Jump to content

[New] Space Launch System / Orion Discussion Thread


Recommended Posts

The trouble is not the reality of SLS, the trouble is that it's not really ideal for anything.

At billions per launch (if they manage 2 a year at some point it might only cost 2.something billion per launch), the fact that a concurrent, 2-launch mission (not counting Gateway, lol) might be possible to get to the lunar surface and back doesn't demonstrate that SLS makes sense for that mission. If the mission goal is long stays on the Moon, the vehicles (SLS and Orion) should have been designed to accomplish that goal. So a comanifested lander (a la Apollo) in 1 flight, or something that entirely escapes me...

What's the throw weight to TLI for the full Block 2 version?

Link to comment
Share on other sites

12 minutes ago, tater said:

The trouble is not the reality of SLS, the trouble is that it's not really ideal for anything.

At billions per launch (if they manage 2 a year at some point it might only cost 2.something billion per launch), the fact that a concurrent, 2-launch mission (not counting Gateway, lol) might be possible to get to the lunar surface and back doesn't demonstrate that SLS makes sense for that mission. If the mission goal is long stays on the Moon, the vehicles (SLS and Orion) should have been designed to accomplish that goal. So a comanifested lander (a la Apollo) in 1 flight, or something that entirely escapes me...

What's the throw weight to TLI for the full Block 2 version?

But you don’t need a second SLS to launch the lander. Use an expendable FH.

Link to comment
Share on other sites

3 hours ago, ZooNamedGames said:

But you don’t need a second SLS to launch the lander. Use an expendable FH.

Even that is not likely, FH is something like 16 tons to TMI, so similar to TLI. @sevenperforce got a lander that was 23 tons, and that requires cryo props, which makes it somewhat unlikely for FH.

Given that we're talking about 2024, they could always just put the Orion/Lander stack inside Starship, I suppose ;)

 

2 hours ago, jadebenn said:

I believe he's referring to the conversation he and I had a few pages back.

Yeah, we're discussing how to do it with just SLS, since the paid Boeing consultant, and former NASA guy was pitching SLS-only to defeat the nasty forces of commercial space working to make Artemis somehow less efficient. because magic (and the 500k$ Boeing has paid him in the last 2 years ;) ).

Edited by tater
Link to comment
Share on other sites

6 hours ago, tater said:

Still, I don't see a cryo lander as a good idea unless there is already a prop depot (something that makes little sense at the Moon if the props come from Earth, IMHO), or IVF is already flying at the very least. I think it's bad entirely from the logistical standpoint. EoR can give you windows most days. Scrub (a common thing with all LVs)? No worries. NRHO has a period of something like 6.5 days I think. If it takes you a week to get out to the pad, then the next launch is really 13 days from the first launch, not 7 (assuming there's a window every week). There might be some slop there by adjusting the TLI burn, assuming there's margin to do this. Even if the window is a few days, that is setting up timing issues, since each scrub day might have an opportunity the next day using some margin, or the following with more excess props required, etc. This could also possibly impact the LOI burn as well (margin required for this on the lander, though faster transit might come out in the wash vs boiloff).

Still, with 1 flight a year on crew, you could very well end up with Orion stuck at Gateway, and they run out of time for a landing attempt (second SLS waiting to leave). I think I'd prefer the lander be there ahead of time.

No need for a prop depot. Just launch the cryo lander from a stack on the SLS. Even if Orion is stuck at Gateway and runs out of time, it's not a LOCV, just a benign LOM, which is not really a problem for the program. 

I agree that using hypergols for the lander is prohibitive.

5 hours ago, tater said:

The trouble is not the reality of SLS, the trouble is that it's not really ideal for anything.

I agree.

5 hours ago, tater said:

What's the throw weight to TLI for the full Block 2 version?

45 tonnes. Almost enough to throw a barebones cryo lander plus Orion for a repeat of Apollo.

4 hours ago, ZooNamedGames said:

But you don’t need a second SLS to launch the lander. Use an expendable FH.

Even expendable FH can't throw 23+ tonnes to TLI, and that's cryo, which is incompatible with FH.

Link to comment
Share on other sites

4 minutes ago, sevenperforce said:

No need for a prop depot. Just launch the cryo lander from a stack on the SLS. Even if Orion is stuck at Gateway and runs out of time, it's not a LOCV, just a benign LOM, which is not really a problem for the program. 

I'm still thinking that the logistics are non-trivial. That architecture requires flying 2 SLS launches back to back. Gateway mission durations seem to be limited to something like 30-42 days, end to end. That buys time for possible slips, but the crew will be out a week before there's any chance of the lander launching it seems, then the lander has to go to Gateway (3 days? @jadebenn said 7 to NRHO), then they have to dock it, board it, and start checking it out. 3 days to LLO? (thought it was half a day) So we have varying accounts such that the time to the surface might be on the order of 17 days, or might be as few as 10 from the day the Orion launches. Any delays screw that up. Yeah, it's not LOV/C, but it's a huge expense for nothing, all because of cryos if the lander launch is delayed.

Also, I have no idea about landing requirements from a lunar day standpoint. Typically they want just the right shadow geometry to be able to see smaller scale surface features during landing ops. Whatever that time range is defines the possible allowable delays.

Link to comment
Share on other sites

2 hours ago, tater said:

Yeah, we're discussing how to do it with just SLS, since the paid Boeing consultant, and former NASA guy was pitching SLS-only to defeat the nasty forces of commercial space working to make Artemis somehow less efficient. because magic (and the 500k$ Boeing has paid him in the last 2 years ;) ).

I'm not totally on-board with a two-stage dual SLS launch architecture. You might get the impression I am since I've been going over the benefits and defending it on a conceptual level (as-in not just putting it down to Boeing shilling a la Berger), but it's got as many issues as the 3-stage commercially-launched architecture, just in different places.

The vastly over-generalized summary is that the 3-part lander has advantages in the near-term but has issues long-term, whereas the 2-part lander struggles in the near-term but has advantages in the long-term.

Edited by jadebenn
Link to comment
Share on other sites

Launch pad turnaround is hard to nail down. The US record was a Gemini Titan at 11 days (there was a Titan attempt at 8 days once but scrubbed, apparently). All others have been closer to 2 weeks at the same pad as a record for the Cape.

A week seems possible, but pretty aggressive. The 2 SLS architecture seems bizarre to me. Strikes me that for billions, it would be nice to have the lander in place, good to go. Not least because the lander should be sent to the lunar surface unmanned as a test at least once before humans climb aboard it (during Apollo this was not really an option, but it could be done now, vs an Apollo 10 style mission).

2 hours ago, jadebenn said:

The vastly over-generalized summary is that the 3-part lander has advantages in the near-term but has issues long-term, whereas the 2-part lander struggles in the near-term but has advantages in the long-term.

 

I don't see the long term advantage of stopping at Gateway at all, if the goal is landing. Refilling props at Gateway is a non-starter, IMO, unless there work on IVF in earnest, plus have a high cadence to Gateway.

Prop depot architecture requires ACES (or similar). A 60 ton (props) ACES has over 11.5km/s of dv. It could take props to Gateway, but it's either disposable (what's the point of a prop depot if you throw awesome, expensive stages away!), or you might need 2 flights for lander props (the LockMart lander in this case). If they were serious about the whole reusable lander thing, they'd push ACES.

Edited by tater
Link to comment
Share on other sites

Now that you mention it, I think you might be right about a week being too aggressive. I wish I could find the actual figure again, but the way I remember it was that the goal was to get a turnaround time at least in-line with the rest of the launch industry. They wanted something shorter than the Shuttle and Saturn's very long pad stays.

A lot of the work around the quicker turnaround was out of sheer necessity. The weight of the ML meant that they couldn't add arms or scaffolding to access the rocket outside the VAB (except for the essentials), so everything has to be ready and good to go the moment the rocket leaves through the doors of the VAB. No more service structures. They'll be using a hybrid of the their traditional methods and EELV methods from now on.

Edited by jadebenn
Link to comment
Share on other sites

18 hours ago, tater said:

Still, I don't see a cryo lander as a good idea unless there is already a prop depot (something that makes little sense at the Moon if the props come from Earth, IMHO), or IVF is already flying at the very least. I think it's bad entirely from the logistical standpoint. EoR can give you windows most days.

Just for gits and shiggles, I decided to rerun the numbers on hypergols instead. With the same expected specific impulse of 316 seconds and a landing stage commensurate in size to a Titan II GLV upper stage (descent stage dry mass est. 2.8 tonnes), you need to throw 31 tonnes to TLI. SLS Block 1B can do it if they ever get the EUS working. There's a dry mass advantage with using hypergols because of the density issue; the lander has the same dry mass even though it carries way more props.

Another option would be to have a reusable lander hab with about 800 m/s of onboard props and no main engine: basically a Dragon 2 with no heat shield, aeroshell, or SuperDracos. For each lunar sortie, you only send a landing stage vehicle with no hab to TLI. It would brake past the moon and rendezvous with LOP-G, then hang out until Orion arrived. Once Orion was there, the astronauts would transfer into the lander hab vehicle and then you'd use a Canadarm to berth the landing stage onto the bottom of the lander hab. The landing stage vehicle would refuel the hab, then would take it into LLO and down to the surface, then bring it back up to LLO, at which point the lander hab vehicle would unberth and return to LOP-G using RCS only.

I estimate the Apollo APS dry mass at 0.7 tonnes, meaning the hab-associated mass of the LM ascent module would have been about 1.36 tonnes. Let's do 150% mass growth on that to allow for more crew, more capability, and down/upmass, bringing it to 3.4 tonnes. This is something Congress would actually like. Getting 3.4 tonnes from LLO to LOP-G costs 770 m/s (to give margin) and requires about 1.1 tonnes of props with about 300 kg of tankage dry mass. Let's say that the fully-loaded "taxi" rounds up to 4.8 tonnes. You'll note this is roughly the same mass as the Apollo ascent module. However, instead of only delivering the module from LLO to the surface (1.87 km/s), we need to deliver it from LOP-G to the surface and back to LLO (4.47 km/s).

A pair of OMS engines will do the job, at 100 kg each. Now, as a single stage on hypergols, getting to 4.47 km/s would be rough; you'd need a whopping 40 tonnes of props and 7.6 tonnes of tankage and structure, not counting what's needed to brake to LOP-G. But we don't have to do that. Getting from the surface to LLO only takes 1.870 km/s, which can be done with the two engines, 665 kg of tankage, and 4.7 tonnes of props. If this is what breaks away from the landing stage, we aren't lugging a lot of dead structure up on that final burn. 

The Apollo descent stage had an engine massing 180 kg, 8.2 tonnes of props, and 1.92 tonnes of structure and tankage. Using that as a benchmark, you end up with an engineless landing "stage" massing 2.53 tonnes and carrying 10.8 tonnes of props, for a gross mass (with cargo) in LLO of 23.7 tonnes. If we add 1.7-tonne drop tanks at this point, carrying about 12 tonnes of props, we will burn 6.75 tonnes of those props getting from LOP-G to LLO. The tanks also need to refuel the reusable hab vehicle, leaving 4.1 tonnes of props for getting from TLI to the LOP-G.

The total stack ends up being 32.58 tonnes...just slightly more than before, but now with a reusable hab that's twice as big as before. That's clever staging for you.

EDIT: Note that the reusable "hab" is only 4.8 tonnes fully loaded and has ample dV to get from TLI to LOP-G on its own. That's well within the capability of an expendable Falcon 9 or a recovered Falcon Heavy. The modular design also allows the sortie stage to be customized for the mission. The base model could just have an airlock; a slightly larger one could also deliver a rover, additional experiments, etc.

Edited by sevenperforce
Adding info
Link to comment
Share on other sites

Wasn't Orion supposed to be reusable?

https://spacenews.com/lockheed-martin-working-to-lower-orion-costs/

Quote

One factor in later cost reductions, he said, will be the reuse of Orion capsule components, including, eventually, the vehicle structure. “We have the internal component reuse that will start even between [EM] 1 and 2, but then when we get to reusing a structure, for instance, that factors in significant savings on a mission basis,” he said.

Hopefully this order is just for the not-reused parts, and not brand new capsules.

Link to comment
Share on other sites

1 hour ago, tater said:

Wasn't Orion supposed to be reusable?

https://spacenews.com/lockheed-martin-working-to-lower-orion-costs/

Hopefully this order is just for the not-reused parts, and not brand new capsules.

It likely is a full order of full spacecraft as even if they wanted to make it reusable- it’s too early in the vehicles development to make that jump. Especially with the weight of a lunar landing. No one wants to be responsible for risking astronauts lives just to save a few bucks. Though eventually, the vehicle would likely make that shift. Just not for a while.

Link to comment
Share on other sites

1 hour ago, ZooNamedGames said:

It likely is a full order of full spacecraft as even if they wanted to make it reusable- it’s too early in the vehicles development to make that jump. Especially with the weight of a lunar landing. No one wants to be responsible for risking astronauts lives just to save a few bucks. Though eventually, the vehicle would likely make that shift. Just not for a while.

 

Reuse was a selling point of Orion. Nice thing for them is that if they push it out a few years, they'll never have to bother, I think.

So $900,0000,000 EACH.

Marginal launch costs for SLS have been estimated to be similar, around a billion, and Orion is literally the only payload.

So SLS launches cost ~2 billion each, without any program costs. Program costs are estimated at ~2.5 B$/yr, so every SLS launch for the foreseeable future costs 4.4 B$ each. If they ever manage 2 in a year, then it's a bargain at 3.15 B$ each.

 

Link to comment
Share on other sites

tater moment

With this award, NASA is ordering three Orion spacecraft for Artemis missions III through V for $2.7 billion. The agency plans to order three additional Orion capsules in fiscal year 2022 for Artemis missions VI through VIII, at a total of $1.9 billion.

The long-term plan is to reuse the recovered crew modules at least once. The first phase of reusability will start with Artemis II. Interior components of the spacecraft, such as flight computers and other high value electronics, as well as crew seats and switch panels, will be re-flown on Artemis V. The Artemis III crew module will be re-flown on Artemis VI.

and:

"With this award, NASA is ordering three Orion spacecraft for Artemis missions III through V for $2.7 billion. The agency plans to order three additional Orion capsules in fiscal year 2022 for Artemis missions VI through VIII, at a total of $1.9 billion. Ordering the spacecraft in groups of three allows NASA to benefit from efficiencies that become available in the supply chain over time – efficiencies that optimize production and lower costs."

Thats ~633 mln USD for each Orion for AVI-AVIII, thou 1.35 bln for AIII-AV.

Am rarted. AIII-AV Orions are 900mln, and AVI-AVIII Orions are 633mln.

"The first six spacecraft will be acquired by cost-plus-incentive-fee ordering. Because the cost of a complex, high-tech system generally decreases over time as the design stabilizes and production processes mature, NASA will negotiate firm-fixed-price orders for future missions to take advantage of the anticipated spacecraft production cost decreases. Furthermore, the cost incentives on the cost-plus-incentive-fee orders are designed to motivate favorable cost performance during early OPOC production and drive substantially lower prices for any subsequent firm-fixed-price orders issued under this contract."

 

Edited by Barzon
Link to comment
Share on other sites

3 minutes ago, Barzon said:

tater moment

With this award, NASA is ordering three Orion spacecraft for Artemis missions III through V for $2.7 billion. The agency plans to order three additional Orion capsules in fiscal year 2022 for Artemis missions VI through VIII, at a total of $1.9 billion.

The long-term plan is to reuse the recovered crew modules at least once. The first phase of reusability will start with Artemis II. Interior components of the spacecraft, such as flight computers and other high value electronics, as well as crew seats and switch panels, will be re-flown on Artemis V. The Artemis III crew module will be re-flown on Artemis VI.

OK, good (sorry, would've "liked" it).

So the only reason the next 3 are cheaper is that they start reusing stuff. 633 M$ each instead of 900 M$ each.

Except the first 3 are cost plus, so they will likely be more (every single thing for this project has gone way over budget using this system, so we have zero expectation of any changes in that regard. If they play their cards right, they'll offset the entire reuse savings ;)

 

 

 

Link to comment
Share on other sites

not cost+
"The first six spacecraft will be acquired by cost-plus-incentive-fee ordering. Because the cost of a complex, high-tech system generally decreases over time as the design stabilizes and production processes mature, NASA will negotiate firm-fixed-price orders for future missions to take advantage of the anticipated spacecraft production cost decreases. Furthermore, the cost incentives on the cost-plus-incentive-fee orders are designed to motivate favorable cost performance during early OPOC production and drive substantially lower prices for any subsequent firm-fixed-price orders issued under this contract."

Cost plus Incentive fee

Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...