There's no atmosphere, so its unlikely Lunar dust would contaminate any equipment. It settles immediately after landing and doesn't blow around. Minimal shielded for touchdown would be all that's necessary.

Perhaps I wasn't clear. This would be an unmanned telescope. We're talking a one time landing of a piece of equipment. Dust will be a non-issue after the initial landing.

Not necessarily. One of the interesting results from LADEE was that the measured lunar dust increased a few hours before the probe landed (attributed possibly to the geminid meteor shower). There's lots of stuff that can kick dust off the lunar surface.

http://en.wikipedia.org/wiki/Lunar_Atmosphere_and_Dust_Envir...