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Comment by sholladay | Hacker News Reader

It annoys me that there wasn't even a mention of the mere possibility that we may have contaminated the planet with the microbes in question. Sterilizing complex machinery is difficult and absolute sterilization of spacecraft has never been a goal of any space agency. Then we find out the microbes are probably in an area where one of our rovers has been exploring for a few years and you have to wonder. Granted, it does seem unlikely, and perhaps the microbes are indeed under the ice and have been since before we got there. But it seems irresponsible to not even consider contamination as a potential cause when we can clearly connect the dots to how that could have happened.

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Whatever process is causing the presence of methane can apparently produce hundreds of thousands of tonnes of the gas in a relatively short timeframe.

Considering that spacecraft have only landed on Mars in the last few decades, a contaminant microbe would have to truly thrive in an extremely inhospitable Martian environment, survive spaceflight and decontamination, yet also be undetectable in the places on Earth where the spacecraft was constructed.

Yes, it's possible, but it seems so beyond the realm of probability...

> contaminant microbe would have to truly thrive in an extremely inhospitable Martian environment, survive spaceflight and decontamination, yet also be undetectable in the places on Earth where the spacecraft was constructed

To be fair, if those possibilities are true, they would also be revolutionary and should be considered (e.g., do they imply a mechanism that makes panspemria feasible?).

Likewise for an previously unknown mechanism of methane production - this itself would help us understand the origin of life. (This is one explanation, "geological" one, mentioned in the article.)

"Single celled microorganisms found to exist in conditions on Mars that mirror some of the conditions in which single celled microogranisms exist on Earth", however, seems to be a more boring one - if turns out not to be true, understanding why that happens to be the case, is also valuable.

> panspemria

Had to look this one up. I’m assuming you meant panspermia.

> the theory that life on the earth originated from microorganisms or chemical precursors of life present in outer space and able to initiate life on reaching a suitable environment.

Microbes could simply be airborne from earth, thriving in the upper atmosphere and attach themselves to the spaceship there.

Are we absolutely sure it's the right gas? Maybe we just read it as methane but it's something else

It was measured with at least two different spectrometers: the Curiosity rover measured it with a laser spectrometer, and Mars Express with its PFS. That leaves little doubt.

Here, here! I was thinking the same. Ever since they first detected persistent earth-borne little buggers living on the exterior of the spacecraft. [1]

I do think the detection of a methane spike by and orbiter and terrestrial rover within a day of each other, is an anomaly on a scale that doesn't seem to make a plausible for the case for earth-based bio-contamination. Perhaps they should have at least addressed that aspect.

That said, I do cringe everytime I see an animation of a screw (rotating) propeller-based submarine exploring the oceans of Europa. Screw propellers will always contaminate some material (not necessarily biological) and there is a risk of a lot of contamination should a seal fail. Propellers are a poor propulsion choice for exploration of pristine liquid environments, including Earth's subglacial lakes [2]. Instead they should either use seaglider [3], or some oscillating foil propulsion like Thunniform locomotion [4] (both do not require any parts to penetrate the hull nd risk contaminating the environment).

I will say though, that per the article, the findings of methane spike by an orbital craft and a terrestrial craft within

1. https://www.google.com/amp/s/relay.nationalgeographic.com/pr...

2. https://salsa-antarctica.org

3. https://en.m.wikipedia.org/wiki/Underwater_glider

3. https://en.m.wikipedia.org/wiki/RoboTuna

It's meant to be basically impossible because we will did sterilize the landers. We know separately there are already rocks going from mars to earth and earth to mars, because we found some on the earth.

As in: from the surface of Earth to the surface of Mars? If yes, how?

It's not uncommon to find meteorites on Earth that originated from Mars. Some examples are "Northwest Africa 7034" [1] and Allan Hills 84001 [2].

Allan Hills 84001 famously caused some controversy in 1996 when scientist believed it contained evidence for life on Mars, which ended in an announcement from the President. In the end the consensus seems to be that there was no evidence for life.

[1] https://en.wikipedia.org/wiki/Northwest_Africa_7034 [2] https://en.wikipedia.org/wiki/Allan_Hills_84001

Mars has a much lower gravity than Earth though, so getting from Mars to Earth is harder than vice versa.

Large meteor hits throwing debris into space, some of it landing on other planets.

If life came there on one of our probes, and at least some of it found Mars to be hospitable enough to spread enough to generate gas on this scale, then we can start growing at least some Earth-based single-cellular life on Mars, right now. We might be able to use that to start terraforming Mars, if we chose to do so.

Did you read the article?

> The presence of methane is significant because the gas decays quickly.

If there were microbes on these spacecrafts and probes, there would have to be a massive rotting carcass producing a size-able amount of methane sitting right in front of the gas analyzers to throw off the instruments. It's more likely that the measurements of methane on Mars are (A) negligible, and (B) are naturally occurring. Especially given that methane on Earth (at any given altitude) is a about 1800ppb [1]. Contrasting with the probes *average measurements of 4ppb.

I'm no scientist, however I am an avid science reader. Here's a great summary quote from Wikipedia on the chemical relationship of methane and carbon dioxide:

> As methane rises into the air, it reacts with the hydroxyl radical to create water vapor and carbon dioxide. The lifespan of methane in the atmosphere was estimated at 9.6 years as of 2001; however, increasing emissions of methane over time reduce the concentration of the hydroxyl radical in the atmosphere.

That's just the nature of the methane here on Earth. [2] But you can probably imagine the relationship is about the same on Mars. In fact, you can read a summary about the chemical relationship here in this abstract. [3] But I would recommend some serious problem solving to piece together what this piece is trying to communicate...

Consider this hypothesis about Mars:

- Organic matter may have existed > now no longer exists.

- Methane was once at Earthen levels > now no longer is.

- Carbon dioxide was once at Earthen levels > now it exceeds it.

- Methane decays into carbon dioxide.

- Is it possible that organic matter continues to exist on Mars in a seasonal/irregular pattern?

What does the data suggest to you /u/sholladay? That these sensors were broken/contaminated? Or that we are trying our best to parse Mars' veiled past?

It's not irresponsible to consider contamination plainly because it's irrelevant — the tenants of this hypothesis are grounded in chemical observations, not biological observations.

[1] https://www.nova-gas.com/analyzers/methane

[2] https://en.wikipedia.org/wiki/Atmospheric_methane

[3] https://www.ncbi.nlm.nih.gov/pubmed/11539176

I interpreted OP's concern as the idea that microbes flourished after they were seeded, perhaps by the landers in the 70s.

It could also be other aliens contaminated Mars. Just saying... if we are talking about possibilities rather than probabilities. If it is us, we probably will find out later anyway, no need to get too emotional about an article.

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