Certain strains of bacteria, including Bacilus Pumilus, may be able to survive on the Martian surface. Image credit: NASA

Bacteria Could Survive in Martian Soil

30 Oct , 2009 by

Multiple missions have been sent to Mars with the hopes of testing the surface of the planet for life – or the conditions that could create life – on the Red Planet. The question of whether life in the form of bacteria (or something even more exotic!) exists on Mars is hotly debated, and still requires a resolute yes or no. Experiments done right here on Earth that simulate the conditions on Mars and their effects on terrestrial bacteria show that it is entirely possible for certain strains of bacteria to weather the harsh environment of Mars.

A team led by Giuseppe Galletta of the Department of Astronomy at the University of Padova simulated the conditions present on Mars, and then introduced several strains of bacteria into the simulator to record their survival rate. The simulator – named LISA (Laboratorio Italiano Simulazione Ambienti) – reproduced surface conditions on Mars, with temperatures ranging from +23 to -80 degrees Celsius (73 to -112 Fahrenheit), a 95% CO2 atmosphere at low pressures of 6 to 9 millibars, and very strong ultraviolet radiation. The results – some of the strains of bacteria were shown to survive up to 28 hours under these conditions, an amazing feat given that there is nowhere on the surface of the Earth where the temperatures get this low or the ultraviolet radiation is as strong as on Mars.

Two of the strains of bacteria tested – Bacillus pumilus and Bacillus Nealsonii – are both commonly used in laboratory tests of extreme environmental factors and their effects on bacteria because of their ability to produce endospores when stressed. Endospores are internal structures of the bacteria that encapsulate the DNA and part of the cytoplasm in a thick wall, to prevent the DNA from being damaged.

Galletta’s team found that the vegetative cells of the bacteria died after only a few minutes, due to the low water content and high UV radiation. The endospores, however, were able to survive between 4 and 28 hours, even when exposed directly to the UV light. The researchers simulated the dusty surface of Mars by blowing volcanic ash or dust of red iron oxide on the samples. When covered with the dust, the samples showed an even higher percentage of survival, meaning that it’s possible for a hardy bacterial strain to survive underneath the surface of the soil for very long periods of time. The deeper underneath the soil an organism is, the more hospitable the conditions become; water content increases, and the UV radiation is absorbed from the soil above.

Given these findings, and all of the rich data that came in last year from the Phoenix lander – especially the discovery of perchlorates –  continuing the search for life on Mars still seems a plausible endeavor.

Though this surely isn’t a confirmation of life on Mars, it shows that even life that isn’t adapted to the conditions of the planet could potentially hold out against the extreme nature of the environment there, and bodes well for the possibility of Martian bacterial life forms. The LISA simulations also indicate the importance of avoiding cross-contamination of bacteria from Earth to Mars on any scientific missions that travel to the planet. In other words, when we finally are able to definitively test for life on our neighboring planet, we don’t want to find out that our Earth bacteria have killed off all the native lifeforms!

Sources: Arxiv papers here and here.

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Manu
Member
Manu
October 30, 2009 11:55 AM

I foresee a strong objection to manned missions to Mars, here.
It’s quite difficult already to avoid contamination by one probe. It will probably be just impossible to avoid when there’s actually a bunch of people up there.

Dave Finton
Member
October 30, 2009 12:11 PM

Manu: That would be an interesting debate. History is rife with examples of how “alien” species can out-compete local ecosystems right here on Earth, with often-times disastrous consequences.

TD
Member
TD
October 30, 2009 12:43 PM
@Manu – This argument doesn’t make sense. If we find life on Mars, there will be renewed interest in going there. Billions will be poured into the space effort. I think the “be afraid to go there” argument is meant to scare the space industry into NOT finding life on Mars. The opposite is actually true. If we don’t discover and analyze life on Mars, then the next meteor from there (carrying a microbe) could spell doom for the human race anyway. We fund a spacewatch program to look for dangerous earth-crossing asteroids. We don’t ignore the threat..we spend money to study it. If we’re meant to be a species that has a place in the galaxy, I’d… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
October 30, 2009 12:47 PM
Biologically, populations that haven’t adapted to the environment, and that includes other species by coevolution, wouldn’t be expected to have a chance against the indigenous life. Those “alien” species are a great example, they out-compete local ecologies by being adapted to similar conditions while being freed of existing competition and parasitism. They find the same niches, except that they are larger. No such luck for terrestrial life on other planets. it shows that even life that isn’t adapted to the conditions of the planet could potentially hold out against the extreme nature of the environment there, Endospores that can’t metabolize nor reproduce, and have to be teased back to life afterwards at an observable ratio (in the paper… Read more »
Manu
Member
Manu
October 30, 2009 1:30 PM
@ TD: I’m starting to see a pattern in some recent debates here about human exploration: critics are dismissed with either “irrational fears” (quoted from another post), “be afraid to go there” and “cowering in some dark lab”. Ridiculing your contradictor is a last resort when you run out of valid argument, I believe. My comments may be blunt at times, but I don’t think I have ever posted that sort of dismissive stuff. Taking part in the debates here is my humble way to “address these questions as [part of the] human family”. There’s not much of a point in debating without a diversity of opinions. Besides, please note my post implies a simple question: how to… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
October 30, 2009 2:35 PM
Here is a podcast about Mars subsurface analogous biospheres, namely caves, by Carl Zimmer and Hazel Barton. Notably in this context is first and foremost a segment ~ 20 minutes in, when they discuss biological contamination. What happens in caves is that life is so harsh (poisonous minerals), starved (no photosynthesis) and competitive (lots of oddball antibiotics) that surface bacterias die out, unless they are constantly replenished by human visitors. They also discuss previous to that how varied the bacterial communities are, typically ~ 1 k species. The reason seems to be that they need to do services for each other, no single bacteria can supply all of the required metabolism. [The “community” found in a South Africa… Read more »
TD
Member
TD
October 30, 2009 6:16 PM
@Manu – I’m sorry if I sounded disrespectful. And I meant nothing sinister by approaching the question of life on Mars as “one human family”, “head held high”….quit the opposite. But I am trying to get a handle on who is saying we shouldn’t go to Mars if there is life there. Who is? I am constantly hearing people say “we better be careful, because if we find life on Mars some people will argue we shouldn’t go there”…but they refer to other people making that argument, not themselves. Do you think we shouldn’t go to Mars if there is life there? Just to give my opinion, I think we’d be crazy, and risk humanity, not to. Like… Read more »
Aqua4U
Member
October 30, 2009 7:44 PM

I’m thinking transpermatic endospores are mutagenic and will survive wherever and whatever level of preconditioned environmental elements are in place and/or will rapidly mutate to the level of survival. Mutants rule?

Aqua4U
Member
October 30, 2009 8:06 PM

Can you say Trick or Treat you little extremophiles?

Pvt.Pantzov
Member
October 30, 2009 10:05 PM

seed mars.

Aqua4U
Member
October 30, 2009 10:35 PM

OR, perhaps as they say in L.A. – Seed THIS!

I.E. Put yer pants back on…. there are dangerous cactus out there!

Lawrence B. Crowell
Member
Lawrence B. Crowell
October 31, 2009 5:09 AM

Invasive species usually proliferate in a new environment because there are no predictors or, in the case of plants plant eaters, to keep the numbers in check. Kudzu in the south is an example. Most Earth bacteria would have a hard time on Mars I would suspect. and just as a tropical plant is not likely to be invasive in Alaska, the same might hold here. Of course this involves words like “might,” and is conjectural.

The 1976 Viking experiments found chemical responses corresponding to life, but it was dismissed. Curiously the gases released had diurnal behavior, which makes it possibly biological. Possibly NASA might have backpedalled on this too quickly.

LC

Jon Hanford
Member
Jon Hanford
October 31, 2009 6:08 AM

I thought everyone knew about how easy it is to terraform Mars, per the movie “Total Recall”. I thought this movie was based on actual events, not some totally unrealistic assumptions (like the current governor of California). smile

Lawrence B. Crowell
Member
Lawrence B. Crowell
October 31, 2009 7:32 AM
Terraforming Mars: Yep it was an idea I cam up with in grade school. I saw this movie called “Silent Running,” which was an improbable scenario of the last ecosystems from Earth in these large domes attached to a spacecraft. For some reason it was out around Saturn. The movie is largely about one guy on the spacecraft going a bit bonkers. Yet it occurred to me, “Why not land these domes on Mars, and set up biozones and eventually change the planet?” I had all sorts of drawings and idea about this. It is a nice dream in a way. It is also in keeping with aspects of the human imagination, where a person sees a prestine… Read more »
lomitus
Member
lomitus
October 31, 2009 8:34 AM
Bio domes vs. Terra forming…I think that it’s important to distinguish a difference here. While it would certainly be expensive by today’s standards, I think it has been safely proven that bio domes would certainly be possible on Mars. Certain precautions would have to be observed in regards to “Mars Quakes”, the high winds and harsh enviroment, etc., but in the end if we ever wish to put humans on Mars, that is essentially what we will need to do. Terra forming on the other hand is a -very- different idea completely. You can’t just go out and start planting trees and various types of vegetation on the surface of Mars (or any other planet we currently know… Read more »
Mr. Man
Member
Mr. Man
October 31, 2009 9:36 AM
I think that if there is any life on Mars, we should quarentine some of it into its own little reservation-like domes. Then we can go there without any fear of destroying them for good (cause there will always be some left in the reservation). Still, I don’t think that fear of harming life there should keep us from going, there are always risks…as its been mentioned before, if we focus too much on the risks involved in anything, nothing will ever get done. Sometimes you just have to do (you should still be cautious just not overly cautious). All I’m saying is its human to be a little daredevil, and we shouldn’t shun what makes us human.
BeckyWS
Member
BeckyWS
October 31, 2009 12:45 PM
I think Manu and TD are talking at cross-purposes. There are 3 arguments about whether sending people to Mars is a good idea in relation to the life that might be there already: 1) Possible risk to humans by pathological effects from Martian life- seems to be what TD is talking of. 2) Increased risk of contamination with Earth-bacteria by sending people as they are harder to sterilise than rovers, thereby making false positive identification of Martian life more likely 3) The possibility that Earth-based bacteria will wipe out indigenous Martian life, which seems to be what Lawrence and others are talking of. Personally I think there is an extremely strong argument akin to the First Directive of… Read more »
TD
Member
TD
October 31, 2009 4:28 PM

Interesting comments. In summary, no one is saying avoid going to Mars completely, just be extremely careful if we do. Which means being open with society about the existence of life there, to attract the best and brightest to the tasks of avoiding forward contamination and avoiding reverse contamination. Any lesser effort is criminal negligence. Agreed?

Lawrence B. Crowell
Member
Lawrence B. Crowell
October 31, 2009 7:51 PM

BeckyWS comes pretty close to my thinking on this. In some ways this is a bit like treating the other planets as “parks,” in the same way national parks preserve, or are supposed to preserve, a region. This is particularly the case with a planet such as Mars, which could bear life and which we stand some chance of putting boots on the ground there. We need to ensure that our activities do not damage the natural systems there.

LC

Astrofiend
Member
Astrofiend
October 31, 2009 9:10 PM
Meh – the chance of Earth-based bacteria thriving and out-competing with indigenous bacteria – pretty much nil. That would be akin to an Emperor Penguin out-competing a desert scorpion – not adapted to that environment at all, and therefor almost useless in it. Same with the idea of martian bacteria being pathogenic to humans or other Earth-bound creatures – why would a bacteria that has evolved in isolation for potentially hundreds of millions of years in a freezing, high CO2, high radiation, extremely salty etc etc environment suddenly just happen to be able to infiltrate the human body, use our cells for their own sinister purposes and give us horrible new forms of hemorrhagic fever or something? Why… Read more »
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