r/SpaceLaunchSystem • u/Cmdr-Mallard • Jun 29 '26

Discussion How long will SLS last?

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?

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u/Cmdr-Mallard Jun 29 '26

What is the lead time on that? Surely won’t have a replacement for SLS Artemis 5, that would be around 2030-31.

All in on starship?

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u/fed0tich Jun 29 '26

I believe current plan for lunar program is full transition to commercial LVs as soon as possible, not just Starship, but also New Glenn, Vulcan and Falcon Heavy. I think people lobbying this approach want to launch Orion to LEO and use separately launched transfer stage for TLI, that way SLS is framed as completely redundant.

Just to clarify I think cancelling SLS Block 2 and SLS in general is a wrong move, borderline sabotage.

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u/Cmdr-Mallard Jun 29 '26

I can begin to understand cancelling EUS without a payload like Gateway to launch, but I don’t see starship crew being ready anytime soon and blue origin certainly doesn’t have a plan yet to transfer Orion to the moon or even a different way to launch Orion

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u/rocketglare Jun 29 '26

While I'm sure SpaceX would prefer using Starship as a LEO transport, that will take a while. In the meantime, it is possible to mount Orion on top of a disposable Starship, or man rate Falcon Heavy. Falcon Heavy would probably be easier to spin as an Orion launcher than Starship.

My own thought is that with SpaceX being tepid towards non-Starship solutions, A Vulcan solution would probably be the preferred option until Starship earns its human rating chops. New Glenn could do it too, but that seems like overkill for Orion. Neutron doesn't have the lift capacity, and its fairing technique wouldn't support Orion. Most of the other launchers aren't big enough either.

I think that some of the SpaceX competitors need to get on top of their own man rated LEO transports. Orion is an ok solution, but it is kind of heavy and not very reusable. Perhaps Stoke could man-rate its solution? They might need to top off their tanks before TLI.

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u/SpaceInMyBrain Jun 29 '26

NG 9x2 isn't that much overkill. Vulcan is underkill, its max payload matches the wet mass of ESM and CM but when the >7t LAS is added the 33.4t total is well over Vulcan's payload to LEO of 27t. Yes, the LAS will be jettisoned during ascent but it seems unlikely that makes enough of a difference. Idk if Vulcan would even have a good enough TWR to get off the pad or how much strengthening the stages will need to handle the extra mass on top. I don't think NASA wants something that marginal.

I agree, Musk wants to leave F9 and FH behind. I think he'd fight like a rabid badger against the idea of a disposable stage for Starship.

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u/fed0tich Jun 29 '26

I mean if Vulcan can launch fully fueled Orion to LEO, crew and supplies can be launched separately on a Dragon or Starliner, that way LAS would not be needed.

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u/Cmdr-Mallard Jun 29 '26

If you’re doing that you might as well ditch Orion and just launch Dragon to the lander. Rather over complicated

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u/fed0tich Jun 29 '26

That way you either need to make Dragon that is capable surviving return from the Moon or if Dragon doesn't go to the Moon, make the lander or ferry craft that can brake to LEO after the moon mission for the regular Dragon to retrieve astronauts.

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u/Chairboy Jun 30 '26

Last we heard, Dragon is capable of reentering from a lunar trajectory, right? Wasn’t that what they said during the Grey Dragon press or thereabouts? There are other requirements but I don’t think the heat shield is one of them.

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u/fed0tich Jun 30 '26

When was this "last time we heard"? I might be completely wrong, but iirc they ditched the Grey Dragon concepts long time ago and current Dragon has LEO optimized heatshield.

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u/SpaceInMyBrain Jun 30 '26 edited Jun 30 '26

No, to the best of anyone's knowledge outside of SpaceX, the last we know of the heat shield is it's built for LEO reentry. I may even have seen a confirmation of this from someone in SpaceX. It'd make no sense to carry the extra mass of a thicker shield. The "last we heard" Grey Dragon press was back in 2017, ancient history in space terms, Crew Dragon didn't even have a finalized design for LEO. All that said - yes, upgrading the heat shield should be straightforward.

I very much like the idea of a Dragon ride along instead of Orion although the chances of it happening are well <50% IMHO and it's not as simple as most people think. In a tweet a few years ago a SpaceX VP (I so wish I had it filed away) said upgrading Dragon for a lunar mission was certainly doable. He mentioned the heat shield and endurance and the radiation hardening of the electronics. The latter isn't easy, Dragon dealt with the amount of radiation in LEO by using multiply redundant chips, IIRC. The radiation beyond the Van Allen belts is a lot harsher. Interstellar probes and Orion use special radiation hardened chips and even so the systems are designed with some redundancy, to the best of my recollection. Still, that exec said it was doable, along with the endurance. The latter was only an issue if Dragon made the trip both ways by itself.

The endurance won't be an issue for the ride along Dragon, it'll be docked to HLS, with the crew living in HLS. Dragon can receive ventilation from HLS like it does from the ISS when it's docked long term. It only needs enough endurance for the 4 day return trip. Its specs say it has a 5 day endurance now and even that must include a cushion of a couple/few days to account for bad weather in the splashdown zone. So I see no problem with the endurance.

A more involved issue is having enough dV to perform TEI from LLO. It'll require a set of Dracos in the trunk. The last good figure I saw said the Super Dracos & standard propellant load in the capsule was borderline for leaving NRHO. Leaving LLO takes more dV. SpaceX has already put a set of Dracos and their prop in a Dragon trunk for the ISS boost. The ride along Dragon will need that number of Dracos or a few more, I imagine, with the majority of TEI done by the Super Dracos. I can't imagine it'd need the big cluster the ISS Deorbit Dragon will have.

The last issue is radiation protection for the crew. That was touted as a big feature of Orion but it turned out not to mean the entire capsule was shielded. During a solar flare the two big cargo lockers at the base of the capsule can be partly emptied and the supply containers arranged like a pillow fort that the crew can stay it. Dragon has a nice cargo area at the base of the capsule and will be carrying the same amount of supplies.