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Mars exploration by (very) remote control 02/08/04 John MangelsPlain Dealer Science Writer Pasadena, Calif. - What time is it? In this sprawling Los Angeles exurb, it's the middle of a cool Pacific night, and a waxing moon bathes the nearby San Gabriel Mountains in a soft, lemony glow. But it's a rusty pinpoint low in the southeastern sky, not the moon or the sun, that rules the clocks here. What time is it? That depends which planet, which robotic rover, even which building floor at NASA's Jet Propulsion Lab (JPL) you're talking about. When Mars is involved, the simplest questions have complicated answers. Up on the fifth level of Building 264, it's early afternoon, Mars local time. Scientists, mostly men wearing jeans, khakis and open-collared shirts, cluster in small, excited knots around desktop computer monitors or big plasma screens. They're devouring the latest batch of data and photos that Opportunity, one of NASA's twin robotic rovers, has just beamed back to Earth in the middle of its Martian workday, or "sol." (Mars takes 39 minutes longer than Earth to rotate on its axis; hence the scientists' and engineers' constantly shifting work schedules are increasingly out of sync with Earth time. On the opposite side of Mars, where the rover Spirit has landed - and in the fourth-floor offices where Spirit's science team works - it's 3 a.m.) "I keep seeing slope here. Is that another crater?" wonders NASA geologist Matt Golombek, whose goofy laugh, broad scientific knowledge and knack for sound bites have made him a favorite with commentary-hungry TV news producers. Golombek and Arizona State University astrogeologist Jim Rice are studying a color snapshot Opportunity's panoramic cameras have taken of the horizon beyond the landing-site crater that the rover currently calls home. "We don't know if those are rocks or outcrops," Golombek says of the dark, distant humps he jokingly calls "buffaloes or SUVs." The uncertainty is killing Rice. He's an old-fashioned field geologist who'd rather be there banging away with a rock hammer and squinting through a magnifying glass than riding a desk 128 million miles from the action. In the frozen Antarctic - "the most Mars-like place on Earth" - Rice has slithered through holes chipped in the 15-foot-thick ice pack to scuba-dive in underground lakes no human has probed. He finds Opportunity's brand of remote sensing "neat, but frustratingly slow." "The best geologist is the one who sees the most rocks," Rice says. But for now, the rovers are "the only game in town." At a nearby workstation, Geoffrey Landis taps the keys of a slim laptop balanced on his knees. The red-bearded physicist from Cleveland's NASA Glenn Research Center is the mission's dust-buster. He supervises an experiment package he designed for both rovers that tracks the amount of fine, light-colored powder swirling in the Red Planet's atmosphere or settling almost imperceptibly on the robots' solar panels, like flour sifting to a kitchen floor. Landis is cataloging the various ideas he and his colleagues have been batting around to try to explain why the floor of Opportunity's shallow landing crater is so dark. It's the hue of dried blood, almost maroon. "On Mars, dark means no dust," Landis says. Other craters are bright-bottomed, but not here. The hypotheses run from the mundane - the crater's rim blocks dust-carrying breezes from shedding their load - to the exotic, proposed by Landis, that atmospheric conditions create a tornado-like dust devil that "lives" in the crater and regularly scours its floor. In the science-fiction books Landis grew up reading, robots were servants and laborers, built to make life easier for their human masters. Behind the scenes at the NASA lab, it seems the opposite. It takes a very high-tech village to care for the childlike rovers. They are marvelous feats of engineering, but they are hardly autonomous. Three hundred sleep-starved scientists and engineers work around the clock to make sure the $820 million pair of robots wake up and go to sleep on time, have enough energy, do their chores, call home regularly, and avoid falling down or getting lost. Like determined soccer moms and dads, the mission teams spend their sunless days and moonless nights checking their offspring's progress, scheduling activities, and trouble-shooting. Each sol is a near-continuous blur of meetings, formal and informal, in rooms whose windows are blacked out in an increasingly futile attempt to fool the occupants' insistent sleep cycles. Walls are papered with tips for getting proper rest, such as avoiding candy, carbs and caffeine near bedtime. "I haven't touched an ice cream in three days," says one portly scientist, referring to the tempting cooler of free treats in the hallway. Many of them have bought "Mars watches," custom-made by a local jeweler to lose the appropriate 39 minutes a day. Even those who don't wear the special timepieces know the mission clock is always ticking - the rovers' solar panels are getting dustier and less efficient, the Martian nights are growing colder, and an irrevocable computer glitch or mechanical failure could be just around the corner. "The planet waits for no one," JPL senior engineer Erik Bailey says of Spirit and Opportunity's inhospitable host. Birth of the lab On Halloween 1936, a ragtag band of tinkerers, students and workers from the aeronautics lab at the California Institute of Technology crouched behind sandbags in a dry Pasadena riverbed to shoot off a small rocket fueled by oxygen and methyl alcohol. Rocketry was in its infancy; Robert Goddard had test-fired the first liquid-fueled missile only a decade earlier. The Caltech group's first launch attempt and several subsequent ones failed, some explosively, earning its members the moniker "the Suicide Squad." But with world war looming and the rockets' military implications clear, the amateur rocketeers got government sponsorship for their research. Caltech christened the Jet Propulsion Lab in 1944. The university-managed center was incorporated into NASA when Congress and President Eisenhower formed the space agency in 1958. By then, JPL had shifted from rocketry to designing unmanned spacecraft, and already had built America's first satellite, Explorer 1. The center's string of successes continued through four decades - the first interplanetary probe, first Mars flyby, first unmanned moon landing, first rover on another planet. That record, and perhaps JPL's proximity to Hollywood, gives the center a certain amount of laid-back California cool and confidence. The rovers' media-savvy science team members get a pat of makeup before their televised daily news briefings, and a JPL producer herds journalists to the front of the room to give it a fuller look on-camera. Reporters from as far as China, Belgium and Ireland have descended, feeding a seemingly insatiable public appetite for rover news. JPL's Web site has gotten more than 5 billion hits since Spirit's landing Jan. 4. The center receives hundreds of e-mails from people offering helpful advice - ideas for windshield wipers on the rovers' solar arrays, or peel-off layers to shed the accumulating dust. When Spirit developed a problem with files in its long-term "flash" memory, computer users wrote to suggest how they had solved similar glitches on their PCs. "You could really see they were worried," says JPL spokesman Guy Webster. "You realize these are their rovers, too." Landis' interest in Chinese culture - he spent a month in China last year - has gotten back to a crew from ETTV America, a Taiwan media outlet. It is NASA tradition to name landscape features on celestial bodies so geologists can differentiate them. Landis explains to the TV reporter that he suggested naming some of the rocks the Mars rovers are examining after various monkeys (Curious George, King Kong) since it's the Year of the Monkey in China. Theories abound The only time JPL scientists get media-shy is when they want to toss around ideas about what they might be seeing in the photos and instrument readings from the rovers, prior to reaching consensus. "We're debating fiercely but collegially what's going on," describes Ray Arvidson, the mission's deputy principal investigator. The discussions are off-limits to journalists, both to encourage scientists to be candid and to avoid someone's speculation ending up in tomorrow's headline. "There are as many theories as there are geologists" about what the rovers are observing," says Jim Bell, lead scientist for the robots' panoramic cameras. There also is spirited discussion within and among the five scientific "theme" teams about what activities the rovers should do next. The scientists and engineers mostly plan moves one sol ahead, based on several factors - what looks interesting in the previous day's observations, how well the rovers are working, how much power is available and needed, how long the work will take, and the duration and hazards of getting to the destination. Because of the 10-minute-or-more time lag for communications between Earth and Mars, it's not possible for JPL controllers to "drive" the rovers in real time. So they have to convert the activity plan for each sol into lines of computer code, then beam it to the rovers when they power up after the Martian sunrise. But first the scientists have to agree on the plan. The specialized theme teams - atmospheric science, geology, mineraology/geochemistry, solid and rock physical properties, and long-term planning - meet individually and later collectively at a kind of U.N. gathering to hash out priorities. Like junior executives vying for a CEO's time, there's strong competition among the groups to get their particular activity on the rovers' tightly packed timetable, an immense chart called the "rainbow schedule" for its color-coded sections. Landis keeps a copy on the refrigerator door in his rental apartment. "Every observation we do has to be argued," he explains. "Our science has to be important enough to kick someone else off." Landis has an edge - his atmospheric measurements are not just interesting science, but a vital predictor of how long the rovers will last before their solar panels get too dusty to recharge the batteries. So it's almost a slam dunk that a command telling the rovers to measure Tau, or how opaque the thin Martian atmosphere is, will be included in daily computer instructions. The rovers can get a Tau reading in several ways: by pointing a filtered camera lens at the sun and comparing the level to predicted brightness; by comparing the sun's brightness at two different positions in the sky; or by aiming the camera at the rover's calibration target. It's a sort of sundial about the size of a teacup saucer, mounted on a solar panel. A short post casts a shadow on the target, which is painted with concentric circles of black, gray and white. The shadow's intensity, compared with what it would be in a pristine setting, determines how much dust is in the air. Many people have wondered why NASA cannot find a way to keep dust off the rovers, perhaps by equipping them with blowers or wipers of some sort. (Landis' Taiwan TV interviewer suggests the rovers could be made to shake like a dog after a bath.) Aside from the fact that more moving parts raise the risk of a mechanical failure, the dust is not easy to get rid of. The cold, dry climate gives it an electrostatic cling, like dryer lint. Questions abound The biggest mysteries on Mars are whether there was ever water, and if so, did it spawn microscopic life. Spirit and Opportunity are on the water trail, but in the meantime, all sorts of questions are cropping up. A particularly nagging one has been: Exactly where is Opportunity? JPL's mission planners carefully chose the rovers' equatorial landing sites for their safety and science value. But the craft can't set down on a dime. Their airbag-protected landing shells can tumble half a mile or more before coming to rest, and there are not enough satellites orbiting Mars to do the kind of global positioning fix we take for granted on Earth. Scientists know the general area, and can tell from ground pictures that Opportunity landed in a small crater. (NASA officials long ago wore out their hole-in-one golf analogies.) But which one? The answer will help determine the rover's driving routes. JPL analysts have been deciphering position data recorded by Opportunity's six gyroscopes and accelerometers - what engineer Bailey calls its "electronic inner ear" - during the rover's 30 landing bounces. And by processing Opportunity's landing-site photos with special software, a team of Ohio State University scientists led by civil and environmental engineering professor Ron Li has created an ultra-precise, three-dimensional contour map of the crater. If it can be matched with satellite photos, scientists will know Opportunity's exact address. For now, the rovers' entry, descent and landing manager, Rob Manning, suggests the "You Are Here" arrow someone has drawn on Opportunity's landing-site photo be amended to say ". . . Or Not." What's next The Pasadena night is fading, and Kevin Burke is thinking about a long sleep. Though he's part of the rovers' mission, his work is winding down as his colleagues' is just beginning. Burke is the lead mechanical engineer on the "egress team," whose job is to use exact duplicates of the rovers to practice over and over their slow roll off the sloping landing shell and onto the Martian surface - the most precarious drive of the mission. The rehearsals take place in JPL's "in-situ instruments lab," in a big, brightly lit bay filled with red lava rocks trucked in from Arizona. At NASA, there's an abbreviation for everything. The standing joke is TWA stands for two-word acronym. The mock-up rover is SSTB, the Surface System Test Bed, but to those who've lived with it for many months, like Burke, it's "Sacrifice" - you can't have opportunity and spirit without sacrifice. Tonight was the 536th and last test. Sacrifice, programmed with the same commands and facing the same descent angle as its Martian cousin, performed the roll-off flawlessly, just as Opportunity would 24 hours later. A crane hoists the retiring rover. An engineer wearing surgical booties rakes away its tracks in the simulated Martian soil. Burke is headed home for a few hours. The next test for him is "how soft and cushy my pillow feels." He and his colleagues have pulled off an amazing feat in a scant three years: designing, building, launching, landing and now successfully operating two robots halfway across the solar system. "We would not want to do this every three years," he admits. "It's a pretty high level of burn for most of the team." But he won't - can't - stay away for long. He'll be given the honor of clicking the computer mouse that sends the drive-off command flashing through space to Opportunity. Then he'll start doing what Landis and all of the other scientists and engineers do: dreaming and planning for the next mission to Mars.
To reach this Plain Dealer reporter: jmangels@plaind.com, 216-999-4842 © 2004 The Plain Dealer. |
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