More than any other planet in the solar system, Mars has always inspired speculation that it once had life and perhaps still does – if not little green men, then at least microbes. NASA’s much-hyped announcement this week about the Red Planet wasn’t earth-shattering, but it certainly keeps such conjecture alive.
The latest discoveries come courtesy of Curiosity, a $2.5 billion spacecraft that landed on Mars back in 2012. In 2013, it discovered some organic molecules in the Martian soil; and in 2014, methane gas in the atmosphere.
Now, its instruments have revealed two other things: a puzzling seasonal ebb and flow of the planet’s methane gas levels; and the existence of additional organic molecules, this time in rocks billions of years old.
Ninety-five percent of the methane on Earth is generated by plants and animals – for example, rotting vegetation and animal flatulence. And organic molecules are, of course, the warp and woof of all life on Earth. So it’s tempting to conclude NASA has found evidence for life on Mars.
But methane gas and organic molecules have non-living origins as well – which the scientists at NASA’s press conference were quick to point out. Methane gas and organic molecules are routinely generated by prosaic geological and chemical processes. So, in truth, the new revelations leave us no closer to or further from answering the burning question: Is there, or has there ever been, life on Mars?
Back in 1877 that tantalizing possibility was seriously raised by Giovanni Schiaparelli, an Italian astronomer who claimed to see canali on the planet’s surface. Canali means “channels,” but people widely mistranslated it as “canals” – as in, Martian-dug waterways.
In 1894 Percival Lowell – the American astronomer who founded Arizona’s famous Lowell Observatory – published elaborate drawings of the alleged canals, which he claimed Martians built to route water from the poles to the equator.
Lowell’s fantastical hypothesis inspired H.G. Wells to write “The War of The Worlds,” a novel about Martians invading Earth. We now realize, however, the canali were an optical illusion fueled by wishful thinking.
The mania didn’t end there. In 1996 NASA scientists announced they had found evidence for fossilized microbial life embedded in a meteorite from Mars. The rock – named Allan Hills 84001, after the Antarctic location where it was found – generated as much media hoopla as Schiaparelli’s canali.
I covered the story for ABC News and was the only reporter allowed to actually touch the black, shiny rock with my gloved hands.
Today, many scientists doubt the veracity of the Allan Hills pronouncement. Which is to say, once again, a much-ballyhooed scientific pronouncement appears to have fallen victim to our stubborn fantasies about life on Mars.
How will history judge the latest NASA announcement? Stay tuned for revelations that will surely come from upcoming Mars explorers, such as NASA’s Mars 2020 rover and the European Space Agency’s ExoMars rover.
In the meantime, Curiosity’s latest discoveries underscore a remarkable reality. Mars, we believe, was once warm, wet, and possibly swarming with elemental life. Today, for various possible reasons, it is frightfully cold, dry, and seemingly lifeless.
At a time when we are arguing about climate change, therefore, NASA’s announcement reminds us that Earth’s warmth is a cosmic blessing – one of the critical fortunes that make it possible for us humans to exist and endure.