The question Did any lander or rover photograph the sun rising or setting during a Martian dust storm? makes me think of the images below showing the stuff blown around and on to martian rovers.

I'm guessing that when propelled by high speed winds the most abrasive and smallest particles could do some damage to protective optical windows.

Question: How are optical windows on martian rovers protected from hazing due to abrasion from martian dust storms? Are they made out of old iPhones sapphire or do rovers "avert their eyes" during a storm, at least those that are moveable? Or both, or neither?

covers over various science and navigation camera lenses as well as laser ablaters, light level meters and whatnot.

From Curiosity is still dirty! How will the ExoMARS Rover keep its solar panels dust-free and collecting sufficient power?:

Curiosity rover covered in dust click for full size

above: even the inclined surface of the high gain antenna seems covered in dust! Cropped from Phys.org's Curiosity says farewell to Mars' Vera Rubin Ridge.

enter image description here click for full size

above: "The deck of NASA's Mars Exploration Rover Spirit is so dusty that the rover almost blends into the dusty background in this image assembled from frames taken by the panoramic camera (Pancam) during the period from Spirit's Sol 1,355 through Sol 1,358 (Oct. 26-29, 2007)... Dust on the solar panels reduces the amount of electrical power the rover can generate from sunlight each sol." From here.

  • $\begingroup$ Unfortunately I cannot find a source and I am not sure where I heard this (I think it was a TV documentary), so I will not post this as my answer, but: because of the consitency of the martian "dust" and the low atmospheric pressure martian dust storms are not very harmful. For surfaces it is more like standing in a floor-dust-cloud $\endgroup$
    – CallMeTom
    Mar 4, 2020 at 13:49
  • $\begingroup$ @CallMeTom how fast are these particles moving in order to stay aloft rather than fall back to the surface? I think they're moving at quite a clip; they're not just hovering. $\endgroup$
    – uhoh
    Mar 4, 2020 at 14:27

1 Answer 1


Image credit: NASA/JPL-Caltech/MSSS

The image above shows the Mars Hand Lens Imager (MAHLI) on the turret of Curiosity's robotic arm.
The reddish circle near the center is the window of MAHLI's dust cover.
In the accompanying text it is said that there's a thin film of Martian dust on it, and that the front window is made of sapphire.
This article tells us that the dust cover on the imager is reclosable.
This story about the global dust storm on Mars writes that the Mastcam was routinely pointed down at the ground after its use to reduce the amount of dust blowing at its optics.
Finally, from one of the Planetary Society's updates:

"We've just had to take a little extra precaution with the MAHLI [Mars Hand Lens Imager] to avoid the amount of time we expose the lens. And, while we're not able to cover the cameras on the mast, we haven't seen any issues with those. They have pretty big baffles around them so the optics are kind of buried inside,"he said.

Curiosity's engineering cameras are the most exposed. "We have seen a few particles of dust adhere to them, but nothing so far that's affected our ability to navigate or the ways we use those cameras," Vasavada reported.

I couldn't find evidence that the other cameras have sapphire windows, but if MAHLI has one with a dust cover, why shouldn't they, without a dust cover, have one ?


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