One way or another, the touchdown of NASA’s Mars Science Laboratory early Monday morning after journey of more than eight months will be a major news event. If the space probe survives its tricky landing sequence, which Jet Propulsion Laboratory scientists have dubbed “Seven Minutes of Terror,” the self propelled, SUV-size laboratory, known more familiarly as Curiosity, will begin rolling across the Martian surface, looking for signs that the Red Planet might have been hospitable to life long ago. It’s the biggest, most capable Mars rover ever, and it’s certain to add valuable new insights into our growing understanding of the most Earthlike planet we know of.
An artist's concept of the sky crane maneuvering during the descent of NASA's Curiosity rover to the Martian surface. Credit: Jet Propulsion Lab/NASA
If the probe crashes, of course, as many Mars landers have in the past, the mission will make headlines of a different sort, especially given it’s approximately $2.5 billion price tag. (Anyone who wants to watch the landing in real time should tune into NASA’s live video feed. Coverage begins at 11 p.m. Sunday with the landing expect to be around 1 a.m. Monday).
Either way, though, this latest mission to the planet next door is part of something much bigger: it’s the latest chapter in an obsession with Mars that dates back more than a century. It was all the way back in 1877 that the Italian astronomer Giovanni Schiaparelli turned his telescope on the reddish orb and reported something astonishing: swimming in and out of view, at the very edge of visibility, he saw a network of what appeared to be straight lines crisscrossing the surface, that looked for all the world like artificial irrigation canals.
“Their singular aspect,” he wrote, “and their being drawn with absolute geometrical precision, as if they were the work of rule or compass, has led some to see in them the work of intelligent beings, inhabitants of the planet. I am very careful not to combat this supposition, which includes nothing impossible.”
The idea that Mars was inhabited immediately inflamed the popular imagination, and no wonder. Scientists had speculated for centuries about whether other planets in the Solar System had intelligent, living beings. If they were, it meant humanity wasn’t alone in the vast universe, and that we might someday communicate with our alien cousins.
The flames got even hotter a couple of decades later, when a rich Bostonian named Percival Lowell built his own observatory in Arizona, and claimed he’d confirmed Schiaparelli’s sightings. Lowell was persuasive enough that the New York Times trumpeted his discoveries as fact, and wrote in a finger-wagging 1909 editorial that “Harvard has ignored Prof. Lowell’s discoveries of water vapor, vegetation, snow caps, and canals, always, more canals, on Mars. The people of this country support Prof. Lowell in his Martian campaign.”
After that, it was off to the races: Edgar Rice Burroughs’ John Carter of Mars and other Mars books were huge hits; so was H.G. Wells’ The War of the Worlds and Ray Bradbury’s Martian Chronicles, along with innumerable other books and movies about life on the Red Planet. And while the existence of canals was finally debunked by more powerful telescopes than Shiaparelli and Lowell had at their disposal, the idea of a living Mars never vanished entirely. In fact, when Orson Welles put on a War of the Worlds radio dramatization in 1938, thousands of people fled their homes in panic (random historical note: the fictional landing spot for Welles’ Martian invaders was just outside Princeton, N.J., where Climate Central is located).
Gale Crater, the target landing area for NASA's Mars Science Laboratory mission. The specific location is within the ellipse drawn in which is about 12 miles long and 4 miles wide (click on the image for an expanded view). Credit: Jet Propulsion Lab/NASA.
It was only in the mid-1960’s that Mars flyby missions revealed the surface to be utterly dry and hostile, and the Viking landers a decade later provided close-ups that confirmed this depressing fact. The search for extraterrestrial intelligence shifted into deep space, with astronomers aiming their radio telescopes skyward to listen for alien transmissions.
But those pictures from space also showed something else: the planet was etched with features that looked uncannily like dry riverbeds and the shorelines of ancient seas. Mars might be a wasteland today, with a vanishingly thin atmosphere, but water flowed freely here billions of years ago — and with water comes the possibility of life. Not ravenous Martian warriors, maybe, or gentle Martian farmers, but bacteria, at the very least. For a few months in 1996, in fact, there was hope that we’d found their traces, in a Martian rock blasted into space and found in an Antarctic glacier.
In the end, the Mars Meteorite turned out to be a dud; the evidence wasn’t as compelling as scientists initially thought. But that hasn’t stopped NASA from sending orbiters and probes to Mars in a steady stream, to search for signs that life might once have flourished there — and may even continue to flourish underground, where water may still be trapped.
Curiosity is the most sophisticated Mars explorer yet. The probe will land in Gale Crater, where ancient sediments, formed when the planet was wet, are exposed for inspection. Curiosity will then drill, scrape and vaporize rocks from different layers to analyze their chemical makeup, looking especially for the carbon compounds scientists believe are the building blocks of life.
An artist's concept depicts the rover Curiosity, of NASA's Mars Science Laboratory mission. Credit: Jet Propulsion Lab/NASA
The rover won’t find life itself — not unless a Martian saunters in front of its cameras, anyway. That task will fall to a later rover, equipped to do the necessary biochemical analysis. If that future probe does find evidence of life, either present or past, it will prove that life arose at least twice, independently, which will raise the odds that it might have happened on millions of other planets across the Milky Way as well.
Or maybe not: we know that chunks of rock have been blasted from Mars to Earth at least 34 times during our shared history, and doubtless many more. It’s at least possible that one of these interplanetary travelers carried hitchhiking microbes, and that this is how life first came to Earth.
If so, we’d still have to assume that life arose only once, that it arose on Mars — and that if we want to stare Martians in the face, all we have to is look in the mirror.