Space reporter Miles O'Brien wrote a lovely farewell to the NASA's rover Spirit on the PBS NewsHour blog today, as NASA ceases attempts to reach the little robot that could.
It discovered silica deposits, carbonates, and evidence for hydrothermal systems and explosive volcanism. Billions of years ago, Spirit's site was a hot, violent place, with hot springs, steam vents, and volcanic explosions, and the little rover managed to suss that out.
But roving on Mars is not easy, and eventually Spirit found some sand that left it stranded. Since the JPL AAA card does not work on Mars, the rover had, in essence, dug its own grave. It was just a matter of time that the batteries would run down for lack of juice from the photovoltaic solar cells.
It is interesting, and somehow fitting, that Spirit was given its last rites on the 50th anniversary of John F. Kennedy's historic speech before a joint session of Congress. Kennedy said, "this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important for the long-range exploration of space; and none will be so difficult or expensive to accomplish."
Image, NASA, 2004: A computer-generated model of Spirit's lander at Gusev Crater as engineers and scientists would have expected to see it from a perfect overhead view. The background is a reprojected image taken by the Spirit panoramic camera on Sol 19 (Jan. 21-22, 2004). The top of the image faces north.