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"People picture this as being like a radio-controlled car, which would be the way to go if we could do that," says Brian Cooper, who will be the one sending the commands that tell the rover where to go. "But with an 11-minute time delay, it doesn't work that way."
Though Sojourner won't get anywhere fast, where it does go should hold a lot of secrets. Ares Vallis was chosen as the landing site in the first place because the now dusty basin was once the largest known floodplain in the solar system. Water rushed into the valley at up to 170 m.p.h., carrying a giant spelunker's bag of rocks with it. Without venturing very far from where the lander set down, the rover could thus use its cameras and X-ray spectrometer to sample geology from all over the planet. Sojourner is scheduled to conduct these studies for up to a month, depending on how quickly the extreme temperatures (from -15[degrees]F by day to -125[degrees]F at night) at last claim it. The Pathfinder lander, with instruments and cameras of its own, could function for as little as a month or as long as a year. Even after it winks out, it will continue to serve an important symbolic function. On Saturday NASA announced that it would rename the spent lander the Carl Sagan Memorial Station.
What was perhaps most remarkable about the spacecraft that set up shop in Ares Vallis late last week is how unremarkable they are. NASA's early interplanetary spacecraft--the Vikings, the Pioneers, the Voyagers--were limousine ships packed with dozens of scientific instruments and countless backup systems. On the surface, of course, this made sense. "If you've never been to Jupiter or Saturn before," says Golombek, "you want a whole bunch of instruments to cover the sphere of what you want to know."
But covering the sphere can get pricey. In 1993, before NASA's Mars Observer spacecraft had even entered orbit around the planet, it blew an aneurysm in a fuel line and spun off into the void, taking nearly $1 billion of NASA funding with it. The twin Viking spacecraft, which accomplished their missions successfully, landing on Mars in 1976, nonetheless set taxpayers back about $3 billion.
When Goldin took over NASA in 1992, he knew that in deficit-conscious times, this kind of trust-fund spending could not continue. From now on, he decreed, the luxury ships of the past would be scrapped. In their place would be stripped-down spacecraft built essentially from available, off-the-shelf parts. What's more, the new ships would not contain a whole science lab's worth of instruments and experiments, but just a handful--generally the ones the scientists deemed absolutely essential to make the trip worthwhile.
The result has been immediately felt. Pathfinder cost $171 million to build, and its Sojourner rover only $25 million. The Global Surveyor orbiter, set to join them at Mars in the fall, carried a price tag of just $152 million. Other ships being developed have had their prices slashed similarly. On the whole, the average cost of a single unmanned spacecraft has plunged from $590 million between 1990 and '94 to $190 million today, and Goldin hopes to get even that pennywise figure down to only $77 million after the turn of the decade. "Because the spacecraft cost less," he says, "we do them faster and we have more in number."