Mars rover works its way out of crater

[Elgin Clock]

Originally Posted by Andy Baker

My guess is that they use materials with impregnated lubricants, or materials which naturally have high lubricity. Most likely, they stay away from grease or oil lubricants, as these can easily attract debris while also not be reliable after being in the vacuum of space for a while.
But that is just a guess. I would be very interested in hearing what is actually used.

Andy B.

What about Graphite powder? That's a non-liquid lubricant, & very effective for unsticking things with repeated use, like car door locks for example... on Earth at least. lol

[Al Skierkiewicz]

Interesing ideas, but I am guessing that sample contamination plays into the spec as well.

[David Brinza]

Graphite isn't a good lubricant in vacuum. Absorbed water vapor and gas between the planes of carbon atoms in graphite makes it "slippery". Molybdenum disulphide (Moly-lube) is a much better dry lubricant in vacuum.

There are special greases that won't outgas or creep out of the mechanism. Finding non-contaminating lubricants that will work well at -100 degC (or colder) was a problem.

The specific lubricants that are used in the rovers probably cannot be disclosed publicly, due to export control (ITAR)* restrictions.

* Even though the rovers are not military in nature, the US State Dept considers space systems technical data to be sensitive information that cannot be disclosed to non-US persons without specific permission. (This is probably a topic for an entirely different thread).