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floating-io | 4 months ago
That's the one thing in your comment I disagree with. Starship-based HLS has basically one base vehicle, modified into three variants (tanker, depot, and the lander itself). Refueling is done in LEO.
Blue Origin's HLS has three completely unique vehicles with no commonality (New Glenn, Transporter, and the lander), and refuels in multiple orbits, one of which is NRHO, which is likely to be far more challenging. And they're doing it with hydrogen.
Blue Origin's Mk1 cargo lander is simpler; their HLS architecture is not.
JMHO.
ACCount37|4 months ago
A major weakness of SpaceX's HLS approach is that it requires them to launch a lot of the same vehicle in a fairly short succession. But SpaceX are the kings of high volume aerospace manufacturing, and they are the driving force behind US launch cadence going up. Even if Starship reusability isn't truly perfected in time for Artemis HLS, they are already building those Starships pretty fast, and can eat some refueling vehicle losses.
Blue Origin doesn't have the raw performance figures of Starship, or SpaceX's unmatched manufacturing and launch cadence. So their HLS architecture is lighter and less launch hungry. That comes at an engineering cost of having to use more specialized vehicles. And they are using LH2 fuel - which delivers more of a punch per weight, but is even harder to stay on top of than CH4. More engineering effort would be required to store and transfer that in orbit, dealing with boil-off and all - but Blue Origin has used liquid hydrogen extensively already, so they have experience with it.
floating-io|4 months ago
The SpaceX approach requires a lot of launches, but they're already proven experts at that. They've launched something like 130 rockets this year alone. That's one every couple of days.
High launch cadence is not complexity for SpaceX. It's normal for them. After the first half dozen or so refuels, it will be second nature, just like delivering satellites with Falcon is.
And they are, in essence, developing a single craft for it, just with a few variations.
Blue's architecture requires three distinct vehicles. Each one has to be developed separately. Then we get to the launch; last I saw, here is the comparison:
SpaceX:
* Launch the Depot
* Launch N tankers to fill the depot (this is the tedium I mentioned).
* Launch the HLS to LEO
* Refill the HLS in LEO
* Send the HLS to NRHO
* Rendevous with Orion in NRHO and transfer people
* Land on and then return from the moon
* Rendevous with Orion in NRHO and transfer people back.
That's a fairly complex architecture, but let's compare that against the last I saw of Blue's [1]:
* Launch the Transporter to LEO
* Launch tankers and refill the Transporter
* Launch the Lander to LEO "dry"
* Fill the Lander from the Transporter
* Send Lander to NRHO
* Launch tankers and refill the Transporter
* Raise Transporter to "stairstep" orbit
* Launch tankers and refill the Transporter again
* Send the Transporter to NRHO
* Refill the Lander again in NRHO
* Rendezvous with Orion and transfer people
* Land on moon and return with people
* Rendezvous with Orion and transfer people back
That is far more complex than what SpaceX is proposing.
The number of tanker launches is really quite irrelevant for both in this context. It's less risky for SpaceX due to their extensive ops experience, but both will be fine there I think. That's just tedium for both of them.
The complexity comes in with the number of operations and precisely where BO is doing the refueling. I'm not terribly worried about the LEO ops; they'll manage those. The NRHO refuelling though? That one strikes me much riskier if only due to comms lag.
And the sheer number of steps in Blue's architecture seems crazy to me.
So no, I can't agree that Blue's architecture is in any way simpler. Quite the opposite, in fact.
[1] https://ntrs.nasa.gov/api/citations/20250008728/downloads/25... :: the last slide in the set.
(edit: formatting)
mortarion|4 months ago
Look up how many refueling launches are required and you'll see the problem, especially because no matter if Elon says so, the upper stage will never be reusable, even if caught.
Every moon mission will require that they pre-build a HLS and probably 15 full stacks.
Ridiculous.
cubefox|4 months ago
The Space Shuttle was reusable, and SpaceX is using an improved variant of the Space Shuttle heat shield, so it seems quite certain that Starship will be reusable. The question is more: how much refurbishment will it need? The Space Shuttle required extensive amounts. SpaceX will likely be able to improve on that a lot, though it isn't clear how long it will take.
floating-io|4 months ago
Even if I'm wrong, though, it wouldn't invalidate the point I'm making in this thread: BO's Mk2 has the exact same issues in a more complex architecture.