What is it about Mars, anyway? Discoveries on Venus or Jupiter or Mercury get their share of attention, but when something happens on Mars, we go flat-out bonkers. The week of heated speculation that preceded this yesterday’s announcement of a discovery that had been described as “one for the history books” was only the latest example of the hold Mars has on us. The findings turned out to be meaningful — smart, important, solidly scientific — but the frenzy that surrounded them was of a piece with a long series of headline-grabbing Mars-related events going back a century or more, all of which turned out to be either bogus or at least badly oversold.
(Photos: Window on Infinity: Pictures from Space)
It the early 1900s, for example, Boston Brahmin and self-financed astronomer Percival Lowell swore he’d found canals on Mars, conjuring images of a super-race living on an irrigated planet and getting from place to place by boat. Orson Welles sent thousands of New Jersey residents fleeing from their homes in panic during his 1938 radio dramatization of a Mars invasion. In 1996, a paper in Science claimed evidence of fossilized bacteria in a meteorite from Mars, setting off yet another media frenzy. The announcement in 2003 that the Red Planet would be making its closest approach to Earth in 60,000 years got the Internet buzzing with its usual mix of fact and fantasy. And let’s not even discuss the preposterous face on Mars, a dusty, 1-mi. wide (1.5 km) knob that has, or had, the distinction of resembling a face when viewed from orbit, until later flyovers by other spacecraft showed that the same Martian wind that sculpted the features had largely blown them away.
The explanation for our fascination, of course, is that Mars is the only planet in the Solar System that looks like a place where life might exist. Lowell was wrong about those canals, not to mention the vegetation he swore he could see alongside them, but the planet’s icecaps, first spotted in the 1600’s, are real, and their waxing and waning with the seasons has given centuries of astronomers the hope that Mars is at least somewhat Earthlike.
More recent discoveries that the planet’s surface bears telltale evidence of having been sculpted by free-flowing water has only added to Mars’ life-friendly promise: that’s why the self-propelled Mars Science Laboratory, a.k.a. Curiosity, which landed on the Red Planet in August was targeted specifically for the once-wet Gale Crater, where it promptly rolled into a dry, ancient streambed.
The rover’s exotic landing site wasn’t quite enough to kick off a new episode of Mars mania, but some unguarded remarks just before Thanksgiving by a Curiosity team member was. Speaking with NPR’s Joe Palca, chief project scientist John Grotzinger declared that “This data is going to be one for the history books. It’s looking really good.” Media outlets around the world jumped all over that one, suggesting that Curiosity might have found evidence of life, or something close. And despite plenty of skepticism from some old space hands, the conspiracy theory suggesting that NASA was keeping Big News under its vest just wouldn’t go away.
It wouldn’t, that is, until scientists made the big reveal at the American Geophysical Union meeting in San Francisco on Dec. 3. What Curiosity had found was…dirt. That itself is impressive enough: not only did the space probe travel across tens of millions of miles of interplanetary space to land safely on another planet, it also worked perfectly once it got there.
But what it did with the Martian dirt was what really counted. The probe collected five scoops of the rust-red stuff, dropped samples of them into five quartz cups (Curiosity has 59 of them in its interior science lab), heated them to nearly 1500°F (816°C), and analyzed their chemical composition. The soil contains water, carbon dioxide, and volcanic minerals, among other substances.
More tantalizingly, Curiosity also detected traces of organic molecules, specifically a form of methane. Isn’t clear yet whether the molecules are indigenous to Mars or were contaminants brought up from Earth—though simply by operating its science hardware some more, Curiosity will soon scrub itself free of any such contaminants. Even if the organics originated on Mars, that doesn’t mean life is, or ever was, present there. “Organics get a little overplayed,” said Grotzinger at a press conference. “We found them on Mercury last week. This is pretty common in the universe.”
It also doesn’t rule life out, of course. But what’s important about the samples is that they seem to resemble the soil seen elsewhere on the planet. “Our bottom line,” said Grotzinger, “is that we have a globally representative material.” That will tell the scientists all sorts of things about the planet’s composition and history. It will also give them a baseline for comparison when Curiosity reaches its main destination: the exposed, layer-cake sediments of Mount Sharp, still several miles away.
As for the misunderstanding over the “history books” statement, Grotzinger had this to say in response to a question by a reporter from Al Jazeera: “What I’ve learned is that you have to be careful about what you say and even more careful about how you say it. We’re doing science at the speed of science in a world at the speed of Instagram.”
Still, just because Grotzinger’s original words got misinterpreted doesn’t mean they were wrong. Every successful mission to Mars, starting with the Mariner flybys of the 1960’s and the Viking landers of the 1970’s, has been literally historic, with each space probe telling scientists vastly more about this endlessly fascinating planet than they’d known before. Curiosity is proving to be no exception. The rover may yet find evidence that life once thrived on Mars—and even, conceivably, that remnants are still hanging on.
But that’s hardly needed to make Curiosity the most extraordinary Mars mission ever. Until the next one.
(From the Time Archives: Space: Onward to Mars)