Spirit's McMurdo Panorama, a 360-degree look at its Winter Haven on Mars, is seen here sans the rover's solar array-covered deck.
NASA's Spirit rover hit the 1,000-Martian day of its mission on the red planet Thursday, but the mission continues for the hardy robot.
To celebrate the Martian milestone, rover mission managers released the McMurdo panorama [image], a mosaic of some 1,449 individual images taken by Spirit's panoramic camera.
"It has been a surprise and delight to see the vehicle survive as long as it has," Jake Mapijevic, engineering team chief for NASA's Mars Exploration Rover (MER) mission. "We had anticipated a much shorter mission."
More than 10 times shorter, in fact.
When Spirit landed on Mars on Jan. 3, 2004, mission scientists and engineers hoped to wrangle at least 90 Martian days - dubbed sols - out of the rover and its robotic twin Opportunity, which touched down on the red planet about 22 days later. At 24 hours and 37 minutes, one sol is slightly longer than one Earth day.
But despite an early software glitch and ongoing wheel issues, Spirit continues to return science from "Winter Haven" at its Gusev Crater landing site. The region served as a sort of red planet retreat during six months of harsh Martian winter, Spirit's second such season on Mars.
"We've gotten through the worst of the winter season," Mapijevic told SPACE.com. "Environmentally, we're going to go into another spring season, which is a period where the atmosphere tends to change quite a bit on Mars."
The mission continues
Altogether, Spirit has spent more time exploring Mars than the last five International Space Station astronaut crews spent in Earth orbit. Its robotic twin Opportunity - currently stationed [image] on the other side of Mars at Meridiani Planum's Victoria Crater - will hits its own 1,000-sol mark in upcoming weeks.
The two MER rovers could likely survive until January, when mission scientists and engineers hope to celebrate the third Earth anniversary of their red planet arrival.
During their mission, Spirit and Opportunity returned evidence that liquid water shaped the distant Martian past. Altogether, Spirit has roamed across 4.2 miles (6.8 kilometers) of Martian landscape at Gusev crater, scaled one of the Columbia Hills and is preparing to head towards other interesting sites nearby.
Opportunity, on the other hand, roved a stunning 5.8 miles (9.4 kilometers), and sits perched on the rim of Victoria Crater, a massive depression that mission scientists hope to descend into in the near future. The rover has its own wheel issues and a motor winding glitch in the shoulder of its instrument-laden robotic arm.
"Otherwise, the rest of the vehicles' systems are pretty much fine," Mapijevic said.
Steven Squyres, lead scientist for the rover mission at Ithaca, New York's Cornell University, has attributed the long life of Spirit and Opportunity to their robust design and talented handlers.
"These vehicles are 10 times past their warranty," he said in a mission briefing last month on Opportunity's travels. "It is really a remarkable team effort."
Spirit still has a long way to go before it catches up with the reigning champions of Martian missions: NASA's Viking 1 and Viking 2 landings in 1976.
Viking 2 lasted some 1,281 sols, a feat eclipsed by Viking 1's four-Earth year mission that ended on Nov. 13, 1982. But unlike Spirit and Opportunity, which draw their power from solar arrays that can decline over the years, the massive Viking landers used radioisotope thermal generators (RTGs) to generate electricity.
Break time on Mars
Spirit and Opportunity are taking a bit of a science break as Mars passes through solar conjunction, a period in which Mars passes behind the Sun as seen from Earth.
"We haven't actually heard from the vehicles for about five days now, and that's all traceable to the noise environment with the Sun between Earth and Mars," Mapijevic said. "We should be out of conjunction by next Monday."
During conjunction, rover handlers don't expect to send many new commands to Spirit and Opportunity, but the robots are expected to send home daily reports to Earth and conduct science observations.
Mission handlers at JPL, in the meantime, are taking advantage of the low activity period for some much needed rest, Mapijevic said.
"I feel quite privileged to have, in my work time, seen this milestone," he added. "This period is kind of like the wildest imagination I could have had."
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