Surveying the Red Planet

The orbiter Mars Global Surveyor arrived at Mars in 1997. It discovered that Mars once had a strong magnetic field. The orbiter also accurately mapped the topography of Mars, revealing, among other things, that the distance from the lowest spot on the surface of the planet to the highest exceeds 18 miles [29 km], compared with just over 12 miles [19 km] for the earth.


The lowest spot on Mars is in the vast Hellas basin, which was evidently formed by the impact of a gigantic asteroid. The highest point is the summit of the immense, 13-mile-high [21 km] volcano Olympus Mons. A camera onboard Surveyor also recorded boulders that appeared to be more than 60 feet [18 m] across, as well as large shifting fields of sand dunes and freshly carved gullies. Another instrument determined that most surface rocks are of volcanic origin.

Although in November 2006 communication with Mars Global Surveyor was lost, three orbiters—the 2001 Mars Odyssey, the Mars Express, and the Mars Reconnaissance Orbiter—continued their surveillance of the red planet. Using more-sensitive cameras and detectors, they examined the Martian atmosphere and space environment and even discovered and mapped abundant ice at the planet’s north pole.

This ice is a focus of the Phoenix Mars Lander, which dropped down flawlessly on the red planet on May 25, 2008. The Lander is equipped with highly advanced instruments to analyze both the atmosphere and the permafrost at the polar region. Scientists hope to learn whether the icy soil has ever supported microbial life. However, the search for life—or at least conditions favorable to it—had begun earlier.

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