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New Clue for Life on Mars?
thhamm writes "Recent analyses of ESA's Mars Express data reveal that concentrations of water vapour and methane in the atmosphere of Mars significantly overlap. This result, from data obtained by the Planetary Fourier Spectrometer (PFS), gives a boost to understanding of geological and atmospheric processes on Mars, and provides important new hints to evaluate the hypothesis of present life on the Red Planet."
Of course, life could probably exist in a totally different paradigm, but it's kind of hard to design space probes or experiments to test for the unknown.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
I'm pretty postive that there is no verified example of silicon based life. Rather, due to the chemical similarities between carbon and silicon it is speculated that life (as we know it) could have or could in the future evolve based on silicon rather than carbon.
This is not a limitation of the viewpoint, but rather an acknowledgement of our intrinsically limited conception of life: life which we will recognize as being life must have certain characteristics to differentiate from..."not life", and it those characteristics hinge on certain chemical processes.
"Stumble before you crawl"
The only problem with terraforming mars is the lack of magnetic field and its weak gravity. The weak gravity allows the atmosphere to escape http://zebu.uoregon.edu/~soper/Mars/atmosphere.htm l and the lack of magnetic field allows the solar wind to blow the rest of the atmosphere away. http://science.nasa.gov/headlines/y2001/ast31jan_1 .htm So, we could make it fit for human habitation, but we would have to continually replenish the atmosphere making it uneconomical.
No, a spectrometer measures reflected (or scattered, trasmitted, emitted) electromagnetic radiation (EM). Methane and water have different spectral signatures. They reflect EM -- or light -- differently. Probably, they're measuring the absorption patterns in the atmosphere.
Seth Shostak of SETI has an interesting article on the silicon-vs-carbon life thing here. Among other thing, carbon dioxide is a much nicer waste product than silicon dioxide.
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There wasn't any free oxygen until the plants made it. They count as life by the way.
They are looking at the stretching vibrations of hydrogen attached to oxygen and carbon. These vibrational frequencies are pretty distinct in the infrared reqion due to the differing masses of carbon and oxygen, and also changes in electron density in the bond.
IIRC, the big discovery about life near ocean vents was that they got their energy from metabolizing the nasty (read, highly reactive) checmicals that spew out of the vents, rather than make energy through photosynthesis, or eating other organisms.
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-- Pablo Picasso
Close. scientists used to say light was essential for life to develop, but then found life forms in deep ocean vents that had a modified photosynthesis chemistry based on heated sulphur, instead of light, stimulating the construction of sugars.
I have alot of problems when scientists claim carbon or water is essential for life. What they should claim instead is that carbon or water is essential for life as know it.
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"Sometimes I think we're alone in the universe, and sometimes I think we're not. In either case the idea is quite staggering." -- Arthur C. Clark
I'm pretty postive that there is no verified example of silicon based life. Rather, due to the chemical similarities between carbon and silicon it is speculated that life (as we know it) could have or could in the future evolve based on silicon rather than carbon.
:) But looking to silicon to replace carbon is a bit silly - carbon will always exceed silicon in abundance by orders of magnitude, as it's one of the end products of the triple-alpha process (hence the reason that CNO are roughly tied for the third-most abundant elements in the Universe, after hydrogen and helium). So silicon-based life will, quite simply, never exist.
Silicon's unstable on long chains. Carbon is not, as evidenced by proteins, DNA, and other "let's make a molecule out of a few thousand atoms!" gigantic molecules that make chemists hide underneath their blankets shuddering, whimpering about pi bonds.
OK, OK, that was a bit severe.
As for why you need water - that's also pretty easy. Water's the simplest strong dipole you can make out of hydrogen, and you need a dipole to make very very weird chemicals like life needs. Ammonia might be possible, but the full dynamics would need to be worked out.
>Mars would be reasonable if it had a working greenhouse effect. Temperatures on Venus would be reasonable (although a _little_ on the warm side) if it didn't.
OT: actually this is not strictly true; a greenhouse effect is the least of Venus's problems. Venus is an Earth-sized world which never underwent a large collision in it's formation and never aquired a lunar body. Earth, conversely, had a small planetoid smack into it some four billion years ago, blasting away most of the atmosphere and putting enough debris in orbit to form a very large moon. The impact combined with the subesquent lunar gravity skimming away the upper atmosphere ensued that the Earth wound up with a _very_ thin atmosphere for a body it's size.
In the case of Mars, the planet is much smaller (around 40% the size of Earth or Venus IIRC). Furthermore Mars has not one but two samll moons in orbit (unlike ours, they're really just captured asteroids but that's beside the point). And Mars has no protective magnetic field, and is consequently exposed to charged solar radiation, further thinning the atmosphere. Thus the pressure on the surface is way lower than terrestrial norms, whereas on Venus the pressure is obscenely high by our standards. The temerature differences are a matter of insulation largely (and solar proximity) but a greenhouse effect is almost moot. You might as well say that lunar nights would be warmer if the moon had a greenhouse effect; it's true but misleading given that the major issue is the simple presence or absence of a gas envelope. And no, the greenhouse effect does not refer to just insulation; it refers to the presence of gases that are trasparent to visible light but reflective to InfraRed (IIRC).
The theory I've heard is that Mars had a higher pressure and surface water at one point before its magnetic field quit. At this stage it would have still been fairly cold, but otherwise suitable for limited life. Life could have evolved then and subsequently died off; the interesting question is whether any life could have survived in niche environments.
Any astrophysicists or biologists care to elaborate/correct?
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Here's an interesting article about a speech that could take place at the International Mars Conference: Enterprise Mission.