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| Figure 1 | Figure 2 |
11 August 2006
One might say that today is Deimos' birthday. To celebrate, we present here
the first and only Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)
image of this tiny moon. Deimos was discovered 129 years ago on 11 August
1877 (U.S. time, it was 12 August UTC), by U.S. astronomer Asaph Hall. It
was the first of two major discoveries that he made that month; less than
a week later, he found the other, inner martian satellite, Phobos.
About a month before the 129th anniversary of its discovery, on 10 July
2006, Mars Global Surveyor was pointed away from the martian surface, out
toward distant Deimos.
Imaging the smaller of the two martian moons was the result of a combined
effort between MGS engineers at Lockheed Martin Astronautics and MOC
operations engineers at Malin Space Science Systems. When the picture was
acquired, Deimos was about 22,985 kilometers (14,285 miles) from MGS. This
results in an image of approximately 95 meters (about 312 feet) per pixel.
Higher resolution images were obtained by the Viking orbiters in the
1970s-some of those pictures were so good that boulders could be resolved
on the moon's surface (see figure 2). While the MOC image is at a
lower resolution than the Viking data, acquiring an image of Deimos helps
refine the understanding of the tiny moon's orbit and geography. The two
craters, Voltaire and Swift, are presently the only craters with names on
all of Deimos. Author Jonathan Swift, in his 1726 Gulliver's Travels, had
coincidentally surmised that Mars has two moons. Sunlight illuminates the
scene from the upper right.
