Evidence of extraterrestrial life-on Mars?
The scientific community, let alone the public haven’t decidedly formed an opinion on this issue of life on Mars-so far as I can tell. I remember the Clinton years, when, in 1996 it was announced that scientists found evidence, albeit controversial, to suggest that signs of Martian “life processes” were represented in the meteorite dubbed ALH 84001. This caused quite a stir back then, as it appeared to represent a well supported and esteemed conclusion – such that the president of the United States had to make a public address to the nation.
Well, even after that 14 yr old announcement, the evidence remains hotly contested to this day. So, it’s surprising then that the astrobiologist Dirk Schulze-Makuch proposed that even better evidence of microbial life on Mars was obtained since the 70’s ,during NASA’s Viking missions.
The Viking lander carried on-board a set of life detection experiments, which, as Makuch suggests, were too ambitious for their time. He holds that position because, since the 1970’s we’ve come a long way in understanding the upper and lower limit environments in which life can thrive, and retrospectively, our experiments were too limited in scope to accommodate current expectations of where, and how life might be found. Even though this is the case, he believes that the Vikings’ life detection experiments’ results don’t write-off the possibility of life’s existence on the red planet. In particular, the results of the Gas Chromatograph Mass Spectrometer (GC-MS) reported no evidence of organic matter in its soil sample. This is a dubious result, considering that today we know that there are in fact organics on the planet. They were found in ALH 8001 and among other martian meteorites, to be sure. So then, why did the GC-MS not detect them? For one, or all three of the following reasons :
1. The concentration was too low.
2. They were in an unrecognizable form.
3. They were all oxidized to CO2 before they could be measured.
Makuch and colleagues believe that some combination of 2 and 3 are to explain that.
The GC-MS apparently found a higher than expected amount of Carbon dioxide in the sample. This could be explained by a theory that Makuch and his colleague posit-that Martian life might use a mixture of Hydrogen Peroxide and Water as their cellular fluids ( as oppose to just H2O, as we do) thereby giving two adaptive properties to Martian organisms, antifreeze properties, and the ability to suck water out of the atmosphere, an advantage to life on a dry cold planet. So, in effect, upon heating up the soil sample in the GC-MS experiment, the hydrogen peroxide destabilized and oxidized the organic compounds, releasing the unexpected amount of carbon dioxide. They claim that this would also explain the results of the Gas exchange and the Pyrolytic release experiments, which were conducted with excessive amounts of water, more than the microbes could handle. He believes that the Pyrolytic experiment conducted under dry conditions is telling, because it showed highly significant rates of organic synthesis -which are consistent with microscopic life.
Essentially, Makuch believes that evidence of life exists on the planet, and that it is a shame that not a single probe/rover or experiment on Mars since Viking, carried out the same methods of life detection that the Viking performed. Armed with an advanced understanding of microbiology since the 70’s, we’re better prepared to interpret a similar experiment performed today.
I find the hypothesis of life put forward by Makuch and his colleague interesting. I also support their critiques, considering that any experiment on top soil, as the Viking landers performed, might reveal the type of microbial life most recently adapted to the planet, which until most recently has been only cold and dry. If Mars was a wamer, and wetter environment many millions of years ago, we ought to find evidence of that life within cave systems or deeper underground. Given that Mars is no longer geologically active, we shouldn’t expect to have to dig too far to find what we’re looking for. Maybe in 15-25 years or so, as Obama suggests, there will be such a mission to find it; perhaps I’ll witness that manned mission.
Read more about Makuch and his new book here Amazon.
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