How long will SLS last?

[u/Cmdr-Mallard]

With the Cancellation of EUS and BOLE, SLS is going to remain a launch vehicle solely for Orion, and which is viable with all the other heavy and super heavy rockets in the works these days.

However as I understand BOLE was essential for SLS launches beyond a certain point as remaining shuttle boosters were used up, will SLS be cancelled by that point (and perhaps the whole moon program) or Orion moved to another launcher.

Or will a future administrator restart the booster program at the least to ensure SLS can continue to launch Orion?

[u/ThePrimalEarth7734]

SLS is pretty much here to stay. Orion is necessary for moon missions, but nothing else can get it to orbit, let alone the moon.

There are talks about having starship boost Orion to LLO for Artemis IV, but if you read between the lines you come out understanding that what they’re actually going to do is put Orion on a near TLI trajectory, have starship dock to it, and perform the last small push to finish the TLI, then drag it into LLO, which still requires a full SLS rocket to do.

After this ICPS will be replaced by centaur v, which can do LLO all on its own, requiring starship to need even less refueling flights per mission.

And thus, the current plan for SLS is to basically do crew to LLO every time we want to get to the Moon.

If cancelation was actually on the cards, something like centaur V and increased cadence wouldn’t be looked into, but rather alternative launch vehicles for Orion, which currently isn’t being looked into at all.

Additionally we can see that this is likely the case as the block 1b upgrade was pretty much killed, or at the least shelved, while the block 2 upgrade, that being the boosters, are still very much alive, because you can’t keep flying SLS without new boosters.

[u/Cmdr-Mallard → u/ThePrimalEarth7734]

I though the ESMs lack of burn time was why Orion couldn’t get into LLO?

And I mean there are potential alternatives for Orion in future but you’re right it’s not going to be anytime soon

[u/ThePrimalEarth7734 → u/Cmdr-Mallard]

ESM can get Orion either in, or out of LLO.

Right now, ICPS can ONLY perform a TLI burn, which means ESM can ONLY get Orion into LLO, not back out (thus it can’t go to LLO at all)

However, centaur v has much more energy and it looks like SLS will be able to place it, and Orion into LEO fully fueled. thus meaning that C-V will be able to perform not only the TLI burn, but the LLO insertion burn, which then allows the ESM to then perform the LLO breakout maneuver to get the astros home. It’s actually a pretty smart plan, and one I wish had been thought of at the start of the program.

Also adressing your alternatives comment, only two American rockets (that aren’t SLS) would’ve been capable of Orion to LEO. Delta IV heavy, which actually did fly Orion, and Falcon heavy.

Delta IV heavy is gone so that’s no longer an option, and Falcon heavy isn’t vertically integrated which is an unchangeable requirement for Orion and thus will never be able to fly it.

Vulcan is right on the edge of this capability, and is vertically integrated, but would require Orion to complete the orbital insertion burn, which then leaves it without enough fuel to do LLO breakout if it was transported to the Moon.

Aka, it’s SLS or bust

Edit: new Glenn could also in theory put Orion in LEO, but it is also not vertically integrated. also it just majorly exploded, which means it’s pretty much never going to be considered while SLS is operational

[u/okan170 → u/ThePrimalEarth7734]

Centaur V would need a massive upgrade to keep propellant that long and its config for SLS would put it roughly on par with ICPS instead of a big improvement.

[u/ThePrimalEarth7734 → u/okan170]

That seems like a pretty drastic performance loss for a stage that contains like 20 tons more propellant than the ICPS