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After more than six years of exploring the Red Planet, the Mars rover Spirit will rove no more. The robotic adventurer is mired in a sand bed, and NASA has officially given up on trying to extricate it. While it will continue to operate as a "stationary research platform" for the time being, there's no denying that the rover's swashbuckling days are over. No longer will Spirit spot an interesting landmark in the distance and gamely trek towards it, with the possibility of a fresh scientific discovery around every corner and under every rock. This photo gallery is a well-deserved eulogy for Spirit, in which we'll survey its travels and achievements. In 2003, NASA's Jet Propulsion Laboratory launched Spirit and its twin rover, Opportunity, on a three-month mission to investigate Martian terrain and atmosphere on opposite sides of the planet. The solar-powered rovers surpassed NASA's wildest dreams, extending their missions by nearly 25 times their anticipated lengths. Since landing on Mars in January 2004, Spirit has snapped more than 127,000 pictures. The robot probed beneath the worn surface of Mars, analyzing the microstructure of rocks and soil with a sophisticated array of instruments: spectrometers, microscopic imagers, and other tools. Spirit has also gathered strong evidence that water once flowed on the Martian surface, which could have created a hospitable environment for microbial life. Spirit and its twin rover (which is still traveling on) will be replaced by more advanced machines that will roll onto the Martian soil in the coming decades. But Spirit will be remembered long after its operating system flickers off for good. Like a robotic Neil Armstrong, the rover has earned its place in the space explorers' hall of heroes.

All text by Aline Reynolds. Image: NASA/JPL/Cornell

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January 4, 2004 After a 302-million-mile, 7-month journey from Earth, Spirit reaches Mars. Parachutes slow the landing craft as it falls through the atmosphere, and the 24 airbags that completely surround the craft cushion its landing. Spirit successfully lands in a Connecticut-sized basin on Mars named Gusev Crater. Scientists believe the crater was formed by a massive asteroid or comet collision long ago. Spirit was given this landing site to investigate past and present environmental conditions there. Later photos reveal that a long, deep valley once provided water to Gusev via a hole in the crater's edge. Once Spirit has safely set down, the airbags deflate and the landing craft opens up to allow the rover to wheel out on to the surface of the Red Planet. In this image, captured by combining the camera's green, blue and infrared filters, the rover looks back at the landing site before heading out to explore. Spirit's twin, the Mars rover Opportunity, lands on the opposite side of the Red Planet on January 25, 2004.

Image: NAS/JPL/Cornell

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January 2004 Complete with a rock-identifying infrared sensor, Spirit is the first space-venturing robot to cut into stone, inspect the inside of a rock, and perform microscopic examinations of soil and rock on a planet other than Earth. The rover uses its spectrometers and a rock abrasion tool to detect minerals and elements in rocks and soils. Soil deposits are especially good markers of recent environmental conditions. Planetary scientist Ray Arvidson, one of the rover researchers, describes the geology that Spirit investigates: "The caprock on the plains is volcanic basalt. It has been broken up by impact cratering, and then wind-blown materials have accumulated into a mantle of soil." Spirit's first target is Adirondack (pictured), a football-sized rock that scientists deem a "time capsule," since probing it has brought to light past geological conditions of the Martian surface.

Image: NASA/JPL/Cornell

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March 2004 Spirit snaps the first photograph of Earth ever taken from the surface of another planet. This image is produced using an assortment of shots captured by Spirit's panoramic and navigation cameras, including a wide view of the sky and four close-ups of Earth. Technicians are able to magnify the contrast in the sky photograph in order to make the tiny dot of Earth appear visible in the picture.

Image: NASA/JPL/Cornell/Texas A&M

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June 2004 Just over 2 miles into its mission, Spirit arrives at the Columbia Hills, a cluster of seven hills about 270 feet high. Spirit examines slopes, rocks, and sand deposits in this spot for over a year to learn about the area's geological history. The rover's spectrometers reveal that the rocks' composition had been significantly transformed by water in ancient times. Husband Hill's peak is a wide plateau of rock outcrops and windblown drifts approximately 300 feet above than the neighboring plains of Gusev Crater. While that hardly qualifies it as a towering peak, researchers still feel a sense of accomplishment when the rover slowly climbs the hill, and takes panoramic images from the summit in August 2005. Husband Hill was named after shuttle Columbia's commander, Rick Husband. The nearby McCool Hill and Ramon Hill commemorate other deceased astronauts of the space shuttle Columbia, which exploded while re-entering Earth's atmosphere on February 1, 2003.

Image: NASA/JPL/Cornell

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June 2004 At the base of the Columbia Hills, Spirit discovers a softball-sized rock named Pot of Gold by researchers. The oddly shaped rock has short stalk-like protrusions topped with knobby nodules. Upon microscopic imaging, scientists conclude that the rock contains the mineral hematite, which is often formed in water (although it can also be formed by volcanic processes). While Spirit answers some questions about the mysterious rock, many more remain. "This rock has a shape as if somebody took a potato and stuck toothpicks in it, then put jelly beans on the ends of the toothpicks," says Steve Squyres, principal investigator for the rovers' science instruments. "How it got this crazy shape is anyone's guess. I haven't even heard a good theory yet."

Image: NASA/JPL/Cornell/USGS

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Mid-April 2005 Spirit tracks Mars's dusty winds hustling across a plain inside the Gusev Crater. Clusters of images, which are captured every 20 seconds by the Spirit's navigation camera, reveal the speed of the Martian dust devils, which scientists could only hypothesize about previously from static images. "This is the best look we've ever gotten of the wind effects on the Martian surface as they are happening," says Mark Lemmon, a rover team member who studies Mars's harried atmosphere. The dust devils have also helped out the mission. The winds have occasionally swept away the dust from Spirit's solar panels, allowing the rover to draw more power from the sun and extending Spirit's lifespan.

Image: NASA/JPL

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May 2005 Using its panoramic camera mosaic, Spirit takes this breathtaking photograph of a Martian sunset, making us feel as if we’re sky-gazing alongside the rover. The strong scattering of sunlight by high-altitude dust in the atmosphere contributes to lengthy, two-hour twilight glows on Mars. Scientists have used these images to examine the amount of dust and ice clouds in the Red Planet's atmosphere, which will be the subject of a future Mars mission. Similar extended twilights sometimes occur on Earth when dust particles spewed from erupting volcanoes spread light rays into the atmosphere. In this photo, the sun is sinking just below the rim of Gusev Crater. It appears about 2/3 the size of the sun as seen from Earth during sunset, since Mars is about 48 million miles farther away from the sun.

Image: NASA/JPL/Texas A&M/Cornell

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March 2006 Spirit turns heads when its wheels churn up bright patches of Martian soil. Upon examination, the soil is found to contain sulfate salts and a hint of water. Similar salty, light-toned soil deposits are dispersed along the floors of the Columbia Hills region of the Gusev Crater. Scientists say the minerals in these soils could indicate volcanic deposits from a wet period of the Red Planet's ancient past. "The soils have provided evidence in particular for the local action of hot water or steam, either from hydrothermal circulation or volcanic venting," says Bruce Banerdt, a researcher with the rover project. Researchers say that soils with high salt concentration often indicate the earlier presence of salty water, since the salt can become concentrated in the dirt as the water evaporates away.

Image: NASA/JPL/Cornell

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Spring 2007 Back in 2005, when Spirit gazed over the Martian landscape from the Husband Hill summit, the rover spotted a strange-looking portion of raised ground in the distance. This, it was soon decided, would be its next destination: Home Plate, a low plateau that was probably formed by a long-ago volcanic explosion. Spirit explores the 6-foot–high plateau, which lies within the "inner basin" area of the Columbia Hills, in spring 2007. Spirit finds strong evidence of ancient volcanism when it comes across "bomb sags" (pictured), where the neat layers of rock on the plateau's lower slopes have been deformed. Researchers think these sags are created when rocks ejected from exploding volcanoes fall back to the ground and hit soft sediment deposits, changing their shapes. These and other findings were documented in a report published in the journal Science.

Image: NASA/JPL-Caltech/USGS/Cornell

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March 2007 Spirit makes one of its best finds thanks to a faulty wheel. The rover's right front wheel stopped working in 2006, causing Spirit to drive backwards dragging the busted wheel behind it. That dragging motion leaves a deep track in the soil, and in March Spirit turns up dirt that has a high concentration of silica, considered "some of the best evidence" to date of the Red Planet's watery past, according to Albert Yen, a NASA geochemist. According to the Spirit's very own C.V., this discovery was its "biggest scientific achievement." The rover's X-ray spectrometer finds that the soil is about 90 percent silica—the main ingredient in window glass. The detected mineral, believed to have formed in hot springs or steam vents, suggests that the Red Planet once had warm water that could have harbored microbial life. "You could hear people gasp in astonishment," said Steve Squyres, principal investigator for the Mars rovers' science instruments. "This is a remarkable discovery."

Image: NASA/JPL/Cornell

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May 1, 2009 Spirit is exploring Troy, a site comprised of three or more layers of soil beneath a dark sand blanket, when trouble begins. Troy is situated next to Home Plate, and the region is considered "one of the most interesting places Spirit has been" on Mars, according to Ray Arvidson, a scientist with the rover team. But Spirit is having difficulties making progress through loose, fluffy soil, and on May 1 the team of rover's drivers realize that Spirit is stuck. With its wheels sunk halfway into the soft soil, Spirit sits and waits for orders. It also conducts what experiments and observations it can from its stationary position. Back on Earth, NASA engineers break out a replica rover and drive it into a sand box to allow them to test escape maneuvers. But months of tryouts in the lab and driving attempts on Mars come to naught.

Image: NASA/JPL

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January 26, 2010 After more than six years of exploring the Martian landscape, NASA announces that the Spirit will no longer roam the hilly nooks and crannies of the Red Planet. But the NASA team puts a upbeat spin on the news that the rover is now a stationary research platform: "Spirit is not dead," says Doug McCuistion, director of the Mars Exploration Program. "It has just entered another phase of its long life." Spirit can do a lot of science at its fixed position (this panoramic image shows its final view). NASA hopes that it will examine the sulfur-rich soil previously churned up by its wheels, and will study winds and the Martian atmosphere. The rover can also inspect the planet's rotational movement by precisely radio-tracking individual points on the planet's surface; tiny wobbles in the rotation may shed light on the composition of the Red Planet's core. "If the final scientific feather in Spirit's cap is determining whether the core of Mars is liquid or solid, that would be wonderful," says Spirit scientist Steve Squyres. But before it can embark on any of those scientific projects, the rover has to make it through the dark, cold Martian winter. The rover's solar panels are not well positioned to catch the winter sunlight, so it will soon go into hibernation mode to conserve power. If Spirit can survive the frigid temperatures, it will communicate with NASA as the Martian spring arrives, and should be able to resume scientific research next September. Says Squyres: "The bottom line is, we're not giving up on Spirit."

Image: NASA/JPL-Caltech/Cornell University

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