Saturday, September 27, 2008

The Earth in its full glory

A couple of days ago, Derek posted a link to an image of the Moon's south pole. That picture was derived from data generated by a European spacecraft called SMART-1. The picture reminded me of another space achievement.

In 1994, a space probe called Clementine was launched. Its mission was to space-test on-board electronics, gather more information about the Moon, and then continue on to a minor planet called Geographos, to do similar things.

During the maneuvre to reorient and propel Clementine to the final target, an attitude control thruster malfunctioned, which made the gathering of data at Geographos almost impossible (the spacecraft was put into a rapid spin). Instead, Clementine was put into a geostationary orbit to explore the effects of the Earth's van Allen radiation belt on spacecraft electronics.

Before all this, though, Clementine generated specialized maps of the Moon, and in the process, took some impressive images. One that strikes me particularly is this one of the Earth as seen over the Moon's north pole (at left - source: USGS). It shows the continent of Africa, almost totally clear of clouds. Click on the image to enlarge it.

What a contrast with the gray and desolate surface of the Moon.