I assume they've been dismantling it fir repairs? Also I've never understood why its mounted like that. Surely it would look better with the Orbiter on its own or mounted vertically as a full stack?
Boldly Going: A History of an American Space Station
- Thread starter e of pi
- Start date
That's exactly what they did OTL for pretty much every lunar lander study in the 1980s and 1990s, so there's zero reason to suppose they wouldn't ITTL as well.
Will be interesting to see what kind of power strategy is developed with the additional modules. Could something akin to a modern ISS solar wing theoretically be added to the station to help with the overall power generation for the station? How would power generation tech be shared across both Enterprise and Minerva?
Plus what kind of self respecting space nerd says no to bigger rocket?
Well, I did once start a thread on here suggesting that the Ares I would've been a better rocket for NASA than the SLS and/or Ares V, so...
I believe @e of pi said upthread and in TTL itself that the SRB joint improvements already occurred after TTL's Discovery disaster.
The SRBs get hate pretty often when, frankly, they were perhaps the most reliable and bulletproof part of the Shuttle. People have said for years that the SRBs were a big safety issue, but the odds were always way higher that foam on the ET or sensors in the SSMEs would get crews killed.
I should stop before I get out the soapbox.
I wonder if they accounted for the cost of having to move all of the office workers out of the VAB and build a load of new office buildings when they chose the solid rocket boosters.
You certainly have a point, and when I first made a draft, I had the ASRMs instead of SLWT, which is why I used "far short" (the ASRMs would have offered a 9,000 lbm payload increase). As for timing, the FWC boosters would probably have a first set available within a year - after all, ITTL shuttles are still launching out of SLC-6 in 1991...
While you are on the right track, Silverbird doesn't really know what to do with the Shuttle. I'd remind the reader that due to the way that the shuttle worked, any payload improvement method tends to increase the payload to all orbits by the same amount. Given that, and the fact that every extra degree of inclination between 28.5° and 57°results in a 500 lbm payload reduction (and each nautical mile of altitude 120 lbm), an orbiter with an LWT can lift 2,250 lbm more to 39° than an orbiter with an SLWT can lift to 51.6°.
Challenger still has a 5,000 lbm smaller payload capacity than Atlantis or OV-105, while Columbia's is 2,500 lbm lower still.
The Soviet Union was interested in selling the RD-170 and derived engines to the west as early as 1989, and there was an extension to the late 1980s LRB studies (pushing the end of that round of studies to 1991) to include said engines in the analysis. This analysis drove toward either a pair of RD-170s or a trio of RD-180s. The former retained the engine-out issues of the F-1A powered LRB designs. I'd also note that two-engine-per-booster was one of the things that NASA wanted to avoid. In a two engine booster, if you loose one of the engines, you can very easily loose the stack. Three engines is less likely, and contractor analysis tended toward the four and five engine solutions. At six engines and above, while the stack could more easily survive and even make the mission on an engine out, the chances of having more than one engine out on a single booster had grown sufficiently to be seen as a risk.
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The Shuttle mockup Pathfinder get restored
The Space & Rocket Center had no choice but to put Pathfinder like this on display.
Pathfinder was just a Mockup build out fiberglass and plywood on a steel frame
Even more rudimentary than 'Explorer' which at least used spares from the shuttles themselves.
It was only ever intended as a clearance check test article (it's not full scale either, if memory serves). The big stuff on display in Huntsville is either a test article or prototype. It's weird to see in this state (instantly made me think of this TL though), but still not as sad looking as when the bottom of the nose fell off 13 years ago.
So I had a thought-
The mid-1990s was an era that saw an explosion of public access to personal computers, as well as the newly-created world wide web and other similar networks, right? Because of that, I'm curious about where Enterprise sits in all of this- was it ever connected to the fledgling internet? The possibility of people being able to electronically communicate directly with the space station seems like it'd be of some interest, especially from a perspective of gaining public interest and engagement with the program. IOT, Mir was the only station active through this period, and for a variety of reasons wasn't able to exploit this, but under a different program with different resources and objectives, what do you all think of the idea of the web reaching space a good 10+ years early? What sorts of situations do you think having it connected would create?
The mid-1990s was an era that saw an explosion of public access to personal computers, as well as the newly-created world wide web and other similar networks, right? Because of that, I'm curious about where Enterprise sits in all of this- was it ever connected to the fledgling internet? The possibility of people being able to electronically communicate directly with the space station seems like it'd be of some interest, especially from a perspective of gaining public interest and engagement with the program. IOT, Mir was the only station active through this period, and for a variety of reasons wasn't able to exploit this, but under a different program with different resources and objectives, what do you all think of the idea of the web reaching space a good 10+ years early? What sorts of situations do you think having it connected would create?
Something like this would look great for NASA media, and be symbolic for the age of connectivity that the late 80s to early 90s, on through the 2000s. An "Email the Station" contest/event would be a good way to get rotated crews connected with students across the world..
marathag
Banned
I had email account that I don't think I sent out directly to another person beyond the sysop until 1995, lack of anyone I wanted to contact directly beyond the local(and not so local) BBS of the era before the WWW
Having a chance for 1200 baud communication TO AN ASTRONAUT in LEO would have been a real interest builder, I believe
This could have big knock on effects for internet utilization going forward, and could inspire an earlier internet boom that OTL.
Oh, good. I never was on board with the 2000-mid 2010s conventional wisdom that reusability was the mistake of STS.
My guess is that the Orbital Propulsion and Avionics Module (OPAM) includes the OMS, and after separation from the ET continues to thrust the sidesaddle payload mounted right on top of it, using the same tank attachments on a standard ET as an Orbiter would use, boosting the payload module and itself to a standard Low Earth Orbit (somewhat lower than the 100 nautical miles, about 180 km, standard for Apollo, say 100 km or a bit more) and then the payload unit, having its own modest thrust orbital maneuvering system, boosts itself on to destination orbit, while the OPAM separately orbits several times to phase to a suitable point for deorbit burn to place the OPAM, after aerodynamic braking, in the close ballpark of some controlled recovery zone. This would require embedding hypergolic propellant tanks and engines to be sure, but the alternative of omitting those and requiring the payload module to include a modestly reduced store of some kind of propellant and heavy thrust orbital insertion engines would leave the OPAM arcing ballistically to splash somewhere in the Indian Ocean. Given USN ubiquity, and the base at Diego Garcia, I guess recovering the OPAM like that, shipping it home to America on a freight plane of some kind, would be feasible, but to me it seems to cost little to incorporate delivery of the full payload to a minimal, not sustainable low orbit, which also enables the OPAM to phase around to a much more convenient near-CONUS recovery zone.
Would NASA not consider something like developing a biconic shell for the OPAM so it can maneuver during entry to a tighter recovery zone?
I've tried to estimate the mass of a suitable module of this type before, and come up with an optimistic 15 tonnes at the low end and maybe 40 pessimistically.
Does it have to splash down in water, or can it manage to land on land without wrecking the SSMEs? If the design included hypergol (or some alternative I'd prefer!) OMS type engines, using small propellant reserves to deorbit, could those reserves be stretched to enable rocket terminal braking to allow dry land recovery?
If the philosophy is to expend the tanks, how much cheaper are brand new lightweight tanks, I suppose assembled at Michoud in parallel with the ET, versus projected higher recovery costs of making the tanks heavy but highly durable, out of high temperature steel perhaps, to enable complete recovery of the whole booster, ideally strong enough that after a quick diagnostic checkout the tanks at least are ready for gas and go? I gather the operational costs of ships capable of hauling home the spent SRB casings was high, but is it really cheaper to make tanks anew for each launch? Where I figured a fully reusable LRB would save money was by avoiding the main cost of solid fuel grain fabrication within the casing segments, and the costs of shipping empty segments back to Utah plus the greater cost of shipping filled segments to the launch sites.
If we make no attempt to recover tank volume, clearly each one-shot tank can be lighter and perhaps cheap to assemble and ship I guess.
Will there be any attempt to drive the recoverable engine module back toward the launch site, or will they just coast and parachute to splash down as far downrange as the SRBs did?
It did seem that the installed power of the original power module would have margin for considerable growth to me. About how much extra power does each Shuttle-load module added draw then?
I was surprised to find that pure ethanol/LOX is indeed higher performance than N2O4/MMH hypergolic mix, which is what I assumed the MRRC was going to use.
Is it reasonably easy to ignite then?
The worst problem I would imagine arising from opting for this versus hypergol is storage stability--something the quote addresses in the context of the more stringent conditions of storing LOX on the Lunar dayside surface. I guess if you can store LOX on the Moon, you can store it in LEO. But how is boiloff prevented?
This is an extra big deal for the MRRC purposed as 8-crew lifeboats on SSE. For that mission you hope never ever to need it, but if it is needed it is liable to be after months or years of being parked on some docking port. I did not consider the prospect of having to have oxygen refill lines supplying the lifeboat ports, the idea of the lifeboat is to dock it and forget it, barring perhaps some modest power draw on the station supply. Fluid exchange seemed clean out.
So LOX can store indefinitely without boiling off, over years of operation when the module being kept in shade or otherwise minded specially should not be a priority?
Was that really the thinking at the time?
That explains a lot of really weird stuff I read from that era, since it looked like everyone laughed at reusability almost intentionally, damn the cost.
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Wow, never thought I'd see this; a return to the Moon not named Artemis.
Truly startling
Between Shuttle and then the X-33, X-34, Kistler, Roton, etc, reusability was not thought of well for about a decade and a half. Something the recent Promise Denied made me think about is that Griffin had personal experience creating and pushing the X-34 program, including the original flyback first-stage demonstrator concept (747-launched with a small upper stage for a few hundred kg to LEO) and then saving it from cancellation as the...less than totally functional suborbital L-1011-launched version when the original idea was cut down as too ambitious. (I say "less than totally functional" due to some issue with engine selection, and the elimination of a designed-in upper stage carrying capacity which limited it to only being a demonstrator of the profile for a future vehicle, not an operational Pegasus first stage replacement.) Anyway, that happened with two RLV programs dead on him only a few years before he lead NASA through ESAS and into Constellation's monster rockets. The "thumb on the scale" about reusability there may have come from some of his personal experiences...which of course makes me think about PoDs.
All rather tangential to anything related directly to this timeline, of course!
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Wow, two dead RLVs, that's an impressive record. I'd heard about those programs, but never thought by the same guy; it would explain why Constellation was largely designed to use 'reliable Shuttle hardware'.
I didn't know either until I read "Promise Denied," which is available for free from NASA:
Promise Denied: NASA's X-34 and the Quest for Cheap, Reusable Access to Space - NASA
Between 1992 and 1996, the American aerospace community vigorously explored the development of a post-Space Shuttle reusable space transportation
www.nasa.gov
But meanwhile, the F-1A is technology in American hands--I suppose the detailed specs, blueprints and test stand data are public record in fact, semi-free for all to use. Sort of--I imagine anywhere outside Soviet or Chinese spheres, there might be issues of patent claims preventing any law-abiding firm from using an exact copy without permission. And meanwhile, while the engine exists on paper and has been verified in tests, the plant that made the test articles is long restructured, the engineers moved on to other assignments, retired or dead; tooling up to make them again would be nearly as expensive as tooling up to make the originals was, adjusted for inflation. Meanwhile even in the compromise edition of this ATL, with the propellant tanks still being manufactured and discarded instead of recovered, the engines at any rate are to be recovered, so they need some redesign to be many times reusable. Perhaps less than one might guess, between the fact that "single use" engines generally undergo extensive test firing before being installed on a launch vehicle and so require service lives considerably longer than the duration of their final actual use, and that engines recovered from splashdowns and dunkings in sea water are often less damaged by this than one might guess.
So, assuming NASA is not content to slowly evolve LRBs with reusable engines (via a stage where engines not designed for reuse are recovered, tested to destruction and incrementally tinkered with to delay that destruction until many times reuse is demonstrated) the engineering goal is to focus on whichever parts break down first being strengthened until they don't. But this sort of robustifying is not all that sexy and contractors can be expected to attempt to justify more sweeping changes just to push the envelope with all that NASA pork. For instance, the F-1A was a champion at sheer magnitude of thrust, but its Isp was mediocre versus Soviet ker-lox engines operational at the same time as Lunar Apollo launches were happening. The Soviets pursued staged combustion at a time Americans were content enough with less efficient gas generator engines such as F-1A and J-2 (I am not sure J-2S would be called "gas generator" since the turbomachinery was driven by tap off from the combustion chamber). Then we leapfrogged to staged combustion with hydrogen in the SSMEs.
Meanwhile I don't think the F-1A gas generator approach needs great improving really; so Isp is reduced by routing some propellant past the core combustion chamber and tossing it over the side in dedicated turbo-power generation; it just means burning somewhat more propellant. Which in turn means somewhat larger propellant tanks and some general waste, but the decision to go for disposable one-shot tanks means these can be light as possible, whereas the inefficiency of a booster engine is relative to the mass of upper stage at booster stage burnout.
We Yankees had a bird in the hand with the F-1A in other words, and if the focus is kept firmly on making it more robust for many times use, we don't need to weep over Soviet/Russian designs that compete.
Of course this means I am assuming the LRBs are ker-lox. The one thing I think we can be sure of is that at any rate they aren't hypergolic. I would think that if NASA (or the contractors) wanted to adventurously mess around with other propellant mixes, that a meth-lox or propane-lox variant of the F-1A-Reusable would perform pretty similarly to the ker-lox version. I've not given alcohol much thought before. I don't think anyone in this TL, not at NASA anyway, will be giving much thought to using hydrogen peroxide for a "room temperature" propellant. Switching from kerosene to methane would seem to be a halfway house toward a hydrogen burning engine, but that would involve larger storage volume for the less dense fuel offsetting some of the performance improvement. Some offhand remarks by RanulfC elsewhere suggest to me that propane might overall be superior to methane (though not if one is focused on in situ fuel production on Mars). Aside from performance improvements these simple molecules might be preferred to lower biochemical hazard a bit while making the whole tank volume cryogenic at similar temperatures.
Anyway we can reliably get the job done with well-known ker-lox tankage and 2-3 F-1 derived engines per booster, perhaps penciling in fooling around with new and exciting propellant mixes for later development.
The actual TL approach might not come anywhere near F-1 based engines of course; there are lots of engines of lower thrust that can work in large numbers, for a strategy similar to Falcon-9 OTL.