The sun still hung low in the east Sunday when the Marsokhod stood ready to climb on its own.
This spot in the Mojave Desert seemed right for a test run. It bears an uncanny resemblance to photographs taken by the pair of Viking lander craft that visited the Red Planet in 1975. The 150-foot rise was strewn with lava boulders and stones.
Ten years after the first inspiration glimmered in a Soviet scientist's mind, the Russian chassis, the Hungarian computers, the French cameras had been joined together. The tether that connected the three-foot-high machine to a human controller had been detached. The Marsokhod--translation: Marsmobile-- was meant to roam the Red Planet and conduct experiments with no human presence required.
"Now, it begins," said Alexander Kermurdjian, at 71 the eminence grise of the Mobile Vehicle Engineering Institute in St. Petersburg.
Five Russian scientists huddled in a trailer around a video image of the view through the Marsokhod's camera "eyes." Next to the monitor was a personal computer they usedto issue orders to the 150-pound rover. In response, a football field away, Marsokhod's six bongo-drum-shaped wheels pulled its hinged four-foot-long body, inchworm-like, over the pockmarked rocks. Despite long pauses for video checks, the contraption finally crawled to the top.
A crowd of about 100 other researchers, space buffs and the media followed its progress from partway up the hill 60 feet away.
Four years from now, if expectations are met, several nations will launch similar explorers to spend months scouting Mars.
The main contender from the United States at this point is known as Rocky IV. Others include the Ambler, Dante, Virgil, the Walking Beam and Attila-II. Russia has scheduled Marsokhod for departure in 1996, with financial help from France and Germany. And the European Space Agency is pondering whether to book its entry aboard a U.S. flight in 2001.
The prospective travelers may bear monikers worthy of the World Wrestling Federation, but they are in fact assemblages of lasers, computers, titanium and generators. In short, they are robots.
Some have six legs; others, six wheels. One stands as tall as three basketball players; another fits comfortably under an office desk.
What they have in common is the ability to move around. They can place instruments against rocks, scoop up soil, drop seismometers and, through their cameras, show earthbound scientists much more of another world at closer range than they have seen before.
Spacecraft have descended to the moon and Mars before, sending photos of their landing sites. But mobile robots are different. "What excites everyone is being able to look and see what's on the other side of the hill," said Steve Price, principal investigator for planetary rovers at Martin Marietta Astronautics Group.
They also fit well into the new Space Age. In a time of shrinking budgets, the robotic rover missions can be relatively cheap. And different countries are cooperating, rather than competing, on where and how to place them. That way, more information can be gathered; it is all expected to be shared.
The robots' creators are busy trying to find out how their prototypes would work on Martian terrain--or at least, the closest approximation thereof.
For two days, an international team of scientists has been testing Marsokhod here. The experiments were organized by the Planetary Society, a private Pasadena-based group that advocates space exploration. Its members donated $150,000 to transport and care for the research team and the rover. Earlier tests in Siberia, Kermurdjian said, had been greatly slowed by rain. "We were there 20 days and worked three," he said.
Next month comes Rocky IV. The Jet Propulsion Laboratory in Pasadena plans to put the 19-pound wheeled rover through its paces in Arroyo Seco, near JPL. A Cornell University scientist is driving across the country, picking up 500 pounds of rock along the way to use in simulating a Viking lander site. Local varieties have been eroded and are too smooth to provide a rugged enough test.
JPL scientists hope to include Rocky, or a descendant, on a 1996 Mars survey they are organizing for the National Aeronautics and Space Administration. If its European counterpart provides a rover for a later lander mission, it would explore a different section of the planet.
Two more rovers are scheduled to explore Mt. Erebus, an active Antarctic volcano, in December. Virgil, a six-wheeled robot, will ferry eight-legged Dante across a lava field and up the mountain slope. Guided via satellite by researchers at Carnegie Mellon University in Pittsburgh, Virgil is supposed to lower a cable that Dante will use to rappel inside the crater and conduct experiments there.
"You've got fire and ice, the light side of the moon and Mars," said David Pahnos, assistant director of Carnegie Mellon's Field Robotics Center.
Southwest of Denver, Martin Marietta has built a two-acre mock-up of various Mars topography, from a 10-foot-deep, 35-foot-wide crater to an erosion channel, where water once flowed, to a sand dune. Small mounds and a permafrost area, where freezing and thawing has produced a tiled effect, complete the simulation. There the company will soon test its "walking beam," two attached instrument platforms, one a tripod and the other with four legs.
The robots' creators, and the bureaucracies financing them, beg the question of whether the inventions will serve as precursors or substitutes for human missions. "Both," said David Lavery, telerobotics program manager for NASA.
Indeed, Lavery said, NASA hopes to someday dispatch robot explorers to asteroids and to Io, a moon of Jupiter, territory much too hostile and distant for humans to dream of reaching. Mobile robots could also prepare the moon and Mars for future colonizers. They would work at a fraction of the cost and risk of a human mission.
"We could at least find out if it's an interesting place," Pahnos said, "so we could make the decision whether to go ourselves."
The idea is not a new one. The Soviet Union put two bathtub-shaped unmanned vehicles called Lunokhod 1 and 2 on the moon in 1970 and 1973, respectively. The first covered about four miles during a year; the second about 23 miles during six months. Controlling Lunokhod was tremendously taxing to Earth operators, who had to direct each turn of the wheel and steering movement. They had to wait several seconds between each command for their radio signals to reach the moon and the machine's acknowledgment to reach this planet.
The Soviets also sent two tiny rovers to Mars on unsuccessful missions in 1970 and 1973. Each rover was tethered to the landing craft by cables that provided power and command links. Those rovers moved on skis and had sensors in front that detected obstacles.
They were to detect the pressure of the Martian soil and test its chemical composition. But the first lander crashed and the second stopped transmitting data after 20 seconds. "Nobody understands why," said Viacheslav Linkin, of the Institute for Space Research in Moscow.
The renewed interest in robotic rovers can be traced to advances in technology as well as to reductions in space budgets. In the past few years, researchers have learned how to make robots capable of plotting their own paths and avoiding obstacles on their own, minimizing the number of commands necessary--that two- or three-second time lag to the moon made for boredom; 40 minutes to Mars would be excruciating if every turn of the wheel had to be choreographed.
"We think we can say now, 'Go to Point X and take a sample.' It has to have an idea where Point X is," said Pahnos. "It has to find its way and it has to keep out of trouble on its own. These are the same kind of directions one would give to a person."
Researchers are also experimenting with different kinds of power sources. Lunokhod ran on a solar battery but had to shut off during the lunar night. Most newer robots are expected to use radioisotope thermal generators to fuel batteries that will last much longer. (Marsokhod is expected to last about two years).
The shapes and sizes, of course, run the gamut. "It won't be the case that one configuration is the configuration," said Pahnos. "It depends where you want to go and what you want to do with it."
Wheels are faster on sand; legs are faster on rough terrain. A great height like the Ambler's--which extends from 18 to 24 feet--helps to see farther away. A tiny rover like Rocky can reach places that Marsokhod couldn't.
"Simplicity," said Gerald P. Roston, a Carnegie Mellon research assistant, "is what's most important. That way, there's less to go wrong. You can't pick up a pair of pliers and straighten a wheel on Mars."