SLS General Discussion Thread 8

[jadebenn]

First, thanks for shifting the discussion of this here. In my view there may well be many more implications to this production change. The first I can think of is that without the engine section attached, could there be room on the barge for longer core stage tanks? And a 10 m engine section with 5 RS-25 engines?  Are they maybe inching their way towards SLS Block 3? By the time they get to Block 5, SLS could be Ares 5! :-/

I've been told the goal is to increase SLS production cadence, with the shuffle allowing the existing MAF workforce to focus on core and EUS production, with the new team at KSC working solely on the engine sections. Hiring issues at MAF (hard to get people to move to the surroundings) may have also played a role. In comparison, the area around KSC is positively bustling right now.

[Hog]

Can I get a whoop-whoop for the RESTART RS25s firing at 111%Rated Power Level for over 8 minutes solid.  the RS25 sustainer action has done a "basic" task since 1981  Use hydroloX to make as much thrust as efficiently as possible because the Orbiter Vehicle margins are crazy tight, you gotta do from pressures at sea level to vacuum with fire durations over 8+ minutes(over 9 minutes in engine out scenarios-operationally flight proven) and you have to be reusable.  That 1970's development campaign was awesome. Thiokol was hard at work back then as well. Well the engines and infrastructure were dictated by government so those same systems will be used.

First stage SLS max thrust was at least 9.6 mega lbs force.  BOLE' boosters and 4 RESTART RS25s thrusting at 111% RPL. The BOLE's will be heavier overall, but more of that mass percentage will be fuel and less on the casing.  Once the 80 Redesigned Solid Rocket Motor(RSRM) segment cases are expended, oops down to 70 now for Arty-2. 7 more flight sets left.
For the faults of government, the RS25, the most efficient staged combustion hydrolox engine and the Redesigned Solid rocket Motor-V(5) RSRMV) is the most powerful rocket engine ever fired and now, flown.  that igniter is sitting on a 177 foot tube of fuel/oxidizer. That pressure wave that builds during ignition must be fierce.  The thrust peaks approx 15 seconds post ignition at approx 4 megapounds force/17.8meganewtons each x 2 plus 420,000lbs/1.87 megaN x 4= 9.68 mega lbs force/42.9 meganewtons thrust and that's being reserved. The RS25s throttle from 100%RPL at Tee zero up to their flight thrust levels, seconds into ascent.  For Shuttle tower clear was the stated point in ascent where the SSMEs went from 100% to 104% and then 104.5% for the full Block II SSME. In essence thats what we saw fly in November, except for Arty-1 they flew at 109%RPL, a power level only used during engine out scenarios for STS. 15 seconds in puts the Block-1 SLS visible fire plume clear of the tower.  Pretty dynamic period

 "111% was authorized for due edit:do or die cases with failures several systems deep"  Wayne Hale

[edkyle99]

In my view there may well be many more implications to this production change. ...

I wonder how they can have a production/assembly crew working inside the VAB when solid motor segments are stacked.  That was considered such a hazard during STS days that NASA closed off and abandoned all of the old office spaces inside the VAB towers.  Doing core "manufacturing" steps in High Bay 2 would surely increase the number of workers in the building exposed to that hazard.  NASA should know better, given its history.  (Delta Spin Test Facility.)

Unless the plan is to (1) assemble the core stage and only then (2) stack the solids, which would very much limit the launch rate.

 - Ed Kyle

[dlapine]

Any thoughts on the current claim that the next Orion won't be ready as planned for any launch in 2024?
...

When the Orion is ready for its next flight is not related to the SLS, and how the Orion schedule affects the next Artemis launch is Artemis related, not SLS.

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then? Yes, the specific discussion of launch dates is more relevant to Artemis project, but the only payload for SLS in near term is Orion. I suggest that for a launch service with a single purpose at this time and for the near future, the availability of your payload is relevant to the discussion.

[DanClemmensen]

Any thoughts on the current claim that the next Orion won't be ready as planned for any launch in 2024?
...

When the Orion is ready for its next flight is not related to the SLS, and how the Orion schedule affects the next Artemis launch is Artemis related, not SLS.

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then? Yes, the specific discussion of launch dates is more relevant to Artemis project, but the only payload for SLS in near term is Orion. I suggest that for a launch service with a single purpose at this time and for the near future, the availability of your payload is relevant to the discussion.

As a specific example, Falcon Heavy was ready to launch, but the payloads kept slipping, so it did not launch for three years starting in 2019. At least with FH, The launch crews still had work to do launching F9. If the same happens to SLS, the hard-won lessons learned from the Artemis 1 launch campaign will begin to fade, people will change jobs or retire, etc.

Thus, the details of a slip are not relevant to this thread, but the effects of a slip are relevant.

[clongton]

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then?

Emphasis mine
None

SLS has all the time in the world to be ready for the next Orion mission without regard to spacecraft schedule slippages. It has absolutely nothing else to do.

[oldAtlas_Eguy]

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then?

Emphasis mine
None

SLS has all the time in the world to be ready for the next Orion mission without regard to spacecraft schedule slippages. It has absolutely nothing else to do.

Yes. I think some interesting reassignments of Artemis 3 SLS tasks being assigned to the SLS team members to keep them busy while waiting.

Otherwise the SLS team would be slow walking or just sitting and twiddling fingers waiting for the work to start when the launch date get closer. Everything that can be done early will get done early so that it is safely out of the way when the crunch of activity starts.

The final stacking work of SRB and everything else has to be realistically scheduled to stay within the 1 year timeframe for SRB stacking since this is a crew flight. Not much likelihood of waivers. From a scheduling point with no Green Run and no WDR should be able to get the time from stacking to launch down to less than a year. Slips from Green Run 5 months and slips from WDR was 7 months for a total of 12 months more than expected. Then additional difficulty with GSE and weather ate several more months. But still ended launching at less than 2 years. Thus A2 should be able to achieve a launch withing the 1 year stack limit.

[mn]

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then?

Emphasis mine
None

SLS has all the time in the world to be ready for the next Orion mission without regard to spacecraft schedule slippages. It has absolutely nothing else to do.

Yes. I think some interesting reassignments of Artemis 3 SLS tasks being assigned to the SLS team members to keep them busy while waiting.

Otherwise the SLS team would be slow walking or just sitting and twiddling fingers waiting for the work to start when the launch date get closer. Everything that can be done early will get done early so that it is safely out of the way when the crunch of activity starts.

The final stacking work of SRB and everything else has to be realistically scheduled to stay within the 1 year timeframe for SRB stacking since this is a crew flight. Not much likelihood of waivers. From a scheduling point with no Green Run and no WDR should be able to get the time from stacking to launch down to less than a year. Slips from Green Run 5 months and slips from WDR was 7 months for a total of 12 months more than expected. Then additional difficulty with GSE and weather ate several more months. But still ended launching at less than 2 years. Thus A2 should be able to achieve a launch withing the 1 year stack limit.

What is a reasonable minimum from stacking to launch? why stack a year in advance? what's the benefit?

[jadebenn]

I think you misunderstood what he said. He is saying they will not be stacking so early this time around, as the stack has much less to do before launch.

[oldAtlas_Eguy]

Stacking all the pieces take a while: SRBs, Core, Interstage, ICPS, Interstage to the Orion, and the Qrion stack. May be some other few items that have to be done as well that cannot be done in parallel. At each stacking task completion is the checkouts to be done to verify the stack is good to continue to the next task.

Such that the start of SRB stacking is a working backwards from best possible launch date through all the expected tasks lengths that have to be done in serial. Which could put the best possible latest start date prior to expected launch date is likely 6 months or more.

Many of the procedural errors encountered before are unlikely to be any longer a problem as the procedures have been changed. This will make most of the stacking to go a little more smoothly and quickly. But since the final tasks are mostly dealing with Orion. It is Orion ready to stack that controls when the launch date will be. So the SRB start stack date is a backup from the Orion stacking date.

[Khadgars]

Any thoughts on the current claim that the next Orion won't be ready as planned for any launch in 2024?
...

When the Orion is ready for its next flight is not related to the SLS, and how the Orion schedule affects the next Artemis launch is Artemis related, not SLS.

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then? Yes, the specific discussion of launch dates is more relevant to Artemis project, but the only payload for SLS in near term is Orion. I suggest that for a launch service with a single purpose at this time and for the near future, the availability of your payload is relevant to the discussion.

As a specific example, Falcon Heavy was ready to launch, but the payloads kept slipping, so it did not launch for three years starting in 2019. At least with FH, The launch crews still had work to do launching F9. If the same happens to SLS, the hard-won lessons learned from the Artemis 1 launch campaign will begin to fade, people will change jobs or retire, etc.

Thus, the details of a slip are not relevant to this thread, but the effects of a slip are relevant.

Artemis II isn't scheduled to launch until 2024 but the CS-2 will begin assembly at KSC Spring of next year.  While yes the launch cadence is measured in year(s) the activity surrounding those launches are not.

[woods170]

Any thoughts on the current claim that the next Orion won't be ready as planned for any launch in 2024?
...

When the Orion is ready for its next flight is not related to the SLS, and how the Orion schedule affects the next Artemis launch is Artemis related, not SLS.

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then? Yes, the specific discussion of launch dates is more relevant to Artemis project, but the only payload for SLS in near term is Orion. I suggest that for a launch service with a single purpose at this time and for the near future, the availability of your payload is relevant to the discussion.

As a specific example, Falcon Heavy was ready to launch, but the payloads kept slipping, so it did not launch for three years starting in 2019. At least with FH, The launch crews still had work to do launching F9. If the same happens to SLS, the hard-won lessons learned from the Artemis 1 launch campaign will begin to fade, people will change jobs or retire, etc.

Thus, the details of a slip are not relevant to this thread, but the effects of a slip are relevant.

Artemis II isn't scheduled to launch until 2024 but the CS-2 will begin assembly at KSC Spring of next year.  While yes the launch cadence is measured in year(s) the activity surrounding those launches are not.

Emphasis mine.

Minor nit: CS-2 is already assembled. What CS-2 will actually start at KSC next year is pre-stacking processing.

[Khadgars]

Any thoughts on the current claim that the next Orion won't be ready as planned for any launch in 2024?
...

When the Orion is ready for its next flight is not related to the SLS, and how the Orion schedule affects the next Artemis launch is Artemis related, not SLS.

Hmmm, exactly what other missions will the SLS be accomplishing within the next five years, then? Yes, the specific discussion of launch dates is more relevant to Artemis project, but the only payload for SLS in near term is Orion. I suggest that for a launch service with a single purpose at this time and for the near future, the availability of your payload is relevant to the discussion.

As a specific example, Falcon Heavy was ready to launch, but the payloads kept slipping, so it did not launch for three years starting in 2019. At least with FH, The launch crews still had work to do launching F9. If the same happens to SLS, the hard-won lessons learned from the Artemis 1 launch campaign will begin to fade, people will change jobs or retire, etc.

Thus, the details of a slip are not relevant to this thread, but the effects of a slip are relevant.

Artemis II isn't scheduled to launch until 2024 but the CS-2 will begin assembly at KSC Spring of next year.  While yes the launch cadence is measured in year(s) the activity surrounding those launches are not.

Emphasis mine.

Minor nit: CS-2 is already assembled. What CS-2 will actually start at KSC next year is pre-stacking processing.

Yup, you are right thanks for the correction.

[sdsds]

It's taking those advocating this approach a bit longer than they expected it might, but the future of SLS is bright. One day they'll want their equivalent of Launch Vehicle 51.0.48, even if it launches only every five years.

[clongton]

51.0.48 is never going to be considered.

[jadebenn]

https://www.nasa.gov/press-release/nasa-commits-to-future-artemis-moon-rocket-production

Dec 9, 2022
RELEASE 22-130

NASA Commits to Future Artemis Moon Rocket Production

NASA has finalized its contract with Boeing of Huntsville, Alabama, for approximately $3.2 billion to continue manufacturing core and upper stages for future Space Launch System (SLS) rockets for Artemis missions to the Moon and beyond.

Under the SLS Stages Production and Evolution Contract action, Boeing will produce SLS core stages for Artemis III and IV, procure critical and long-lead material for the core stages for Artemis V and VI, provide the exploration upper stages (EUS) for Artemis V and VI, as well as tooling and related support and engineering services.

In October 2019, NASA provided initial funding and authorization for Artemis III core stage work and targeted long-lead materials and cost-efficient bulk purchases. The finalization of this contract extends production activities and preparations for future work through July 2028. As part of the contract NASA may order up to 10 core stages and eight exploration upper stages total to support future deep space exploration missions.

“NASA’s Space Launch System rocket is the only rocket capable of sending large cargos and soon, astronauts to the Moon,” said John Honeycutt, SLS Program manager. “The SLS core stage is the backbone of NASA’s Moon rocket, producing more than 2 million pounds of thrust at launch, and the addition of the exploration upper stage will enable NASA to support missions to deep space through the 2030s.”

The SLS rocket delivers propulsion in stages and is designed to evolve to more advanced configurations to power NASA’s deep space missions. Each SLS rocket configuration uses the same 212-foot-tall core stage to produce more than 2 million pounds of thrust to help propel the mega rocket off the launch pad.

For the first three Artemis missions, SLS uses an interim cryogenic propulsion stage with one RL10 engine to send NASA’s Orion spacecraft to the Moon. Beginning with Artemis IV, the SLS Block 1B rocket configuration will be propelled by the more powerful EUS with larger fuel tanks and four RL10 engines to send a crewed Orion and large cargos to the Moon. All the structures for the rocket’s core stage and EUS are manufactured at NASA’s Michoud Assembly Facility in New Orleans.

The contract comes as NASA optimizes manufacturing capabilities as Boeing will use Kennedy Space Center in Florida to perform some core stage assembly and outfitting activities beginning with the Artemis III rocket. In tandem, teams will continue all core stage manufacturing activities at Michoud.

Teams continue to make progress assembling and manufacturing core stages for Artemis II, III, and IV. The Artemis II stage is scheduled to be completed and delivered to Kennedy in 2023. The engine section for Artemis III was recently loaded onto NASA’s Pegasus barge for delivery to Kennedy, where it will be outfitted and later integrated with the rest of the rocket.

With Artemis, NASA will land the first woman and the first person of color on the lunar surface and establish long-term exploration at the Moon in preparation for human missions to Mars. SLS and NASA’s Orion spacecraft, along with the commercial human landing system and the Gateway in orbit around the Moon, are NASA’s backbone for deep space exploration.

For more information about the Space Launch System, visit:

https://www.nasa.gov/sls

-end-

Photo caption:

NASA and Space Launch System stages prime contractor Boeing are in various states of production on core stages for future Artemis missions. Together with its twin solid rocket boosters, the Space Launch System core stage will produce 8.8 million pounds of thrust to send NASA’s Orion spacecraft, astronauts, and supplies beyond Earth’s orbit to the Moon. A powerful upper stage will be incorporated into the rocket beginning with Artemis IV. NASA joined the Space Launch System rocket’s core stage forward assembly, seen here, with the 130-foot liquid hydrogen tank in March 2022.
Credits: NASA/Eric Bordelon

Before anyone asks: The Artemis 4 EUS is already under contract, which is why it's not listed here. I believe that's a holdover from when Artemis 2 (then EM-2) was going to be the first Block 1B mission.

[su27k]

So $1.6B for core stage + EUS, add to that $400M for 4 RS-25, $350M for 2 SRBs, that's already $2.35B just for major parts, doesn't include integration cost and small items like RL-10s.

NASA IG-22-003 lists SLS per launch cost as $2.2 billion (doesn't include ground system or R&D), looks like 1B will exceed this by no small amount.

[Coastal Ron]

So $1.6B for core stage + EUS, add to that $400M for 4 RS-25, $350M for 2 SRBs, that's already $2.35B just for major parts, doesn't include integration cost and small items like RL-10s.

NASA IG-22-003 lists SLS per launch cost as $2.2 billion (doesn't include ground system or R&D), looks like 1B will exceed this by no small amount.

Unfortunately this press release does not provide enough information to determine unit costs, since they have grouped specific unit production in with long lead procurement - none of which is defined enough to determine specific unit costs.

Regarding RL-10's, the last contract info I saw indicated that per unit costs were $20,255,153 for SLS #3

[sdsds]

During the NSF livestream comments indicated the engine section for A-3 (and following) will be transferred to the SSPF for outfitting and then transferred again to the VAB for integration with the remainder of the core stage. Does that activity in the VAB involve welding, or does the engine section "bolt on" to the core?

[jadebenn]

During the NSF livestream comments indicated the engine section for A-3 (and following) will be transferred to the SSPF for outfitting and then transferred again to the VAB for integration with the remainder of the core stage. Does that activity in the VAB involve welding, or does the engine section "bolt on" to the core?

I believe it's bolted-on.