By Kimm Fesenmaier Mission to Mars Close to midnight on Black Friday, 2011, John Grotzinger was standing in the swampy darkness at Cape Canaveral, snapping photos of an Atlas V rocket, when a car pulled up behind him. “Oh boy,” he thought. “This is it . . . I’m getting arrested.”
It wouldn’t have been your typical the illuminated rocket and steel- these people have worked on what’s arrest: Grotzinger leads the team ing himself to be hauled off to jail. inside it, and that this rocket is going of scientists that had prepared the He wasn’t. The man who drove up to deliver their dreams to the surface precious payload atop that rocket— behind him that night turned out to of another planet . . . To see it up this the Mars Science Laboratory (MSL), be one of the engineers from the Jet close in the dark of night is a reminder the most capable robotic mission Propulsion Laboratory (JPL) who had of the miracle of engineering, and that ever sent to the Red Planet. Earlier been at Cape Canaveral doing final we should never take this for granted.” that November day, a colleague had checkouts of MSL’s car-sized Mars When the rocket blasted off the mentioned to Grotzinger that his rover, Curiosity. In fact, with his escort next morning—sending MSL on badge should allow him to get and photography privileges, the engi- its 352-million-mile trip to Mars— a close-up look at the Atlas V. neer was able to take Grotzinger right Grotzinger was cheering with the And so, after a series of uncertain up to the base of the rocket. science team in the bleachers at the turns and a bit of off-roading on the Grotzinger was awestruck. “You Banana Creek viewing area. The launch beach, Grotzinger found himself in get up close and see this enormous marked the end of the first phase of the the dark, just outside the fenced-off thing that you know is going to leave mission for Grotzinger, nine principal launch pad, taking in the beauty of Earth,” he says, “and you know all investigators, and their team of about 300 scientists from around the world. That team had worked with engineers to design, build, test, and integrate the suite of 10 scientific instruments that make Curiosity a fully automated, roving geological laboratory capable of collecting and analyzing samples on the surface of Mars. Now the clock is ticking down as they prep for the next phase, when they will begin receiv- ing images and measurements from Curiosity and using that data to seek evidence of a Martian environment
Due to Curiosity’s size and mass, a new sky-crane touchdown system will lower the rover to the Martian surface. Once Curiosity touches down, the bridle will be cut and the descent stage will fly away.
summer 2012 ENGINEERING & SCIENCE 13 that could have once supported bounce landing like theirs is out of the fied the chemical signatures of clays microbial life. question. This time around, stages and sulfate minerals, which are formed That phase will begin on August 5 will jettison, an enormous parachute through interaction with water, in the of this year when—if all goes well— resplendent in orange and white (in lower parts of the mountain. On Earth, MSL will blaze through the Martian Caltech’s honor) will unfurl, and eight these minerals are often found with— atmosphere, traveling at a speed retrorockets will fire. Then, in a dramatic and help protect—organic compounds. final act, MSL’s descent stage, posi- All this makes the mountain a promising tioned above the rover, will behave like place to begin investigating the planet’s a sky crane, lowering Curiosity on long past habitability. tethers to the surface of the planet. “We don’t know what the story is going to be at Gale Crater, but we’ve got We lcome to Gale Crater a wonderfully simple exploration model,” That action-packed entrance should Grotzinger says, “We’ll just start at the leave the rover poised on all six wheels bottom of the mountain, interrogate the inside Gale Crater, an ancient impact layers and make the crater just south of the Martian equator. measurements, and see Roughly the size of the Los Angeles what the planet’s trying Basin—at 154 kilometers (96 miles) in to tell us. I don’t think diameter—the crater is the kind of place we can lose.” geologists would head to on Earth to Ideal though the search for evidence of past life. They location may be, it took hope to find organic compounds, the the scientific commu- carbon-containing chemicals consid- nity about five years to ered necessary for life. So finding the settle on Gale Crater of some 13,200 miles per hour. In crater on Mars, at a safe elevation with as MSL’s landing site. less time than it takes to boil a pot moderate environmental conditions, “The amazing thing is of water—a nail-biting period known made it a natural choice for the mission. that, thanks to MSL’s as the “six minutes of terror”—the The floor of Gale Crater is at a low landing system, we spacecraft will go through a series elevation relative to its surroundings, scientists got to con- of maneuvers to put on the brakes which means that if water once flowed sider—for the first time and touch down. This will be no across Mars, Gale might have been a ever—the absolute best small feat: at nearly 2,000 pounds, location in which groundwater col- places on Mars,” says Curiosity weighs more than five times lected and perhaps even emerged as Grotzinger. “The whole as much as the previously launched an ancient lake. But the main attraction time we were debating, Mars Exploration Rovers (MERs) at Gale is a mountain that rises five I had seasoned veter- Spirit and Opportunity, so an air-bag kilometers (three miles) from the crater ans telling me, ‘John, floor.T he science team has dubbed don’t get your hopes this geological feature Mount Sharp up, because in the end Above: Curiosity’s landing plan puts it within Gale in honor of the late Robert P. Sharp (BS engineering constraints Crater, an impact feature on Mars that’s more ’34, MS ’35), the beloved former chair will probably kill all of than 3 billion years old. The layered mountain at of Caltech’s then Division of Geological these choices. Be prepared to accept its center, dubbed Mount Sharp by the science Sciences, who built the Institute’s pro- whatever’s left on the table.’ But we team, is a major scientific focus for the mission. gram in planetary sciences. Scientists didn’t have to settle. In the end, we Right: These are replicas of the wheels on hope to use Curiosity and its scien- chose the site that was actually the Sojourner (center), the first rover on Mars; the tific instruments to read the history of science team’s favorite, and the Mars Exploration Rovers (left); and Curiosity (right). Mars by characterizing Mount Sharp’s engineers could support it.” Curiosity’s wheels are approximately 20 inches strata—beginning with its oldest layers (50 centimeters) in diameter while Sojourner’s were at the bottom and inching up to those SAM I Am closer to 5 inches (13 centimeters). deposited more recently. Previous Curiosity is uniquely equipped to select, orbital missions have already identi- sample, and analyze rock and soil
14 ENGINEERING & SCIENCE summer 2012 targets once it arrives on Mars. Indeed, Once Curiosity drills into a rock or wipe away traces of organics because JPL deputy project scientist Ashwin scoops some soil to harvest a sample, it is also an oxidant. So even if life had Vasavada (PhD ’98) describes the rover its six-foot robotic arm will go through once thrived on Mars, scientists would as “a Mars scientist’s dream machine.” a series of tai-chi-like maneuvers to be hard pressed to find traces of it.I n Its onboard tool kit includes not only process and deliver the materials to fact, on Earth—a planet that teems with devices that are the equivalent of the the rover’s belly, where they can be life—the record of life in the form of hand lens and drill geologists rely upon analyzed by two advanced onboard organic matter is rarely preserved over in the field, but also the spectrometers laboratories. One, called CheMin, will geologic time. and other analytical instruments they use X-ray diffraction to identify minerals Not to fear, though: MSL’s success might use in the lab to identify the in the sample. The other, called SAM does not hinge on finding organic chemical elements, minerals, and gases (for Sample Analysis at Mars), is a suite matter. Simply by driving up the mound in their samples. The rover sports sev- of three analytical instruments—two in Gale Crater, taking samples, and eral cameras that will allow it to observe spectrometers and a gas chromato- reading the layered record it encoun- its surroundings in high definition and graph—that can check for large organic ters, Curiosity will improve our under- molecules and other important chemi- standing of the evolution of Mars. And cal elements, measure isotope ratios if it can reach a spot about a quarter to look for signs of past planetary of a mile (about 400 meters) up Mount changes, and determine concentrations Sharp, it should find a break point that of gases in both surface samples and may mark a geologic transition between the Martian atmosphere. the period when Mars was able to form “Such information will be invaluable hydrated materials and when the planet in reconstructing the geological and began to dry out. “The deterioration of environmental history of Mars which, in Mars’s early, more clement climate to my view, is the key to addressing the the inhospitable conditions that char- capacity of past and present Martian acterize the planet today is one of the environments to support life as we great mysteries of planetary science,” know it,” says Edward Stolper, Caltech’s says Grotzinger. provost and William E. Leonhard Pro- fessor of Geology. He served as MSL’s Meanwhile, back on Earth chief scientist from 2005 to 2007 and While Curiosity wends its way to Mars, helped coordinate early development of Grotzinger and his team of scientists the rover’s scientific capabilities. are doing more than just twiddling Although Curiosity is equipped to their thumbs. At JPL, rover drivers are identify organics (and finding them practicing their Martian navigation using would certainly be a grand slam for the Curiosity’s earthbound doppelgänger, mission) the likelihood of such a find is remotely controlling the movements of extremely low. That’s because the sur- the rover and its arm in either a ware- face environment at Mars is thought to house test bed or an outdoor “Mars be chock-full of chemicals that degrade Yard.” And the rest of the science team organic matter. Compounds such as is working out final details related to the in three dimensions. Its laser eye, called hydrogen peroxide and perchlorate, rover’s instruments. ChemCam, will zap rocks and other which can convert organics into carbon One working group, for instance, targets of interest from as far away as dioxide and other chemicals, have been is compiling a list of all the different seven meters (23 feet), enabling an detected in the Martian soil and atmo- situations that could be serious uh-ohs onboard spectrometer to get a sense of sphere. Ultraviolet solar radiation and for Curiosity’s sample-handling system— the target’s composition. And Curiosity high-energy radiation from incoming such as materials that give off fluid, will have the ability to measure radia- cosmic rays can produce highly reactive become sticky upon heating, or are tion, screen for water in the ground, radicals that readily alter organic matter, extremely hard. “Realizing we’re and monitor the Martian weather. rendering it undetectable. Even water, going to see minerals on Mars that which enables life to exist, tends to we’ve never seen before, and that we
summer 2012 ENGINEERING & SCIENCE 15 An early parachute design undergoes testing in the NASA Ames Research Center’s wind tunnel. Although the final parachute design is slightly different, it retains Caltech’s colors.
will have no way to really know what they are before we sample them, we have to do some haz- ard assessment before we would ever risk drilling into them,” says Vasavada. That’s why the group is testing terrestrial samples with some of these potentially prob- lematic characteristics, and doing so in a chamber that replicates the humidity and temperature at Mars, all to see how the sample- handling system responds. The most recent group of research- and Opportunity—which landed on the couple of weeks of subsisting off ers to join MSL’s science team is also planet within a few weeks of each other ice cream were a good camaraderie- busy prepping. These “participating sci- in January 2004—as an undergrad. She building experience for us.” entists” were selected last November and the rest of the MER team even lived That sense of camaraderie comes up based on what they proposed to con- on “Mars time” for a few months, which time and again when people describe tribute to the mission. Caltech geologist essentially meant starting each workday working on missions like MSL. Part of Bethany Ehlmann wants to improve 40 minutes later than the one before. that closeness is based on the fact that the science team’s ability to respond (Martian days, or sols, last 24 hours and everyone is pretty much in the same to the data Curiosity sends back about 40 minutes.) Curiosity’s team also plans situation—waiting for new data, trying potential rock targets. Plastic tubs in to live on Mars time for at least a few to make sense of it once it arrives, and her office at Caltech are filled with months, arriving each day just before working to make the best decisions for basaltic rocks that have been altered the downlink of data from the rover’s the rover. There’s also an understanding in different ways through interaction previous sol and working through the that every member brings a different base with water—the same types of altera- Martian night to come up with and of knowledge and experience to the team tion that rocks on Mars might show if upload fresh commands for Curiosity and that each skill set will be vital to the they have come into contact with water to execute the next Martian morning. mission at different times. for various amounts of time. She plans One of the hardest aspects of living Geochemist Kenneth Farley, for to fully characterize as many of these on Mars time, Ehlmann says, is eating. instance, brings a wealth of expertise in rocks as possible, even taking them to “If your 12- or 13-hour shift plus your measuring noble gases in rocks. He was Los Alamos National Laboratory, where sleep time misalign with when the selected to be a participating scientist she and her students can zap them with grocery stores or restaurants are open, based on his proposal for determining a laser similar to the ChemCam laser you can start to wonder, ‘How do I get the age of some of the geologic features on Curiosity. This should help the team food?’” she says. When JPL thanked Curiosity will encounter. He plans to use recognize which rock targets on Mars the MER team for its hard work by filling the rover’s SAM suite of tools to measure are worth taking a closer look at, and coolers outside the workrooms with ice- concentrations of a helium isotope, heli- which to leave behind. cream treats, the running joke became, um-3, in heated samples. Helium-3 is the This isn’t Ehlmann’s first time at “How many ice creams have you eaten result of the extremely energetic nuclear this kind of Martian rodeo. She today?” Ehlmann laughs. “There were particles that are always bombarding the helped operate the rovers Spirit a lot of three-ice-cream days. Those surface of Mars in the form of cosmic
16 ENGINEERING & SCIENCE summer 2012 Below: Curiosity is the most scientifically capable rover ever sent to another planet. A rotating turret at the end of its robotic arm includes tools for studying rocks up close, as well as a brush, scoop, and drill for collecting fine samples of rocks and soils for study by the rover’s analytical instruments.
rays; when they hit rocks, they shatter But while Grotzinger was unearth- like being back in the field. He’ll admit atomic nuclei and form isotopes such ing rocks in Oman, trying to better that maybe, just maybe, he misses as helium-3. “If you know the rate at understand the composition of the fieldwork. But then he’ll remind you which these catastrophic interac- biosphere 500 million years ago, a that he’s even more eager to see what tions occur and you measure the colleague suggested he submit a his team’s robotic emissary will find in isotopes that come out, then you can proposal to become a participating the Martian fields. determine how long something has scientist on the MER mission. All “Even if we don’t ever find life on been exposed on the surface,” Farley the pictures Grotzinger had seen of Mars, if we understand the evolution of says. This could help the team select Mars featured basaltic—rather than its environment, we might understand sample rocks that have been exposed sedimentary—rock, but he decided why life didn’t evolve on Mars or why for shorter periods and should thus be to give it a shot. “If nothing else,” it took the particular pathways it did less altered than those that have been he says, “I figured it would be a fun on Earth. And that,” he says, “would on the surface longer. experience, and if I didn’t have much be remarkable. It’s what science is Since Mars geology isn’t his main to add in the end, I could go back to all about.” research area, Farley thought his pro- what I was doing.” posal might be a long shot. “But,” he As it turned out, shortly after says, “it just seemed like something Opportunity landed, the rover started John Grotzinger, chief scientist for the that could be tried.” relaying images of layered rock Mars Science Laboratory, is the Fletcher Back in 2001, John Grotzinger outcrops, and Grotzinger’s expertise Jones Professor of Geology at Caltech. might have said something very became absolutely essential; now, similar. An expert in the analysis of at the helm of the 300-plus-member Ashwin Vasavada (PhD ’98) is one of two sedimentary rock, Grotzinger has science team, he’ll tell you he’s never deputy project scientists for MSL. He is a spent the majority of his career really looked back. research scientist at JPL. studying geology all over the world— But, if you push a little, he’ll from Northern Canada to Siberia, admit that maybe, just maybe, he Bethany Ehlmann is an assistant profes- from Western Australia to Namibia enjoyed that evening visit to Cape sor of planetary science at Caltech and and Zimbabwe. Canaveral and the Atlas V rocket a research scientist at JPL. so much because it felt something Kenneth Farley is chair of the Division of Geological and Planetary Sciences and the W. M. Keck Foundation Professor of Geochemistry at Caltech.
JPL built MSL’s rover and descent stage and manages the mission for NASA’s Science Mission Directorate in Washington. More information about Curiosity is online at http://www.nasa. gov/msl and http://mars.jpl.nasa.gov/ msl/. You can follow the mission on Facebook and Twitter at http://www. twitter.com/marscuriosity.
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