Author Topic: Replacing SLS/Orion using Starship HLS and Crew Dragon  (Read 30441 times)

Online TheRadicalModerate

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #140 on: 10/23/2023 09:11 pm »
Maybe you should be comparing to cost of LEO for SLS.  I suspect 2350t of prop (your savings) is cheaper than one launch of SLS.

We did, somewhere up-thread.  It's almost impossible with whatever conops you dream up using a D2 and an OTV-LSS, or a D2 and an HLS-LSS staged from LEO--even if the Starship tankers can't be reused--to get a mission that costs more than about half of the comparable mission using SLS/Orion as the OTV.

That said, looking for an optimum mission in the D2/OTV-LSS kludge space is worthwhile, and solutions can vary by several $100M.

Offline DanClemmensen

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #141 on: 10/23/2023 09:50 pm »
Maybe you should be comparing to cost of LEO for SLS.  I suspect 2350t of prop (your savings) is cheaper than one launch of SLS.

We did, somewhere up-thread.  It's almost impossible with whatever conops you dream up using a D2 and an OTV-LSS, or a D2 and an HLS-LSS staged from LEO--even if the Starship tankers can't be reused--to get a mission that costs more than about half of the comparable mission using SLS/Orion as the OTV.

That said, looking for an optimum mission in the D2/OTV-LSS kludge space is worthwhile, and solutions can vary by several $100M.
Absolutely, but with a definite time limit to avoid never-ending optimization prior to the first mission. In an ideal fantasy world, NASA would get funding for a "backup Artemis architecture" and set up a program to award a competitive contract, which SpaceX would win. The contract would be fixed price but with an incentive bonus to fly a mission no later than six months after Artemis III. That program structure might actually focus the team. Structured like CCP with a demo followed by two guaranteed missions and NASA options for up to six additional  fixed-price missions. "Option B" increases would increase the number of seats on later missions. Fantasies like this are nice, but I suspect the realities of congressional appropriations and NASA contracting would bring it all crashing down. Note that all of this is in parallel with the existing Artemis program, at least until it fizzles out.

Further reality check: Starship has not yet reached orbit. Lots of bad things might happen.

Offline deltaV

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #142 on: 10/23/2023 10:24 pm »
The contract would be fixed price but with an incentive bonus to fly a mission no later than six months after Artemis III.

If SpaceX won that they would have a perverse incentive to delay Artemis III. It would be better to give a bonus for meeting a fixed calendar date.

Online TheRadicalModerate

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #143 on: 10/23/2023 11:00 pm »
The contract would be fixed price but with an incentive bonus to fly a mission no later than six months after Artemis III.

If SpaceX won that they would have a perverse incentive to delay Artemis III. It would be better to give a bonus for meeting a fixed calendar date.

I suspect that a "Commercial Crew Cislunar Transit Services" contract is a possibility, and it has the nice property of providing a fig leaf for winding down SLS/Orion on whatever timeframe is the most palatable (or, in the case of the incumbents and their patrons, the least unpalatable).  Just like CCP, I'd expect the BAA for such a service to have an aspirational date (again, adhering to the "least unpalatable" standard), and be written as an IDIQ FFP contract.

I'm... not sure that SpaceX would be the only bidder.  The SLD version of Blue Moon can't do LEO-NRHO-LEOpropulsive on one tank of prop, but it could be refueled at Gateway during the surface sortie.  Blue would have to find somebody willing to launch the crew to LEO (with D2 and Starliner being the only possible options), but they might want to bid anyway.

Even in the fantasy world, I wouldn't see NASA start to actively lobby Congress for something like CCCTS funding before the Option A test article mission was complete, which, best-case, wouldn't allow funding for issuing a BAA much before Arty 3.  Then add on 18 months for bidding, source selection, and Blue suing, and another year to get the conops and mission planning done.  That puts you no sooner than Arty 5, and more likely Arty 6.

Offline DanClemmensen

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #144 on: 11/05/2023 12:29 am »
An additional thought:  The one thing SLS/Orion can do that the kluge cannot is handle co-manifested elements of Gateway (like I-Hab) and dock them to Gateway. SLS/Orion handles this by using Orion as the space tug. Orion and I-Hab will be launched together on an SLS block 1B for Artemis IV. After TLI, Orion detaches from the stack, turns around, and docks to I-Hab, which tehn detaches from SLS. Orion/I-HAB proceeds to NRHO and Orion docks Orion/I-Hab to Gateway. I-Hab is completely passive.

The Kludge has the energy to take I-Hab from LEO to NRHO, but how? I-Hab is 10 tonne. I think I-Hab can be launched to LEO on an F9. HLS OTV can dock to I-Hab using its nose dock, and can carry it to NRHO on its nose and dock it to Gateway.

Issues:
    -- Can I-Hab handle the acceleration in this configuration during the TLI burn?
    -- Can SS dock I-Hab to Gateway in this configuration?
    -- If I-hab is completely passive, how can HLS OTV dock to I-Hab in LEO?
    -- If HLS OTV has only one IDSS port, How and when does the crew get into OTV from D2?
       --D2 docks to OTV first and transfers crew, or
       --since I-Hab has four IDSS ports, D2 docks to I-hab After OTV is already docked to I-Hab

Online TheRadicalModerate

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #145 on: 11/05/2023 08:32 pm »
An additional thought:  The one thing SLS/Orion can do that the kluge cannot is handle co-manifested elements of Gateway (like I-Hab) and dock them to Gateway. SLS/Orion handles this by using Orion as the space tug.

Excellent point and a good catch.

Quote
Orion and I-Hab will be launched together on an SLS block 1B for Artemis IV. After TLI, Orion detaches from the stack, turns around, and docks to I-Hab, which tehn detaches from SLS. Orion/I-HAB proceeds to NRHO and Orion docks Orion/I-Hab to Gateway. I-Hab is completely passive.

I'm not particularly worried about I-Hab, because its design is hedged so it fits on various CLVs.  (The bus to move it around is another story--see below.)  However, at least in theory, the USA can host a 10m x 4.56m co-manifest (section 6.3), which would require a Category C (stretched) fairing on a CLV.

Quote
The Kludge has the energy to take I-Hab from LEO to NRHO, but how? I-Hab is 10 tonne. I think I-Hab can be launched to LEO on an F9. HLS OTV can dock to I-Hab using its nose dock, and can carry it to NRHO on its nose and dock it to Gateway.

Issues:
    -- Can I-Hab handle the acceleration in this configuration during the TLI burn?

For a 10t payload on the NDS near Orion burnout (17.3t), The OMS has 27kN of thrust, which would produce a burnout acceleration of 1m/s▓, so the max load expected on the NDS would be 10kN.

IDSS and NDS specify four different load cases:

Case 1: 5.0kN pressurized
Case 2: 7.7kN pressurized
Case 3: 13.7kN pressurized
Case 4: 300kN unpressurized (based on Constellation requirements, likely EDS+Altair)

I think that a particular implementation doesn't need to handle all four cases.  (Anybody know?)  Case 4 would be more than adequate, but my guess is that Orion is designed to Case 3 (since Case 2 isn't enough to handle a max co-manifest).

I have no idea whether the LSS's IDSS implementation will handle case 4.  If it does, we're fine.  But if it only handles Case 3, a single RaptorSL burning at 50% throttle, at post-flyby burnout, would have ~1200kN of thrust and a wet mass of about 350t, which would be an acceleration of 3.4m/s▓, which would result in a reactive force on the dock of 34kN.

So there's potentially a problem.

It's certainly possible that SpaceX will plan ahead, but it would be un-SpaceX-like to overdesign a component before they had an application for it.

Quote
    -- Can SS dock I-Hab to Gateway in this configuration?
    -- If I-hab is completely passive, how can HLS OTV dock to I-Hab in LEO?

I think it's safe to assume that LSS's port will be active/passive, because it has to be designed to handle docking to both Orion and Gateway.  If not, then there's always the good ol' active-active docking adapter kludge.

Quote
    -- If HLS OTV has only one IDSS port, How and when does the crew get into OTV from D2?
       --D2 docks to OTV first and transfers crew, or
       --since I-Hab has four IDSS ports, D2 docks to I-hab After OTV is already docked to I-Hab

It's a mess.  Docking off-axis and far away from the CoM would be interesting, and would apply bending loads on the I-Hab for which it may or may not be designed.  It does have to handle similar off-axis loads at the Gateway, so it might be OK.  If you load the crew first, it's an extra RPOD, but it's one that's similar to what Orion was going to do in the first place.  I think the second F9 launch actually hurts more.

However, all of this feels a bit like a "Doctor, Doctor, it hurts when I do this" kind of problem.  Three alternatives:

1) Assume that the CLV folks aren't stupid and will provide a bus.  Stripping a Cygnus of its pressurized cargo module sounds about right, although with a 10t payload, it'll probably need its tanks stretched.  SpaceX might also want to strip off the PCM from DXL, which probably would leave more delta-v available.  (Somebody either up-thread or on one of the other jillion threads similar to this one convinced me that Cygnus was the better bet, but I suspect both are on the table.)

2) Do the work on the OTV-LSS to strip out the airlocks an replace the EVA hatch with a set of payload bay doors and an arm.  Four problems here:
a) We've violated the "do as little as possible" rule.
b) Co-manifested payloads would need at least one grappling point installed.
c) It's unlikely you'll get 10m of payload bay height on an OTV-LSS.
d) Worst of all, the payload needs to be integrated on the ground, which means you need a new OTV-LSS for each co-manifest.

3) Launch 'em on a vanilla uncrewed Starship with a chomper.  I would assume that the chomper's payload tilt-table will swing out to 90║, so the Starship can provide the oomph for the RPOD with no problem.  But we know very, very little here.

Offline DanClemmensen

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #146 on: 11/05/2023 09:36 pm »
    -- Can SS dock I-Hab to Gateway in this configuration?
    -- If I-hab is completely passive, how can HLS OTV dock to I-Hab in LEO?
I think it's safe to assume that LSS's port will be active/passive, because it has to be designed to handle docking to both Orion and Gateway.  If not, then there's always the good ol' active-active docking adapter kludge.
I have already assumed that Starship HLS will have an active/passive IDSS port, for many reasons. Sorry I was unclear, but that was not my question. Picture a completely passive I-hab in LEO. What holds it in one stable orientation so that HLS can dock to it? I think that when SLS/Orion is co-manifested, I-hab remains stuck to SLS while Orion maneuvers to dock to it, similar to the way the CM docked to the LM 50 years ago. If I-hab launches on F9, can the F9 US just hang around stuck to I-Hab to provide this stability while HLS docks to it?

We actually considered the co-manifesting problem early in this thread or its antecedents. I wanted to solve the problem by cancelling the Gateway and replacing it if necessary with a much more capable Starship CLD in NRHO. I'm revisiting co-manifesting so we have answers if someone insists of a straight-up SLS/Orion replacement.

If there is a way to dock Starship to I-hab in LEO, then a quick-and-dirty Starship CLD based on HLS is simpler, because it is a net gain of three IDSS ports with no new hardware. Probably more expensive than designing a Starship CLD from scratch, though.
« Last Edit: 11/06/2023 02:08 am by DanClemmensen »

Online TheRadicalModerate

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #147 on: 11/06/2023 04:24 am »
I have already assumed that Starship HLS will have an active/passive IDSS port, for many reasons. Sorry I was unclear, but that was not my question. Picture a completely passive I-hab in LEO. What holds it in one stable orientation so that HLS can dock to it? I think that when SLS/Orion is co-manifested, I-hab remains stuck to SLS while Orion maneuvers to dock to it, similar to the way the CM docked to the LM 50 years ago. If I-hab launches on F9, can the F9 US just hang around stuck to I-Hab to provide this stability while HLS docks to it?

Ah, gotcha.

Yeah, I'd say that pushing the mission life of the F9 S2 long enough for the OTV to do an RPOD would be the only thing that would work.  You'd already have to have the crew on the OTV (otherwise you'd lose attitude control when you undocked the co-manifest to board the crew), but then any hiccup in the co-manifest F9 launch starts eating into mission time.  And of course you'd have to have enough cold gas to maintain attitude for the RPOD.

Note that, if you put the crew on after the co-manifest you can't use the I-Hab's extra ports, because it's not commissioned yet, and its ECLSS won't be up and running.  I don't know if they even launch it pressurized.  And of course there may be co-manifests that aren't ever going to be habitable volume.

A CLD violates the "minimal engineering" rule pretty seriously.

Quote
I'm revisiting co-manifesting so we have answers if someone insists on a straight-up SLS/Orion replacement.

Well, if they're insisting on exactly the same conops, then we're left with FrankenStarship.╣  We've already added a pair of RPODs with the kludge.

I'm willing to bet that somebody would be more than happy to provide a tug.  And if that doesn't work, surely a chomper Starship will be available by the time this would be an issue.

___________
╣Even with the FS, there's an issue:  The co-manifest is still on its PAF during TLI, but after transposition and docking on the LSS's nose, 425m/s is probably large enough to require a Raptor burn for fast-flyby and NRHO insertion.  That then raises the issue of whether the OTV-LSS's docking hardware can handle the load.

Offline DanClemmensen

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #148 on: 11/06/2023 04:58 am »
A CLD violates the "minimal engineering" rule pretty seriously.
Sorry, I was mixing scenarios.

Kludge can operate for any mission that has no co-manifested Gateway components. Basically, an Artemis III mission. Kludge also does not need Gateway for any mission, since the OTV HLS can support part of the crew in NRHO if desired while the rest of the crew does a long lunar landing mission, not like Orion that needs Gateway.

However, If NASA wishes to maintain the fiction that Gateway is useful for anything except its Orion nanny function, then instead of building the existing modular Gateway, they should use a Starship CLD. This does not violate the "no new hardware" rule, because it is not needed for the kludge missions. It's a separate part of the program, and it does not affect the schedule of the initial kludge missions. In one possible future history, it's not new hardware at all. The Gateway Starship CLD is just another instance of the LEO Starship CLD, which will be built because it's the most cost-effective LEO CLD available and NASA (or someone) chooses to pay for it before ISS is de-orbited.

Online TheRadicalModerate

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #149 on: 11/06/2023 08:33 pm »
However, If NASA wishes to maintain the fiction that Gateway is useful for anything except its Orion nanny function, then instead of building the existing modular Gateway, they should use a Starship CLD.

I think Gateway is useful for allowing OTV Provider A to exchange crews with HLS Provider B, and vice versa.  It's also a done deal, so replacing it seems unlikely.  And it's off-topic.

Just from a topology standpoint, it's possible that co-manifests are designed with only one IDSS/GDSS port on them, so the first thing to pull it off of the PAF (irrespective of how it got launched and where it's being extracted) is the last thing that can touch it before delivery to NRHO.

It's certainly possible that many co-manifests will have ports one either end, and either of them can be used.  That would allow you to pre-launch the payload, park it with a nanny, and have the OTV come retrieve it after the crew arrives.  But if you have a nanny with attitude control, you might as well give it 150-200m/s of delta-v and just launch it and the payload to TLI.

I'm pretty much ready to mark the co-manifest issue down as a minor deficiency in the kludge architecture.

Offline DanClemmensen

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #150 on: 11/06/2023 08:56 pm »
Just from a topology standpoint, it's possible that co-manifests are designed with only one IDSS/GDSS port on them, so the first thing to pull it off of the PAF (irrespective of how it got launched and where it's being extracted) is the last thing that can touch it before delivery to NRHO.
If a co-manifest has only one port, then it could not be docked to Gateway by Orion. I was just looking at replacing the Orion functionality.

Online TheRadicalModerate

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #151 on: 11/06/2023 10:14 pm »
Just from a topology standpoint, it's possible that co-manifests are designed with only one IDSS/GDSS port on them, so the first thing to pull it off of the PAF (irrespective of how it got launched and where it's being extracted) is the last thing that can touch it before delivery to NRHO.
If a co-manifest has only one port, then it could not be docked to Gateway by Orion. I was just looking at replacing the Orion functionality.

The Gateway will eventually have an arm, which could berth things, or simply hold them until an EVA did something with them.  You could also have reprovisioning or re-cargo-ing of an HLS.

Early co-manifests are almost certainly going to be hab modules, which should have at least two GDSS ports, one on each end.  But even then, we don't know if there are operational restrictions that force all transfer maneuvers to occur with one of the two ports.  CoM could be such a restriction, as could directional acceleration.

Offline Bob Shaw

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #152 on: 11/06/2023 10:36 pm »
Did I not see a report the other day that NASA has issued a formal RFP to SpaceX for a Starship intended to offer a LEO Space Station variant? If that's the case, then sending one to the Moon and docking Gateway to it is surely the answer to these discussions here? Don't dock the huge Starship to a smaller set of modules - dock them to Starship!

Online OTV Booster

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Re: Replacing SLS/Orion using Starship HLS and Crew Dragon
« Reply #153 on: 11/06/2023 11:55 pm »
The contract would be fixed price but with an incentive bonus to fly a mission no later than six months after Artemis III.

If SpaceX won that they would have a perverse incentive to delay Artemis III. It would be better to give a bonus for meeting a fixed calendar date.

I suspect that a "Commercial Crew Cislunar Transit Services" contract is a possibility, and it has the nice property of providing a fig leaf for winding down SLS/Orion on whatever timeframe is the most palatable (or, in the case of the incumbents and their patrons, the least unpalatable).  Just like CCP, I'd expect the BAA for such a service to have an aspirational date (again, adhering to the "least unpalatable" standard), and be written as an IDIQ FFP contract.

I'm... not sure that SpaceX would be the only bidder.  The SLD version of Blue Moon can't do LEO-NRHO-LEOpropulsive on one tank of prop, but it could be refueled at Gateway during the surface sortie.  Blue would have to find somebody willing to launch the crew to LEO (with D2 and Starliner being the only possible options), but they might want to bid anyway.

Even in the fantasy world, I wouldn't see NASA start to actively lobby Congress for something like CCCTS funding before the Option A test article mission was complete, which, best-case, wouldn't allow funding for issuing a BAA much before Arty 3.  Then add on 18 months for bidding, source selection, and Blue suing, and another year to get the conops and mission planning done.  That puts you no sooner than Arty 5, and more likely Arty 6.
I pretty much agree with your time line. The fig leaf may be the most important element.


If Boeing doesn't shy away from keeping Starliner alive beyond contract commitments AND IF it gets past it's teething problems, it would be another option for Blue. Taking outside work is an element of what NASA considers a viable system. Working with Blue might be just what Boeing needs to get Starliner somewhere near the black. 


OTOH, maybe Blues new leadership can make them a bit more dynamic and (here's another maybe) maybe they can kludge together a capsule out of their partnership.
We are on the cusp of revolutionary access to space. One hallmark of a revolution is that there is a disjuncture through which projections do not work. The thread must be picked up anew and the tapestry of history woven with a fresh pattern.

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