InSight Surface Operations, 26 Nov 2018- 21 Dec 2022 Options

[nprev]

Congratulations to the InSight team on a successful landing! We'll discuss the remainder of the mission here.

[elakdawalla]

I'm actually really intrigued by how deep the footpad has sunk. That's fascinating. I don't think any other footpad on any other mission has done that. Is the soil compressible? Was it blown away, undermined, during the final moments of landing? How did that happen?

[pioneer]

I'm actually really intrigued by how deep the footpad has sunk. That's fascinating. I don't think any other footpad on any other mission has done that. Is the soil compressible? Was it blown away, undermined, during the final moments of landing? How did that happen?

A scary thought just came to mind : what if the lander landed on quicksand? It's ridiculous, right?

[HSchirmer]

A scary thought just came to mind : what if the lander landed on quicksand? It's ridiculous, right?

Nope, not ridiculous at all. In hindsight, just unlikely.

The Surveyor landings on the Moon were (in part) to make sure the lunar seas were really cooled lava flows that you could land on, not tens of meters of uncompacted or electrostatically levitated dust that you'd sink into.
Turns out there ARE tens of meters of lunar dust, but it's compacted and mixed with larger grains so that it can support the weight.

There are some weird bodies that appear to have "quicksand" surfaces, i.e. just dust without a solid surface.
One is Saturn's egg-shaped moon Methone, which seems to be just dust.
Others are the "dust ponds on asteroids, which seem to accumulate dust in depressions,
https://www.sciencemag.org/news/2001/09/dusty-ponds-space
or at the low gravity point between contact binaries.

Now, for trying to answer the question- the problem wouldn't be "quicksand" but "deep loose dust"-
I think the answer would depend on what triggers the landing rockets to shut off.
If the landing rocket shutdown is triggered by foot-probes AND the dust has no bearing strength, (i.e. acts like a fluid) then the rockets don't get a shut-off signal and continue to fire as the lander approaches the dust.
I'll guess the lander has a fail-safe "when in doubt, hover, don't crash" routine so it should hover in place until it touches ground, that should be time enough to blow out the loose dust?
If the landing rocket shutoff is triggered by a proximity radar, then the loose dust probably reflects enough to fool the lander into thinking it's approaching solid ground, and the lander sinks into the dust.

[atomoid]

Nope, not ridiculous at all. In hindsight, just unlikely.

The Surveyor landings on the Moon were (in part) to make sure the lunar seas were really cooled lava flows that you could land on, not tens of meters of uncompacted or electrostatically levitated dust that you'd sink into.
Turns out there ARE tens of meters of lunar dust, but it's compacted and mixed with larger grains so that it can support the weight.
.......snipsnipsnip........

Clarke's (pre-Surveyor) classic immediately comes to mind