Skylab was never meant to be resupplied, so even if Apollo hadbe extended, the station would only have had one or two missions left to it.A follow-on station, however, would have been soon realized.In fact, the answer to all of this is seen in the Russian space program over the same decades. They kept their "Apollo", and developed space stations that evolved from their Skylab (Salyut 1) to the Mir Space Station. We would have done the same, but in the end, our "Mir" would have been a vast cluster of Skylabs.
This is an excellent question, which I have often asked myself! I actually came to quite similar conclusions.I'm assuming Shuttle is cancelled in 1971 for budget reasons.
Nixon is not interested in and allocates no money for a lunar return. Instead, NASA's new mission is to be LEO space stations to match recent Soviet developments (and a possible threat of military space stations, which, as we now know, actually flew as Almaz).
The first big fight is whether to continue the Saturn/Apollo line or whether to centralize everything on the Titan launcher.
In this scenario, I'm assuming Airforce will oppose making Titan available for manned launches (they want to keep their own booster), so the Saturn line will be continued and used for NASA manned missions.
However, the Saturn V and Saturn IB will both be retired after flying their last missions.
NASA proposes to replace them with a New Saturn (based on the INT-20 http://www.astronautix.com/lvs/satint20.htm). This vehicle can be flown in the 2, 3 or 4 F-1A version with a payload to LEO of around 22 up to around 64mT. It would replace both the Saturn IB and be a launcher for future "wet-workshop" derived Skylabs. It will be called Saturn 2, 3 or 4 (depending on the number of engines and with Arabic numerals to set itself apart from the previous generation) .
So, I would guess maybe the following timeline:Up to 1975 (ASTP), as actually happened. Development of INT-20 continues apace along with the F-1A and J-2S, which is now also optimized for mass production and cost reduction. Pad-39B is reconfigured, with a new permanent access tower for the 85m Saturn 2/3/4. Also, development of the block III Apollo (smaller, lighter SM, and solar panels, optimized for LEO work, up to 5 man crew). Then:1976: Maiden flight of Saturn 21977: Launch of Skylab-5, using a Saturn 2 and block II leftover. Around 90 days in orbit,1978: Launch of Skylab-6, using the new block III, 4 man crew, station reboost, 70 days. Skylab B is cancelled for good, instead development of Spacelab, a modular spacestation based on 35 ton blocks to be launched by Saturn 3 and assembled on orbit.1979: Skylab-7 (4 man, 100 days). Last Skylab flight because the station has major problems, cutting mission short after only 32 days. Maiden flight of Saturn 3.1981: Launch of Spacelab-A (core module, unmanned, on Saturn 3). Development of Apollo Block-IV, capable of loitering for 200 days) and Apollo-C (cargo version). Maiden flight of Apollo IV in LEO.1982: Launch of Spacelab-B (hab module, on Saturn 3) and Spacelab-1 (first crew, 3 man, EVA assembly of Spacelab). Spacelab-2 continues assembly. Maiden flight of Apollo C, unmanned, automatic docking test.1983: Launch of Spacelab-C (experiment module). Spacelab 3, 4, and 5, assembly and science. President Reagan invites "our friends and allies" to participate (yes, we get Space Station Freedom).1985: Launch of Spacelab-D (2nd experiment module). Launch of Expedition 1, first permanent crew. From now on, it's pretty much ISS with crew and cargo, with JAXA and ESA participation. Studies begin on a "lunar return" using derived hardware...I'll leave it at that for the moment. A lunar return in the 1990s is possible. We can continue along this line of thought if there is interest.
In fact, the answer to all of this is seen in the Russian space program over the same decades. They kept their "Apollo", and developed space stations that evolved from their Skylab (Salyut 1) to the Mir Space Station. We would have done the same, but in the end, our "Mir" would have been a vast cluster of Skylabs
I hate to rain on your parade a bit, but assuming you are using this hardware to get out of LEO, then you would have most likely lost a crew in the 1974-1975 timeframe due to solar activity or the reliability of the hardware. Don't forget to factor the recovery for the crew loss as well as the public's and Congress' reaction to that changing your budget. Of course that only applies if going beyond LEO.Your costs are going to be very high using this hardware for LEO only. You might want to convert a Saturn IB flight to today's dollars and assume you have to build all new hardware (development is the expensive side).And, then while we are factoring real world stuff in this exercise, don't forget test flights of hardware that has to be changed because the manufacturing processes that originally built those vehicles no longer exists. A J-2X becomes needed much earlier because you can't build the original J-2 anymore. I forget how many items on the original Saturn were "lifetime buys", so that NASA stored enough through the last Saturn V and then would have to go back to the drawing board if more were needed.It's not all roses in this alternate reality, is it?Andy
The most glaring need was the risky pure O2 atmosphere had to go.
Even if they had had some sort of inflatable foamed aeroshell stowed under their seats to survive the thermal environment of re-entry and the breakup of the orbiter cabin,
You mean a non existing, non demonstrated feasibility, Scifi type system?
Nitrox systems make sense for a fully developed and mature space infrastructure.
There were a lot of things that could have been done to improve the Saturn vehicles the most obvious would be to redo the S-IC to be stage and a half this is called the S-ID.You can have the crew LV be just a S-ID which is called the Saturn V-Bhttp://www.astronautix.com/lvs/saturnvb.htmCargo add an S-IVB to the I-ID making the Saturn V-Chttp://www.astronautix.com/lvs/saturnvc.htmThis had an 81,000kg payload smaller then the Saturn V but larger then the INT-21.It gets rid of one of the most expensive parts the S-II and cuts the expended F1s down the just 1.The future would have likely be reusable ferries like the Nerva shuttle or the chemical OTV along with SEP tugs for LEO to lunar transport so TLI would less important then LEO payload.http://www.astronautix.com/craft/otv.htmAs for Apollo I think Big Gemini or some sorta lifting body vehicle would replace it for LEO use.The Apollo CSM might in an updated form still have been used well into 80s for BEO.It was in clear need of updates by the 70s but no shuttle they would have had spent only on them.The most glaring need was the risky pure O2 atmosphere had to go.Eventually they probably would loose the large SM as confidence in the OTV builtup or one of the LEO lifting bodies modified to BEO.Quote from: alk3997 on 09/03/2011 03:41 pmI hate to rain on your parade a bit, but assuming you are using this hardware to get out of LEO, then you would have most likely lost a crew in the 1974-1975 timeframe due to solar activity or the reliability of the hardware. Don't forget to factor the recovery for the crew loss as well as the public's and Congress' reaction to that changing your budget. Of course that only applies if going beyond LEO.Your costs are going to be very high using this hardware for LEO only. You might want to convert a Saturn IB flight to today's dollars and assume you have to build all new hardware (development is the expensive side).And, then while we are factoring real world stuff in this exercise, don't forget test flights of hardware that has to be changed because the manufacturing processes that originally built those vehicles no longer exists. A J-2X becomes needed much earlier because you can't build the original J-2 anymore. I forget how many items on the original Saturn were "lifetime buys", so that NASA stored enough through the last Saturn V and then would have to go back to the drawing board if more were needed.It's not all roses in this alternate reality, is it?AndyIt depends on a lot of variables.If they have a lunar base they'd likely have some sorta solar storm shelter.If in transit the CSM can provide enough shielding by keeping the SM between the crew and the sun.They might have an increased risk of cancer but I heard it described as the difference between being a little radiation sick and needing a bone marrow transplant.The danger zone is if they're on the surface away from the base as the LEM it's self provides little protection.
For something actually operational you need a mixed atmosphere.
For short duration pure O2 is not risky but for weeks it starts becoming a health risk.(snip talk about Atelectasis)
Your costs are going to be very high using this hardware for LEO only. You might want to convert a Saturn IB flight to today's dollars and assume you have to build all new hardware (development is the expensive side).
And, then while we are factoring real world stuff in this exercise, don't forget test flights of hardware that has to be changed because the manufacturing processes that originally built those vehicles no longer exists.
A J-2X becomes needed much earlier because you can't build the original J-2 anymore
IF the need was there (and it's VERY doubtful it was or could be justified) then developing a new first stage, powered by the same F-1/F-1A's powering the Saturn V evolution, might barely have squeezed through... (though I doubt it). Such a 260 inch twin F-1 powered first stage could have acted as an LRB for Saturn V (though of course this would have had enormous consequences at KSC).
If you adopted the ISS' architecture of dedicated modules for power/life support/research, you could do really awesome things with a hypothetical follow on Skylab E.Such as launching a S-IVB based/sized module to provide electrical power, life support, and attitude control, etc for Skylab E; and then following it up with a S-II sized module for living quarters and experiments.It's certainly possible to put a S-II sized module up -- the dry mass of S-II-11 was 80,362 lbs; while S-II-13 was 80,463 lbs.It won't be as dense as Skylab, so it makes sense to chain it up with a smaller, more dense module which provides hotel power.According to "Description of S-II Stage Structures" from 20 April 1967; the S-II's LH2 tank was 36,883 cubic feet; which means a S-IVB + S-II station would have a pressurized volume of about 45,000~ cubic feet.Contrast this to the 32,000~ cubic feet ISS will have when the last major module is docked in 2012.Assembly costs would be massively lower too, you'd only have to pay for two Saturn INT-21 launches, which would have cost only $861~ million to fire off, versus the roughly $14,400 million needed for the 36 shuttle missions which delivered components to ISS and had spacewalks occur while docked to the ISS.
