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At NASA, missions are expected to go the extra mile.
The Voyagers are, perhaps, the best known example. Launched in the 1970s to explore the outer planets, the iconic spacecraft have zoomed far beyond their original targets to the edge of interstellar space itself, 9 billion miles from Earth and still making discoveries.
Pioneer 10 and 11, Ulysses, Stardust-NEXT, Deep Impact, and others have similar track records. It has become almost routine for superbly-engineered probes to wrap up their prime missions, then travel a few million (or billion) bonus miles for extra science.
Against this backdrop of sweeping overachievement, we pause to salute a robot that might never move another inch.
Well done, Spirit.
“For the past seven years, Spirit has been on a journey as extraordinary as any mission in NASA history,” said Mars Exploration Rover project manager John Callas of JPL. “But now it may be time to say thanks and farewell.”
NASA hasn't heard from Spirit in more than a year, and on May 25 the agency sent a final transmission in its series of attempts to regain contact.
The trouble began in April 2009 when the rover trundled into a sandtrap in a place called “Troy,” breaking through an apparently safe crust into soft sand below.
Stuck in place, Spirit couldn't turn its solar panels squarely toward the sun; at the same time, dust accumulated on the panels, reducing sunlight even more. These impediments curtailed power just when Spirit needed power most, during the deep freeze of an approaching Martian winter.
“Where Spirit is, winter temperatures drop as low as -130 C, far colder than any place on Earth,” said Callas. “Without sufficient electricity to power internal heaters and warm critical systems, Spirit went into hibernation.”
NASA has used Deep Space Network antennas and two of the agency's Mars orbiters to try to reestablish contact – but no luck.
Whether the rover is damaged or merely “sleeping,” no one can say, but most engineers believe the possibility of contact is now extremely remote.
Spirit landed on Mars on Jan. 4, 2004, for a mission designed to last merely three months.
After quickly accomplishing its primary science goals, the rover went on to work for almost six more years.
In all, Spirit has traveled almost eight kilometers, explored several large craters, scrutinized thousands of rocks, scraped off topsoil to reveal hidden minerals, photographed Martian dust devils and sunsets, observed the moons of Mars, and took the first picture of Earth in the night sky of another planet. Bonus-time, indeed.
