But yeah, I think SpaceX will prove it all works and then NASA has the option to change the plan. In the meantime, officially keeping SLS keeps Congress happy.
Does that also effect the Lagrange points for the moon? Do human currently have anything parked at earth moon lagrange points?
"the radius for a selenostationary orbit is much farther than the Hill radius, meaning that no stable orbit can be achieved as it would be too much perturbed by the Earth and/or the Sun"
"all of the Lagrangian points of the Earth-Moon system are stationary relative to the Moon surface"
...but then it is explained that stationary doesn't mean stable.
Links: https://astronomy.stackexchange.com/questions/20499/is-it-po...
Conversely landing on the moon and returning to Lunar orbit takes 1.72 km/s twice, which is again consistent with my numbers if we assume the payload mass is constant. That may not be the case of course but any cargo taken from the Lunar surface to Lunar orbit will also need to be brought back to Earth somehow.
It will either be discarded after use or refueled and reused fully in space.
Even before announcing the choice of Starship for HLS, NASA was already talking about bypassing Gateway for the first crewed lunar landing (Artemis III) and only visiting it on later missions – https://spacenews.com/nasa-takes-gateway-off-the-critical-pa...
They haven't completely decided yet though. They don't know when the bits will be ready. If come time for the first crewed landing, SLS+Orion and Starship are ready but Gateway isn't, they'll just do the landing without Gateway. On the other hand, if Gateway is already ready by then, they might consider using it. One advantage Gateway has, is it gives the two astronauts who stay-behind on Orion a bit more room. It would also give them something to do – testing out Gateway systems.
While Starship can go to from earth to moon with a refueling stop alone? Even if sticking to the space dock why not the WAYYYY cheaper Dragon which just worked today (using a recycled rocket)?
I'm no fan of SLS, but check your terminology here: You're talking about Starship in the present tense, but it hasn't launched _either_, so you can't say it "can" go to the moon etc either.
Starship is awesome, but it's an insanely ambitious project. No one knows how long it'll take to get it right.
But SLS is in no way able to go to moon or earth with what they are currently building?
What makes this so weird to me is that SpaceX does have Dragon already which just brought more people into orbit this week - e.g. proven and way cheaper of what SLS is supposed to do in this mission - unless I'm missing or not understanding something.
So you're right the starship portion to moon (and hopefully mars) is similar to SLS in that it's not realized ye
But looking at the part SLS is supposed to play in this production, that role has already been acted successfully by Dragon. I'd say spacex gets the space oscar for it, though i doubt they get the trophy this weekend :)
Orion basically is ready. There is an uncrewed full stack test flight around the Moon scheduled for November this year, Artemis I. Decent chance it will slip by a few months, but still highly likely to happen by early next year. And then in 2023 they have planned a crewed test flight (orbiting the Moon but not landing, like Apollo 8).
I think SpaceX wants to focus as much of their development resources as possible on Starship. They'd rather focus their energies on that rather than on coming up with new versions of Crew Dragon. Starship, if successful, is going to kill SLS/Orion in the medium-to-long term. I don't think there is any great benefit to SpaceX in trying to kill it in the short-term. That'd be walking into a potentially expensive and risky political battle with vested interests in Congress, and why get them offside when doing so isn't on your critical path to your ultimate goal?
Starship itself?.. Being built with such technologies, so cheap (Elon mentioned that Boca Chica works are quite small percents of what SpaceX is doing in terms of money), so fast - and yet we already have a successful-ish landing from ~10 km height.
Of course, we don't know for sure. But it surely doesn't seem too bad, especially now - and for some it was clear when SpaceX was just created.
Also considering the planned SLS "landing" mode they are also on par so far.
Because Moon-bound Starship will be quite different from Earth-bound - not enough to not call it Starship, but still - the Moon-bound will be optimized for less gravity (different legs?), no atmosphere (no wings), braking using engines in the middle of the body, not in the tail section, Moon-specific systems like ladder or elevator etc.
Starting new missions from outside a strong gravity field seems like such a huge advantage. I guess most people want a destination and not just a more long term established presence.
You don’t get to do this, period. All your crew and all your materials are ultimately coming from Earth (or, in some plans, are mined in-situ). You use considerably more resources getting to your waypoint than you save by leaving from there.
Being farther out of the gravity well isn’t entirely positive either; you’re losing out on significant savings from the Oberth effect. Earth-Moon Lagrange points are well past the minimum-cost orbit.
Wait till we start making LOX (and later, I think, metals) on the Moon from regolith. The process is old and tested on Earth, the missing part is actually experimenting with this on the Moon. And as soon as we have more or less robust Earth-Moon transportation, this will become important, as it will significantly simplify near Moon operations.
Do you know NASA runs, right now, competitions for e.g. lunar ice extraction and purifying?
This is the key state differentiator.
If you bring everything from Earth, it doesn't make sense. (So why are we doing it now?)
But once you start procuring resources from outside gravity well, things look different.
But this isn't necessarily advocating for a full time in-orbit refuelling station either. The plan might be to instead launch 2 or 3 rockets, 1 with the stuff and the others with fuel. They meet up in orbit and the fuel rockets refill the stuff rocket so it can go on to Mars or wherever, then they return to Earth for the next mission.
Such a thing might make sense once there are, say, 50 or 100 starships.
For the foreseeable future, all missions will "start" in Earth's gravity well due to the fact that the o2 and ch4 are all down here. It will be some years until we have significant fuel stores in space.
The choice of having it in Earth orbit vs. Lunar orbit comes with some tradeoffs. It may make more sense to leave it in Earth orbit, but ultimately having it at all substantially changes the calculus on a Mars trip.
If launches are cheap, then refueling in LEO makes a lot of sense. Historically, this has not been the case at all, but it's all part of SpaceX's model for Starship.
If fuel for interplanetary missions is produced on the Moon, a space elevator would make a huge sense for refueling of the ships.
And even if you do so, the main advantage of an elevator can also be had with an accelerator, there is no need to build an elevator. Because there is no atmosphere you can simply fling stuff into orbit for pretty much exactly the same price but far, far, far, far less investment.
The one place elevator actually makes sense is Mars potentially. But that is a very long way off.
And even then gas station in Lunar orbit is useless. If there is a need to refuel, you will simply get fuel into orbit directly from whatever container in the elevator to the ship nearby. There is zero point in inserting a proxy station in the middle of this process.
However we juggle the possibilities of space travel, in 99% of all schemes gas station in space is useless.
The best sites for permanent outposts are the poles though, it would be quite a drive from the equator.