Beating the Viking 2 Record
Published on Sep 10, 2007 at 12:31 pm.
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Filed under Mars, NASA, space exploration.
The Mars Exploration Rovers had a rough time the last few months. A massive dust storm cut sunlight to the rovers. Since the Sun is the source of energy for these craft, the dust storm threatened their continued operation. According to a recent press release, the dust storm has apparently abated enough for the rovers to resume their missions. Sort of lost in the news, though, is that they have passed up a long standing endurance record for Mars. Until almost three weeks ago, the longest that any spacecraft remained operational on the surface of Mars was 1290 sols (a sol is a Martian day). The 1290 sol mark was set by the Viking 2 Lander, which landed on Mars September 3, 1976.
But, three weeks ago, the Spirit, the first of the Mars Exploration Rovers to land, passed the 1290 sol mark. Today, Opportunity also reached 1290 sols. That is really quite remarkable, considering that both rovers are so far past their design lifetimes.
Mars is very tough on spacecraft. The landers have to endure bitter cold throughout the Martian night, and Martian winters are amazingly cold. It can get so cold in the winter on Mars that carbon dioxide, the major component of Mars’ atmosphere, begins to freeze out of the air. Of course, space is tough on spacecraft, too. But, a spacecraft orbiting Mars can get sufficient solar energy from the Sun to keep itself alive for a long time, and the all time record for an operational Mars mission is held by an orbiter. But, being on a planetary surface is more difficult. The spacecraft is in contact with the air and ground, and these can act as heat sinks. In space, the spacecraft is surrounded by a vacuum. That presents its own problems, of course. However, keeping the spacecraft warm is easier in a vacuum because a vacuum doesn’t conduct heat (after all, what makes a Thermos work the way it does is that it is a vacuum bottle!). Also, an orbiter is in Mars’ shadow for at most an hour. A lander has to survive very long Martian nights of bitter cold. Add to that the dust storms, etc, and you have a really tough environment for any spacecraft. Surviving this long is really amazing.
However, as amazing as Spirit and Opportunity’s endurance records have become, they will likely fall in just a few years. The next generation of Mars rovers will be larger and more robust even than the Mars Exploration Rovers. They are designed to last much longer, and they should (barring unforeseen circumstances) significantly outlast both Spirit and Opportunity. But, for now, let’s celebrate the two amazing rovers on Mars now.
-Astroprof
Image courtesy of NASA, JPL
