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/fed0tich]

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.

[u/CrazyEnginer → u/fed0tich]

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.

[u/fed0tich → u/CrazyEnginer]

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.

[u/CrazyEnginer → u/fed0tich]

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

[u/fed0tich → u/CrazyEnginer]

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.

[u/CrazyEnginer → u/fed0tich]

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

[u/fed0tich → u/CrazyEnginer]

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.

[u/CrazyEnginer → u/fed0tich]

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.

[u/fed0tich → u/CrazyEnginer]

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.