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Mars Exploration Rover - Spirit

Mars Exploration Rover - Spirit mission graphic

Phase: Past

Launch Date: June 10, 2003

Mission Project Home Page -

Program(s):Mars Exploration

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The Mars Exploration Rover (MER) Spirit landed on Mars on January 4, 2004. The rover was originally designed for a 90 Sol mission (a Sol, one Martian day, is slightly longer than an Earth day at 24 hours and 37 minutes). Its mission has been extended several times as it continues to make new and profound discoveries about the red planet.

Mars Exploration Rover Spirit West Valley Panorama
Spirit's West Valley Panorama (False Color)
NASA'S Mars Exploration Rover Spirit captured this westward view from atop a low plateau where it spent the closing months of 2007.
Image credit: NASA/JPL-Caltech/Cornell University


Spirit is equipped with a powerful set of tools to study a diverse collection of rocks and soils that may hold clues to past water activity on Mars. These tools include multiple cameras: a panoramic camera (Pancam), as well as a navigational camera (Navcam), and a microscopic imager (MI) which obtains close-up, high-resolution images of rocks and soils. There are also several instruments for analyzing composition and mineralogy: a miniature thermal emission spectrometer (Mini-TES), a Mossbauer spectrometer (MIMOS II) which provides unique information about iron-bearing minerals, and an alpha particle x-ray spectrometer (APXS) which tells us the chemical makeup of individual rocks and soils. Finally, the rovers are equipped with a “rock abrasion tool” (RAT) which exposes fresh material beneath the dust and weathered rinds that typically coat martian rocks.

Spirit landed on the opposite side of Mars from its twin, Opportunity, in Gusev crater, a 170 km diameter crater which formed three to four billion years ago. A channel system drains into the crater that likely carried liquid water, or a combination of water and ice, at some point in Mars' past. The crater appears to be an old lake bed filled with sediments. It was hoped that sedimentary material from this early era could be studied, although at first the region proved disappointing in its lack of available bedrock on the flat lava plains of the crater. Spirit eventually made its way to the Columbia Hills, a small group of low-lying hills about 3 km from the landing site, and rocks examined there do show evidence of interaction with small amounts of briny (salty) water.

Despite a few problems—Spirit has completely worn down the drill bit on her RAT tool and one of her wheels has quit working requiring that she be driven backwards—the rover has exceeded expectations and continues to return exceptional data.