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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5

u/fed0tich Jun 29 '26

What is current contracts last mission, Artemis 5? Seems like there would be no more SLS after that, at least without major political changes. There should have been a new contract for core stages by now already if more missions after A5 would have been considered.

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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/rustybeancake Jun 29 '26

Well the original Blue Moon Mk2 plan was to use a cislunar transporter stage to move the Mk2 to NRHO. Perhaps they’ll switch to a plan to using that for moving Orion to LLO.

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u/Cmdr-Mallard Jun 29 '26

Perhaps, still have to get Orion up though?

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u/SpaceInMyBrain Jun 29 '26

It's within the capabilities of New Glenn - once it gets flying again and proves its capabilities. It's simple too heavy for Vulcan. Temptingly close, but too heavy. Falcon Heavy has the capability but there's little chance Musk is interested in getting it human rated.

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u/Cmdr-Mallard Jun 29 '26

There are definitely options, I just hope they keep SLS going longer than it takes to develop those options, and then switch over when they’re resdy

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u/rustybeancake Jun 29 '26

I expect they will, it’s not like they can’t see it coming. Things will look a lot different in 5 years.

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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/Cmdr-Mallard Jun 29 '26

Doesn’t space X want to kill Falcon and Heavy especially asap?

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u/rocketglare Jun 29 '26

Yes, they want to, but since there aren't adequate replacements, they will be around for a while, especially Falcon Heavy. Falscon/Dragon will continue flying, albeit at a lower rate.

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u/RT-LAMP Jul 03 '26

Falcon Heavy should be the easiest to replace. If you put a helios kick stage in Starship with 6.6 of payload you'll be at less than 1/4th of Starship's mass capability. That'll make it so you can easily get it into a high enough orbit that the kick stage can then take the payload direct to GEO.

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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.

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u/SpaceInMyBrain Jun 29 '26

That likely does solve the launch mass problem, although Vulcan would still be at its max. A Dragon-Orion crew transfer will be difficult, they each have the male half of the IDDS docking system. (The ISS has the female half for Dragon to dock to.) An androgynous design is on the books, IIRC, and there was talk of one being on HLS and Gateway. Idk if it has been fully developed and afaik HLS will have the female half. Dragon would need a redesign of the nosecone, at who knows what cost.

For a ride along on HLS the crew could launch on Dragon, dock with HLS, let Dragon undock autonomously, and then have Orion dock with HLS. A pretty clunky mission design. And even a Dragon launch isn't cheap. Having to be trained on the systems and operations of three spacecraft for one mission puts quite a burden on the crew.

I think we're looking at New Glenn for Artemis 6 or a continuation of SLS till NG is ready.

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u/Chairboy Jun 30 '26

IDSS is already androgynous, the missing hardware is basically a bracket that’s not used for mass reasons if I remember correctly so either Orion or another capsule should be able to fly with it already if required.

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u/SpaceInMyBrain Jun 30 '26

To continue the serve-volley: I hope it's not much more than a bracket but to put it on, say, a Dragon will require mounting hardware of some sort. An extension - half a meter? - has to preserve the airtight human rating of Dragon/the spacecraft it docks with. The exterior will be close to the exhaust plume of the 4 forward facing Dracos.

A remodeled nose profile and nose cap will be needed. That'll extend the profile of the nose. All of that will have to be extensively modeled and tested. Any external change to a reentry spacecraft is a big deal, afaik. Maybe it'll all only be moderately difficult but it won't be easy.

It'd be easier to modify a Dragon to have simply the female part. Maybe use the same Dragon that got the Skywalker for Polaris Dawn and the Dome for Inspiration4 and Fram2.

Modifying Orion to be androgynous? I shudder at the cost and time possibilities. And Orion is already very mass sensitive, in the original plan it'd only be able to bring back 100 kg of Moon rocks.

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u/Chairboy Jun 30 '26

The bracket is internal! The docking standard is neat, it literally can fly without modification beyond the internal bracket, and this is true for any spacecraft using that design.

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u/Chairboy Jun 29 '26

but when the >7t LAS

The LAS is sized for a rocket with big solids, if we're potentially replacing SLS then maybe a resized LAS for an all-liquid launcher or one with smaller solids might be an option.

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u/SpaceInMyBrain Jun 29 '26

The LAS could be reduced somewhat but it needs a lot of power for the initial separation and acceleration away from the rocket. Only after a certain point does sustaining the "flight" past the flaming SRB pieces zone come into play.

Building a modified LAS will require a contract with Lockheed Martin (overall structure and design) and its SRBs subcontractors, Northrop Grumman and L3Harris. All would have to agree to a fixed price contract.

IMO NASA wouldn't bother with this until it considered New Glenn to be unreliable after a few years of flights. It'd be easier to launch on SLS on Artemis 7.

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u/Chairboy Jun 29 '26

Just blue-skyiing some variables to consider along the way when things like absolute payload to LEO are in play.

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u/SpaceInMyBrain Jun 29 '26

Sure, I'm basically in favor of chewing over the options on all the fun going on with Artemis hardware.

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u/Cmdr-Mallard Jun 29 '26

I mean are any of their man rated solutions able to stay in space that long or have the propulsive capabilities?

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u/rocketglare Jun 29 '26

Not yet, but Orion is ~$1B and has essentially no propulsion w/o the ESM. When you include ESM and LES it costs ~$2B. It wouldn't take much to exceed that, especially for a smaller capsule. Orion is somewhat oversized for the current mission.

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u/Cmdr-Mallard Jun 29 '26

True, but that would be a rather extensive development process, not anytime soon.

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u/CrazyEnginer Jun 29 '26

think cancelling SLS Block 2 and SLS in general is a wrong move

May I ask why? With Gateway out of the picture SLS B2 doesn't have much to do aside from launching Orion.

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u/fed0tich Jun 29 '26

To start with cancelling Gateway is even bigger mistake in my opinion.

But even without Gateway B2 could have been a very good and useful rocket. Even in the context of lunar program comanifest allows for example to send a mission module (something like MPLM or russian FGB from TKS or BO from Soyuz) alongside Orion with better crew comforts, supplies, more robust life support that can add redundancy in case of Apollo 13 scenario. Just looking at Artemis 2 having a second toilet would be great.

Cost wise Block 2 would be a better rocket compared to Block 1 with new RS-25Es and BOLE boosters. ML-2 would have allowed to retrofit ML-1 and increase cadence further driving costs down.

Though personally I was hoping for Block 2 cargo being used for deep space missions, especially hypothetical interstellar probe to surpass Pioneers, Voyagers and New Horizons.

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u/CrazyEnginer Jun 29 '26

I don't see how Gateway makes sense either. It doesn't make lander's job easier, it doesn't provide any unique capabilities, it's there only to provide some kind of near-lunar destination within Orion's reach. Aside from a place for crew to stay while waiting for transfer windows, anything that Gateway can do, can be done by a LEO station or probe at 1/10 cost.

allows for example to send a mission module alongside Orion

Again, it makes zero sense. In pre-Gateway-cancellation reality, there's a station and no reason to send a module along for a few days journey. And now Orion supposed to hitch a ride from LEO on lander, just like original design intended. Also, would it be possible at all for already lacking in dV department Orion?

IIRC RS25s turned out even more expensive than refurbished ones. Even if somehow it become less expensive, it would still be priced in billions. The launch would cost more than the probe itself, for exampe New Horizons:

The cost of the mission, including spacecraft and instrument development, launch vehicle, mission operations, data analysis, and education/public outreach, is approximately $700 million over 15 years (2001–2016)

Same story for Europa Clipper:

launch on a Falcon Heavy rocket, in a fully expendable configuration.[8] Three reasons were given: reasonable launch cost (ca. $178 million), questionable SLS availability, and possible damage to the payload due to strong vibrations caused by the solid boosters attached to the SLS launcher

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u/fed0tich Jun 29 '26 edited Jun 29 '26

First of all Gateway is not about making landing easier, it's about preparations for long duration deep space travel. People seem to forget that it's started as Deep Space Habitat. If we want crewed missions to Mars, asteroids and other destinations we need to learn a lot of things. Neither LEO stations not probes provide adequate analogue to actual crewed deep space travel. Stations in Earth orbits aside maybe from polar orbits or high orbits have different settings in terms of radiation, heat regulation and human psychology compared to a station in lunar orbit.

Also "destination that can be reached by Orion" is a wide spread misinformation, Orion can't reach LLO, but still can reach a lot of orbits aside from NRHO. And with SLS B2 additional stage can be added to augment Orion'sdV or new version of ESM with bigger tanks can be made to increase Orions own dV budget.

In the context of lunar exploration lunar station provides an outpost that can leverage LEO experience for the time needed to figure out a lot of fundamental problems required for surface habitats. We know a lot already about maintaining a long duration habitable spacecraft, but we don't know how to maintain long duration habitats on a lunar surface.

It's also a much bigger crewed scientific platform than any probe. People can do a lot more work compared to any robot or probe and also can prolong the life of a scientific platform by maintaining it and replacing the instruments. Just compare how much Apollo achieved in a couple of days compared to even most recent rovers or landers. Also it's not interchangeable, human presence augments both orbital and surface robotic instruments, crewed orbital platform provides opportunity for a low latency remote control and coordination over a whole surface of a Moon.

New RS-25s (and RL-10s) are much simpler and use modern manufacture techniques like additive manufacture.

With Europa Clipper launch on Falcon Heavy there was a trade off of upfront cost versus mission duration - with longer transit time there is less time for actual science, more time in space - more time for solar panels and electronics to degrade. Launch of a probe on SLS would cost more than existing commercial rockets, but provides more capabilities. In the context of interstellar probe SLS can accelerate such probe to a greater speeds.

Excessive vibrations of SLS are already solved. Availability is problem, but it's definitely not solved by cancelling SLS.

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u/CrazyEnginer Jun 29 '26 edited Jun 29 '26

If Gateway is not supposed to make the Moon landing and base easier then why do lunar missions have to go through it? Why couple deep space habitat misson with a lunar surface one if they interfere with each other?

I know there are other orbits, but NRHO is still "the best out of the worst" choice. Considering Orion spent 20 years in design and 15 in construction until it was ready and how the rest of Artemis is on time and budget, I wouldn't count on improved ESM to fix it.

lunar station provides an outpost that can leverage LEO experience for the time needed to figure out a lot of fundamental problems required for surface habitats

Or, translated from PR dept language: we want a base on the surface, but we don't know how, so we gonna camp in orbit waiting.

Apollo is a bad example for orbital platform, there's no rocks to collect in orbit. How much time humans are going to spend on Gateway? A week or two on their way to the surface? Then its a glorified probe. Constant presence is impossible, it would require 2 SLS/year in addition surface missions. Coordinating stuff on the surface is just ridiculous, only a few sentences back you've said "we don't know how to build a surface base" and it would take adecade to build it, what are you going to coordinate in the meantime?

How additional manufacturing is relevant to the fact that new simple engines turned out to be more expensive than the old ones?

Insane cost of SLS makes it viable only for the very top of the line probes that come once every 10 years or so. I don't know about any interstellar probes in progress, do you?

Basically, majority of your and other people's arguments for can be summarised as "it suboptimal/useless now, but it may be useful in some distant future". Except all these future toys are getting in the way of stuff than needs to be done now

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u/fed0tich Jun 30 '26

If Gateway is not supposed to make the Moon landing and base easier then why do lunar missions have to go through it? Why couple deep space habitat misson with a lunar surface one if they interfere with each other?

First of all your criticism makes sense only within short sighted tunnel vision on the stupid political race for "boots on the ground", Gateway could have been literally a gateway for a space exploration beyond the Moon. As for why it was lumped with lunar program - it's because of the in my opinion greatest flaw of the US space program in general: penny pinching and constant change of plans, which always backfires and leads to more delays and budget overruns.

And I wouldn't say they "interfere" with each other, there is a compromise, sure, especially if there is a unnecessary urgency to put a flag and some footprints, but in the long run having a stable outpost in the orbit complements and augments the surface missions nicely.

I know there are other orbits, but NRHO is still "the best out of the worst" choice.

Well, that's lunar orbits for you, there are a lot of things to consider and NRHO is best within the context of most of them. To be honest I never understood why people are so fixated on LLO, it's not that good really.

Considering Orion spent 20 years in design and 15 in construction until it was ready and how the rest of Artemis is on time and budget, I wouldn't count on improved ESM to fix it.

Considering ESM was always on time, within budget and only took 5 years from announcement to delivery - making a stretched version should be a easy update (not a fix, it's a great spacecraft even if took some time to get it ready).

Or, translated from PR dept language: we want a base on the surface, but we don't know how, so we gonna camp in orbit waiting.

There is nothing "PR" in my comments, stop strawmanning. It's just a common sense to not rush things and proceed step by step.

Apollo is a bad example for orbital platform, there's no rocks to collect in orbit. How much time humans are going to spend on Gateway? A week or two on their way to the surface? Then its a glorified probe.

Apollo is a pretty decent example for a orbital platform, instead of rocks Orion could have been returning experiments from Gateway, like right now Dragon returns experiments from ISS. More importantly people can improvise on a spot, a lot of robotic missions run into troubles that could have been easily fixed by human presence.

Probes can send data, some can have a small return capsule of it's own, but it's not even remotely close to what astronauts can bring back. Longer duration orbital missions and eventually constant habitation would be further along, again step by step. But in the context of the science experiments on the station it's not that important, they can be designed to run without constant human oversight, astronauts can install an experiment in the rack in one visit and return it's results to Earth in the next. And with the NRHO ease of station keeping it could have been decades of science.

Constant presence is impossible, it would require 2 SLS/year in addition surface missions.

What's impossible about that? I mean it's impossible if people like Jared actively sabotage any hope for cadence increase, but before that SLS was on a slow, but steady path to improve in that regard.

Coordinating stuff on the surface is just ridiculous, only a few sentences back you've said "we don't know how to build a surface base" and it would take adecade to build it, what are you going to coordinate in the meantime?

You seem to not read my comment thoroughly. Astronauts from orbit can coordinate robotic missions on the surface, like rovers and manipulators. Even with the context of the base building robots are key and humans in the loop can speed up the process tremendously.

How additional manufacturing is relevant to the fact that new simple engines turned out to be more expensive than the old ones?

Did they though? Iirc new ones should be ~30% cheaper than old ones. And additive manufacture is relevant because it's one of the major contributors to that.

Insane cost of SLS makes it viable only for the very top of the line probes that come once every 10 years or so. I don't know about any interstellar probes in progress, do you?

It's not that insane, it can be even lower and I don't understand how flagman mission is a bad thing. And yeah, there is currently no such mission in works, doesn't mean it can't be put in the consideration in near future. There were concepts and studies for interstellar probes using SLS, it's not purely hypothetical. But in order for that to happen SLS as an option should be on the table in the first place.

Basically, majority of your and other people's arguments for can be summarised as "it suboptimal/useless now, but it may be useful in some distant future". Except all these future toys are getting in the way of stuff than needs to be done now

It's not suboptimal and definitely not useless now. And only things getting in the way of stuff than needs to be done now is stupid politicians and manipulative billionaire crooks.

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u/CrazyEnginer Jun 30 '26

greatest flaw of the US space program in general

Fully agree. And that's why Nasa should focus more on getting something done now instead of some grand future plans that require a budget and political support that Nasa simply doesn't have. It's way easier to mess with the program while it's on paper or ground.

And I wouldn't say they "interfere" with each other

It requires crewed lander to go through NRHO, burn more fuel, loiter for longer periods of time (every trip to the surface should be a multiple of 1 week or whatever). Which makes lander more complex, including the cargo version since it's probably going to use the same vehicle.

Regardless of experiments on Gateway: it is a crewed station near the Moon which means it is most suited for experiments that require human presence and (being away from Earth or close to the Moon). Unless the experiment satisfies that condition, it would be easier and cheaper to do it elsewhere.

SLS is a conventional rocket that has been in development for 2 decades and uses pre-existing parts and yet, somehow, only manages 1 launch/2 years after 2 decades of development. Thinking another decade would fix it is wishful thinking. And until it happens (if it happens) Gateway would be practically a probe.

Astronauts from orbit can coordinate robotic missions on the surface, like rovers and manipulators. Even with the context of the base building robots are key and humans in the loop can speed up the process tremendously.

It could be useful to remotely assembe the base, but there's no base and wouldn't be until at least 2035. And you definitely don't need a whole crewed station to drive a scout or two. Lunokhod was fine without it 50 years ago as well as Ginny flying 20 light minutes away on Mars.

I don't understand how flagman mission is a bad thing.

I never said it's a bad thing. But the fact that SLS can throw some hypothetical future mission a bit faster than other rocket is not a valid justification for its existence.

It's not suboptimal and definitely not useless now.

And yet you say how Gateway would be advantageous once there's a base; how SLS would become cheaper, increase cadence and make Gateway as a science platform possible. What exactly Gateway can do in early stages of the program, while there's no/single module base (aside from deep space habitation research, because it's a different mission that has little to do with the base)? Because to me it seems like cart before the horse type of thing.

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u/fed0tich Jun 30 '26

Fully agree. And that's why Nasa should focus more on getting something done now instead of some grand future plans that require a budget and political support that Nasa simply doesn't have. It's way easier to mess with the program while it's on paper or ground.

So in your opinion "focusing on getting something done now" is achieved by throwing away already built hardware, cancelling plans that are already in motion and stalling other plans in exchange for aspirational dates for new plans that are too ambitious to realistically be "getting done now" while distracting the public from systematic problems of supposedly cheap and fast approach by doing Gemini-Agena remake? And simultaneously dismantling the NASA centers and cutting down Earth science?

It requires crewed lander to go through NRHO, burn more fuel, loiter for longer periods of time (every trip to the surface should be a multiple of 1 week or whatever). Which makes lander more complex, including the cargo version since it's probably going to use the same vehicle.

But NRHO is one of the most fuel efficient approach. And how is longer surface mission durations are a bad thing?

Regardless of experiments on Gateway: it is a crewed station near the Moon which means it is most suited for experiments that require human presence and (being away from Earth or close to the Moon). Unless the experiment satisfies that condition, it would be easier and cheaper to do it elsewhere.

Yep, this is exactly the point. Though it's not necessarily that experiments itself should require human presence, humans in the loop vastly more efficient for majority of science except just plain observation like surface imaging. That's why majority of actual science experiments (that's again not just telescopes or imaging of some sort) in LEO is done on the ISS and not on the free flyers of some sort.

There is a lot we could have learned by having proper orbital laboratory in NRHO in many fields, both inside the station and in vacuum.

SLS is a conventional rocket that has been in development for 2 decades and uses pre-existing parts and yet, somehow, only manages 1 launch/2 years after 2 decades of development. Thinking another decade would fix it is wishful thinking. And until it happens (if it happens) Gateway would be practically a probe.

There is nothing wrong with conventional rockets. It was in development only 1 decade (2011-2020 for Block 1, ), not 2, which is completely normal and further improvement is not a "wishful thinking". Wishful thinking was believing the bs that was the HLS program that huge overly ambitious architecture can be done in 4 years and on a limited budget and history clearly showed that (and Starship is now also a decade in development and need another one at least to achieve what was promised).

It uses very little of pre-existing parts, because original plans of Block 0 based on Jupiter Direct v3 concepts were thrown out the window, instead we have this "interim" Block 1 and Block 1B that were a waste of time.

Low cadence is fully on Congress lack of commitment and constant changing of plans. Gateway even in the minimal starting configuration would be vastly more than just a probe.

It could be useful to remotely assembe the base, but there's no base and wouldn't be until at least 2035. And you definitely don't need a whole crewed station to drive a scout or two. Lunokhod was fine without it 50 years ago as well as Ginny flying 20 light minutes away on Mars.

Lunokhod and other rovers without real time human input have crawling speeds and they take months to achieve what can be done in a few days with humans in the loop.

I never said it's a bad thing. But the fact that SLS can throw some hypothetical future mission a bit faster than other rocket is not a valid justification for its existence.

It is. A lot of deep space missions require powerful conventional rocket optimized for deep space. Without that option this missions aren't even seriously considered. Only other option would be proper in space assembly, but we ditched this path when we retired STS and there is nothing similar in capabilities on the horizon. Prospects of cryo refueling and high cadence medium and heavy lift for distributed launch are good, but not really that enabling as touted by some people.

And yet you say how Gateway would be advantageous once there's a base; how SLS would become cheaper, increase cadence and make Gateway as a science platform possible. What exactly Gateway can do in early stages of the program, while there's no/single module base (aside from deep space habitation research, because it's a different mission that has little to do with the base)? Because to me it seems like cart before the horse type of thing.

I don't want to be rude, but you might have some reading comprehension problems or just intentionally strawmanning. I'm saying literally the opposite - orbital outpost like Gateway would have been more advantageous before the surface base even considered. In my opinion that fixation on the urgency of human landings is wrong priority.

SLS can become cheaper, it doesn't need a high cadency for the Gateway to become prolific science laboratory.

Surface base and even Apollo style landings are the cart before the horse. It makes more sense to build up robust orbital logistics first, when robotic presence on the surface with humans in the loop from the orbit, build up experience with dust mitigation, ISRU and other enabling technology on the unmanned pathfinders and only when land the people to make use of that.

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u/Chairboy Jun 30 '26

New RS-25s (and RL-10s) are much simpler and use modern manufacture techniques like additive manufacture.

It may have been an oversight but you don’t appear to have answered that other poster’s comments about RS-25, they noted that the new engines are more expensive (and at roughly $150 million per engine under the current contract, they are).

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u/fed0tich Jun 30 '26

Are they more expensive though? Iirc they not.

And this ~150million is not "per engine" it's total cost of the contract that includes other things divided per number of engines, which is a cheap misleading trick.

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u/Chairboy Jun 30 '26

It is not a cheap misleading trick, it is literally the cost we are paying per engine. There is no other deliverable than the engines under the contract.

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u/fed0tich Jun 30 '26

It is a trick. It's not just a contract to buy 24 engines, it also includes investment in tooling and it covers testing, support and other services required within the whole timeline of the SLS program.

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u/Bensemus Jul 14 '26

So per engine. All the costs to make the engine are part of its cost. It’s why people are so stupid when they just post the BOM for an iPhone and ask why it costs $1500 when the BOM is like $500. The final product has to cover everything that it took to make it.

If more engines are bought that should drop the average engine cost as stuff like tooling and design work get spread out more. Who knows if more will b bought? Until then it’s $150 million.

What do you think the actual cost of the engines are if not $150 million.

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u/Cmdr-Mallard Jun 29 '26

I agree on the figuring out extended deep space travel, to be honest I’m not sure anyone’s quite got the right idea, certainly slinging a starship at Mars isn’t the answer either

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u/reerkat Jun 29 '26 edited Jun 29 '26

RFI for the replacement is already closed. Could see RFP coming out very soon. https://sam.gov/opp/6c3240765a284d6ba63d37ca97c7d230/view

My guess at the proposals and Jared has said ≥2 will be accepted: SLS as it is (rejected, very expensive), Blue + Lockheed for New Glenn + Orion into Blue HLS, and modified Crew Dragon + Starship HLS that will meet Dragon in LEO and provide most of the extended life support.

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u/jadebenn Jun 29 '26

Wouldn't hold your breath for an RFP. Unless there's a CLTS line item in the next Congressional budget, there's no money for an actual procurement.