WASHINGTON, Jan. 9 (UPI) -- The landing of the Spirit rover on the surface of Mars marks the thirteenth time in 36 tries that a spacecraft was sent successfully from Earth to the red planet. But if NASA has its way, the twin Mars Exploration Rovers, Spirit and Opportunity -- which is due to land on Jan. 24 -- will just be the latest in a string of robotic missions that will continue indefinitely.
Perhaps, as President Bush is expected to announce next week, humans will join the Mars explorations sometime within the next 20 years. But even if they do not, the body of knowledge about the red planet figures to expand rapidly in the future due to the growing armada of robotic spacecraft set to embark on interplanetary journeys, their enhanced capabilities endowed by their mission scientists and engineers.
Not that the process is anything new. The world's spacefaring nations have been striving to reach Mars for 44 years, ever since an unnamed Russian probe bound for the planet failed to reach Earth orbit in October 1960. The first success came with the U.S. Mariner spacecraft, which flew by Mars in July 1965 and returned 21 images. Over the next seven years, three more Mariners visited Mars, including Mariner 9, the first successful orbiter, which returned more than 7,300 images.
Between then and now, there have been some astounding successes and more stunning failures. The twin Viking landers and their companion orbiters transmitted more than 50,000 images of the Martian surface. The tiny Sojourner rover, rolled a few dozen feet from its Pathfinder lander and became the world's mascot for nearly four months in 1997.
The recent failures have included the U.S. Mars Climate orbiter and Polar lander, both lost on arrival in 1999, and the Japanese Nozomi spacecraft, whose mission had to be aborted last month due to a propulsion problem.
Probably most disappointing of all was Britain's Beagle 2, the little lander that hitched a ride to Mars aboard the European Space Agency's Mars Express orbiter. Deemed to have landed on Christmas Day, the Beagle has not been heard from since.
Mars Express, on the other hand, entered Martian orbit also on Christmas Day and, aside from attempting to listen for Beagle's radio signal, it is gearing up to conduct a detailed survey of the planet's surface.
Between now and 2011, NASA has planned three more landers and two orbital missions. All figure to surpass the capabilities of Spirit and Opportunity, and of the Global Surveyor and Odyssey spacecraft, which have been orbiting Mars since November 1996 and April 2001, respectively. But all also will continue the strategy of mounting complementary missions involving both orbiting survey craft and rovers to land on the Martian surface.
"The idea is to go down to the ground and confirm what has been seen and suggested at the larger scale" of orbiting observations, said Bruce Jakosky, director of the University of Colorado's Center for Astrobiology in Boulder.
First to come will be the Mars Reconnaissance orbiter, scheduled for launch next year. Its goal is to provide more
detailed information about thousands of possible future Martian landing sites. The craft's telescopic camera will photograph landscapes in resolutions sharp enough to reveal details the size of an office desk, the mission's planners said.
The radar aboard Mars Reconnaissance will probe hundreds of yards below the surface, seeking layers of frozen or melted water, while another instrument will track the dynamics of water vapor in the atmosphere.
The Phoenix Mars Scout is supposed to touch down three years later, in 2008, on a mission to analyze the ice-rich soil in the northern latitudes. The lander will carry powerful microscopes to study rock and dust samples in great detail. Phoenix is actually a recycled spacecraft. It will use the components of a lander built for a 2001 mission that eventually was cancelled.
NASA will scavenge more leftover components to send a twin Mars Scout to the planet in 2011.
During 2009, the two most advanced spacecraft to date will fly out of Earth orbit. The Mars Science Laboratory will land at a site chosen based on the Mars Reconnaissance orbiter's surveys. Powered by a thermonuclear generator, the rover, about the size of a Volkswagon Beetle, will traverse the Martian surface for a Martian year -- about 700 Earth days -- or more, operating both day and night.
Above the MSL, the Mars Telecommunications orbiter will serve as the nerve center for all existing missions to the planet and many of the future ones. Its purpose is to expand greatly the capacity for data transmissions. It will do so via an optical communications terminal that uses a laser beam to communicate with Earth receivers.
Despite the variety of these craft and their individual functions, their overall missions are nearly identical: Continue to focus on finding evidence of water on Mars and the interaction of water with minerals.
"We know life started with water, we just don't know how," said Michael A. Meyer, a senior scientist for astrobiology at NASA headquarters in Washington. If the missions to Mars continue to seek evidence of water, they will have the best chance of finding evidence of Martian life.
Even if no such evidence appears, NASA's mission scientists think the expeditions still will be valuable. Whatever is found by these efforts, the Mars Exploration Rovers team concluded in a background document, "scientific exploration of the planet may yield critical information unobtainable by any other means about the pre-biotic chemistry that led to life on Earth. Mars as a fossil graveyard of the chemical conditions that fostered (such) life ... is an intriguing possibility."
Phil Berardelli is UPI's Science & Technology Editor. E-mail email@example.com