Life on Mars

So, we don't know if there was life on Mars—or even, I suppose, if there still is some.

But, to take it from another angle, if Mars were earth and then became Mars as it is now, wouldn't the various rovers have seen unambiguous signs of past life?

Interestingly Tim, I am not sure that the primary goal of Curiosity was to discover evidence of life.

I think it was less ambitious. To discover whether Mars had environments that were habitable.

The lake bed in which Curiosity landed was likely habitable - flowing water, likely long enough, with adequate chemistry.

http://mars.jpl.nasa.gov/msl/mission/science/objectives/

Spirit and Opportunity - determine past water activity on Mars

http://mars.jpl.nasa.gov/mer/overview/

I think later missions may have the specific goal of discovering life.

http://www.sciencemag.org/content/343/6169/1242777.abstract

"Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars. "

>2 richardbsmith:

No, I know. I'm asking a very layman's question here. If the various rovers had come to earth, after earth had lots its atmosphere and so forth, would evidence have jumped out?

There is a lot of geological evidence of life on earth, but it's open to question how much of it would be accessible to a robot car.

Just life, not intelligent life?

If we are talking about a world in which life was long past, seeking evidences of water and potentially biological chemistry would likely take the same steps. Look for organic chemistry.

Although if Mars had life as abundant and as globally and as varied as Earth, and if that life had existed post Late Bombardment, it might very well shout out look at me.

But it may be that any life on Mars after the Late Heavy Bombardment was not global, and not particularly varied. If that link above is correct and liquid water stayed in that lake for a million years, how much variety might be expected?

Your point may be correct, if I understand it, that there was likely not abundant, global, and varied life on Mars after the Late Heavy Bombardment, or it should be more evident.

Although I still think the point needs to be remembered that the rovers have not specifically taken life seeking experiments, rather the focus has been to locate water or evidence of ancient water and to evaluate habitability in a specific lake bed.

>6 richardbsmith: Thanks! That was very interesting.

1> I don't think anyone believes that Mars was like Earth. If there was life on Mars it was likely single-celled or whatever passes for cells in an extra-terrestrial life form and that is what they're looking for.

>8 jjwilson61:

If all you have are single-celled organisms, do they end up being more, or less, prevalent? Does life build on life, or does more-than-single-celled life keep single-celled life in check?

9> More I imagine. Multi-cellular life creates a whole new set of environments for single-celled creates to colonize. I read somewhere that there are more bacteria in our bodies than there are human cells.

There is an entire microbiome for which we serve as a home.

http://en.wikipedia.org/wiki/Microbiome

>4 timspalding: Kind of an unfair question. The experiments/tools on the rovers are all designed to pick up info for the known conditions existing on Mars. If the same rover chassis were used loaded with equipment specifically designed for earth, I think life or not would jump out in the data. I seem to remember in different articles that bringing back samples would be the gold standard for finding life on Mars. Of course having people on Mars would trump that.

300 million years ago, there was a thermonuclear strike or strikes against Mars. We know that because there are predictable decay products from the use of any nuclear weapons over time spans of hundreds/thousands/millions/tens of millions/hundreds of millions of years. In recent years, some of those decay products have been detected on and around Mars, dating back to 300 million years ago. The classic view of nuclear war assumes that two sides of conscious and intelligent groups of the same or different species are involved in any conflict that is ended by the use of nuclear weapons. Based on this more recent information on scientific evidence of these products of the use of nuclear weapons against Mars, the next question could be, "Who were those battling civilizations and where did they go?"

Link for data on historic thermonuclear explosions on Mars:

https://www.researchgate.net/publication/340952315_EVIDENCE_OF_A_MASSIVE_THERMON...

As far as I can tell, anyone can post a paper to researchgate and it doesn't have to be peer reviewed so I'd take anything on that site with a mountain sized grain of salt

>13 MaureenRoy: Aha, oh yes the “Silurian hypothesis“, after the technologically advanced dinosaurs migrated to Mars and avoided the asteroid extinction event on Earth there must have been a severe disagreement between themselves or another species! ;-)

https://en.wikipedia.org/wiki/Silurian_hypothesis#:~:text=The%20Silurian%20hypot....

Fun science fiction.

>13 MaureenRoy: A more cautious researcher might stick with the argument that the Martian atmosphere contained material consistent with a nuclear strike, and see where that goes, not go on to propose they've solved the Fermi paradox. :)

>14 jjwilson61: Actually it is worse than that. It's also my understanding Researchgate will take anything and publish it if you pay for it.

In addition to this they hoover up connections to peer reviewed papers various journals have placed on open access and list them on their site. I'll never forget the surprise I got the first time I went looking for one of my peer reviewed papers (I had forgotten the publisher) and the top listing on Google was that paper listed under the Researchgate imprimatur.

When they present papers collected in this manner they make sure their logo is prominently displayed. You have to double check to see if it was accepted for publication by Researchgate as opposed to having been published in a peer reviewed journal and just listed by them.

By listing actual peer reviewed papers in this manner they are able to give themselves an undeserved aura of respectability.

On a side note I've just bought A City on Mars which seems to make for a fun (but also quite serious) read.

>19 bnielsen: Thanks for mentioning A City On Mars. It looks better than another somewhat recent book I read earlier called How We'll Live on Mars, which goes into enthusiastic detail without mentioning that surface Martian settlements are a big ask, at least for initial Mars astronauts, since Mars lacks a magnetic field ... therefore the hazards of life on the Martian surface are considerable at this time. It may be better to set up living quarters in a good-sized lava tube underground, far more survivable initially than any surface dwellings for Mars that I've seen so far.

A recent months-long Mars simulation experiment on Earth ended with everyone complaining about the food they had to eat ... does that book City On Mars discuss food options? I ask because all the in-depth planning I've seen for Mars exploration admits that meals on Mars will have to be vegetarian for a very long time.

There are lots of ways to make vegetarian meals tasty, but it really helps to have had some personal experience surviving as a vegetarian, at least for awhile. Currently 5% of the US population is vegetarian or vegan, however few dieticians are, and even fewer nutritionists.

>20 MaureenRoy: It has a long discussion about food; 9. Outputs and Inputs: Poop, Food, and "Closing the Loop. And yes it pinpoints that not nearly enough work on this has been done. Biosphere 2 inhabitants starved. Biosphere 2 cost about one tenth of a percent of ISS. So maybe if we build hundreds of them we might some ways of growing tasty food there.
And this was on native Earth soil, not on poisonous sterile Mars regolith :-)

And on page 190 there is a recipe for making liquor inside Biosphere 2 :-)

Summa summarum: Yes, it is a great problem. Even if taste didn't matter. And it is time-consuming too. The biosphere 2 workload was on average: eight to ten hours a day five and a half days a week. And that still left them slightly starving. And they didn't have to maintain a space settlement with complicated machinery at the same time.

I see. Every human culture has found some way to make alcohol, so I won't think of Martian colonists in a bad way if they start making beer, sake, and the like. After I developed a serious eye problem (retina) 20 yrs ago, I decided to switch to a macrobiotic diet + lifestyle for as long as possible. The good news is that 6 weeks later, my eye doctor told me my vision had returned to normal. Wow. The bad news is that such a radical diet change left me feeling angry, every day, for that 1st year ... it was only after surviving thru the 4 seasons, each with its own dietary changes, that I knew I could manage long-term on that protocol. Note: As a devoted reader, I only made that dietary switch because I had to take seriously any threat to my ability to see and to read.

NASA project to get a ride:

https://arstechnica.com/space/2023/11/nasa-will-launch-a-mars-mission-on-blue-or...

A new book, A City on Mars: can we settle space, takes a fresh look at the most recent evidence for and against space colonization by Homo sapiens. This book is recommended by the one and only Andy Weir.

Large polygon shapes found under the Martian surface:

https://www.msn.com/en-us/news/technology/mars-reveals-strange-polygon-structure...

Employment opportunity:

https://phys.org/news/2024-02-martians-nasa-simulated-yearlong-mars.html

There has already been one months-long US remote volunteer camping experience in a simulated Martian base. Food rations provided were vegetarian, and looked like some kind of freeze-dried stuff. Afterwards, there were a lot of complaints about the food. So you might want to ask a lot of questions about food choices before you sign up.