SLS - On the Scent of Inevitable Capitulation

[TunaBug]

In terms of $ just to get to the moon again, in isolation, yes.

But I think there is a school of thought that having the entire space industry privatised effectively into the hands of one man is not a great idea. This is an investment into technology outside of SpaceX, and a good boost to the national pride (as per Apollo).

My pride is not boosted by SLS. I think the only thing it serves to demonstrate to other countries is an inability to execute.

 

[Max Spaghetti]

My pride is not boosted by SLS. I think the only thing it serves to demonstrate to other countries is an inability to execute.

The common sense question has always bothered me too.

1. SpaceX launches a Starship into LEO to perform the role of a fuel depot.
2. SpaceX launches multiple Starships into LEO to rendezvous with and fill the fuel depot with fuel.
3. SpaceX launches an HLS version of Starship into lunar NRHO
4. NASA launches SLS/Orion into lunar NRHO to rendezvous with HLS
5. HLS lands on moon, then launches backing lunar NRHO to rendezvous with Orion
6. Orion returns to Earth and conducts re-entry.
7. HLS remains in lunar NRHO and may or may not be useful for a later mission.

Now, the advantage of the above is that HLS doesn't need to ever conduct an atmospheric re-entry, so it doesn't need a heat shield.

Is that the only advantage for HLS?

We could achieve all of the above but do the crew transfer in Earth LEO instead of Lunar NRHO (both directions). What would change?

1. Orion would only need a smaller booster which is LEO capable.
2. HLS would need additional life support for a few more days.
3. HLS would need additional fuel for a transfer back from lunar NRHO back to LEO.
4. HLS would now be back in LEO in a more useful location for re-use for a later mission.
5. Optional: The crew could launch from Earth in the HLS instead of Orion, reducing the number of crew transfers from 2 to 1. Orion merely serves as a re-entry vehicle.

This would reduce NASA's contribution and increase SpaceX's contribution, but would seem to make more sense considering the cost of SLS.

National pride could be one reason why they would seemingly go down the path of less efficiency?

 

[JB47394]

We could achieve all of the above but do the crew transfer in Earth LEO instead of Lunar NRHO (both directions).

Starship HLS can't make it from the Moon back to LEO because it doesn't have enough delta-V. That's ultimately why Orion goes; it is a much smaller vehicle and can make it back to Earth's surface, using atmospheric reentry to reduce the needed delta-V tremendously.

Remember too that Starship's thermal system is designed for LEO reentry, not reentry from the Moon, which involves greater velocities and temperatures. Starship's thermal system is designed to tolerate 1,377 C, while Orion's can handle 2,760 C. As a point of comparison, the Shuttle's thermal system is designed to tolerate 1,260 C because it also comes down from LEO.

I suspect that the cost of making a Starship able to tolerate 2,760 C would be prohibitive. It has a vastly-larger reentry surface than a capsule such as Orion.

 

[Max Spaghetti]

Starship HLS can't make it from the Moon back to LEO because it doesn't have enough delta-V. That's ultimately why Orion goes; it is a much smaller vehicle and can make it back to Earth's surface, using atmospheric reentry to reduce the needed delta-V tremendously.

Yes, I was figuring HLS using pure delta-V to regain LEO (not atmospheric drag), but if it can't carry the round-trip fuel for that then that answers that question, thanks!

I guess they'll need another way to get back from Mars down the track too...

 

[JB47394]

I guess they'll need another way to get back from Mars down the track too...

It's funny that you mention Mars because going from LEO to the surface of the Moon (5,660 m/s) is about the same delta-V as going from LEO to the surface of Mars (5,710 m/s). That's because we get to use Mars' atmosphere to brake. A propulsive landing on Mars does burn a bit more fuel than the equivalent maneuver on the Moon, which isn't worked into those numbers.

The big difference between returning from the Moon and returning from Mars is that they're supposed to have a propellant depot on Mars. If they can do the same sort of on-orbit tanking that they plan to do here in LEO, then it's manageable. Even a V2 100 ton Starship can provide the necessary 5,710 m/s with 150 tons of payload and a 30 ton propellant reserve (5,854 m/s) to get from Low Mars Orbit to LEO.

So the returning Starships would be tanked in Mars orbit. Fortunately, Starship is a Single Stage To Orbit (SSTO) vehicle on Mars, cutting down on propellant requirements for tankers tremendously because there's no need for boosters. Unfortunately, it's still a lot of propellant.

A fully-loaded V2 tanker could deliver about 400 tons of propellant to orbit if it also drains its own tanks to reserve levels (just enough for reentry and landing). That means that you've only got to launch three tankers to load a returning Starship. That's a total of 3600 tons of propellant just for tanking. So those propellant farms on Mars are going to have to be pretty capable.

 

[ecarfan]

Eric Berger: Boeing says it will cut SLS workforce “due to external factors”

On Thursday senior Boeing officials leading the Space Launch System program, including David Dutcher and Steve Snell, convened an all-hands meeting for the more than 1,000 employees who work on the rocket. According to two people familiar with the meeting, the officials announced that there would be a significant number of layoffs and reassignments of people working on the program. They offered a handful of reasons for the cuts, including the fact that timelines for NASA's Artemis lunar missions that will use the SLS rocket are slipping to the right.

 

[scaesare]

Eric Berger: Boeing says it will cut SLS workforce “due to external factors”

The article also says:

So in some sense, these cuts were inevitable. Boeing required a lot of resources to design, develop, test, and write software for the rocket. Now that the development phase is over, it is natural that the company would be scaling down development activities for the core stage.

Which makes sense... When the job is largely done, then if there's nothing waiting on deck, folks have to go...

 

[ecarfan]

Eric Berger: NASA may alter Artemis III to have Starship and Orion dock in low-Earth orbit

Multiple sources have confirmed that NASA is studying alternatives to the planned Artemis III landing of two astronauts on the Moon, nominally scheduled for September 2026, due to concerns about hardware readiness and mission complexity.

No surprise there.

Under one of the options, astronauts would launch into low-Earth orbit inside an Orion spacecraft and rendezvous there with a Starship vehicle, separately launched by SpaceX. During this mission, similar to Apollo 9, a precursor to the Apollo 11 lunar landing, the crew would validate the ability of Orion and Starship to dock and test habitability inside Starship. The crew would then return to Earth. In another option NASA is considering, a crew would launch in Orion and fly to a small space station near the Moon, the Lunar Gateway, and then return to Earth.

So a multibillion dollar SLS launch that doesn’t even get humans to lunar orbit?

This is not sustainable.

 

[JB47394]

So a multibillion dollar SLS launch that doesn’t even get humans to lunar orbit?

Right now, the only way to get Orion on orbit is with SLS. Perhaps they're considering a means of getting it to orbit another way. Falcon Heavy has the lift capability. It's not human rated, but they could launch the crew in Dragon. They they transfer to Orion, dock to Starship, do their test, and reverse the process. It's a patchwork, but it's also rather cheaper than launching an SLS. Then there's the possibility of using New Glenn or Vulcan.

SLS is over $2 billion per launch.
A Falcon Heavy launch is roughly $200 million.
A Falcon 9 launch is roughly $100 million.

So you're looking at $0.3 billion versus $2.0 billion. Plus the complexity and risk as a result of the novelty. Can a Dragon dock to an Orion? I assume they use the same docking mechanism, but who docks to whom? Can Falcon Heavy handle the dimensions of the Orion capsule? I assume they don't have to get the service module on orbit because they're only doing a docking test in Orion, and the habitability test will be for HLS.

Wait. This LEO mission with an HLS Starship means either dumping the Starship after the mission, making it capable of reentry and bringing it down, or leaving it on orbit.

What a mess. It's almost as if they should wait until proper hardware comes together before trying to go to the Moon. But... the Chinese.

Anyway, I say they just put a Starship and an Orion capsule on dollies, do a ground mock up test, and call it done. Amazon has SIMPLI-MAGIC dollies for $39.99, and it's a two-pack.

 

[ecarfan]

But... the Chinese.

And that is the core of the problem. If the Chinese weren’t accelerating their human space program so rapidly, and impressively, I don’t think NASA would have the funding that it does. That said, NASA is having to cut space exploration robotic missions to keep SLS going as near as I can tell. Which is sad. And the Chinese do not yet have the hardware needed. But it would be unwise to underestimate them.

If NASA had awarded a $3 billion contract to SpaceX five years ago the US might now be poised to put humans on the lunar surface and taxpayers could have saved billions. I say “might”.

 

[scaesare]

Man what a lot of Rube Goldberg engineering for mission that honestly feels "meh".

 

[Grendal]

If I am understanding this correctly, and NASA is only having SLS and Orion take astronauts into LEO then that really makes no sense. You could have F9 and a Dragon take the astronauts to the ISS and transfer them to the HLS Starship there for the Moon. You do the same thing on the way back and you haven't spent a couple billion to get astronauts to LEO and back.

If you're doing a rendezvous with a Moon-Earth orbiting HLS then SLS and Orion would be necessary.

 

[Mike1080i]

If I am understanding this correctly, and NASA is only having SLS and Orion take astronauts into LEO then that really makes no sense. You could have F9 and a Dragon take the astronauts to the ISS and transfer them to the HLS Starship there for the Moon. You do the same thing on the way back and you haven't spent a couple billion to get astronauts to LEO and back.

If you're doing a rendezvous with a Moon-Earth orbiting HLS then SLS and Orion would be necessary.

If I understand this correctly, Artemis III would be much like Apollo 9, where there was a full test of the docking, crew transfer, operation, and redocking of the LEM / CSM in LEO. There was no need to fly to the Moon to do this, nor is there a need to do it with Orion and Starship. Breaking the mission down into smaller, less risky steps to prove they are both ready for the next step is probably the right thing to do here.

 

[JB47394]

If I understand this correctly, Artemis III would be much like Apollo 9, where there was a full test of the docking, crew transfer, operation, and redocking of the LEM / CSM in LEO.

Right. There's no argument against the mission goals, only the manner in which NASA wants to achieve them. The mission goals are to put Orion and HLS Starship in LEO so that they can do some testing. Great. But they plan on using a $2 billion rocket when something better suited to the task and far less expensive could accomplish the same thing. Apollo didn't have that luxury - the only rocket that could get the command and service modules to orbit was an Apollo rocket. These days, there are options, and it would be good if NASA could save nearly $2 billion dollars by using them. Use SLS where it is appropriate,

There are at least two issues:

1. What would it take to get Orion to LEO on another launcher?
2. Does a service module need to go up with Orion? That might complicate the choice of launcher.

 

[Mike1080i]

Right. There's no argument against the mission goals, only the manner in which NASA wants to achieve them. The mission goals are to put Orion and HLS Starship in LEO so that they can do some testing. Great. But they plan on using a $2 billion rocket when something better suited to the task and far less expensive could accomplish the same thing. Apollo didn't have that luxury - the only rocket that could get the command and service modules to orbit was an Apollo rocket. These days, there are options, and it would be good if NASA could save nearly $2 billion dollars by using them. Use SLS where it is appropriate,

There are at least two issues:

1. What would it take to get Orion to LEO on another launcher?
2. Does a service module need to go up with Orion? That might complicate the choice of launcher.

Well, there were two options back then. As I recall, the original plan for crewed LEM testing was to launch the LEM and the CSM to LEO on separate Saturn I's then perform rendezvous and proceed with the testing. I believe the thinking at the time was Saturn V's wouldn't be ready in time. As it turned out, they were ready and could loft both in one launch, so why not use one and they did. Were 2 Saturn I's cheaper than a single Saturn V, probably so, especially since Saturn I's were already capable, crewed rated and had the ground infrastructure for crewed Apollo spacecraft.

1. For crewed launch? Likely quite bit... probably quicker and easier to fly on SLS, which is already capable and rated. While I'm not an SLS fan, in this case it's likely the right tool for the job.

2. Service module... Since that's where Orion's power and propulsion is, I would think it would be required.

 

[JB47394]

1. For crewed launch? Likely quite bit... probably quicker and easier to fly on SLS, which is already capable and rated. While I'm not an SLS fan, in this case it's likely the right tool for the job.

I mentioned this above; launch Orion on a Falcon Heavy and launch the crew on Dragon. Dock and transfer the crew. That would get all the pieces on orbit, and allow the testing that they're after.

2. Service module... Since that's where Orion's power and propulsion is, I would think it would be required.

I was hoping to avoid throwing away a service module. Send the crew up on Dragon, then dock to Orion, transfer, and Orion docks to HLS. Orion would only exist to go through the docking procedure. The service module plays no role - unless they want to exercise the service module as well, which would make its presence mandatory.

Orion and its service module mass a total of 26 tons, so Falcon Heavy can handle the mass, and I think it can also handle the volume.

Again, the goal is to complete the mission objectives without using an absurdly-expensive booster. It galls me that the hardware would be discarded afterwards, except for Orion.

In the end, they'll launch the SLS.