SpaceX is making water-cooled steel plate for launching and landing the two stages of the SpaceX Super Heavy Starship. The launch and landing pad challenges for the moon and Mars are far less than for the Earth.
For the Moon, NASA has awarded a lunar landing pad contract to ICON.
From the lab to the field to the Moon….it’s time to build. Check out ICON’s Project Olympus –> https://t.co/H9OSxGLK3v #lunarconstruction @NASA @NASA_Technology pic.twitter.com/Y62ailxPF4
— ICON (@ICON3DTech) November 29, 2022
This contract, which is valued at $57.2 million and runs through 2028, is a continuation of ICON’s current Small Business Innovation Research dual-use contract with the U.S. Air Force which is partly funded by NASA. The new contract will support the development of ICON’s Olympus construction system that will use local resources on Mars and the moon to build materials.
ICON has previously printed a 1,700-square-foot simulated Martian habitat that will be used during NASA’s analog mission starting in 2023.
ICON is also working on 3D printing buildings, bases and other structures on Mars. They have done test construction on Earth.
Changing the Location of Landing Engines for Lunar and Mars Landing
For the moon, SpaceX Lunar Starship has small engines mounted near the top about 100 feet from the base.
Thus it can land and take off without wrecking the regolith. The moon’s gravity is 1/6th of Earth gravity. This means 1/6th of the thrust for take off and landing. However, we are also only landing the upper stage which is only 25% of the total weight with the booster. First landing is with almost empty fuel tanks. There is 1200 tons of fuel in a 200 ton vehicle and then another 100 tons of payload. It should be landing with about 300 tons of weight. A Lunar Starship would be landing with 1% of the thrust of Earth booster and Starship launch.
After, Lunar Starship lands on the moon then a landing and launch pad needs to be built.
Mars has 38% of Earth Gravity. A rocket needs 38% of the thrust to take off and land versus the same weight on Earth. Starship only is landing. The Super heavy booster is not landing on Mars. Starship has 25% of the mass of the combined two stages and has 7 engines instead of 33. 9.5% of total Earth launch thrust. First Landing would be nearly empty fuel tanks. Land once with about 3% of the thrust and then build the launchpad.
There is talk about adding binder into the exhaust or dropping a deployable temporary landing pad material. This would mitigate debris on the first landing.
I think SpaceX will need to make over-sized landing thrusters for the Mars Starship. Oversized relatively to the Lunar Starship landing thrusters.
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A lot less thrust to absorb but 1000 times harder to build the pad. No metal for reinforcement, no water for cooling and dampening etc.
And failure is not an option.
The Starship moon lander design doesn’t make much sense other than the ship looking similar to Earth variants. These landers will only ever land on the Moon won’t they?
So aerodynamics doesn’t exist other than when getting the ship up from Earth in the first place. Why use valuable internal space for the engines when they can be attached at the nose flap hardpoints and sit on the outside. This will also give them more gimbaling headroom.
Will they survive max Q on Earth ascent? If not, assembly has to be done in orbit.
It has aerodynamics because it has to take off from Earth, even if it is never returning. Also, in some mission profiles you do an aerobraking maneuver on return to Earth orbit.
Yes, a bespoke lunar lander built in orbit could have awesome performance. It would also be more expensive, and fly a lot later.
Looking at ICON. Not a big fan of printed buildings – very inflexible in layout and often a ‘brittle’ shell type approach – itching for a catastrophic failure. ‘Living off the land’ methods are appealing of course if you’re going adobe or tunnelling or igloo-type. If you’re going to print/ form/ cure shapes – post and beam (or the 3D truss/frame) is better with reinforcing, like concrete and durable connectors. Still thinking that having redundant inflatable can provide significant benefit.
Do we really care about regolith debris on the moon at launch? – maybe as a hazardous projectile – but regolith doesn’t glom, just dust.
I’ve looked into this. The printed structures have a lot of ‘gosh wow’ appeal to the right sort of people, but the utility doesn’t look like it’s there.
The optimum approach is probably inflatable structures covered with sandbags. The ratio of weight to livable volume is very low in these, as the load is all tension. The mass of the air inside is actually comparable to the structural mass!
But sandbags don’t have a lot of gosh wow appeal to the sort of people currently running NASA.
“Mars has 38% of Earth Gravity. A rocket needs 14.4% of the thrust to take off and land versus the same weight on Earth.”
I think you’re going to have to explain the math there for me; I’m not seeing how you get from 38% to 14.4%. Are you assuming identical payload, and reduced fuel load due to the smaller delta V?
Certainly, the Mars landing Starship will not be identical to an Earth landing Starship. It doesn’t need the thrust to weight ratio, but it does need landing legs, and the flaps might have to be larger to have enough control authority in the thinner air.
I was assuming some kind of squaring related to gravity. I guess I got that wrong. I changed it.
It IS rocket science, after all. 😉 Those of us who grew up watching Apollo, and as teens filled notebooks learning how to calculate the Delta-V necessary for interplanetary trips from Newtonian physics. tend to have a bit more of an intuitive feel for it.
The Moon lander design with small thrusters near the top of the rocket for landing seems like a viable approach for very low gravity airless bodies. You still have to use the main engines for most of the landing delta V, the upper thrusters would only be used for the final approach.
I don’t think it’s really viable for Mars, given the higher thrust requirements, and the way the secondary thrusters might interfere with heat shielding necessary for the aerobraking maneuver, though. They’ll have to identify an especially good landing site, maybe an exposed rock shelf. I understand there are a lot of areas of exposed bedrock, scoured clean by wind, some of them of volcanic origin, and thus not so likely to suffer steam explosions due to loss of water of hydration, like we’ve recently seen cement does.
Though finding one in close proximity to buried water might be a challenge.