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| New breed of robots to
explore the planets Keay Davidson, EXAMINER SCIENCE WRITER |
Sunday, August 22, 1999
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A swarm of cunning robots - some only several inches wide - soon may swarm, float, walk, swim, fly, creep, burrow and hop across the alien worlds of the solar system. Two summers ago, the world thrilled to the sight of a skateboard-size Mars robot, Sojourner, venturing like an excited puppy around the Red Planet, "sniffing" soil and bumping into rocks. But Sojourner looks like a lazy pooch compared to NASA's futuristic robo-critters, including: *A four-legged robot the size of a cigar box that will hop around an asteroid like a grasshopper. *A snakelike tube that will drill thousands of feet into the Martian crust, seeking subsurface water and, perhaps, microbes. *A two-legged "walking" robot under development at NASA's Ames Research Center in Mountain View. *A hot-air balloon with TV cameras that would bob through the atmosphere of the giant planet Jupiter. It would pass above and survey multicolored mega-hurricanes bigger than Earth. *Mini- "helicopters" able to maneuver through the Martian atmosphere. *A robotic "submarine" that would plunge into an icy ocean on Europa, a moon of Jupiter, and seek weird life forms in its dark depths. AH: Smaller, cheaper, faster < Some of the robots would be far smaller than today's space probes. The drive toward smaller robotic probes is part of NASA Administrator Daniel Goldin's push for "smaller, cheaper, faster" missions to get the biggest bang out of the ever-diminishing post-Cold War NASA budget. The lighter the payload, the lower the cost of launch, says Brian Wilcox, supervisor of the robot vehicles group at Jet Propulsion Laboratory in Pasadena. "Mass reduction is very important because of the cost of the launch vehicle," he says. "The cost of a Delta launch vehicle is about $60 million." Ironically, such cost-saving micro-gadgetry is potentially threatened by a recent proposed cut to NASA's budget. On July 30, the House Appropriations Committee voted to cut NASA's space science budget for fiscal year 2000 by 8 percent, or $164 million, and the overall NASA budget by 7 percent, $12.7 billion, compared to current funding. The cuts to robotic research and other space science projects "from a scientific point of view would be devastating," says Peter Norvig of Ames. He runs the lab's computational science division, which oversees robotic development at the Mountain View facility. The final fate of NASA space science is uncertain "until the Senate acts and until this budget impasse between the Congress and administration gets settled. Gosh knows where it's going to end up," says Louis Friedman, executive director of the Pasadena-based Planetary Society. Co-founded by the late Carl Sagan, the society is the nation's leading pro-space lobbying group and has 100,000 members; it is leading a national fight to salvage the NASA budget. AH: Enter the nanobots < If NASA's robotic program survives the budget cuts, a new breed of "astronauts" will soar skyward in the next decade or two - astronauts made of metal and microchips, and as small as cigar boxes or smaller. Because of their diminutive size, they have been dubbed nanorobots or "nanobots." ( "Nano" is the scientific prefix that refers to billionths of something. For example, a nanometer is a billionth of a meter.) Conceivably, NASA could cram numerous nanobots aboard a single launch vehicle, then send them to Mars or another world. There, they would disembark and form a "robot colony," in the words of Ames systems engineer Hamid Berenji. The colony could scout out in different directions to survey the entire planet. Such fleets would be mechanical versions of the great human terrestrial exploring teams of the past, such as Lewis and Clark. At Ames, Berenji and biomechanical-electronics engineer Ron Jacobs are developing a two-legged robot that walks with a normal walking motion. It could navigate over rough terrain, such as the rock-strewn, crater-scarred surface of Mars. Berenji and Jacobs work for a NASA contractor, Intelligent Inference Systems Corp. of Sunnyvale. Ames researchers are developing a spherical robot that can float aboard a spaceship and fly around, propelled by small propellers. Its purpose: to allow a busy astronaut to check on an experiment in another lab, or a potentially dangerous situation - say, a gas leak - without getting directly in harm's way. Originally, Norvig says, it was called the Personal Satellite Assistant, "but no one liked that name." So they renamed it the Spacecraft Micro-Robot, although some Ames researchers have nicknamed it "S2D2" or Space Shuttle Digital Droid in honor of the doughty fictional robot R2D2 of the film "Star Wars." For sheer cuteness, none of the proposed nanorobots can rival a "hopping" robot under development at JPL. It's part of a joint U.S.-Japan space mission scheduled for launch aboard a Japanese rocket to an asteroid in July 2002. The asteroid is so small - the diameter of six football fields - that it has very low gravity, about 1 / 100,000ths that of Earth. The robot will have to move very gingerly about its surface, lest it accelerate to so high a speed that it escapes into space. "Escape velocity" for the asteroid is 3 feet per second (compared to several miles per second for Earth). That's about strolling pace for a long-legged adult. The nanobot would "hop" by gently compressing its "legs" together, allowing it to "spring" upward at a speed of 8 inches per second. "We could hop 100 or more meters (more than 300 feet) into the sky," Wilcox says. AH: Chill factor < Nanobots would have an inherent disadvantage: They get cold easily. A well-known principle of physics is that smaller objects cool off faster than large ones, because the smaller object's surface is bigger relative to its overall volume than a larger object's. (This is one reason why small planets like Mars apparently have no active volcanoes: Their internal heat escaped to space long ago.) And the nanobot will be too small to carry an on-board heater. Scientists could give it heat shields to keep it warm (as well as to protect it from high-speed interstellar particles called galactic cosmic rays), but the added weight of shielding would obviate the advantage of its small size. So the JPL team is trying to develop nanobots whose electronics can endure the temperature extremes of deep space - which range from boiling-hot daytimes to nighttime temperatures about 300 degrees below zero Fahrenheit, far colder than the South Pole. On Thursday, NASA announced plans to launch into Earth orbit three small satellites, dubbed the "Nanosat Constellation Trailblazer" mission. Each satellite would be an octagon 8 inches high and 16 inches long. Among other things, the minisatellites - to be launched in 2003 - will test the ability of new electronics and other equipment to survive "near the boundary of Earth's protective magnetic field," agency spokesman Donald Savage said. Robotic balloons or "aerobots" are also under development. These could float through the atmospheres of Mars, Venus, Jupiter and Titan, a moon of the ringed planet Saturn. JPL scientists are designing a Venusian aerobot that would float more than 30 miles above the searing-hot planet. The probe would drop TV-equipped instruments or "sondes" toward the surface, snapping pictures as they dropped toward the surface, which is typically veiled by an extremely dense atmosphere. Another possibility is a balloon that would periodically lower its instruments to the Venusian surface, briefly take measurements, and intermittently rise to cool off. Otherwise the instruments would melt on the extremely hot surface, which, according to JPL's Jim Cutts, is hot enough to melt lead. In one daring mission, a balloon would lower toward the Venusian surface, allowing the robot to gather rock samples. Then the balloon and robot would rise into the sky, where an on-board rocket would fire the rock samples into orbit. There it would rendezvous with another rocket, which would ferry the samples to Earth. AH: Atmosphere lighter than air < A different type of balloon would be required for the atmosphere of Jupiter, the biggest planet in the solar system. Its atmosphere is rich in hydrogen gas, the lightest of gases; hence an Earth-like hydrogen-gas balloon would not be buoyant enough to float. A Jovian balloon would be a special kind of "hot-air" balloon. It would be kept aloft partly by heat absorbed from sunlight. It could also be kept floating by the large amounts of "internal" heat Jupiter emits as it slowly contracts under the pull of its enormous gravity, Cutts says. This summer, JPL engineer Jack Jones is testing hot-air-type balloons for Mars missions at a blimp hangar in Tillamook, Ore. One of the strangest proposed robots is a worm-like device. It would drill into the Martian crust, like a super-worm. "We are building a (worm-like) device a few inches in diameter and 3 to 6 feet long, and 1 1/4 inches in diameter," says Wilcox, 47. Ideally, it could drill at least a mile into the Martian crust to look for buried microbes in ground water. The robot would be connected to the surface by long wires and capillary tubes. The former would transmit electric power from solar panels on the surface. The tubes - filled with liquefied carbon dioxide condensed from the Martian atmosphere - would pump subsurface grains (perhaps even microbes) back to the surface. The "worm" would drill through the crust by repeatedly firing a tungsten "hammer" into the rock. Its technical name is "robotic subsurface explorer" or SSX. But "I prefer to describe it as a self-hammering nail," Wilcox jokes.< |
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