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by nomel 454 days ago
For any of these landings, it's a problem of 3d positional/velocity precision. SpaceX has prove that they can reliably land on a target, usually within meters, with negligibly delta velocity on contact.

In other words, they've proven they have the control systems in place for placing a craft at a precise location, with a precise velocity. What requirement do you see outside of this that are far outside of placement and velocity? Autonomous mapping and adjustments for approach maybe?

Let's not assume they're going to try to use their current earthly landing legs.

> land on some random beach,

They did this I believe two starships ago, when they landed in the ocean. Came to zero xyz velocity some target distance above the water, and hovered for a bit. Unfortunately, the surface tension of the sea couldn't support the weight once they lowered for touchdown.
1 comments
literalAardvark 453 days ago
> 3d positional/velocity precision. SpaceX has prove that they can reliably land on a target, usually within meters

On Earth, which has GPS. On a very highly engineered landing surface.

Landing on inertial guidance on soft regolith is a whole different ballgame.

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nomel 453 days ago
> Landing on inertial guidance

Which is not the future. Optical/lidar/positioning radio is the future, to make it closed loop (NASA’s Laser Retroreflector Array for high, lidar/optical for low altitudes).

> On a very highly engineered landing surface.

As I mentioned, we shouldn't assume the earthy landing legs are used. That would be a very silly assumption.

From what I can extract from your comment, you believe that the positioning system and landing legs are the issue, rather than the control systems. I suspect both are somewhat related: positioning system to place it over predictable regolith with some, yet-undeveloped, landing legs that need to work at 1/6th gravity.

I'm of the opinion that it's possible/solvable, as is NASA. It would be helpful if you would answer why you think it's not possible: what requirement do you see that make positioning and landing on regolith unachievable for SpaceX?

[1] https://www.nasa.gov/centers-and-facilities/langley/nasas-la...

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literalAardvark 453 days ago
It may be possible. It may also be that the regolith is too fluffy in that area to support such a large structure without a pad. I don't believe we know.

Athena had multiple laser altimeters on board: they failed to get a fix, perhaps because of the weird surface.

It's my opinion that this isn't something that's easy to do, even for a company that has landed on Earth.

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