HLS

HLS Starship SpaceX Render image credit: SpaceX

First, Artemis (see Wikipedia article here) is very complex yet underfunded, requiring voluntary contribution from many nations that in turn employ many contractor and sub-contractors for critical elements as the following graphic shows (and that's just for Gateway and Orion). Also add on SLS (Boeing and others) for launches. Each of these nations and organisations need to maintain (taxpayer) funding to have a hope of delivering on time. A SpaceX solution for non-SLS and non-Orion components would be all under one manager/integrator/private funder. Much lower risk and faster to solution. image credit: NASA

Why LEO -> Lunar Surface -> LEO won't work

Unfortunately Starship HLS is poorly matched to the Artemis architecture ... it's like taking a tug boat across the ocean (Orion) then docking with cruise ship to get the 10 miles to shore. One might hope that a 100% fuel up in LEO would allow it to round trip from LEO -> Lunar Surface -> LEO and use CD to shuffle crews in LEO ... but the DV needed is far ... far too much for a heavy vehicle (DV=6 km/s up and DV=6 km/s down).

So its pretty much a 100% LEO refuel -> Lunar Orbit -> Surface -> Lunar Orbit ... then you need another 8-10 Cargo Starships of fuel to 100% re-fuel 1 Cargo Starship in LEO to make a refuel run to Lunar Orbit so that you can Lunar Orbit -> Surface -> Lunar Orbit again. For that you get about 60 tons of crew-cabin-cargo if Starship dry mass is only 110,000 kg ... in this application every kg counts again (like in all other lunar surface concepts it seems) so losing the flaps and TPS will help. You still need the normal 6 engine set to minimize gravity loss to LEO ... no saving there ... you lug those extra 3 normal raptors around for no additional value = 5 tons total. And big landing legs.

On the other hand Cargo Starships to the moon are a great capability ... delivering 100t of cargo at shot on ship that might only cost $50M to build and $200M to fuel ... but HLS Starship is badly mismatched to the constrains of Orion/Gateway unless you think of HLS Starship as an active part of Gateway itself ... then it's a much larger HALO outpost ...

HLS Starship Needs to as light as possible !!!

A 110 ton Dry Starship mass could enable up to 100 tons of HLS specific outfitting, crew and cargo. A 150 ton Dry Starship mass would leave only 20 tons for this ... probably not workable.

On the first HLS Starship run to Lunar Orbit will have 238,000 kg of fuel left with a 60,000 kg payload (cabin, equipment, supplies) is HLS Starship's mass is only 110,000 kg (best case). If HLS Starship's mass is 150,000 kg then only 20,000 kg can be brought and have enough fuel for a one-time Lunar orbit -> Lunar Surface -> Lunar Orbit round trip. HLS Starship will need to be refilled in Lunar Orbit by a Cargo Starship for every run. Price is likely to be $400M per run (including HLS investment recapture and 50% profit over 10 uses) given that it will take 8-10 tanker runs to the LEO fuel depot to refuel a Cargo Starship headed to Lunar Orbit 100% (which is needed to have enough spare fuel for HLS and still return the Cargo Starship to Earth). Each fuel run to the LEO fuel depot will likely have a long term cost of at least $20M.

A Gateway Alternative: LXGateway (Lunar eXporation Gateway)

This assumes that Crew Starship is not approved by NASA for Artemis Gateway operations. If it was ... a Crew Starship could dock directly with HLS Starship in Lunar Orbit and there would be no need for any additional component. 1 Cargo Starship would also be needed for each HLS Lunar Orbit -> Lunar surface -> Lunar Orbit round trip ($200M cost).

Instead of piecing together the proposed Lunar Gateway ... SpaceX could modify a HLS Starship to act as that Gateway ... call it LXGateway. In addition to very roomy crew and cargo transfer capabilities it features a fuel depot to optimize the amount of fuel needed to perform and surface and back mission ... the rest can be stored at LXGateway for another mission. As a cryogenic fuel depot LXGateway must have the fuel tanks always shaded from the sun. The following render shows the sun shade casting a compete shadow over the surface of the tanks. The front of LXGateway should always be pointing at the sun. This also maximizes the power to the Roll Out Solar Arrays (ROSA). It also minimizes sun on the radiators that point to deep space (and Earth). Large interior gyros and gas thrusters maintain this alignment.

LXGateway adds and subtracts the following to the HLS Starship design

Add:

+ Large Sun Shade with Fold Out Solar Array (FOSA)
+ Space Station Class Radiators, Gyros, Orientation Thrusters
+ 2 additional ISS Standard Docks

Less:

- Lunar Solar Array, Radiators
- Soft Landing Thrusters
- Large Landing Legs (4)
- Cargo Bay with External Elevator
- Extra Buffer Batteries

Mission Structure

Cost of 100% SpaceX defined HLS Starship: $1B (SpaceX assumed cost)
Cost of LXGateway: $1B (SpaceX assumed cost)

Price of HLS Starship to NASA: $600M per round trip (mostly for fuel costs paid by SpaceX)
Price of LXGateway to NASA: $200M per mission
Price of cargo run to LXGateway to NASA: $400M per mission
Average price of cargo on mission: $100M (taxpayer paid to a variety of sources and contractors)
Price of SLS and Orion to NASA: $3-4B (yes, crazy high ... but it not a SpaceX component)

First Mission: Deploy LXGateway (Unmanned)

1) Launch LXGateway to LEO ... pop off port and equipment covers, nosecone in low LEO so they burn up quickly
2) DeployLXGateway's Reflective Shield, Roll Out Solar Arrays and Radiators automatically
3) Activate and test life support systems (an ISS type system)
4) 100% Refuel LXGateway with at least 8 Starship Cargo runs
5) Depart for Lunar Orbit
6) After 3 days LXGateway arrives in Lunar Orbit

Second Mission: Deploy HLS Starship to LXGateway (Unmanned)

1) At least 8 Cargo Starship Cargo runs to SpaceX's multi-mission LEO FuelDepot
1) Launch HLS Starship to LEO
3) Activate and test life support systems (an ISS type system)
4) 100% refuel at SpaceX's multi-mission LEO FuelDepot
5) Depart for Lunar Orbit
6) After 3 days HLS Starship arrives in Lunar Orbit
7) HLS Starship docks with LXGateway

Recurring Manned Missions

1) Supply ship is sent to LXGateway
2) 2 "One Way" Cargo Starships brings 100,000 kg each of fuel to the LXGateway fuel depot
3) A nearly empty "One Way" Cargo Starship is boosted into a graveyard orbit
4) SLS Launches Orion directly to Lunar Orbit with Crew (3 days)
5) Orion Docks with LXGateway
6) Crew occupies LXGateway and connected HLS Starship ... more pressurized space than a 747
7) Crew boards and departs on HLS Straship for Lunar surface
8) HLS Starship lands on Lunar Surface
9) Crew spend a month or two on surface
10) HLS Starship launches from Lunar Surface and docks again with LXGatway
11) Crew transfers perhaps 100 kg of lunar materials to Orion, and departs for Earth (3 days)
12) Orion splashdown

You need 4 components: HLS Starship, LEO Fuel Depot, Cargo Starship and Crew Starship (all reusable)

1) With a 100% fuel up at the LEO Fuel Depot a Cargo Starship can carry enough fuel to HLS Starship in Lunar Orbit to do round trip mission from Lunar Orbit -> Any Lunar Surface Location -> Lunar Orbit

2) Crew Starship (with a 100% re-fuel LEO Fuel Depot) can rendezvous directly with HLS Starship (no gateway of any form needed), exchange crews, deliver to HLS Starship maybe 20 tons in supplies, get maybe 5 tons of return cargo, the return directly to Earth Surface.

3) System requires 16-20 Cargo Starships to LEO ($300-$400M) to fill the LEO Fuel Depot twice (one 100% fill for the Cargo Starship to Lunar Orbit, and one 100% fill for Crew Starship).

Mission price for 10-20 crew members, 20 tons of supplies and perhaps 2 months on lunar surface = $600M. Compare to a $4B mission using Gateway/SLS/Orion/HLS combo for 5 crew and 5 tons of supplies.

HLS Starship for NASA

Starship is a Mars optimized system ... it's application as a Human Landing System (HLS) from NASA's Lunar Gateway is a forced fit ... but it may still be the most cost effective option for NASA

Why LEO -> Lunar Surface -> LEO won't work

HLS Starship Needs to as light as possible !!!

A Gateway Alternative: LXGateway (Lunar eXporation Gateway)

Mission Structure

Another Option: A Starship Only HLS

The best solution ... but NASA probably won't go for it: simply delete any form of Gateway and NASA SLS/Orion and add Crew Starship

You need 4 components: HLS Starship, LEO Fuel Depot, Cargo Starship and Crew Starship (all reusable)