Eight years on Mars...!!!!

Spirit Mars rover - view from Husband Hill summit Spirit snapped this self portrait from the summit of Husband Hill inside Gusev crater on Sol 618 on 28 September 2005. The rovers were never designed or intended to climb mountains. It took more than 1 year for Spirit to scale the Martian mountain. This composite image was created by an international team of amateur astronomers and appeared on the cover of the 14 November 2005 issue of Aviation Week & Space Technology magazine and the April 2006 issue of Spaceflight magazine. Also selected by Astronomy Picture of the Day (APOD) on 28 November 2005. Credit: Marco Di Lorenzo, Douglas Ellison, Bernhard Braun and Kenneth Kremer. NASA/JPL/Cornell/Aviation Week & Space Technology

January 2012 marks the 8th anniversary since of the daring landings of “Spirit” and “Opportunity” – NASA’s now legendary twin Mars Exploration Rovers (MER), on opposite sides of the Red Planet in January 2004. They proved that early Mars was warm and wet – a key finding in the search for habitats conducive to life beyond Earth.

This story focuses on Spirit, first of the trailblazing twin robots, which touched down inside Gusev Crater on Jan. 3, 2004. Opportunity set down three weeks later on the smooth hematite plains of Meridiani Planum. Team was seriously thinking both Spirit and Opportunity would be finished by the summer of 2004. But, every Sol was a gift and both rovers push themselves as hard as they can.

'Calypso' Panorama of Spirit's View from 'Troy'
This full-circle view from the panoramic camera (Pancam) on NASA's Mars Exploration Rover Spirit shows the terrain surrounding the location called "Troy," where Spirit became embedded in soft soil during the spring of 2009. The hundreds of images combined into this view were taken beginning on the 1,906th Martian day (or sol) of Spirit's mission on Mars (May 14, 2009) and ending on Sol 1943 (June 20, 2009). Credit: NASA/JPL-Caltech/Cornell University

Spirit endured for more than six years and Opportunity is still roving Mars today!

The dynamic robo duos were expected to last a mere three months, or 90 Martian days (sols). In reality, both robots enormously exceeded expectations and accumulated a vast bonus time of exploration and discovery in numerous extended mission phases.Spirit survived three harsh Martian winters and only succumbed to the Antarctic-like temperatures when she unexpectedly became mired in an unseen sand trap driving beside an ancient volcanic feature named ‘Home Plate’ that prevented the solar arrays from generating life giving power to safeguard critical electronic and computer components. Spirit was heading towards another pair of volcanic objects named von Braun and Goddard and came within just a few hundred feet when she died.

Everest Panorama from Husband Hill summit

It took Spirit three days, sols 620 to 622 (Oct. 1 to Oct. 3, 2005), to acquire all the images combined into this mosaic, called the "Everest Panorama". Credit: NASA/JPL-Caltech/Cornell University

By the time of her last dispatch from Mars in March 2010, Spirit had triumphantly traversed the red planets terrain for more than six years of elapsed mission time – some 25 times beyond the three month “warranty” proclaimed by NASA as the mission began back in January 2004.

The "Columbia Hills" in Gusev Crater on Mars

Husband Hill is 3.1 kilometers distant. Spirit took this mosaic of images with the panoramic camera at the beginning of February, 2004, less than a month after landing on Mars. Image credit: NASA/JPL-Caltech/Cornell

Altogether, the six wheeled Spirit drove over 4.8 miles (7.7 kilometers) and the cameras snapped over 128,000 images. NASA hoped the rovers would drive about a quarter mile during the planned 90 Sol mission.

Carbonate-Containing Martian Rocks discovered by Spirit Mars Rover

Spirit collected data in late 2005 which confirmed that the Comanche outcrop contains magnesium iron carbonate, a mineral indicating the past environment was wet and non-acidic, possibly favorable to life. This view was captured during Sol 689 on Mars (Dec. 11, 2005). The find at Comanche is the first unambiguous evidence from either Spirit or Opportunity for a past Martian environment that may have been more favorable to life than the wet but acidic conditions indicated by the rovers' earlier finds. Credit: NASA/JPL-Caltech/Cornell University

Spirit became the first robotic emissary from humanity to climb a mountain beyond Earth, namely Husband Hill, a task for which she was not designed.After departing the Gusev crater landing pad, Spirit traversed over 2 miles to reach Husband Hill. In order to scale the hill, the team had to create a driving plan from scratch with no playbook because no one ever figured that such a mouthwatering opportunity to be offered.

Spirit Rover traverse map from Gusev Crater landing site to Home Plate: 2004 to 2011

It took over a year to ascend to the hill’s summit. But the team was richly rewarded with a science bonanza of evidence for flowing liquid water on ancient Mars.

Spirit then descended down the other side of the hill to reach the feature dubbed Home Plate where she now rests and where she found extensive evidence of deposits of nearly pure silica, explosive volcanism and hot springs all indicative of water on Mars billions of years ago.

“Spirit’s big scientific accomplishments are the silica deposits at Home Plate, the carbonates at Comanche, and all the evidence for hydrothermal systems and explosive volcanism, What we’ve learned is that early Mars at Spirit’s site was a hot, violent place, with hot springs, steam vents, and volcanic explosions. It was extraordinarily different from the Mars of today.

NASA concluded the last attempt to communicate with Spirit in a transmission on May 25, 2011.

Spirit Rover traverse map from Husband Hill to resting place at Home Plate: 2004 to 2011

The Last View Ever from Spirit rover on Mars
Spirit’s last panorama from Gusev Crater was taken during February 2010 before her death from extremely low temperatures during her 4th Martian winter. Spirit was just 500 feet from her next science target - dubbed Von Braun – at center, with Columbia Hills as backdrop.
Mosaic Credit: Marco De Lorenzo/ Kenneth Kremer/ NASA/JPL/Cornell University
Mosaic featured on Astronomy Picture of the Day (APOD) on 30 May 2011 - http://apod.nasa.gov/apod/ap110530.html

Opportunity keeps chugging along

Opportunity landed on the opposite side of Mars from its twin, Spirit, on a flat plain known as Meridiani Planum. The evidence suggests that Opportunity’s landing site was once the shoreline of a salty sea. This region had been chosen because the Mars Global Surveyor mission had identified concentrations of the mineral hematite there and on Earth the presence of hematite is often associated with water. Opportunity’s landing is often referred to as a “hole-in-one” because the spacecraft unexpectedly came to a rest inside a small crater.

Opportunity did indeed find hematite here, in the form of small concretions nicknamed “blueberries.” After thoroughly investigating its landing site, Eagle crater, Opportunity traveled to several other craters, the slightly larger Endurance Crater, the shallow crater Erebus, and finally, after a long journey, to the much larger Victoria Crater, located roughly 7 km from the landing site. The layers of sedimentary rock exposed in the walls of these craters contain minerals, such as sulphites and jarosite, and chemicals, such as chlorine and bromine that require considerable interaction with water to produce.

Edge of Victoria crater

This image was taken by opportunity Image source: Nasa

Surviving on mars is not easy task and she made it. During her travel on mars between 26 April 2005 and 4 June 2005 Opportunity was stuck in a Martian sand dune. After that in 2007 she survived through the Martian dust storm which was lasted for three month.

After a three-year trek, Opportunity made it to the 14-mile-wide (22-km) Endeavour Crater in August 2011. The robot has spent the last few months poking around Endeavour's rim, where it recently uncovered what researchers say is the best evidence yet for liquid water on ancient Mars.

Now, the Martian winter is setting in, and Opportunity has already found a nicely sloped outcrop where it can hunker down. But the rover won't go into hibernation; it will stay awake, studying the surrounding rocks and perhaps even moving a few feet now and then, researchers have said.

Over the next few months, the rover team also plans to track radio signals from Opportunity, using the robot's movement as a proxy for the rotation of Mars. Scientists can thus get very precise measurements of the planet's spin, which could reveal information about Mars' interior structure.

Opportunity should be ready to rove again by June or July, researchers have said. While the robot is showing some signs of its advanced age, such as an arthritic shoulder joint in its robotic arm, there's no reason to think it won't hit the ground running. Mars Exploration Rover team said that she's in excellent health.

Opportunity Rover seen by Mars Reconnaissance Orbiter NASA

Opportunity will soon have some company on the Martian surface. NASA's 1-ton Curiosity rover is set to land on the Red Planet in August this year. Curiosity is five times larger than Mars Exploration Rovers Spirit and Opportunity and carrying ten times the mass of scientific instruments. She is already on the way towards Mars and is expected to operate for at least one Martian Year(686 Earth days). This mission will try to gauge whether Mars is, or ever was, capable of supporting microbial life.

The League of Mars Exploration Rovers: Pathafinder(centre), MER Rover(left)and Curiosity(right)