Recent Luna landers.

[Grump Martian]

It has been proposed that the Space X Starship be taken on as NASA's Artemis Luna lander. It may prove to be a great spaceship transportation vessel. But looks too top heavy with small landing legs. Trying to land on heavily cratered Luna landscape without flat paving may well be too differcult.  Chances are high of it toppling over in my opinion. It's center of gravity looks to be very high.

More fuel was added to this notion with NASA's very tall Odysseus lander falling over.

Agencies are trying to land on much more rugged land than the Apollo landers. So why not design a lander that is both wide and a lower center of gravity.

Possibly with adjustable legs .The legs can then be adjusted at short notice to suite whatever ruggedness is encountered. 

I don't profess to be an aeronautical engineer. But I would'nt like to be an astronaut try to land with those short legs. 

An interesting link about the Odysseus lander failure.

https://futurism.com/the-byte/why-tall-moon-lander-fell-over

Edited March 6 by Grump Martian
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[ONIKKINEN]

Starship landing on the Moon seems very problematic, I'll believe they are seriously considering doing that when they actually attempt the landing but we are a ways off from attempt #1.

Apollo lunar descent module was wide with a low center of gravity. I wonder why we are trying to "re-invent the wheel" with landers since the Apollo design worked for what it was supposed to do. The reason why these recent landers tend to be vertical is that there is only so much space inside the fairing of whatever launch vehicle launched the thing, and most of that space is vertical rather than horizontal. You could fit the spacecraft sideways, but that creates extra engineering problems with the design. Some kind of folding landing gear system that expands after the lander portion of the spacecraft is detached from the transfer stage would do the trick, but again more moving parts = more failure points which is an undesirable feat for safety reasons.

I'm no NASA engineer either, just played too much Kerbal Space Program and tipped over probably dozens of spacecraft due to being top heavy designs. A good lander is about as wide as it is tall, and lands the last portion of the journey vertically with no horizontal movement. The recent lander that fell over had too much horizontal velocity and tipped over as soon as one of the legs dug into the lunar surface which cant happen for manned missions.

 

[Guest]

So the Odysseus lander I believe had stabilising engines which fired for a while after landing to keep it upright but eventually ran out of fuel.  You can see them firing in one of the final images sent and also one of the legs lying on the ground.  They're still speculating as to exactly what happened and why it actually tipped over, so not sure the horizontal residual velocity was a factor.  Could be.

But for the SpaceX landing vehicles horizontal movement is no longer an issue as they have pretty much perfected the software to eliminate that...on earth.  Problem with the moon there is no gps, so ground recognition and lidar seem to be the goto tech for that, which Odysseus had issues with (which is why it was patched at the last minute which in turn caused other issues).

Landing on uneven ground will definitely be an issue, and Starship's design will need to be redone possibly.  Although with Musk's obsession with Mars I can't imagine they haven't considered that problem already.  The Falcon boosters do (or at least did) have adjustable struts with massive absorbers, and they are also moveable, so I can see a similar design maybe for Starship.  I don't know.  But it is doable.  Musk has proposed Starship for the moon before so I'm thinking his team has thought about that issue.  

 

At one point I was a doubter that such top heavy designs would be controllable in vertical flight at all tbh.  Never mind that ridiculous mid flight flip maneuver Starship has been doing.  But those guys and gals seem to know what they're doing.

 

As to why reinvent the wheel in other ways.  The original Apollo program cost billions for each mission, even after the enormous initial research funding.  The Odysseus cost around 100 million in today's money.  That I think is cheaper than a Boeing 737.  They want cheap space flight, and that's why those things fail a lot.  India and China spent far more than that on their landers and they worked.  I don't know how much Japan spent but probably a good bit less than India or China.  Russia, well, they still build rockets that blow up so no comment on their tech or their spending.  But money buys you odds in the space race.