Mars-Like Conditions Sufficient to Sustain Earth-Bound Microbes 78
skade88 writes "Does life exist on Mars? We might assume if there ever was life on Mars then it most likely came about when Mars was a wetter and warmer place than it is now. So the question is, if life did exist on Mars in the past, does it still exist? Ars takes a look at how microbes have survived on Earth in environmental conditions much like we currently see on Mars."
Re:No, the question is: what happened (Score:2, Interesting)
The sun isn't getting hotter [skepticalscience.com]. Water vapor isn't light enough to escape Earth's gravity well in any appreciable quantity [sbc.edu]. Plate tectonics are driven by convection currents in the Earth's mantel [wikipedia.org], not the oceans, and if anything the (extremely unlikely) ceasing of tectonic activity would decrease CO2 emissions [columbia.edu].
=Smidge=
Re:Good and bad (Score:0, Interesting)
Why do we have to be careful of contaminating a barren wasteland that only the most ignorant could possibly believe ever contained life. I can understand lying about the possibility of life to get funding and continuing to do so until it is practical to actually terraform it.
The idea of preventing life from spreading from Earth is the most immoral thing I can imagine.
Re:No, the question is: what happened (Score:5, Interesting)
Yes, the Sun is getting hotter as it evolves across the main sequence of the Hertzsprung-Russell diagram. However, this is happening on a time scale of hundreds of millions of years. You are right that it has absolutely no effect on our climate today, but it will over the next 200 million years or so. Water vapour does not escape into space, but it will become a larger part of the atmosphere as the Earth heats up, and water vapour is a very potent greenhouse gas. Eventually the water vapour will be lost. First, as the atmosphere heats up the random motion of water vapour molecules will increase, so more of them will end up in the high-velocity tail of the Maxwell-Boltzmann distribution, and thus have enough speed to escape. Second the changes in the chemistry of the atmosphere will make it easier for water molecules to chemically dissociate (and cosmic rays will contribute too). The net effect is that water vapour will be lost, but on time scales of hundreds of millions of years. Plate tectonics are driven by convection currents in the mantle, but they are lubricated by water. If there are no oceans it is much harder for plates to subduct. Once the oceans are gone plate tectonics become much more difficult. This is thought to be the reason that Venus, a planet with essentially the same mass and internal composition as the Earth) shows no evidence for having plate tectonics. My understanding is that this is still somewhat hypothetical, but that there is an emerging consensus in the the geological community that oceans play a major rôle. Finally, plate tectonics do not drive geological CO2 emission, vulcanism does. While it is true that plate tectonics does cause vulcanism volcanos can happen without it, as we see on Venus, and in Hawaii. So, when plate tectonics stop there will still be CO2 emission from vulcanism. However, the carbonate-sillicate weathering cycle will have stopped, and this is the primary geological way of removing CO2 from the atmosphere. The net effect will be CO2 being added by volcanos, but with nothing to remove it the concentration of CO2 in the atmosphere will increase. Unless if we buy some Puppeteer world-moving technology Earth is in for a hot time around its 5,500,000,000th birthday.
Re:Good and bad (Score:4, Interesting)
One of the problems with terraforming Mars (and potentially lots of other rocky, goldilocks zone planets) is the lack of a substantial magnetosphere. Earth’s magnetosphere greatly mitigates solar wind and radiation. Solar wind can strip a planet of its atmosphere and solar radiation isn’t good news for ‘earth like’ life.
The conditions for life might be quite common in the universe, but the conditions for complex Earth like life are much, much more rare (but perhaps still substantial given the numbers). We have a lot going for us here. We are part of a solar system in a ‘quiet’ part of the galaxy. The vast majority of stars in our galaxy, and most others, are in areas of great cosmic violence. They are too close to the galactic core, or too close to a star that goes supernova or hypernova during the evolutionary process. There are planets that don’t have a moon or nearby supergiant plants (like Jupiter, Saturn, etc.) to protect them from comets and asteroids, and they don’t have strong magnetospheres. Of course a planet like Mars does have a lot of these things going for it, it doesn’t have a strong magnetosphere which is a sizable technological hurtle to terraforming (assuming we are terraforming for us).
Most likely humans will become largely virtual data based organisms long before we develop the technology or focused the resources on things like terraforming planets. If this happens, the need to do things like terraforming other planets kind of goes away.