Dark microbiome in Atacama fossil delta unveils Mars life detection limits | Hacker News Reader

Dark microbiome in Atacama fossil delta unveils Mars life detection limits

ncbi.nlm.nih.gov

65 pointsbenbreen26 comments

What would be wrong with the following:

Launch a spacecraft to Mars full of organic material. Add the toughest possible bacteria (the kind that manages to survive in volcanoes for thousands of years), vegetable growing experiments, etc...

Then see what sticks. Maybe it's nothing. But in the small chance something sticks, then humanity might have done the most useful thing ever, even in case humanity would go extinct: seed life on another planet.

But instead we seem to be carefully disinfect any spacecraft launched to Mars from biological life instead...

Is this for:

A) to avoid contaminating possible life that would already be there?

B) to ensure that if life is detected, we're sure it's not life from Earth that was present on the spacecraft itself?

But, is the chance that life is already present there considered that high?

How long can we keep maintaining that? At some point we've gotta either send something that's good enough to inconclusively tell whether there already is life there (when are we expected to have the tech to achieve that?), or send something with life.

I imagine it’s for both reasons A and B, and we will keep doing it for as long as we can presume Mars to be pristine. If we get to the point of having millions of human colonists roaming the landscape, it will probably no longer be worth sending highly clean spacecraft.

There has to be some stage in-between millions of human colonists and the current state though.

Also, why Mars specifically? Does this "must be pristine" policy also apply to other plants? Not to the moon at least, that's for sure.

It does apply to the moon.

Everything we have sent to the moon has been carefully disinfected as far as we know.

Even when people visited, opening and closing doors (even if indirectly through an airlock)?

The Lunar Module didn’t have an air lock. They just depressurised and opened the hatch.

With the Moon there's at least the argument that any contamination likely couldn't travel too far due to the lack of wind. So any contamination there would just be around the landing site, only going as far as the depressurization might've allowed it to go. Plus since the Moon is exposed to completely unshielded solar radiation, any unsheltered contamination will probably have broken down.

Mars on the other hand has wind, is slightly more protected by the atmosphere and increased distance from the Sun and around the equator summers are actually at decent temperatures for life.

It’s not just Mars, but there are nuances and exceptions. There’s a ton of history on why we do this and what the limitations are:

https://en.wikipedia.org/wiki/Planetary_protection

Mars and some other places like Europa are suspected to host or to have hosted life at some point. It's worth applying this policy uniformly because spores are quite hardy and it can be surprising where fragments of contaminated celestial bodies might end up. Even thoroughly scrambled genetic material could influence the development of extraterrestrial microbes whose biochemistry might or might not be compatible with the genetic language of life on Earth.

> Launch a spacecraft to Mars full of organic material. Add the toughest possible bacteria (the kind that manages to survive in volcanoes for thousands of years), vegetable growing experiments, etc...

> Then see what sticks. Maybe it's nothing. But in the small chance something sticks, then humanity might have done the most useful thing ever, even in case humanity would go extinct: seed life on another planet.

How would it be useful (in the sense I think you mean it to be)? Mars is pretty dead, and seems likely to stay that way forever (e.g. cold, dry). Any seeding, if successful, isn't going to result in some Star Trek-like scenario that results in intelligent life arising in a billion years. The only result will be bacteria eking out an existing in a marginal habitat for a billion years.

> How long can we keep maintaining that? At some point we've gotta either send something that's good enough to inconclusively tell whether there already is life there (when are we expected to have the tech to achieve that?), or send something with life.

The only upside I see to sending a spacecraft like you propose is to irreversibly contaminate Mars with life to eliminate the scientific basis for avoiding colonization and exploitation of it.

The reason is mainly B with a little A. I agree with you though. But maybe we should try it on the moon first.

Nothing will survive on the moon. It’s simply too hostile to life in all essential dimensions.

It's for reasons A and B, at least. There have already been issues with "B", for example: https://www.smithsonianmag.com/smart-news/crashed-spacecraft...

Look at how "well" transferring species around has worked out on Earth, regardless of intentionality:

https://wildlife.org/eradication-lets-rat-island-shed-its-na...

https://www.nbcnews.com/news/forget-lantern-fly-mysterious-n...

... actually, here, let's just cover things more completely/ efficiently:

https://en.m.wikipedia.org/wiki/Lists_of_invasive_species

It seems wise, for multiple reasons, to try not to cross-contaminate, for the moment. Just in light of unintended consequences with past "cross-contamination" events.

Something like "Andromeda Strain" may be unlikely, and, it may be that we don't find anything particularly interesting on Mars, period, say... But, we're still very early on in this phase, I'd say ... trying to avoid some of the consequences created by past explorers (who spread diseases, rats, etc. everywhere - whether European or Pacific Islander or etc.) seems prudent...

Apparently it's for both reasons, but I think both are bullshit. I love Star Trek, but the Prime Directive is not my flavour of Kool-Aid.

In the case that life has only evolved here, it is our duty as the agents of DNA to spread it far and wide! We should be initiating panspermia to anywhere, starting with the places it is most likely to take hold. Send cultures of every extremeophile available and hope that sentience re-evolves after millions of years.

I just found this and expect to agree with their manifesto: http://www.panspermia-society.com/

So you want to dump invasive species in protected environments. Great plan. Nothing could ever go wrong with that.

> most useful thing ever ... seed life on another planet

I don't intend to change your mind on this point, but I'll just say I disagree (:

Why not pave over national parks and build more cities? Seems "useful"...

This is very much a "Red Mars / Green Mars" sort of debate (see the books by Kim Stanley Robinson; not that I'm a huge fan, but it's very topical).

You'll always have some people who want to forcibly mold the world/universe into something else, and some people who want to preserve what's there, and a whole spectrum in between.

If nothing else, once you do contaminate/bless Mars with life, there is no going back. So, it seems reasonable to take advantage of the unique opportunity to study it before crossing that line.

Just my 2¢

If my childhood experiments with anything amenable to a screwdriver are anything to learn from, you'll learn more from breaking it than looking at it. We can always use all those pointless atomic bombs we spent billions on to sterilize it from a safe distance if things get out of hand.

I don't see how you can think nuking something just "resets" it. The whole point of sanitizing probes and not introducing foreign microbes to Mars is specifically so that we keep it separate from human intervention. Once you introduce a microbe, there's no coming back.

Nuking it isn't a solution and "move fast and break things" is extremely irresponsible and ignorant when it comes to things like ecology and geography.

Most of these contamination concerns are only relevant while we're still at the robotic exploration stage. When humans inevitably set foot on the planet in a couple of decades most contamination concerns become moot since it's basically impossible to contain the amount of life that comes along with any animal, especially when you have the systems to sustain those animals for years.

It's a somewhat ironic situation I think, since with how limited our ability to explore is with robotic probes and how limited even the sample return's sampling area would be, the only serious shot at actually ruling out the potential for native Martian life would come with a years long human presence (as would be needed due to the 2 years between arrival and return windows) and the associated ability to more thoroughly explore - either in terms of actually having people going around and exploring or in terms of just being able to be more flexible in performing experiments on samples brought over by robots.

In a way the sample gathering (and potential return) is also in preparation for this inevitability. NASA is well aware that if the plans working up to boots on Mars materialize, having 'pristine' reference samples will be pretty important, so even if they can't bring them over to Earth yet, they can at least preserve them for later reference.

Or we can do as the authors propose and bring samples back. Win win!

https://phys.org/news/2023-07-nasa-mars-ascent-vehicle-sampl...

We don't know for sure Mars is sterile. Seeding our own ecosystem is not worth losing the precious opportunity to see if there's life on Mars, and if it's anything like ours. That alone would advance science and philosophy significantly. Even finding fossils would be incredible.

Also, if there's actually life in Mars, nothing guarantees our life will prevail over it. Maybe the nutrient-deprived native life will have a feast on ours, if our evolved defenses are innefective against their unknown threat.

Interesting choice to use 16s sequencing for analysis vs. shotgun metagenomics. I guess they were intentionally looking for bacteria but shotgun would give a more unbiased and comprehensive view of any microbial (or other) species present

> Our analyses by testbed instruments that are on or will be sent to Mars unveil that although the mineralogy of Red Stone matches that detected by ground-based instruments on the red planet, similarly low levels of organics will be hard, if not impossible to detect in Martian rocks depending on the instrument and technique used. Our results stress the importance in returning samples to Earth for conclusively addressing whether life ever existed on Mars.

This study seems to support the Mars Sample Return Mission, which has been controversial lately due to its high costs: https://arstechnica.com/space/2023/07/the-senate-just-lobbed...

> The concern expressed by some scientists, including former NASA science chief Thomas Zurbuchen, is that the ballooning cost of Mars Sample Return will cannibalize funding from other science missions. And if the price is already approaching $10 billion now, then it is likely to spiral further out of control.

> Our results stress the importance in returning samples to Earth for conclusively addressing whether life ever existed on Mars.

If nothing is found in the returned samples, how would that be conclusive?

Those samples could indeed only prove that life existed. Proving the nonexistence of something is, as expected, much more difficult.

Life as we know it

It's possible to find something else entirely detached from what we call life, although this would be much more unlikely.

Reply on news.ycombinator.com