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Planetary News: 2001 Mars Odyssey (2005)

Martian Orbiter Takes Pictures of Neighboring Crafts Passing By

By Amir Alexander
May 19, 2005
Mars Odyssey from Mars Global Surveyor
Mars Odyssey from Mars Global Surveyor
This double image of Mars Odyssey was taken by Mars Global Surveyor in April 2005 and represent the second picture taken by one spacecraft of another at Mars. Source Credit: NASA / JPL / Malin Space Science Systems

Even though a human mission to Mars is still far off in the future, there's no denying that the Red Planet has become a bustling place these days. Two rovers, Spirit and Opportunity have been ranging the Martian wilderness for over a year now; several recent wrecks, including NASA's Mars Polar Lander and Mars Climate Orbiter, as well as ESA's Beagle 2, dot the planet; numerous landers from past missions, such as the two Vikings and Mars Pathfinder sleep silently on the surface, awaiting a future visitor; and no less than three orbiters - NASA's Mars Global Surveyor and Mars Odyssey, and ESA's Mars Express – are circling the planet taking note of all that is happening below.

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With so much traffic swirling on and above Mars, it is not altogether surprising that these robotic emissaries are finally taking a break from surveying the Red Planet, and are instead turning their sites on each other. Two weeks ago the Mars Global Surveyor spotted "something," which just might be the wreckage of the lost Mars Polar Lander. Now, for the first time in the annals of planetary exploration, a spacecraft orbiting a planet other than Earth has taken pictures of other spacecraft in its vicinity.

During April 2005, the Mars Global Surveyor happened to pass relatively close to Odyssey and Mars Express. This has happened many times before, and on all occasions these lonely ambassadors from Earth, so far away from home, have passed each other like strangers in the night. Not this time. Using the Mars Orbital Camera (MOC), which had served it so well in its detailed survey of the Martian surface, the Mars Global Surveyor turned to face its fellow orbiters and took their picture. What resulted were remarkably clear pictures of human-made spacecraft orbiting and alien world. Both the Odyssey and the Mars Express were last seen by humans years ago, before they were launched on their way to a different world.

Best view of Mars Odyssey from Mars Global Surveyor
Best view of Mars Odyssey from Mars Global Surveyor
Credit: NASA / JPL / Malin Space Science Systems
Annotated drawing of Mars Odyssey as seen from Mars Global Surveyor
Annotated drawing of Mars Odyssey as seen from Mars Global Surveyor
Credit: NASA / JPL / Malin Space Science Systems

The image of the Odyssey actually appears twice within the same frame, once from a distance of 90 kilometers (56 miles) and again from a distance of 135 kilometers (84 miles). This double appearance came about because of the diverging orbits of the two spacecrafts, which first took Odyssey out of the MOC's field of vision, but then returned it again during the same exposure.

The image of the Mars Express is in fact a composition of two pictures taken of the spacecraft by the MOC from distances of 250 and 370 kilometers (155 and 230 miles). Due to the large distance between the Mars Global Surveyor and the Mars Express, and their great relative speed, the image is more blurred and less detailed than that of Odyssey. Nevertheless the general outlines of the European spacecraft are clearly discernable.

With more missions to Mars now in the works, the day may not be far when such encounters between human surrogates will occur not just in orbit, but on the planet's surface as well. And when that happens, perhaps encounters between real humans will not be far behind.

Image of Mars Express from Mars Global Surveyor
Image of Mars Express from Mars Global Surveyor
This represents the first image taken by one spacecraft of another in orbit around Mars. It was acquired by Mars Global Surveyor on April 20, 2005 from a distance of about 250 kilometers (155 miles). Credit: NASA / JPL / Malin Space Science Systems
Drawing of Mars Express as seen from Mars Global Surveyor
Drawing of Mars Express as seen from Mars Global Surveyor
This drawing shows the orientation of Mars Express when Mars Global Surveyor snapped a photo of it. Credit: NASA / JPL / Malin Space Science Systems