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As we accumulate small additional likelihoods of Martian life, I wonder if humans will 1) put more resources into manned missions for intensive and flexible study to get to the bottom of these mysteries, or 2) defer plans for manned missions for reasons of environmental preservation/protection (or even fear) and stick to robotic or other light-touch/sterile explorations for a while. Just a passing thought.
They do sterilize spacecraft before sending them to mars, that's a real thing. I believe we'd very carefully sterilize humans spacesuits and ships before sending them. I think the likely outcome of this is blind indifference to the importance of discovering life on another plan. No increase in Nasa budgets or plans for discovery.
"Rovers scheduled for launch next year -- one by NASA, one by a Russian-European collaboration -- will carry instruments designed to search for the building blocks of life, although neither is designed to answer the question of whether there is life on Mars today."

I don't get it. You'd think that whether there's life on Mars today is the most interesting and important question to answer. Why aren't any of these rovers designed to answer it?

it sounds like a technicality in the scope if the instrumentation. I'd assume that if you can find the building blocks of life, you can guide and establish the next set of tests. I assume that if there is life, the current test would pass and by being broad it has a better chance at getting a hit if it's there.
My best guess: it's much cheaper and more reliable to start with detecting building blocks before investing in detecting life.
I think this is at least partly a political decision. If you bill your new rover as having a mission to find life, then you can fail pretty spectacularly when you don't. Open-ended chemistry testing is more likely to succeed at least partially, and the public won't care or try to interpret results.
"fail pretty spectacularly" ???

That's a failure of a spectacularly stupid way of framing the question. More a case of "One of the many things we'll look for is signs of current life on Mars" rather than "Our mission is to boldly find life on Mars. Don't care about anything else"

How is it failure to ask the question, then be able to answer it? It just is. It's as interesting to know as if there was life on Mars in the past. It's not, however a failure by any stretch of the imagination.

This is indeed one perspective to have on it, but unfortunately we cannot control what others think. Saying that you'll look for life will lead people to expect you to, for better or worse.
Yet the Viking landers in the seventies were quite happy to look for signs in the soil. I don't remember anyone thinking it a failure, just that it was bloody amazing, and wow those photos leading the news every night.

Sure I see how simplistic social and web news has made things, and the promotion of minority views, but did we really descend that far into the Idiocracy? :(

I think it's actually exactly the opposite.

We don't have the ability to definitively detect or not detect life on Mars. So if we send a machine with the goal of detecting life and it doesn't, well maybe it's there we just didn't detect it.

So it's better to pretend that we can't actually detect while actually sending detectors.

The Viking landers era was different. There was money for space exploration. Nowadays, space missions need to continuously prove their value, which I think changes how they're presented and ultimately their mission profiles.

You send a probe to find life, it found no life? No money for the mission ops next year, cut the comms and go do something else. You send a probe to perform scientific measurement around life-bearing capability past and present? You can exploit the sunk-cost fallacy to request ops budget year after year, because it's now hard to just cut people off from a firehose of sweet science data. "Look how much we got for X$, for a few extra Y$ we can have a whole year more of that!".

> Sure I see how simplistic social and web news has made things, and the promotion of minority views, but did we really descend that far into the Idiocracy? :(

I think the truth is closer to "individuals are smart, societies are dumb".

But Viking looked for signs; and the results were equivocal. So that's the ulitmate failure basically.
Because you get public support, and hence funding, as long as you search for life. Not sure that anyone at those organizations cares about that question, it looks more like an obsession of the public and the media.
> Not sure that anyone at those organizations cares about that question, it looks more like an obsession of the public and the media.

I highly doubt this.

Why is it that some people think that scientists are all lying about their motives for money? Scientists tend, on the whole, to be fairly bright. Hightly technical people who have money as their objective, are generally not working at the sharp end of highly speculative research. I know one of the UK experts on glide characteristics of hypersonic vehicles, he refuses to work military but sometimes gets consulted by NASA on aerodynamic assisted slingshot concepts. He makes a living as a driving instructor.
You might want to point as to where in my previous comment I said that someone in those orgs is not bright.

And then to suggest how, being bright as a thousand suns, you would obtain fancy space rovers if you say “I want to check out moon chemistry” and the public goes “pffft.”

You have this somewhat arse about tit. There's a lot more money available for looking at the moon's chemistry than there is for looking for life on it.
You can only carry a certain amount of instruments at a time, so you want to start off broad, then send incrementally more specific detectors as you identify things that are interesting. An 'is this definitely life?' experiment will probably not be sent until we have some very good likely candidates and the mission will probably be to get samples back off planet and into to a earth or LEO lab (depending on paranoia) where in depth experiments can be put together in person without the brutal restrictions on equipment that come with extra terrestrial rovers.
Because even if life exists, we do not yet know where to look for it, or what we would be looking for. The surface is bombarded by UV and radiation, so very unlikely. Should we look in cliff shadows? Near ice deposits? The bottoms of craters? Near the equator where it is warmer? Or near the poles where there might be water? We could look a long time without ever learning whether or not life exists.

Instead, we look for things associated with life. Methane can be produced by life, so let's see where it's coming from first and then worry about whether we can send a probe there. Maybe look for organic molecules, then try to see if there is a trail to life. Try to figure out where on Mars liquid water exists, since that is a prerequisite for life as we know it.

And in the meantime, there's plenty of basic science to be done. Geology teaches us about what Mars was like a long time ago. That too can give us a hint towards whether life was possible, and where. Understanding the atmosphere and its routine seasonal swings helps us understand the environment so that later, when looking for life, we don't get excited and confuse a weather phenomena with evidence of life.

Lastly, physics of our probes dictates where we can send them. For our best, heaviest probes, we don't have room on the rocket for a lot of fuel to slow down. So sites need to have low elevation to give parachutes a chance to slow us down. If we want the probe to be powered by solar, we need to be near the equator. Even if not powered by solar, we probably want to avoid being near the poles where winter can last a whole Earth year.

"Should we look in cliff shadows? Near ice deposits? The bottoms of craters? Near the equator where it is warmer? Or near the poles where there might be water? We could look a long time without ever learning whether or not life exists."

Somewhere near water might be a good start. There are plenty of candidates for this on Mars already.

Also, I'm sure plenty of people at NASA and other space agencies have thought of this, and there are probably some good reasons for not doing it, but why not take some deep core samples and look through them with a microscope for anything moving?

Not that creatures that can be seen moving under a microscope would exhaust all possible forms of life, but wouldn't it be a good start rather than looking for traces of what might have existed on Mars millions or billions of years ago?

Looking for basic components of or traces of life and only then later starting to look for existing life itself seems like the going the long way around. Why not just go for the gold from the start?

> Also, I'm sure plenty of people at NASA and other space agencies have thought of this, and there are probably some good reasons for not doing it, but why not take some deep core samples and look through them with a microscope for anything moving?

I would guess the difficulty of taking that sample would be one reason - in particular, the difficulty of building, shipping and operating necessary hardware. The best we've done so far is AFAIK the 5m thermometer-tipped drill on the Insight lander, which drilled ~30cm down and broke. We really need cheaper access to Mars for such missions, so that we could send more and heavier hardware for less.

I am probably the least knowledgeable on this subject, especially compared to the NASA scientists but why don't they send more "complex/capable" robots like the ones from Boston Dynamics instead of their rovers? I feel like a human type of robot mechanically would be much more capable of doing such tests than a rover with limited range of motion. The rovers already have a continuous wear and tear to their wheels (something I will guess the Boston Dynamics might be a bit better at as there is lesser surface area and rolling friction)?
Because for science per kilogram sent there, you'd get very little from such a robot. Hence very little science per dollar. (Also, I'd expect such a robot to break in short order.)
here is a talk about the architecture of a Mars rover: https://media.ccc.de/v/35c3-9783-the_mars_rover_on-board_com...

Boston Dynamics Atlas probably wouldn't survive the journey, nor the radiation, nor the heat swings. Mars rover is specifically designed to do handle crazy unknown failures, that's what makes it complex. Having a complex robot and trying to make it resistant to all those failure modes is simply too difficult for today's engineering.

A lot of living things would not be seen as moving. Probably even the majority of lawki.
I think that this is because people want to answer the question definitively. Currently there is not enough information to create a strong consensus on the tests and evidence required to say that there is / is not life present. The idea of the exploratory program is to move to a point where the community says : we need to do x and then that will settle this pretty clearly. Then we can do x.
Because it's hard. Seriously. Go somewhere dry and grab a handful of dirt that contains no macroscopic biomass. A construction site with a big mound of just-exhumed dirt, maybe. Now... prove it's got "life" in it. I mean, it surely does, right? How do you do that?

You could try throwing it under a microscope, but environments like that have very few actual organisms per mass. You're looking for a needle in a haystack of tiny rocks.

One way that does work is that you take it to a lab, treat it appropriately to extract the soluble DNA or RNA and then dump the results into a giant PCR machine to sequence whatever comes out. The reaction amplifies whatever might be there, so you're guaranteed to get a partial sequence, which you can then match to a database of known organisms and see if you found anything new. In fact this is a real technique and new microbes are discovered regularly doing this.

Now put all that stuff on a 1000kg spacecraft.

The point is that you don't just "design a spacecraft to answer the question of whether there is life on Mars today". It's expensive, and you have to match your science to your budget. These instruments looking for biochemistry are a valid and useful first step.

Isn't it a foregone conclusion that we'll bring some microbes over sooner or later? Don't we have lots that can thrive in that atmosphere, there's sunlight, etc. It just takes a few cells, why should we assume there will be 0 cells in all of Mars, even as we constantly send stuff there?
The surface of Mars is very hostile to life.
I'm tempted to qualify your comment with a quote from Dr McCoy but I'd better not.
Is it though? Isn't our scientists' classification of life limited to what we have on Earth? What if there is even tinnier or other form of life on Mars? I am mostly asking because we already know of extremely small bacteria being able to survive after 32,000 years in ice on Earth. So what if something similar is there on Mars too?
The extreme radiation, extremely low pressure, extreme cold, anoxic atmosphere, soil toxicity, and almost total lack of humidity make it highly unlikely any earth bacteria could survive for long on the surface.

If there is life it is buried under metres of rock and/or ice, probably in areas of hydrothermal activity.

There is natural exchange of material between earth and mars from large asteroid strikes. So - the question isn't really about cross contamination as we know that has happened at scale fairly recently, but really is there a functioning ecology that runs independently ?
News on findings such as these assert my belief that the UFO sightings on Earth incl. the recent F18 videos have nothing to do with Aliens, because if it were; why spend Billions to get excited on 'Puff of Gas' on the neighbor planet.
No one seriously believes the recent UFO nonsense is actually aliens, except for a clueless representative in congress that keeps pushing for these reports.
The center of Mars is most likely hot that might release Methane produced by bacteria.

"The core of mars is actually molten. The pressure there is 40 gigapascal. hat is 400,000 times the pressure of earth’s surface. The core is about 1500 degrees Kelvin, or 1230 Celsius."

There is bound to be an equilibrium between 1230C and the surface temperature

Surface temperature of Mars Celsius −143 °C[12] −63 °C 35 °C

" 6° C per km" https://astronomy.stackexchange.com/questions/14875/what-is-...

6C*6km = 36C degrees Celsius at 6km depth which would be a favourable temperature for bacteria.

We have drilled a 12km on Earth in Russia Kola peninsula so we should be able to build a robotic oil drill platform send it To Mars and drill deep into the Mars core. The drill will have temperature monitoring sensors. https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole https://en.wikipedia.org/wiki/German_Continental_Deep_Drilli...

"Methanogens have been found in several extreme environments on Earth – buried under kilometres of ice in Greenland and living in hot, dry desert soil. They are known to be the most common archaebacteria in deep subterranean habitats. Live microbes making methane were found in a glacial ice core sample retrieved from about three kilometres under Greenland by researchers from the University of California, Berkeley. They also found a constant metabolism able to repair macromolecular damage, at temperatures of 145C to –40C °" https://en.wikipedia.org/wiki/Methanogen

Mass of Mars robot, 500 kg?

Mass of Kola drill platform? 100 000 tons?

If you took the back seat out, that’d save—what?—80lbs. Seems like we’re on a roll, here; next idea, step up!
The dreadful consequence of finding life on Mars would be that we could never go back to seeing Mars as just another innocent rock floating around the neighbourhood.

It would forever become a harbinger, reminder that life can come and go on any planet.

Curious why that would be "dreadful" and I thought most assumed there is most likely water and life on mars (microbial that is), but just under the surface and with the unimaginable number of planets assuming we are the only planet with life would probably be similar to the early thinking the sun resolves around the earth.
Dreadful, if you take the Dark Forest theory to heart (see Liu Cixin's second book in the Three Body Problem trilogy).
1) it would be a visceral demonstration of the fragility of life on Earth

2) overnight, it would shift our estimate of the likelihood of life forming into "terrifyingly likely". Terrifying, because if life forms on any planet even roughly like Earth, the idea of aliens showing up one day and killing us all is suddenly horribly plausible.

Although, life on Mars could have a common origin with life on earth. There are after all meteorites on Earth that are believed to be of Martian origin. If microbes from Mars seeded Earth or vice versa, then finding life in both places doesn't mean the odds of it arising are higher than we thought.
In any case, what I said stands for the relatively more likely scenario of "signs of past life now gone"
One "dreadful"consequence could be quarantine lest we violate the prime directive