Nineteen miles up, experiment reveals Earth microbes' likely fate on Mars

March 31, 2017 by Abby Tabor
A scientific balloon is seen being filled with helium in the New Mexico desert before launching to the stratosphere, on October 10, 2015. Credit: NASA/Christina Khodadad

Understanding the limits on what microbial life can endure is important for preventing contamination of the Red Planet with terrestrial microbes when our human and robotic explorers arrive. It's also necessary for avoiding false positives from organisms we may have brought with us, when searching for life beyond our own planet. One of the fundamental questions that NASA aims to answer is whether Mars was ever home to microbial life, and whether it is today.

In October 2015, a giant research balloon carrying a NASA experiment launched to an altitude of 19 miles (31 kilometers) above the Earth to determine the likely fate of any bacterial stowaways on future spacecraft destined for Mars. The study found that within a day of direct exposure to light, a vast majority of the bacteria will be destroyed by ultraviolet (UV) radiation from the sun, on the Martian surface.

Led by David J. Smith of NASA's Ames Research Center in Silicon Valley, the Exposing Microorganisms in the Stratosphere or E-MIST experiment carried samples of a very hardy microbe in a protective, dormant state, called an endospore, that some bacteria adopt when environments are unfavorable. Exposing them to the harsh conditions of Earth's stratosphere offers a good simulation of the surface of Mars, since both locations are similarly stressful for life as we know it: extremely cold and dry, with low air pressure and fierce radiation.

Once the bacterial samples were parachuted back to Earth for analysis, Smith's team found that after just eight hours of exposure, 99.999% of the bacteria were dead. The researchers checked the genes of the few that had survived the onslaught of UV rays above the protective layers of Earth's atmosphere, and found several small differences in their DNA compared to a population of the same bacteria kept on the ground. This result suggests that if any microbes hitching a ride on a spacecraft to Mars did manage to survive the journey, they could potentially experience genetic changes. However, more studies will be needed to determine if those mutations would have any consequences for the or their ability to survive.

The E-MIST experimental hardware floating 19 miles above the Earth aboard a NASA scientific balloon. Each of the white dots contains endospores of the bacterium Bacillus pumilus SAFR-032. The hardy microbe was collected from a spacecraft assembly room, despite extensive efforts made to decontaminate such locations. Credit: NASA

"Another point for consideration is that we only tested a single bacterial strain with this flight," said Smith. "Follow-on studies will be needed with more test species so we can find out if every 'bug' dies as quickly. What about the ones under a pile of dead endospores, or covered in dust? We don't know. These will be topics for future scientific balloon flights."

The E-MIST experiment was conducted in coordination with the NASA Balloon Program Office, managed by the agency's Wallops Flight Facility in Virginia. E-MIST was funded by the Core Technical Capabilities Special Studies at the Kennedy Space Center in Florida, and the Space Biology Project at Ames. The results were published online on March 21, 2017 in the journal Astrobiology.

Explore further: Ballooning experiment to study bacteria on the edge of space

More information: To learn more about the E-MIST experimental hardware, visit: www.nasa.gov/content/nasas-e-m … in-earths-atmosphere

Christina L. Khodadad et al. Stratosphere Conditions Inactivate Bacterial Endospores from a Mars Spacecraft Assembly Facility, Astrobiology (2017). DOI: 10.1089/ast.2016.1549

Related Stories

Hunting for high life: What lives in Earth's stratosphere?

November 16, 2012

What lives at the edge of space? Other than high-flying jet aircraft pilots (and the occasional daredevil skydiver) you wouldn't expect to find many living things over 10 kilometers up—yet this is exactly where one NASA ...

Recommended for you

In search of the ninth planet

October 17, 2017

A University of Michigan doctoral student has logged two pieces of evidence that may support the existence of a planet that could be part of our solar system, beyond Neptune.

To keep Saturn's A ring contained, its moons stand united

October 17, 2017

For three decades, astronomers thought that only Saturn's moon Janus confined the planet's A ring - the largest and farthest of the visible rings. But after poring over NASA's Cassini mission data, Cornell astronomers now ...

Microbes leave 'fingerprints' on Martian rocks

October 17, 2017

Scientists around Tetyana Milojevic from the Faculty of Chemistry at the University of Vienna are in search of unique biosignatures, which are left on synthetic extraterrestrial minerals by microbial activity. The biochemist ...

10 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

catsolco
2.2 / 5 (5) Mar 31, 2017
Useful study. What about the bacteria carried by humans to Mars? Presumably they die; then the humans since we can't live without bacteria. Or will there be enough of them to mutate successfully migrating to the underground of Mars? What price colonising then? Long live evolution.
Tishers
4.7 / 5 (3) Mar 31, 2017
If we do visit Mars or create colonies we will end up populating that planet with life from Earth. It is inevitable as we cannot live in a totally sealed off little bubble from the surrounding environment.

For now, sending probes to Mars to find if there is any native life should be possible if we follow proper procedures for maintaining a sterile environment. Space travel of up to a year between planets will also be tough on anything that hitches a ride.

The hypothesis of panspermia is that life or its precursors (proteins, ammino acids) have bombarded most planetary bodies for billions of years and that this may have led to the development of life on Earth.
aksdad
not rated yet Apr 01, 2017
Send up some tardigrades. They'll probably do just fine.

Btw, why would anyone want to colonize Mars? It's a stretch to imagine anything more than a modest research station and that would be prohibitively expensive to support. Mars is only slightly more habitable than the moon. No oxygen and deadly radiation is kind of a big deal. The Dry Valleys in Antarctica are vastly more habitable but no one lives there, not even researchers.
Edenlegaia
not rated yet Apr 01, 2017
Send up some tardigrades. They'll probably do just fine.

Btw, why would anyone want to colonize Mars? It's a stretch to imagine anything more than a modest research station and that would be prohibitively expensive to support. Mars is only slightly more habitable than the moon. No oxygen and deadly radiation is kind of a big deal. The Dry Valleys in Antarctica are vastly more habitable but no one lives there, not even researchers.


Well, we'll need some new places to inhabit and spread. Mars is still not that number one place we HAVE to colonize, simply a very tempting candidate. What's more, it's still slightly more secure, when you can have the same life on both space colonies and Mars, to be on Mars than some floating place who can suddenly explode because something suddenly went wrong thanks to whoknowswhat.
And you can try to go to Antarctica. You won't stay there for long and it won't be because of the environment.
TheGhostofOtto1923
5 / 5 (1) Apr 01, 2017
Useful study. What about the bacteria carried by humans to Mars? Presumably they die
This might be a problem if we go walking around outside in our underwear.
proper procedures for maintaining a sterile environment
We cant detect 90% of germs because we cant grow them in a lab. All the probes that have landed on mars were probably contaminated. If anything touched the subsurface ice it could still be growing.
https://www.jpl.n...ure=1895
Btw, why would anyone want to colonize Mars? It's a stretch to imagine anything more than a modest research station and that would be prohibitively expensive to support
We are capable of creating unlimited habitable space underground with nuclear-powered earth borers and nuclear explosives. Mars has all the raw material we would need to support independent colonies.

Living underground would be little different from living in cities, apartment buildings, and malls.
Michael-the-Ogre
not rated yet Apr 01, 2017
Send up some tardigrades. They'll probably do just fine.

Btw, why would anyone want to colonize Mars? It's a stretch to imagine anything more than a modest research station and that would be prohibitively expensive to support. Mars is only slightly more habitable than the moon. No oxygen and deadly radiation is kind of a big deal. The Dry Valleys in Antarctica are vastly more habitable but no one lives there, not even researchers.


Simple. Mars is slightly more habitable than the moon. Commute's a bit of a problem, but Earth is (at least for now), the ONLY place we know we can grow food. Unless we get our industrial plant OUT of our agricultural plant, we're boned.
DavidDcomments
not rated yet Apr 02, 2017
Remains of biotic material were found in 4.1 billion-year-old rocks in Western Australia.
Life arose quickly on earth and is likely common throughout the universe.
see: wikipedia - Panspermia
If we are to learn to be a space faring species lunar lava tubes can't be beat for our first shelters because they have withstood the test of time and are close by.
see: wikipedia - Lunar_lava_tube
If polar ice on the moon is insufficient we could redirect a comet to deliver a mountain of ice to the moon.
Also Low Gravity is a huge benefit. We will want to get to and from the surface often, and low gravity makes momentum exchange tethers possible with Kevlar cables.
see wikipedia - Momentum_exchange_tether
In the early days of lunar industry we will want to manufacture many square miles of solar panels in lunar orbit so for early material shipment a railgun could be used as a lunar-mass-driver to ship moon dust for separation in orbital smelters.
see wikipedia - Railgun
DavidDcomments
not rated yet Apr 02, 2017
Comets are invaluable! Why ship rocket fuel from earth when there are mountains of the stuff floating around for the taking.
The beauty of comet redirect is that all you need is heat; the reaction mass is the comet itself. The heat is easy if you make a 'ram jet' throat out of uranium. It would heat the ice and eject hot gas as thrust. Simple small cheap. By using a dozen or so steering a comet should not be that hard.
Jayded
not rated yet Apr 03, 2017
Im so over this non contamination party. I get that people want to find life on Mars or other planets but my desire to terraform outways this question. My feeling is that we should be pounding mars with as many microbes as we can carry.
antialias_physorg
not rated yet Apr 03, 2017
, when you can have the same life on both space colonies and Mars, to be on Mars than some floating place who can suddenly explode because something suddenly went wrong thanks to whoknowswhat.

On Earth you can just walk away when your habitat is about to explode. On Mars you'd be in just as much trouble as you would be on a space station. Really the only thing Mars offers is a bit of gravity and maybe a somewhat easy access to a larger variety of deposits of useful materials. But as for the 'life sustaining' part it's no better than living on a space station (potentially even worse - since a space station could be spun up to simulate 1g, while Mars can't. And we really don't know whether a baby would grow up healthy in the reduced gravity of Mars)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.