NASA's Curiosity rover finds fresh signs of ingredients for life on Mars

March 24, 2015 by Amina Khan, Los Angeles Times
Curiosity Rover at the John Klein drill site where some of the samples were taken. Credit: NASA/JPL-Caltech/MSSS

Mars's life-friendly past just got friendlier. Using samples previously collected by the NASA rover Curiosity, scientists have discovered evidence of nitrates in Martian rock: nitrogen compounds that on Earth are a crucial source of nutrients for living things.

The findings, published in the journal Proceedings of the National Academy of Sciences, lend further support to the idea that the Red Planet, now barren and dry, could once have hosted habitable environments.

Although planetary scientists have been on the hunt for organic carbon - the type of carbon-containing molecules that could be used and produced by living things - nitrogen also plays an essential role in life as we know it, said lead author Jennifer Stern, a planetary geochemist at NASA Goddard Space Flight Center in Greenbelt, Md.

For example, nitrogen is a key component of nucleobases that make up RNA and DNA, and of amino acids, the building blocks of proteins.

"People want to follow the carbon, but in many ways nitrogen is just as important a nutrient for life," said Stern, a science team member for the Mars Science Laboratory mission, as Curiosity's mission is formally known. "Life runs on nitrogen as much as it runs on carbon."

So the scientists examined data from three samples processed by the Sample Analysis at Mars, or SAM, instrument, which is part of a formidable laboratory in Curiosity's belly. They looked at samples pulled from three spots near its landing site: aeolian deposits from Rocknest and mudstone deposits from John Klein and Cumberland.

These sites were all visited during a detour from Curiosity's main mission, which was to drive to Mount Sharp, the 3-mile-high mound in the middle of Gale Crater whose clay-rich layers looked like an ideal spot to search for signs of past habitable environments. Going off course was a risk, but it paid off; the John Klein and Cumberland mudstones have previously turned up a smorgasbord of chemicals and water-altered minerals that would have made it a potentially prime place for life, if it ever existed on the Red Planet. Now, this fresh analysis of the in these rocks further strengthens that idea.

The rock samples were cooked in SAM's oven and the resulting gases were analyzed. The researchers found a significant amount of , a compound that, before it was cooked, probably came from , Stern said.

"What we're detecting is nitric oxide, but we know from lab experiments that when we heat up nitrates, they break down in a predictable way," Stern said. "And that's why we think these are nitrates."

The researchers had to carefully subtract out the amount of contamination that would be coming from the rover itself, to make sure they were not getting a false signal.

When they finished, they were still left with a significant amount of nitrogen - enough to account for 110 to 300 parts per million of nitrate in the Rocknest sample, 70 to 260 parts per million in John Klein and 330 to 1,100 parts per million in Cumberland. That's comparable to the amount of nitrates you'd get in extremely dry places on Earth, such as the Atacama Desert in South America.

Nitrates are important molecules because it's easier for living things to access nitrogen and put it to work, Stern said. Nitrogen in the atmosphere is typically made of two nitrogen molecules that are triple-bonded to each other, making it a tough molecule to cut apart. Nitrates consist of a linked to three oxygen atoms with only single or double bonds, and are much easier to disassemble.

Most nitrates on Earth are produced by living things, Stern said. But in the case of Mars, the team believes the nitrates were created during a "thermal shock," such as a lightning strike or an asteroid impact.

Among the next steps, she says, is to see whether whatever process that generated these nitrates is still happening on Mars.

"We're going to try to understand whether this process is still happening today at all," Stern said, "or whether this all happened in the past in a different Mars, in a different climate regime, in a different atmosphere."

Explore further: Life on Mars? Maybe not: NASA rows back on findings

More information: Evidence for indigenous nitrogen in sedimentary and aeolian deposits from the Curiosity rover investigations at Gale crater, Mars, www.pnas.org/cgi/doi/10.1073/pnas.1420932112

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16 comments

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syndicate_51
1 / 5 (9) Mar 24, 2015
Find a fossil.
Shootist
1.6 / 5 (8) Mar 24, 2015
We're all Martians (unless we're Ceresians).
TheGhostofOtto1923
2.8 / 5 (6) Mar 24, 2015
Nitrates can be mined to support underground colonies growing their own food.
gkam
4.3 / 5 (6) Mar 24, 2015
I agree essentially with the posters above. I think the first folk might have to inhabit the caves or live in subterranean environments to avoid radiation levels, with no magnetic field at Mars.

Plants would have to be engineered for the environment and spectrum of radiance, which is weaker at Mars than the Earth, but unfiltered.
TheGhostofOtto1923
1.2 / 5 (5) Mar 24, 2015
Plants would have to be engineered
And I guess we would have to find some genuine engineers to do it wouldnt we?
gkam
5 / 5 (4) Mar 24, 2015
You certainly would.
viko_mx
1 / 5 (8) Mar 25, 2015
There will be never human mission to Mars. Just insanely impractical. But now nourish the myth to the people that humankind pace with rapid steps forward. But in reality nothing like that.

I do not know what curiosity detect on Mars and what medias are served to people. But I know that on the market there are rich variety of fruits and vegetables, which themselves never cooked dishes, and again have to touch the human hand and participate human intelligence to realize the idea for a particular dish. The spells does not work.
Torbjorn_Larsson_OM
5 / 5 (4) Mar 25, 2015
Volcanic nitrates (or rather its NO product that Curiosity found) is what the root metabolism use for oxidizer in Russell et al's emergence theory, the best tested as of yet. They appear in carbon dioxide atmospheres with ammonia volcanic outgassing. [Review in "The Drive To life on Wet and Cold Worlds", Astrobiology, 2014]

Also from the LSP conference as this result is, Curiosity has perhaps observed fatty alcohols by way of that pesky CMDB leak it has. But they have to work on it before they can be certain.

That is a either a trace fossil or, theoretically at least, a product of hydrogenation of products from Fischer-Tropsch hydrothermal reaction after the Gale impactor hit. But I note that there is little evidence of the latter possibility occurring on Earth...
Torbjorn_Larsson_OM
5 / 5 (6) Mar 25, 2015
@syndicate: Fossils is irrelevant for the initial habitability (water) and then organics search, which is what Curiosity is tasked to do. One step at a time, the ExoMars rover is the first one that has dedicated instruments for fossils.

And even so, it is _hard_ to find fossils or, better yet, fossil beds here on Earth. Perhaps one in a million specimens leaves fossil, and then they have to weather out...

However, funny you should ask, because Curiosity has nevertheless presented two fossil candidates already. (The bacterial mats MISS fossil candidate in December, and now this fatty alcohol I described in my previous comment. I haven't read the LPSC conference proceedings, so I don't know if it has made it there. That is some way from peer review. But the MISS candidate is in Astrobiology.)

@viko: To travel to Antarctica, the top of Mount Everest, the bottom of the Mariana trench, to low Earth orbit or the Moon is insanely impractical.

That doesn't seem to be the issue.
TheGhostofOtto1923
2.6 / 5 (5) Mar 25, 2015
there will never be a human mission to Mars
The more we learn the more we realize what a precarious position we are in. The solar system is a very dangerous place. And we have developed effective ways of extincting ourselves by various means.

And so we need to establish independent colonies off-planet ASAP in order to preserve the species. The best place to start is Mars. Finding nitrates there is very good news because it will allow us to grow foods there with very little modification.

We will still need to do so underground because of the radiation. Earth plants need the 24 hour cycle to survive and we can maintain this easily underground. Mars offers a protective atmosphere, natural gravity, unlimited resources, and the ability to create unlimited space underground.

None of these things are available in orbiting habitats and so they could not be considered independent. Planets and moons are our only option for truly autonomous sustainability.
gkam
3.7 / 5 (3) Mar 25, 2015
"We will still need to do so underground because of the radiation."
-------------------------------------

I already posted that. You did not like it then.
TheGhostofOtto1923
1 / 5 (3) Mar 25, 2015
"We will still need to do so underground because of the radiation."
-------------------------------------

I already posted that. You did not like it then.
No you posted
Plants would have to be engineered for the environment and spectrum of radiance, which is weaker at Mars than the Earth, but unfiltered
-which shows you dont know what you are talking about, as usual. See if you can find a def for 'spectrum of radiance'.
ratrodcattleprod
1 / 5 (2) Mar 25, 2015
There are ingredients in my local grocery store for making a cake. But unless someone creates that cake, guess what happens, not a darn thing, they just sit there. .
gkam
1 / 5 (1) Mar 27, 2015
" I think the first folk might have to inhabit the caves or live in subterranean environments to avoid radiation levels, with no magnetic field at Mars."

Apparently otto does not understand English. Maybe it is his second language.

And if you had to look up "spectrum of radiance", you are truly ignorant. It refers to the wavelengths of irradiance from the Sun at Mars. It may not be some "official" term, so you will not understand it, since it is not listed in Wiki.

Take the phrase apart, and look at the separate words. What to they mean, . imply? Yes, it means the range of spectral frequencies reaching the surface of Mars. Higher frequencies (shorter wavelengths), are required for photosynthesis, something the rest of us learned in High School. The longer wavelengths are used for heliotropism.
gkam
1 / 5 (1) Mar 27, 2015
I wonder if otto has looked up heliotropism yet.
TheGhostofOtto1923
1 / 5 (3) Mar 27, 2015
"spectrum of radiance"... It may not be some "official" term, so you will not understand it
Ahaaahaaaa meaning you made it up yourself.
the range of spectral frequencies reaching the surface of Mars. Higher frequencies (shorter wavelengths), are required for photosynthesis, something the rest of us learned in High School
Indubitably. And lets deconstruct your logic to further understand you thinking processes...
Plants would have to be engineered for the environment and spectrum of radiance, which is weaker at Mars than the Earth, but unfiltered
-in conjunction with:
live in subterranean environments to avoid radiation levels
-So plants exposed to martian radiance spectrums would also be exposed to martian radiation would they not?

This does not fit the widely accepted definition of 'underground'. Perhaps you need to look it up -?

Lets review; martian sunlight... martian radiation... underground... ?

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