So how did you spend the last twelve months? Do much traveling? Get a lot of work done? Good for you. All the same, it probably doesn’t pay for any of us to compare our past year to the one the Curiosity rover just spent on the surface of Mars.
It was at 1:32 AM EST (5:32 AM UTC) last August 5 that the one-ton rover made its high-wire landing in Gale Crater, just south of the Martian equator, lowered the final 25 ft. (7.6 m) by cables from a hovercraft—a nifty way to get the Mars car safely on the ground without leaving the landing area cluttered with debris. The prospect of such an improbable maneuver kept people up late across the country, with crowds in Times Square watching the scenes from NASA‘s Jet Propulsion Laboratory (JPL) on outdoor jumbotrons, and slumber parties at Chicago‘s Field Museum and elsewhere, allowing families to watch together they way they did long ago during the first moon landing.
No one pretended that that level of public fascination would be maintained during the years of work the rover would have ahead of it, and nor should it—science can be slow and tedious even for the people practicing it. Still, Curiosity has made a lot of news in the past year, in part simply for living up to its ambitious design and functioning almost flawlessly in so punishing an environment and at so great a distance.
As the rover completes its 355th Martian sol, or day (which is just 37 minutes longer than an Earth day), it has sent home more than 70,000 pictures, fired more than 75,000 bursts from its laser to vaporize rock and soil and analyze their chemistry, drilled into rocks, collected scoops of dirt for on-board analysis, and put more than 1 mile (1.6 km) on its odomoter. That off-road motoring is more impressive than it seems, in part because the rover moves at of just 300 ft. (90 m) per hour and in part because it was never suposed to travel very far from its landing site in its shakedown year. What’s more, Mars is currently nearly 222 million miles (357 million km) from Earth, which means that controlling the rover is a lot harder from simply hitting a joystick at JPL and telling the thing where you want it to go. Even traveling at light speed, a command from Earth takes 19.8 minutes to get to Mars. Then it takes another 19.8 minutes for word to come back that all went well and Curiosity didn’t just drive off a cliff. So things proceed painstakingly.
Still, in the little footprint of land in which it has moved about, Curiosity has sent back some tantalizing science. Last December, its Sample Analysis at Mars (SAM) instrument—an on-board chemical sniffer—reported that it had found methane in the Martian soil. There are a number of possible sources for the critical hydrocarbon, but one of them is waste material from bacterial life. This is just the kind of preliminary (stressing the preliminary) finding that gets scientists studying exobiology excited. Alas, in an interview with NPR before the results were revealed, the Curiosity chief scientist spoke a little hyperbolically about the then-pending announcement, promising that it would be “one for the history books.”
The fact is, that’s just what it was—provided those history books are being written by scientists who know how to keep things in perspective. But the quote exploded across the Internet and elsewhere, leading to breathless speculation that life had been found and requiring JPL to issue an everybody-calm-down statement. In a later e-mail exchange with TIME, JPL spokesman Guy Webster framed things perfectly. “As for history books,” he wrote, “the whole mission is for the history books.”
More moving than the methane news were the pictures the rover beamed home, and one in particular—of rounded, water-polished pebbles in a dry, ancient stream bed that looked exactly like the same kinds of pebbles found at the bottom of every brook you’ve ever seen, except that these were located a full planet away. The shape and size of the pebbles suggested that the long-ago stream was about ankle deep and rushed along at a speed of 3 ft. (1 m) per sec. It was, in turn, part of a much larger alluvial fan—a delta-like formation in which water from a main riverway spills out in multiple directions, leaving deposits of sediment behind.
Gale Crater’s waterlogged past is the very reason it was chosen as Curiosity’s landing site, and its complex geology (and, yes, possible signs of biology) also helps explain why the rover has taken its sweet time poking around. Its eventual goal, however, is nearby Mount Sharp, a 3.4 mi. (5.5 km) tall peak located about 5 mi. (8 km) from the main landing site. Mount Sharp’s flank is eroded away, revealing a layer-cake of geological deposits—a chemical and mineralogical history book of the past few billion years. That is where Curiosity is headed now, making a slow, months’-long crawl to the base of the mountain.
On the way to Mt. Sharp, the rover will be doing other kinds of work—sampling the Martian air, winds and weather, and also studying the planet’s radiation levels, critical information if humans ever plan to make the trip. “Wheel tracks now will lead to boot prints later,” said NASA Administrator Charles Bolden, in a statement. That “later” could, realistically, mean much later. Even NASA doesn’t envision a human landing any time before 2030—and if the manned space program’s history over the past couple of decades proves anything, it’s that all deadlines slip, often by quite a lot.
Still, there’s no denying that until humans actually do arrive on Mars, Curiosity—and all of the machines that have preceded it and will follow—can serve as magnificent proxies. One way or another, humanity is hard at work on another planet, and the year just past has been our best yet.
(FROM THE ARCHIVES: Onward to Mars)