November 25, 2011 | 5
Starting this Saturday, a 24 day window of opportunity opens for the launch of NASA’s Mars Science Laboratory, now also known as the Curiosity rover. If all goes well (very well) then in August 2012 a new visitor will barrel down into the martian atmosphere through a six-and-a-half minute maneuver involving hypersonic speeds, air-braking, parachutes, powered descent, and a skycrane lowering a 2,000 lb (Earth weight) radioisotope (plutonium) thermo-electric-powered six-wheeled robotic avatar to the dusty regolith of this distant world.
If that sounds a bit tough, well, that’s because it is. Putting objects into space is one thing, getting them to another planet and down safely onto the surface goes to a whole other level. Both endeavors carry enormous risk due to the potent combination of complex engineering, extreme physical conditions, and the variance of natural conditions at any given moment. Occasionally I’ll find myself in a conversation about these challenges that ends up with someone saying that “we’re just not a real spacefaring race and we’ll never get to visit much of the universe.” I’m always struck by the glum expression of certitude about our Earth-bound nature, but the optimist in me wonders if this can really be true?
A while ago National Geographic published one of their terrific graphical illustrations that summarized 50 years of human space exploration. I can’t do it justice here, so go take a look. The incredible thing is just how much space exploration we’ve actually tried (and quite often succeeded at). One target is particularly evocative, and that is Mars. I think it’s fair to say that going to Mars has always been far less about politics than some other, much closer, destinations. Mars looms big in our imaginations, the red planet, awfully familiar, yet awfully different. There is incredible poignancy in the list of missions to Mars. A majority have been failures, years of effort and extraordinary technological know-how thrown to the sacrificial plinth of the void. Yet those that succeeded have genuinely transformed both our understanding of this other world, and transformed our relationship to space exploration.
Here’s the list, starting in 1960, with successes (albeit some partial) high-lighted in boldface:
Mars 1M (failed), Mars 2M (failed), Sputnik 22 (failed), Mars 1 (failed), Sputnik 24 (failed), Mariner 3 (failed), Mariner 4 (flyby), Zond 2 (failed), Mariner 6 (flyby), Mariner 7 (flyby), Mars 1969A (failed), Mars 1969B (failed), Mariner 8 (failed), Cosmos 419 (failed), Mariner 9 (orbit), Mars 2 (orbit), Mars 3 (lander), Mars 4 (failed), Mars 5 (orbit), Mars 6 (failed), Mars 7 (failed), Viking 1 (orbit/lander), Viking 2 (orbit/lander), Phobos 1 (failed), Phobos 2 (failed), Mars Observer (failed), Mars Global Surveyor (orbit), Mars 96 (failed), Mars Pathfinder (rover), Nozomi (failed), Mars Climate Orbiter (failed), Mars Polar Lander (failed), 2001 Mars Odyssey (orbit), Mars Express (orbit), Beagle 2 (failed), Spirit (rover), Opportunity (rover), Mars Reconnaissance Orbiter (orbit), Phoenix (lander), Phobos Grunt (failed, probably).
That’s 40 missions, 17 successes (even if only partial), yielding a 42.5% pass rate.
Each of these launches, each chunk of alloy and package of electronics, was made to reach across interplanetary space. There was nothing glum about this. Bottles cast into the currents full of tentative human optimism and love and care. All the hallmarks of a space faring species negotiating its first steps. All for a minuscule fraction of resources across the years compared to wars, financial crises, pharmaceuticals, and political shenanigans. To my mind we are already a space faring species, we just haven’t quite realized it yet.
Which brings us back to the launch of the Curiosity rover. This device, this mission, has had its share of problems even before leaving the Earth. Embarrassingly large cost overruns plagued the Mars Science Laboratory during its development, and terrific instruments that would have gone onto it were dropped to save money and time (for example, there will be no 3D movies from David Malin’s and James Cameron’s cameras). Even choosing a landing site was a great challenge, constrained by simple spacecraft flight requirements, and by the huge array of science questions that everyone wanted the rover to tackle. But for all the wrangling and upsets here it is, and it’s a beast.
In brief, the array of instruments on the Curiosity chassis are designed to continue and greatly extend the mineralogical, geophysical, and climate system investigations of the Spirit and Opportunity rovers and the devices that came before them, like the Viking landers. Most critically it will push our analyses of Mars further into the chemical and bio-chemical regime. The list of capabilities is lengthy, but among them are juicy tools like a laser ablation device. Yes, a “LASER” – the Laser-Induced Breakdown Spectroscopy system that is part of the ChemCam set of sensors can target material up to 7 meters (23 feet) away. A very brief flash of the infrared beam then vaporizes surface material into a small puff of gas that a high-precision fine-imaging camera can observe and pull out spectral data on, leading to a fingerprint of chemical composition.
One of the other experiments to watch is the Sample Analysis at Mars instrument package (SAM). Here (to the left) is its cube-like block being carefully installed onto the rover. SAM is full of spectrometers (including one with another, internal, laser), gas chromatographs, and two ovens. The ovens will enable Curiosity to cook samples to examine volatile components and to further analyze rocky structure. And I can’t resist saying that the sample manipulation mechanisms that bring bits of Mars into SAM were designed and built in New York by Honeybee Robotics, just down the street from Penn Station.
The reason to keep an eye on what SAM finds is that it is capable of sniffing for organic (carbon) molecules – the most rudimentary pieces of life as we know it. It should also help resolve one of the most exciting, albeit still controversial, claims in recent years – the detection of seasonally varying plumes of methane gas in the martian atmosphere. These measurements, made remotely, indicate that there must be a re-supply mechanism for that methane, since it would otherwise be removed from the atmosphere by natural chemistry. Here on Earth, most methane you will encounter has a biological origin (not cow farts, but the methanogenic archaea that live inside cows, and in innumerable other niches), and so renewable methane on Mars could, just possibly, have something to do with life – living or extinct.
One further clue would be if the carbon atoms in martian methane are statistically skewed to the lighter isotopes – life on Earth tends to prefer light isotopes, for kinetic chemical reasons. And the instruments in SAM can go one better than just confirming the concentration of atmospheric methane, they can begin to check for that isotopic smoking gun.
This is big scientific stuff, really big stuff. But it carries a hefty price tag not only in dollars, but also in risk. A marvelous piece of engineering like SAM contains an astonishing 600 meters (650 yards) of wiring, 52 microvalves, a 100,00 rpm pump, and lots of other pieces. Of course it’s all been designed, tested, re-designed and re-tested. However, it must not only survive launch, interplanetary travel, atmospheric entry and landing, but also work flawlessly as Curiosity prowls across at least 20 kilometers (13 miles) in temperatures ranging from -127 to +30 Celsius (-197 to +86 F), for at least a year. That’s a tall order, pushing the limits of engineering and technology. It’s the nature of space exploration though, and each time we succeed, we learn for the next time and so the risk becomes worth it.
So here’s a heartfelt wish for Curiosity’s success, but also a recognition that no matter what happens right after the launch engines are lit, the mere act of building it took us further down the long hard road to Mars, and perhaps eventually the universe.
(Some of this text comes from an older post made on Life, Unbounded in June 2010)