnation uses a chip built by the company . The team is already testing parts of SETG in the field. They have brought it to an active volcano in Argentina that is chemically similar to Mars, and they plan to return there in January.
Might DNA survive longer on Mars than on Earth?
It鈥檚 possible, says at the University of Copenhagen, Denmark, who led the DNA half-life study. Conditions on Mars are very different from those on Earth, he says. The surface of Mars is bombarded with radiation, for instance, which could accelerate the break down of DNA in Martian soil. 鈥淗owever, with its dry and cold environment, one could speculate that post-mortem DNA would generally last longer on Mars than on Earth.鈥�
Allentoft鈥檚 team found that DNA decay rates accelerate in the presence of water and oxygen, so the apparent absence of both from the surface of Mars 鈥� at least in the recent past 鈥� could be a bonus for Venter鈥檚 DNA hunt. 鈥淚t really is just speculation though,鈥� Allentoft cautions.
There鈥檚 bad news too. The assumption is that Martian life is, or was, microbial. 鈥淎ny Martian DNA would not be preserved inside hard tissue but in small cells or as fragments of free DNA,鈥� says Allentoft. Without the protective environment provided by bone or teeth, DNA degrades much faster, he says.
All these plans assume Martian life is built on a DNA blueprint. If it is, that may add strength to the argument that life on Earth originated on Mars or that life arrived on both planets from meteorites or comets. But it鈥檚 also possible that Martian life has a different blueprint.
Is Venter a visionary?
鈥淗e seems to be very certain that there鈥檚 DNA there,鈥� says Carr. 鈥淭hat鈥檚 actually really concerning to me鈥揑 think there鈥檚 a good case for why we would do this, but it makes the effort seem more 鈥榝ringe鈥� by having certainty.鈥� He adds: 鈥淲e think there鈥檚 a good chance that it鈥檚 there, and I definitely think we should be looking for it.鈥�
