An area of Mars called the Murray Formation, an ancient mudstone formation, where the Curiosity rover found ancient organic molecules. Photo courtesy of NASA/ JPL-Caltech
“I’d like to get away from Earth awhile,” I keep hearing Robert Frost declaim lately. “And then come back to it and begin over.”
While standing on the deck just before dawn, specifically, trying to forget about the pandemic for a few minutes. Looking into outer space at three bright-shining objects just over the treetops, and trying to remember what it’s like to leave the yard freely, never mind travel the deep, interplanetary expanse.
The three bright lights are Jupiter, Saturn and Mars. Brightest is Jupiter at magnitude –2.3, but it’s Mars that’s never very far from consciousness. For me, anyway. It’s the reddish one. The one most like Earth, and most likely to house extraterrestrial life. There it is, a launching-point to the realm of mind, and I’m off for a while.
Because, as it happens, the scientific evidence is mounting — with tectonic slowness — that there are living beings on Mars. For a while now it’s been clear that much more water than previously thought is locked up in Mars’s surface and ice caps; water is the cradle, so to speak, of life as we know it. Just recently, the Curiosity rover found thiophenes, an organic compound, in a mudscape formation. How the thiophenes got there is a puzzle. The scientists say they’re more likely to result from biotic processes than chemical processes. They could be signs of ancient life.
Another thing the scientists have noticed recently is that levels of oxygen and methane in the atmosphere in the rover’s vicinity have been fluctuating more or less seasonally. Oxygen levels have increased up to 30% during spring and summer, then dropped back down in fall and winter, in tandem with roughly similar increases and decreases in methane. These gases do not co-exist well, but on Earth they’re abundant because living things replenish them all the time. No one knows if living things are growing during Martian spring and summer, producing oxygen and methane, and then going winter-dormant.
No one knows for sure one way or the other. The original tests for life on Mars were performed by the Viking landing crafts in 1976. The landers, 4,000 miles apart, collected soil samples, injected them with a drop of nutrient solution, then watched for radioactive byproducts of metabolism, which would signal the presence of life. The tests were positive. It looked like life was there. However, the landers performed another test for the presence of organic molecules in the soil. Those tests were negative. No organic molecules, no life. So the results of the Viking tests were deemed, officially, inconclusive — which over the years has been tantamount to negative.
But one of the test designers, Gilbert Levin, has thought for the whole time that the test results reliably indicated the presence of microbial life on Mars. The chances the results were created by non-biotic causes, in other words, are slim to none, in his view. He wonders why for more than 40 years, while more landers have been sent to Mars, none has been equipped with followup tests for life. They’ve been gathering all kinds of other ancillary data, but not focusing on the central question: Has there ever been life up there?
There is a meteorite fragment that came from Mars which NASA scientists have argued contains the fossils of microorganisms. Levin also points out that, among other things, spectral analyses by Viking’s imaging system found that green patches on some Mars rocks are identical in color, saturation, hue and intensity to terrestrial lichens; the Curiosity rover found large structures resembling calcium carbonate material generated in Earth sediment by cyanobacteria; a statistical analysis of the structures’ complexity showed less than a 0.04% probability that the similarity could have resulted by chance.
It sounds a lot like the astrobiologists are just waiting for the very last piece of the 10,000-piece puzzle to tell us that there is, or at least has been, life on Mars.
I’m thinking all this and envisioning the rock-red gravel surface of Mars, and I wonder if that Martian life is some kind of virus. Suddenly I’m back on the deck with the slow-brightening sky and the April morning chill. May no fate willfully misunderstand me, half grant my wish and snatch me away to Mars, never to return. Earth’s the right place for life, virions and all.
There, that’s a little better.
Dana Wilde lives in Troy. You can contact him at naturalist1@dwildepress.net. His recent book is “Summer to Fall: Notes and Numina from the Maine Woods” available from North Country Press. Backyard Naturalist appears the second and fourth Thursdays each month.
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