If We Find Evidence of Life on Mars Should We Risk Going There?

[Stephen Palmer]

Certainly not alive. A fossil would be intriguing.

See my short story in Ian Sales' anthology "Rocket Science".

 

[BAYLOR]

That happens a bit later on. One billion years from now the big change will be the absence of carbon dioxide in the atmosphere, which halts all photosynthesis. Animal life fades as a consequence. Bacteria etc will be just fine for a long while afterwards.

Science is not my strong point, but how does the earth end up losing all it's CO2 ? if animal life still exists in a billion or so years, wouldN'T there still be carbon dioxide produced ? And if there was carbon dioxide there would still be plants therefore photosynthesis ? And doesn't volcanism also produce CO2? And doesn't sea water also contain CO2?

 

[J Riff]

No Vacancy.

 

[Dennis E. Taylor]

Science is not my strong point, but how does the earth end up losing all it's CO2 ? if animal life still exists in a billion or so years, wouldN'T there still be carbon dioxide produced ? And if there was carbon dioxide there would still be plants therefore photosynthesis ? And doesn't volcanism also produce CO2? And doesn't sea water also contain CO2?

the oxygen/carbon cycle is a complex one. Every tree that breathes is turning CO2 into oxygen. But also, every tree alive has a bunch of carbon locked up in its tissues. Ditto animals. Every tree that rots releases that carbon to the environment. Every tree that gets buried and turned into coal or oil, does NOT release that carbon back into the environment. Those are carbon sinks.

Look up carbon sinks and carbon sources. The interactions are complex, but we've been lucky in that most of them are negatively reinforcing, i.e. processes that produce more carbon tend to create effects that slow them down, and vice versa. Self regulating. The reason scientists are so worried about AGW is that beyond a tipping point, processes can become positively reinforcing, i.e. processes produce results that accelerate the process. Think Venus.

 

[Stephen Palmer]

Science is not my strong point, but how does the earth end up losing all it's CO2 ? if animal life still exists in a billion or so years, wouldN'T there still be carbon dioxide produced ? And if there was carbon dioxide there would still be plants therefore photosynthesis ? And doesn't volcanism also produce CO2? And doesn't sea water also contain CO2?

CO2 was the "method" the Earth's self regulating environmental system (Gaia - James Lovelock) used to stay comparatively warm in its early days, when the sun wasn't quite so hot; without that blanket (composed also of a few other gases) there would likely be a very different biosphere now. Slowly however the sun has warmed up, and Gaia has as a consequence reduced the amount of CO2 in the atmosphere. (If you look at the average temperature of the planet over the 4 billion years so far, it is extraordinarily stable.) A point will come, maybe 800 - 1000 million years from now, when the planet does not need any CO2 to stay at life's optimum temperature - if it did have any greenhouse gases, it would over-heat. Once CO2 is effectively gone, there can be no photosynthesis, and therefore no complex animal life. Bacteria, archaea etc will be fine for a while, though...

 

[Venusian Broon]

CO2 was the "method" the Earth's self regulating environmental system (Gaia - James Lovelock) used to stay comparatively warm in its early days, when the sun wasn't quite so hot; without that blanket (composed also of a few other gases) there would likely be a very different biosphere now. Slowly however the sun has warmed up, and Gaia has as a consequence reduced the amount of CO2 in the atmosphere. (If you look at the average temperature of the planet over the 4 billion years so far, it is extraordinarily stable.) A point will come, maybe 800 - 1000 million years from now, when the planet does not need any CO2 to stay at life's optimum temperature - if it did have any greenhouse gases, it would over-heat. Once CO2 is effectively gone, there can be no photosynthesis, and therefore no complex animal life. Bacteria, archaea etc will be fine for a while, though...

I'm not sure I agree with this SP. I think the reason we had a lot more CO2 in the atmosphere in the deep past was that there was no significant amounts of life so it just was not getting soaked up fast enough - but was being produced in large amounts by mechanical processes such weathering and added by volcanic eruptions. Remove plants and I'd expect CO2 to creep back up to 13%+ levels etc... (and therefore probably generate a very quick runaway greenhouse effect!)

I'd argue it has been the biosphere that has been the main regulator of CO2 for the past 600 million years or so (and if you look at what's happened in that time period the CO2 concentrations seem to fluctuate quite wildly depending on biological circumstances) but I'd guess plants in some form have been absorbing most of the mechanically released CO2 in that time period. Note even the iceball Earth period ~650 my ago, where weathering of rock was effectively curtailed by a globe of ice/slush eventually lead to to the build up of enough CO2 (that 13% of atmosphere apparently) via volcanic eruptions to cause temperatures to rise to melt everything 'back to normal'.

Plants if given enough time will try and adapt to heat via evolution, and when pushed to a point they can not tolerate any further heat, yes, will dissappear.

However your cycle doesn't quite make sense to me then - if CO2 levels were driven down to zero to regulate the temperature (by what - plants?) then it actually will limit the growth and number of plants and thus the control of the CO2 levels will slowly disappear overtime therefore leading to CO2 levels grow and further push the temperature way past the point of no return.

I am not a climate scientist so I am happy for my logic to be shown to be faulty!

 

[Stephen Palmer]

Weathering is a carbon-reducing process, not adding.
Apart from that - right enough you're basically saying what I'm saying.
CO2 is driven down by Earth's self-regulation process as a whole; this is made up of innumerable factors, not just CO2.
In the deep past there were vast amounts of life - bacteria/archaea. The fact that life appeared just about as soon as it was possible for it to appear is one argument in favour of the "life everywhere in the universe" hypothesis.
Plants themselves have evolved to adapt to reducing CO2 levels - the C3 to C4 evolution.

 

[Venusian Broon]

Weathering is a carbon-reducing process, not adding.
Apart from that - right enough you're basically saying what I'm saying.

oops, serves me right for posting a comment before drinking a coffee - that's my excuse - I stand corrected <Gives Stephen a deep bow>

 

[Mirannan]

Regarding the far-future situation with CO2 levels: Assuming that humans don't act to keep up CO2 levels (a very shaky assumption!) it would appear that the level will be driven down by currently-unknown mechanisms to a level where plants can't live on it - and then, by means already mentioned, go up sharply. But there is another issue here with the greenhouse effect this will cause. High temperatures caused by CO2 going up will cause at least two other greenhouse gases, methane and water vapour, to go up sharply. (Methane is currently bound in all manner of places such as deep-ocean methane clathrates and permafrost, along with the bottoms of arctic lakes, much of which would be released.) Which leads to a runaway.

It's quite likely that the Earth of 1 billion AD will be an even worse hothouse than Venus is now, because Venus doesn't have any significant water to amplify the greenhouse effect and of course because the Sun will be hotter then.

 

[Stephen Palmer]

Essentially true. Although, since tectonic plate movement seems to be life-dependent, the adding of CO2 to the atmosphere could slow down greatly. That too far in the future to predict, I suspect. Methane is a greenhouse gas - 25x worse than CO2 - but it lasts for a much, much shorter time in the atmosphere. Water vapour is likely to be a future factor.
The mechanisms aren't unknown, just manifold, so I didn't list them here. Plenty of work on this online, in books etc.
The methane clathrates issue is interesting. Quite likely they caused the long-term heating of 50-odd million years ago, it seems.

 

[Mirannan]

Sure methane is short-lived. But its presence for a few years might just be enough to tip the balance.

 

[Dennis E. Taylor]

oops, serves me right for posting a comment before drinking a coffee - that's my excuse - I stand corrected <Gives Stephen a deep bow>

That's not an excuse, it's a reason. A good one. First the coffee, then reality.

 

[Venusian Broon]

That's not an excuse, it's a reason. A good one. First the coffee, then reality.

I woke up in Universe 863, where my original comment made sense, then the coffee punched me through to Universe 23 and a bit closer to where I should be - but I've been feeling weird all day (Again I blame not enough coffee - I had to dash out after only one cup) so I think I must have opened my front door onto Universe 116 - and as we all know Universe 116 makes Universe 102 look like Universe 56 (pink)

That's the sort of day I've been having.

 

[BAYLOR]

the oxygen/carbon cycle is a complex one. Every tree that breathes is turning CO2 into oxygen. But also, every tree alive has a bunch of carbon locked up in its tissues. Ditto animals. Every tree that rots releases that carbon to the environment. Every tree that gets buried and turned into coal or oil, does NOT release that carbon back into the environment. Those are carbon sinks.

Look up carbon sinks and carbon sources. The interactions are complex, but we've been lucky in that most of them are negatively reinforcing, i.e. processes that produce more carbon tend to create effects that slow them down, and vice versa. Self regulating. The reason scientists are so worried about AGW is that beyond a tipping point, processes can become positively reinforcing, i.e. processes produce results that accelerate the process. Think Venus.

Or at the very least something on the order of the Devonian /Permian extinct event of 250 million years ago which wiped out 90 percent of the species on Earth. Scientist have theorized that global warming may have been the culprit there .

 

[Stephen Palmer]

Or at the very least something on the order of the Devonian /Permian extinct event of 250 million years ago which wiped out 90 percent of the species on Earth. Scientist have theorized that global warming may have been the culprit there .

100% recommended read!

 

[Anne Spackman]

Of course, but with our current technology, maybe a manned trip to Mars is too risky. I would still like to see us go for it as best we can.

 

[BAYLOR]

Of course, but with our current technology, maybe a manned trip to Mars is too risky. I would still like to see us go for it as best we can.

We have some of the basic technology but it would still be a be a pretty hazardous undertaking.

 

[BAYLOR]

Recently they've found evidence of flowing water. It could mean there is more water there then we think.

 

[Karn Maeshalanadae]

Evidence of life?


Or evidence of SENTIENT life? The wording is important here, folks.


I believe microbial life has already been proven to have existed on Mars, at least, within soil samples.


Regardless, yes, we SHOULD risk trying to go there. Some might think we can't afford the risk if we find evidence of sentient life.


I say we can't afford to NOT take the risk, whether that evidence is there or not. Earth is dying, slowly and surely, at least, its ability to sustain 7,000,000,000+ people is.


Mars or bust, folks. Mars or bust. We can't leave our solar system, the moon has no atmosphere and is too small as it is, and every other planet besides Mars is either too hot, or a gas giant as it is. Without space colonization, we're through.

 

[Venusian Broon]

I believe microbial life has already been proven to have existed on Mars, at least, within soil samples.

Not yet, there was some puzzling results with Viking but I believe the consensus is now that it was chemical reaction rather than biological. Still a few people argue about it as maybe, perhaps...

I don't remember any of the other probes or rovers picking up any biological material at all.


I also think your being too pessimistic about the Earth . The Earth's ability to sustain the 12 billion or so humans that we think we'll peak it at, yes, that is likely to collapse if we keep on going the way we're going. And if it does, it will be a massive problem for said humans and a chunk of other species. But Life will continue on, just as it always has when extinction level disasters have hit the planet. (Of which this planet has experienced many.)