[New] Space Launch System / Orion Discussion Thread

[YNM]

11 hours ago, tater said:

What useful crewed mission goal can be achieved with an SLS/Orion flight? Heck, even multiple flights in a cadence that can actually be demonstrated as likely (in which case boil off clearly matters)?

I don't mean an SLS/Orion flight, plus a large, indeterminate number of commercial launches, just SLS.

Honestly SLS is only to pre-position mission elements IMO. Can't see a lot of Orion flights myself. SLS would mostly be relegated to lift up the heaviest stuff like modules etc. for the station and maybe some surface elements.

Looking at the partners for Artemis (and Gateway) itself at least one other government does look up to commercialization of the mission itself beyond the initial efforts so SLS as it arrives today isn't going to be used apart from a few early key things.

[tater]

SLS B2 cargo could send 45t to TLI, nd with RL-10s, 25 tons of dry mass could land on the Moon.

So yeah, SLS could land a decent sized hab on the Moon.

[RCgothic]

Gateway's core elements are going up on Falcon Heavy.

And there is no large surface element that isn't going to have to go down on HLS, which will be commercially launched.

So which large elements would SLS be pre-positioning exactly, at maybe one flight a year and an unreasonable cost per flight?

From where we are now there's no sensible use case. Falcon Heavy and Commercial Crew changed everything.

[tater]

7 hours ago, RCgothic said:

So which large elements would SLS be pre-positioning exactly, at maybe one flight a year and an unreasonable cost per flight?

None exist, I'm trying to come up with something for SLS to do that doesn't suck.

 

[StrandedonEarth]

26 minutes ago, tater said:

None exist, I'm trying to come up with something for SLS to do that doesn't suck.

 

So launching Megamaid is out then....

(on mobile or I’d post the pic, but I think most ppl here know what I’m talking about...

Edited March 23, 2021 by StrandedonEarth

[tater]

16 minutes ago, StrandedonEarth said:

(on mobile or I’d post the pic, but I think most ppl here know what I’m talking about...

Spoiler

 

ObActualContent:

 

[sevenperforce]

19 hours ago, tater said:

Yeah, DIRECT was great.

Pick a set of mission goals, then design something that can accomplish those mission goals.

A Jack of all trades approach (master of none )I am actually fine with—but SLS is definitively not a JoaT, since it is not really a Jack of any trade. To be a multi-purpose system, it would have to be capable of multiple mission profiles.

I decided to play around with some of the numbers using Silverbird Astronautics, and...dang.

Even with just a single SSME on the bottom of a Space Shuttle external tank, and assuming that the upper and lower tank adapters nearly triple the dry mass of the external tank, this bare-bones "Jupiter 110" configuration could still deliver over 50 tonnes to the ISS...more than enough for Orion Lite and co-manifested cargo. Of course, only having one engine might make for a painfully long burn time so that's an issue.

• Two SRB, one SSME, no upper stage: ~58 tonnes to ISS
• Two SRB, two SSME, no upper stage: ~69 tonnes to ISS
• Two SRB, three SSME, no upper stage: ~73 tonnes to ISS
• Two SRB, four SSME, DCSS upper stage: ~109 tonnes to ISS
• Two SRB, four SSME, DCSS upper stage: ~29 tonnes to TLI via ISS staging orbit

I guess I can see why opponents of DIRECT said it was overpowered for LEO.

I wonder if the gimbal range on the Shuttle SRBs and on the SSMEs would have been enough to allow a single-SRB launch for an even more minimal mission profile to the ISS. With just a single SRB and two SSMEs mounted opposite, you could get over 40 tonnes to the ISS, provided gimbal range allowed it.

[tater]

29t to TLI exceeds B1 SLS, lol.

While that is overkill for ISS... they could literally build a new station with it, using what they have learned from ISS to build a better ISS. They could assemble a lunar stack.

The actual Shuttle-derived systems were not optimized for BLEO work, but they could have been flying literally decades ago.

[sevenperforce]

For a truly minimal ISS mission, you could even use the same core with two SSMEs and just add four of the AJ-60A solid motors used by Atlas V from 2003-2020. That will get you 22 tonnes to the ISS, which is plenty of margin for Orion Lite, especially if it uses its service module for orbital insertion. Liftoff TWR isn't great -- just 1.05 -- but you always have space to throw on a couple more solid motors if you need it. Then you could have been servicing the ISS with Orion Lite for substantially less than the cost of a Shuttle flight, even if operating Orion was exactly the same price as operating and refurbishing the Shuttle (which it would not have been).

10 minutes ago, tater said:

29t to TLI exceeds B1 SLS, lol.

Well, I think the Silverbird Astronautics performance calculator may overestimate performance somewhat. For example, when I manually input each of the actual values for SLS Block 1, it tells me that I get 34 tonnes (27.5-42.4 tonnes, 95% CI) to TLI, where TLI is defined as 417 x 362600 km at 52 degrees (that would be a staging orbit reachable from the ISS). That's the same orbital parameter I used above. So if we take as gospel NASA's claim that SLS Block 1 can only send 27 tonnes to the moon, then perhaps Jupiter DIRECT 241 (with the DCSS as above rather than the larger six-engine Jupiter Upper Stage proposed by DIRECT v3.0) could only send 23 tonnes to the moon.

But, again, that's with NO upgrades from Shuttle hardware. We could have been doing that a decade ago, with plenty of time to develop a proper upper stage.

The decision to stretch the SLS core stage rather than work on a better upper stage makes no sense, to me. The Shuttle external tank was already oversized for a sustainer stage; making it bigger just made the problem bigger.

[tater]

5 minutes ago, sevenperforce said:

Well, I think the Silverbird Astronautics performance calculator may overestimate performance somewhat. For example, when I manually input each of the actual values for SLS Block 1, it tells me that I get 34 tonnes (27.5-42.4 tonnes, 95% CI) to TLI, where TLI is defined as 417 x 362600 km at 52 degrees (that would be a staging orbit reachable from the ISS). That's the same orbital parameter I used above. So if we take as gospel NASA's claim that SLS Block 1 can only send 27 tonnes to the moon, then perhaps Jupiter DIRECT 241 (with the DCSS as above rather than the larger six-engine Jupiter Upper Stage proposed by DIRECT v3.0) could only send 23 tonnes to the moon.

Yeah, it might also really need a "human spaceflight" trajectory that includes a LAS mass, and deals with the shallow climb that allows for crew aborts. I see some of this in SLS numbers for cargo vs crew TLI, cargo is always higher mass, I assume it's mostly trajectory optimization.

5 minutes ago, sevenperforce said:

But, again, that's with NO upgrades from Shuttle hardware. We could have been doing that a decade ago, with plenty of time to develop a proper upper stage.

The decision to stretch the SLS core stage rather than work on a better upper stage makes no sense, to me. The Shuttle external tank was already oversized for a sustainer stage; making it bigger just made the problem bigger.

Yeah, sustainers are dumb. The ONLY reason Shuttle had that system after all was to save the engines which were attached to the Orbiter.

[sevenperforce]

46 minutes ago, tater said:

Yeah, it might also really need a "human spaceflight" trajectory that includes a LAS mass, and deals with the shallow climb that allows for crew aborts. I see some of this in SLS numbers for cargo vs crew TLI, cargo is always higher mass, I assume it's mostly trajectory optimization.

I did account for LAS mass, actually. I think that the Silverbird coding does a poor job of handling the sustainer stage architecture, generally. It says to enter the vacuum thrust and vacuum specific impulse and it will adjust down, but I don't think it adjusts down properly when dealing with the RS-25. 

46 minutes ago, tater said:

Yeah, sustainers are dumb. The ONLY reason Shuttle had that system after all was to save the engines which were attached to the Orbiter.

It's fascinating to read through the design history of the orbiter and see how it was just a series of kludges being re-kludged.

"This orbiter is too big, which makes our piloted reusable booster too big. What if we put the hydrogen in disposable tanks?"

"Wow, putting the hydrogen in disposable tanks makes the orbiter so much smaller and gives us lots of space! But where do we put them? A pair of tanks would occlude the orbiter's wings. What about underneath?"

"Hey let's just move the oxygen into the nose of the hydrogen tank and expand the cargo bay."

"There's no way for our piloted reusable boosters to have abort modes now because the external tank is in the way. Let's use a pressure-fed liquid booster that splashes down."

"Wait we want to use the Saturn V first stage as our booster! And we can even give it wings and fly it back!"

"No, that's too much trouble. Let's use a cluster of 7 solid motors and split the external tanks up on either side."

"We can use fewer solids if we stretch the external tank, put it back in the middle, and light all the engines at once!"

And thus the Shuttle was born.

[wumpus]

23 hours ago, tater said:

Yeah, it might also really need a "human spaceflight" trajectory that includes a LAS mass, and deals with the shallow climb that allows for crew aborts. I see some of this in SLS numbers for cargo vs crew TLI, cargo is always higher mass, I assume it's mostly trajectory optimization.

Yeah, sustainers are dumb. The ONLY reason Shuttle had that system after all was to save the engines which were attached to the Orbiter.

There aren't many good reasons to use sustainers.  Particularly sustainers that go from launch (sea level) to orbit.  I think mostly they have been used when there wasn't enough confidence in lighting the engines during flight (expect to see it more often in lower budget rockets, but even then more often as a 2.5 stage instead of a 1.5 stage).

[sevenperforce]

16 minutes ago, wumpus said:

There aren't many good reasons to use sustainers.  Particularly sustainers that go from launch (sea level) to orbit.  I think mostly they have been used when there wasn't enough confidence in lighting the engines during flight (expect to see it more often in lower budget rockets, but even then more often as a 2.5 stage instead of a 1.5 stage).

Sustainer stages from sea level to orbit are stupid unless you are aiming for reusability and your sustainer engine can throttle low enough to perform a landing burn. Then, at least, you have some justification. But to make that work you have to solve EDL.

[wumpus]

1 minute ago, sevenperforce said:

Sustainer stages from sea level to orbit are stupid unless you are aiming for reusability and your sustainer engine can throttle low enough to perform a landing burn. Then, at least, you have some justification. But to make that work you have to solve EDL.

Considering the shuttle landed the sustainers without the need to throttle this seems a bit odd.  It would certainly help if you could throttle the boosters and vertically land them*.  It would also help a lot if you could return the fuel tank.  Thanks to the density of the fuel tank, I have to wonder if spacex's various tricks could return the fuel tank (not applicable to designs signed off in the 1970s).

* sure, the shuttle recovered the boosters via parachutes and reused them.  But they were basically extremely strong steel pipes which hit the Atlantic at >100mph.  All the tricky bits involved making the aluminum perchlorite and mixing it in those steel pipes without air bubbles or flaws.

[tater]

At $470,000,000 each, it seems like figuring out a cost effective way to recover the SRBs might be, you know, slightly sensible. Cost effective for those of us paying for them, mind you, clearly better for the mfg if they get bought over and over.

[wumpus]

25 minutes ago, tater said:

At $470,000,000 each, it seems like figuring out a cost effective way to recover the SRBs might be, you know, slightly sensible. Cost effective for those of us paying for them, mind you, clearly better for the mfg if they get bought over and over.

$.47B Filled.  While the SLS appears overpriced everywhere, I doubt they are paying hundreds of millions of dollars for a steel tube.  Filling them is the tricky part.  One more important detail might include not stacking them until the green run is complete (although I don't want  to know how much extra that would cost, presumably all the guys hired to stack the things being paid to not do any stacking).  Now the SLS is on a specific deadline, one which nobody knows if it is really ready to meet.

One of my biggest disappointments in "things KSP lied to me" was that SRBs are not that cheap (and also tend to explode).  They do have pretty good Isp, especially from sea level, unlike their kerbal counterparts.  I have spent a lot of time building rockets that primarily used SRBs and they are extremely price-effective in KSP (unless you are using the bigger lie of airbreathers).

[tater]

 

4 minutes ago, wumpus said:

$.47B Filled.  While the SLS appears overpriced everywhere, I doubt they are paying hundreds of millions of dollars for a steel tube.  Filling them is the tricky part.  One more important detail might include not stacking them until the green run is complete (although I don't want  to know how much extra that would cost, presumably all the guys hired to stack the things being paid to not do any stacking).  Now the SLS is on a specific deadline, one which nobody knows if it is really ready to meet.

True, but that is the price in volume for 35 segments (7 SRBs, 1 was used for the static test, the other 6 for 3 Artemis flights). It's simply ridiculous.

 

[sevenperforce]

36 minutes ago, wumpus said:

45 minutes ago, sevenperforce said:

Sustainer stages from sea level to orbit are stupid unless you are aiming for reusability and your sustainer engine can throttle low enough to perform a landing burn. Then, at least, you have some justification. But to make that work you have to solve EDL.

Considering the shuttle landed the sustainers without the need to throttle this seems a bit odd. 

I mean, I stand by what I said -- it's still not a very efficient approach. I can't remember whether the refurb costs for the SSMEs was lower than build cost during the program or not, but either way, it's a lot of dead weight. At least if the engine is throttleable then you can use it on orbit and use it for a throttled landing burn.

47 minutes ago, wumpus said:

It would also help a lot if you could return the fuel tank.  Thanks to the density of the fuel tank, I have to wonder if spacex's various tricks could return the fuel tank (not applicable to designs signed off in the 1970s).

I wonder if they could have used a Zenit booster approach. Spray one side of the tank with ablative paint, give it cold-gas thrusters for control, and then add parachutes with retrorockets. Simple splashdown; tow it back.

[StrandedonEarth]

38 minutes ago, wumpus said:

$.47B Filled.  While the SLS appears overpriced everywhere, I doubt they are paying hundreds of millions of dollars for a steel tube. 

I read somewhere awhile back that refurbing  the steel SRB casings after fishing it out of the ocean didn’t really save any money and may have cost more than making new ones. At least they won’t try that with SLS, if only because a Five-segment SRB ends up with the nozzle so deep it needs highly specialized divers to plug it

Edited March 24, 2021 by StrandedonEarth

[sevenperforce]

23 hours ago, StrandedonEarth said:

I read somewhere awhile back that refurbing  the steel SRB casings after fishing it out of the ocean didn’t really save any money and may have cost more than making new ones. At least they won’t try that with SLS, if only because a Five-segment SRB ends up with the nozzle so deep it needs highly specialized divers to plug it

Did RS-25 refurb cost more than new engines?

Not for SLS (obviously yes) but during the Shuttle program.

[wumpus]

On 3/25/2021 at 1:56 PM, sevenperforce said:

Did RS-25 refurb cost more than new engines?

Not for SLS (obviously yes) but during the Shuttle program.

According to the infallible wiki, in 2005 each mission was budgeted ~$300 million for "flight hardware".  This includes the entire fuel tank, refilling and stacking the SRBs, retilling the orbiter (I'm sure Columbia cost more to retile.  Not sure if she flew in 2005), as well as rebuilding the RS-25s.  The RS-25s are staged combustion, so presumably extremely  expensive to make.  I wouldn't be surprised if a few were quietly retired during the shuttle program as too hard to rebuild, but I doubt they were ready to build more of them (this certainly helped profits during the SLS program).

There were always cheaper engines that had higher performance for less money (for the cheaper engine vs. refurbishing the RS-25s), but there was never an engine that could fit into the shuttle program quite the way the RS-25 did.  It was a full staged combustion engine, so that had to be costly.  A J-2 engine might make more sense, and was considered early in the Shuttle program.  It wouldn't start at sea level (but didn't have a problem starting in  the Apollo program), and would require slightly more powerful boosters.  Unfortunately I can't find a cost for the J-2 engine, but it had to be cheaper than the RS-25 (and as a gas generator, it should be relatively cheap).

 

[tater]

2 minutes ago, wumpus said:

According to the infallible wiki, in 2005 each mission was budgeted ~$300 million for "flight hardware".  This includes the entire fuel tank, refilling and stacking the SRBs, retilling the orbiter (I'm sure Columbia cost more to retile.  Not sure if she flew in 2005), as well as rebuilding the RS-25s.  The RS-25s are staged combustion, so presumably extremely  expensive to make.  I wouldn't be surprised if a few were quietly retired during the shuttle program as too hard to rebuild, but I doubt they were ready to build more of them (this certainly helped profits during the SLS program).

Wow, how can the 5 segment SRBs possibly cost 470 million EACH if they spent a fraction of that on all the things during Shuttle.

Looks like from the mid 80s to 2021, based on inflation, SRB costs should have doubled or tripled. Each Shuttle SRB apparently cost 23M$. How is it that the first 7 SRBs for SLS cost 471M$ each? 60M$ for the first 4 segments, then 410M$ for the last segment?

It's NOT dev cost, that was billions budgeted separately, the 471M$ cost is the unit cost of them in production.

[RyanRising]

13 minutes ago, tater said:

Wow, how can the 5 segment SRBs possibly cost 470 million EACH if they spent a fraction of that on all the things during Shuttle.

Looks like from the mid 80s to 2021, based on inflation, SRB costs should have doubled or tripled. Each Shuttle SRB apparently cost 23M$. How is it that the first 7 SRBs for SLS cost 471M$ each? 60M$ for the first 4 segments, then 410M$ for the last segment?

It's NOT dev cost, that was billions budgeted separately, the 471M$ cost is the unit cost of them in production.

Perhaps lower production volume is what gets you? If you don’t make as many things, each one tends to cost more.

[Minmus Taster]

I have to say this feels like a waste of money on NASA's part.

For over ten years they've been just slogging along slowly as a snail and at this point I'm desensitized to to the delay's and problems.

And to think SpaceX has flown several prototypes in a few months of they're larger more ambitious rocket and only been developing for a few years, I think it's safe to say NASA's human spaceflight has been a joke since the space shuttle.

Edit; And I would at least take the program seriously if they didn't calling S.L.S (Space Launch System? Really? What kind of name is that???)

Edited March 29, 2021 by Minmus Taster

[tater]

27 minutes ago, RyanRising said:

Perhaps lower production volume is what gets you? If you don’t make as many things, each one tends to cost more.

Except the Shuttle SRBs were refilled, SLS needs more SRBs than the Shuttle program, not fewer.