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by kevin_thibedeau 1151 days ago
It is also indicative of how their lunar starship will damage itself on descent. At least NASA came to it's senses and funded a backup plan.
1 comments

It is not indicative of that.

Lunar Starship is the second stage, this was the first that did the damage. Even that is different from the one launched in the recent test; it’s a variant that will do the final landing on different engines high up on the rocket. Per Wikipedia:

> Within 100 meters of the lunar surface, the variant will utilize high‑thrust RCS thrusters located mid‑body to avoid plume impingement problems with the lunar regolith.

Landing is also very different than takeoff; the F9 takes off with nine, lands with one. Likewise, Super Heavy launches with 33, but Starship lands with 3-6, and three of those are the vacuum variant, with much less focused plumes.

> Landing is also very different than takeoff;

Lunar Starship is going to use the same engines for takeoff, assuming they don't get smashed by flying debris.

Much fewer, half of them are vacuum variants (much less focused plume), and lunar gravity is much lower, meaning dramatically lower thrust required to get off the ground.
> but lands with 3-6, and three of those are the vacuum variant

First stage will likely use more than 3-6, none will be the vacuum variant.

The first stage isn’t going anywhere near lunar regolith. Ever.
You were talking about F9 landing, and taking off with 33 engines. Only the first stage lands on the F9. Only the first stage has 33 engines. I guess it's more confusing when Starship is what the whole ship is called, and possibly the second stage.
Falcon 9 is a specific clear example of landing != takeoff.

Starship != Super Heavy

Lunar Starship != Starship

Earth != Moon

All of these differences combined make the test not the slightest bit indicative of how things would work for a lunar Starship landing.

And second stage has different engines since when? Starship proper is not that different, it has fewer engines, its landing gear provides worse conditions than the launchpad.
Second stage (Starship) has always had different engines (both in quantity and construction; some are vacuum Raptors) than Super Heavy. Lunar Starship is itself a variant of the regular second stage; it'll need the cargo elevator, for example, which is shown in NASA's announcement graphics.

https://www.youtube.com/watch?v=KEnz8V97Qck&t=2100

> for the terminal descent of Starship, a few tens of meters before we touch down on the lunar surface, we actually use a high-thrust RCS system, so that we don't impinge on the surface of the Moon with the high-thrust Raptor engines. ... uses the same methane and oxygen propellants as Raptor.

(We'll see if that winds up being the actual final solution, but they've clearly at least thought about this aspect.)