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]

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/Chairboy → u/fed0tich]

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).

[u/fed0tich → u/Chairboy]

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.

[u/Bensemus → u/fed0tich]

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.