MOC2-960a: Spirit track from lander to Columbia Hills Composite of MOC images R15-02643 and R20-01024 |
MOC2-960b: Annotated, segmented view of Spirit track Composite of MOC images R15-02643 and R20-01024 |
MOC2-960c: Faded rover track and new dust devil streak MOC images R15-02643, R20-01024; MER-A Navcam Images (courtesy NASA/JPL) |
The Mars Exploration Rover, Spirit, landed in Gusev Crater a year ago. Over the course of its mission, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has been tracking Spirit's progress from orbit. During the rover's 90 sol primary mission, it drove from the lander to nearby Bonneville Crater. When the extended mission began, the rover was already making progress down toward the Columbia Hills, several kilometers to the southeast.
The first picture shown here, MOC2-960a, is a composite of MOC images R15-02643 and R20-01024, showing the complete rover track from the lander to the Columbia Hills. Spirit's rover track shows up nicely from orbit, because the surfaces disrupted and churned by the wheels are darker than the surrounding, dust-coated plain.
The second picture, MOC2-960b, is a segmented view of the first. In this case, the location of the lander, parachute, and backshell are indicated in frame A, and the rover track down toward the Columbia Hills can be traced through A, B, and C. In frame A, Bonneville Crater is the largest crater in the upper right quarter of the image. Spirit drove up to Bonneville's rim, before driving away from it, toward the southeast. The base of the Columbia Hills is seen in the lower right quarter of frame C. In frame B, notice that the rover track followed along the edge of a lighter-toned and wider dark streak, believed to have been formed by a dust devil sometime before Spirit landed. The proximity of the rover to this streak was not recognized in rover images.
The third picture, MOC2-960c, includes additional annotations that can be used in reference to the previous pictures, indicating the location of the rover track and lander. This third picture illustrates the occurrence of a new dark streak thought to have formed by a dust devil that was bigger and wider than the Spirit rover. This dust devil was not observed by the rover. The first picture in the upper left is MOC image R15-02643, acquired on 30 March 2004 (Spirit's sol 85). The second picture, upper right, is MOC image R20-01024, obtained on 18 August 2004 (Spirit's sol 223). A dark streak occurs in the larger crater in the lower right quarter of the August 2004 image. This streak was not present when the March image was obtained. Inspection of Spirit's navigation camera images obtained on 20 April 2004 (Spirit's sol 106), when the rover was at the rim of this crater, revealed that the streak was present on 20 April 2004. Thus, the dust devil must have occurred some time between 30 March 2004 and 20 April 2004.
In addition to the formation of a new dust devil streak in the 30 March to 20 April 2004 period, another change seems to have occurred at the landing site. The rover track between the lander and the rim of Bonneville Crater (the largest crater in MOC2-960c) seems to have faded between 30 March and 18 August. This could be an artifact of the different sunlight illumination conditions between the two images, or it may indicate that fine dust settled on the older portions of the track, obscuring it from view. Assuming the MGS MOC mission will continue for several more years, the MOC team plans to re-visit the Spirit lander site from time to time, to see what other changes may occur.
Previous MGS MOC Images of the Spirit landing site:
Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, California. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, California and Denver, Colorado.
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