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Life in Space: Genome Hunters Go After Martian DNA To Find Extraterrestrial Life (using Deep Sequencing Methods)

Life in Space: Genome Hunters Go After Martian DNA To Find Extraterrestrial Life (using Deep Sequencing Methods) | The Cosmos | Scoop.it
J. Craig Venter may have just started a race to discover alien life on the Red Planet.

 

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 his company, Synthetic Genomics, would develop a machine capable of sequencing and beaming back DNA data from the planet.

 

Separately, Jonathan Rothberg, founder of Ion Torrent, a DNA sequencing company, is collaborating on an effort to equip his company's "Personal Genome Machine" for a similar task. "We want to make sure an Ion Torrent goes to Mars," Rothberg said.

 

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. "There will be DNA life forms there," Venter predicted, "you just need the right tools to look for them". Venter said researchers working with him have already begun tests at a Mars-like 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.

 

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 extraterrestrial 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 three 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."

 

"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.

 

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 four billion years ago, the two bodies exchanged about a billion tons of rocks and debris. So far, NASA researchers have searched Mars for traces of water—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. Sending a DNA sequencer to Mars would be a "high-risk, high-payoff" experiment. It might very well find nothing, but if DNA were discovered, that would provide nearly irrefutable proof of extraterrestrial life.


Via Dr. Stefan Gruenwald
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Panspermia - could alien life forms have landed on Earth and evolved into life as we know it?

Panspermia - could alien life forms have landed on Earth and evolved into life as we know it? | The Cosmos | Scoop.it

We know a lot about the history of life on Earth, but how it began is still one of our greatest scientific mysteries. One hypothesis is that life actually originated on another planet, and many scientists today take the idea quite seriously. Though it sounds like the plot from recent scifi movie Prometheus, it's an old idea that even the celebrated nineteenth century physicist Lord Kelvin and Nobel winning geneticist Francis Crick have advocated. That's right — the evolution of life might have its beginnings on another planet.

 

Over 120 years ago, Kelvin shocked the British scientific community in a speech about what he called "panspermia," where he suggested that life might have come from planets smashing into each other and sending bits of life hurtling through space. He and a few colleagues had hit upon this notion after observing the massive 1880 eruption of a volcano on Krakatoa. To be more precise, they observed the aftermath of the volcano, which completely sterilized the island. No life was left at all. But then, within months, seedlings began to sprout and life took hold again.

 

Cal Tech geologist Joe Kirschvink has suggested that Mars is a likely origin for life in the solar system because it would have been habitable long before Earth was. 4 billion years ago, when Earth was still a roiling cauldron of methane and magma, Mars was a stable, cool planet covered in vast oceans. It would have been the perfect place for microbial life to take hold. But how did that life make it all the way from the seas of Mars to the seas of Earth? Most likely, meteorites crashing into Mars would send fragments of the planet's surface back into space — packed with millions of microbes. In fact, around the time that Mars might have been developing life, the solar system was undergoing what astronomers call the "late heavy bombardment," a time of countless intense meteorite strikes.

 

Purdue geologist Melosh, who has spent most of his career studying meteorite impacts, has actually done experiments where he and a team recreated what might have happened when meteorites slammed into Mars billions of years ago, sending ejecta out of the atmosphere and eventually all the way to Earth. This process is sometimes called "ballistic panspermia," or "lithopanspermia," because it depends on rocks being ejected into space. To recreate one part of this process in their experiments, Melosh and his team shot a bacteria-covered rock with an aluminum projectile moving at 5.4 km per second, and the shattered chunks flew over a kilometer. The bacteria survived the trauma of what Melosh and his team called "extremes of compressional shock, heating, and acceleration. A lot of the microbe species actually die, but a lot also survive in a dormant state. In space, their journey would take possibly millions of years. But it's as if atmospheres are almost designed for this transfer of life. The meteorite comes from Mars, full of microbes protected from radiation by the rock. It enters Earth's atmosphere, and as it comes in at high speed the outside melts because of friction and gets hot, but the inside is protected just like a spacecraft capsule. The microbes inside are protected. Then the aerodynamic forces in the lower atmosphere fracture the meteorite, exposing the interior."

 

A big question is why scientists are entertaining this idea at all? NASA planetary scientist Chris McKay offered a terrific, point-by-point explanation of why panspermia is, as he put it, "a valid scientific hypothesis" worth taking seriously:

 

1. The geological evidence for the earliest life on Earth is very early, soon after the end of the late bombardment. There is good evidence for life on Earth at 3.5 billion years ago, indirect evidence at 3.8 billion. The end of the late heavy bombardment is 3.8 billion years ago.

 

2. The genetic evidence indicates that the last universal common ancestor (LUCA) of life could have been roughly 3.5 billion years ago (but with large uncertainties) and that LUCA was a fairly sophisticated life form in terms of metabolic and genetic capabilities. 1 and 2 together give the impression that life appeared on Earth soon after the formation of suitable environments and it appears to have come in being remarkably developed - like Athena born fully formed from the head of Zeus.

 

3. Rocks from Mars have traveled to Earth and the internal temperatures experienced in these rocks during this trip would not have sterilized the interiors. Thus in principle life can be carried from Mars to Earth.

 

4. Mars did not suffer the large Moon-forming impact that would have been detrimental to the early development of life on Earth. 3 and 4 have lead to the suggestion that Mars would have been a better place for life to start in the early Solar System and it could have then been carried to Earth via meteorites.

 

5. Organic molecules are widespread in comets, asteroids, and the interstellar medium.

 

6. Comets could have supported subsurface liquid water environments soon after their formation due to internal heating by decay of radioactive aluminum.

 

7. As comets move past the Earth they shed dust which settles into Earth's atmosphere. 5, 6 and 7 have lead to the suggestion that life could have started in the interstellar medium or in small bodies such as comets and then been carried to the Earth by comet dust.

 

So, yes panspermia is a valid scientific hypotheses and warrants further investigation.


Via Dr. Stefan Gruenwald
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