November 4, 2010 weblog
Scientists to test if life on Mars could be related to life on Earth
Over the course of the Earth's history, about a billion tons of rocks have been exchanged between the Earth and Mars. Scientists think it's possible that one or more of those rocks might have contained tiny microbes that successfully made the journey from one planet to the other. In 2018, they plan to test this hypothesis by searching for Earthling-like DNA under Mars' surface.
The NASA-funded project, called the Search for Extraterrestrial Genomes (SETG), is being undertaken by MIT scientists including engineer and scientist Christopher Carr. The researchers are designing a device that can detect and identify nucleic acids, whether they be in Martian ice, brine, or soil. Although any organic material on the surface would likely have been destroyed by ultraviolet rays and radiation, DNA hidden underground could remain viable for about one million years, the scientists estimate.
While most scientists expect organic materials to be on Mars, it's more difficult to predict what exactly those materials might be. In the SETG project, the researchers are focusing on specific genes that are fairly common in life on Earth. If there is DNA or RNA on Mars similar to that on Earth, then the new device should be able to find it.
"We would feel awfully silly if we spent a lot of time looking for something that was very different and didn't spend time looking for something that was very similar," Carr said. "Life could have arisen independently, but that is not the most likely scenario."
In two years, the researchers plan to test the DNA-detecting technology on Earth in locations including the Atacama Desert in Chile and in the cold, dry valleys of Antarctica, where the conditions are similar to those on Mars. Then they plan to fly the device on a joint NASA-ESA mission to Mars, projected to launch in 2018.
via Discovery News
© 2010 PhysOrg.com
User comments
When (and if) they confirm the existence of squid and urchin or other similar fossils on Mars, they will be at a loss to explain this parallel evolution. Evolution doesn't happen that way - you don't start with similar microbes and end up with identical species on two different worlds. Evolution means random variation in response to environmental conditions, and parallelism is NOT the rule. That's basic Darwin stuff. Variation is the rule, increasing over time.
The amazing conclusion must be that these amazingly durable sea creatures evolved on Mars (Notice how they can survive large pressure gradients?) and were transplanted to Earth by some other intelligence when Mars began to die.
Evolution doesn't prevent parallel phenotypes. Look at the Hyena (which is a feliform) and the Lycaon pictus (which is a caniform).
Second, would you like to tell us where you get the idea that they'll find encephalopodia on Mars?
Who said they're going to find anything other than potentially just DNA? Are you, mistakenly, replying to some other story on Physorg, by chance?
While parallelism in evolution is possible, The Hyena / Lycaon pictus example you describe is marginal, superficial and by no means the norm between species.
I'm getting this thought from an image of a possible squid fossil that was floating around the internet a few years back. It was about 3 cm long and in one of the rocks images taken by the rovers. It wasn't 100% certain, but I am willing to bet on Martian sea life. Here's a link:
http://www.xenote...65a2.jpg
Relax guys, it's just speculation right now. But it's intriguing.
Mars' surface is extremely hostile to current life (at least life from Earth). For starters, the surface is too cold and dry: any water-based (Earth) microbe would be instantly dessicated. The surface is also strongly reactive (has peroxides and other neat stuff mixed in with the top soil), which makes it act like a natural microbicide. Lastly, as mentioned in the article above, the surface is bathed in UV and cosmic rays, due to the ultra-thin atmosphere and lack of a strong planetary magnetosphere, respectively. Whatever microbes hitched a ride on one of the Mars probes, it's unlikely they survived, never mind thrived and spread, on Mars' modern surface.
Things might have been different in the very distant past, when Mars was warmer and wetter, had a thicker atmosphere, and perhaps a planetary magnetosphere as well. So what they'll be looking for is fossil DNA, or perhaps subterranean Martian life that might show up in "recently" active hot springs...
Ever read about the extremophiles they've found on earth, pretty much everywhere they looked, even where they thought life would not be possible. Miles underground, with no light or oxygen, in steam vents, in boiling hot water, in heavily acidic water, below freezing, ones that eat sulfur or don't need water, etc, et al. Microbes in one experiment were still alive 553 days later after being put OUTSIDE the space station, with more UV and cosmic rays than they'd get on Mars, at near absolute zero in the vacuum of space. And you say they'd all die on Mars?
Life has proven to be amazingly versatile and hardy, and seems to survive pretty much anywhere and everywhere.
Getting freeze-dried for a few hundred days, and then revived once put into warm/wet conditions, isn't quite the same thing as actively spreading and thriving.
Moreover, even the space station resides in low-Earth orbit, well inside the magnetosphere and well beneath the deadly Van Allen radiation belts.
Lastly, those microbes exposed to the vacuum weren't simultaneously being exposed to strongly oxidizing agents. Oh, and I doubt they were "near absolute zero", either. If they ever spent time in direct sunlight, they would've been heated up to hundreds of degrees K...
Yes, there is a possibility of surviving subterranean/extremophile life on Mars. I do believe I mentioned that in my previous post...
So if they were in sunlight and heated up to hundreds of degrees K, then when the space station was on the night side, they would be plunged again to nearly absolute zero, over and over again 15.7 times a day for 553 days. Seems even more extreme than straight "freeze-drying", non? (Unless the orbit is such that it is in constant sunlight; couldn't find the info easily on-line.)
And I never said that Earth bacteria could survive on the surface of Mars, but it is pretty well accepted that there is water not far below the surface in many places on Mars.
I don't think I said "absolute zero" just near it, which space certainly is.
I really don't think we're far apart on the possibility of life existing on Mars. I was only concerned about the potential for contamination of the tests for life from the next rover by our own prior probes.
There's an interesting article today on this site that discusses some of these issues in regards to another extreme earthly environment, previous thought to be dead but which surprised scientists with the biodiversity, deep underground in deep water. http://www.physor...ean.html
As to water on Mars, it's believed they found liquid water condensing on the legs of the Phoenix lander, and IIRC, spotted some frozen surface water in craters. The methane mystery still exists too.
Anyway you cut it, it's going to be an exciting decade for astronomy (assuming we don't discover how to wipe ourselves out first.)
http://science.na...marsice/
I don't think anybody disputes existence of water ice on Mars. I'm just saying that life can at best be preserved in ice, but it cannot thrive in ice. Life needs actual liquid water -- or at least conditions allowing for liquid water (even if it's full of antifreeze.)
That (and other reasons mentioned previously) is why I'm personally not worried about probes from Earth accidentally inoculating Mars' surface with life, which might be confused for native life by future probes. IMO, the odds are astronomically against such an eventuality.
Controversial, yes, but read it anyway.
First, they're suggesting high concentrations of perchlorate as antifreeze agent. They do mention that perchlorate is toxic to earth life. So here again, you have a natural microbicide in plentiful abundance at the surface.
And of course, there is still no confirmation that what they're seeing is in fact water (with or without any additives), or that it's in a liquid state.
Main explosive in many landmines. I found that out when I checked when someone said they could make explosives with a particular household chemical. Thought it couldn't be done. Wrong. Dangerous but not as dangerous as playing with the ingredients for high explosives.
I don't think life from Earth is likely to be able survive on Mars. The thing is that the extremophiles that MIGHT be able to handle the cold, dry, oxygen free air are kind of fragile in comparison the stuff that collects on pretty much everything. They can't compete against most of the other bacteria in normal Earth environments.
Thus leaving the stuff a little contaminated with non-extreme life might keep the extreme stuff from getting a foothold on the vehicle before launch.
Ethelred
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