Eyes Turned Skywards

Post 7: Skylab 2 and Skylab Repairs
Well, it's Wednesday again, and you know what that means: new ETS! Today's mission:

FIX ALL THE THINGS!

Eyes Turned Skywards, Post #7:

Ten days after Skylab's launch, another launch day dawned cold and clear at the Cape after a late January cold snap and overnight freeze. While those at the Cape were confident that the cold snap and freeze would not hamper their ability to conduct launch operations, flight controllers in Houston were less sure. The future of the program had been gambled upon the success of Skylab, and any failure now could be fatal not just to the crippled station in orbit, but to NASA in its entirety. Having participated in some of the development effort at NASA to find a solution to the myriad issues plaguing Skylab, the astronauts were more sanguine about their prospects than the flight controllers. Commander Pete Conrad summed this up in a phrase shortly after liftoff that quickly became the unofficial motto of the mission: "We Fix Anything". Additionally, however, it was obvious that there was an urgent need to repair the station. Another five days of non-functionality could permanently cripple the station and prevent it from ever being used, and without NASA ever attempting a repair. In the end, go-ahead was given and Skylab 2 experienced a picture-perfect liftoff, smoothly climbing into orbit ready to rendezvous with the station and begin repair attempts.

The first priority was to examine the jammed solar panel. It was possible that it was merely stuck, and a good hard pull would set it free, but the data flight planners had available could not resolve the issue. After rendezvousing and taking a short lunch break, the crew set out to discover if this was the case. Visual inspection seemed to be favorable, although not compelling, and they were given the go ahead to make the attempt, with Paul Weitz taking the lead during the EVA. Unfortunately, things would not prove so simple. While Weitz was able to use the "shepard's crook" tool to grab the stuck panel, his efforts to simply pull it free were futile, instead causing noticeable motion of both the Apollo spacecraft and the station itself. Faced with this defeat, ground planners decided to instead focus on deployment of the parasol developed at Johnson Space Center. While the power supply issues caused by the jammed panel were serious, the extremely high interior temperatures caused by the loss of the sunshade/micrometeroid shield were far more pressing. Happily, the high temperatures had not caused toxic materials in the interior to degass, and the parasol was quickly and successfully deployed from the sun-side scientific airlock. Unfortunately, this would prevent some of the planned scientific agenda from taking place, as the airlock remained blocked for the remainder of Skylab's lifespan.

With the failure of the first attempt to unjam the solar panel and the success of parasol deployment, the Skylab 2 crew settled in to begin working on their scientific agenda while the ground crew worked on a different procedure to fix the station's power supply problems during a space walk near the end of the flight. This agenda consisted of three major areas: solar physics, earth observation, and biomedical studies, with observations of Comet Kohoutek (then close to perihelion) also included when possible. Each proved highly successful, with the biomedical research providing particularly important results that validated NASA's focus on further space station development. Contrary to the fears of some before the flight, astronauts proved entirely able to function in space and space sickness turned out to be much less debilitating on long missions than had previously been suspected. Indeed, being in space appeared to provide some protection against motion sickness, at least once an initial acclimatization period was completed.

Finally, after several weeks on the station, the ground crew had developed a plan to unjam the solar panel and restore full functionality to the station. The first step would be building a jury-rigged EVA path from the edge of the main Skylab module to the solar panel root. As it was never intended that astronauts would be spacewalking down the habitat, and the outer skin was supposed to be protected behind a pop-out solar/micrometeroid shield, no handholds, footholds, or other assistance devices had been provided leading to the spot, and from Gemini experience NASA knew that it would be nearly impossible for astronauts to reach the panel without something to hold on to. Using this rail, one of the spacewalkers would move to the panel and place a cutting tool on the strap which had prevented the panel from opening. Then, using the improvised EVA rail as a lever, he would force the cutting tool's jaws closed and cut the strap. Unfortunately, this would not quite be the end, as the panel mechanism had probably jammed due to space exposure since launch. Therefore, the rail would see one final use to help force the mechanism open, hopefully curing Skylab's power supply woes once and for all. After an intensive review of the plan with the ground and a good night's sleep, Pete Conrad and Joe Kerwin stepped out of the airlock nearly halfway through the mission to begin their spacewalk. Three and a half hours later, they reentered the airlock having accomplished the first inflight repair of a spacecraft in history (and what was at that point the longest spacewalk in history). The solar panel had been successfully deployed, and juice was already flowing into the station's batteries.

After the drama of Skylab's first few weeks, the remainder of the mission seemed to flash by as if a dream. Another spacewalk took place nearly two weeks after the main one, this time to retrieve and change out film in the Apollo Telescope Mount, but it was no longer a life-and-death matter. The success of the repair had boosted NASA's credibility to new heights back on Earth. Critics who had questioned the value of astronauts and the usefulness of space stations as opposed to robotic platforms were silenced by the salvaging of a mission that would otherwise have caused the write off of hundreds of millions or even billions of dollars of equipment and training. Finally, after 28 days in space, the first Skylab crew returned to Earth, splashing down in the Pacific Ocean near the recovery ship USS New Orleans.
 
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Well, actually....there really hasn't been much use of Atomic Rockets in the prep of this TL. I like Atomic Rockets, I've spent hours on the site (and the naming of the Apollo 18 LM is a nod to that), but the material there just isn't suited to writing a hard scifi story based on current or near-term tech. (Which is largely because Winchell is a scifi reader interested in raising the level of science in novels, not a rocket scientist.) It owes more to Astronautix and Schilling's Launch Vehicle Performance Calculator, really. I love the site, it's a great primer on realistic space stories, but largely this isn't based on material from it. I do happen to know Eyes Turned Skyward has Winchell's Official Atomic Rockets Seal of Approval though:

"It's the sort of thing I'd be writing, if I was a real engineer, instead of just playing one on the internet."--Winchell Chung
 
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Bump back to the first page. To add some real content, thanks to all our readers who've helped get us to over 3000 views already. If anyone has an comments, questions, or speculations, I'd love to hear them.

EDIT: Over 3200, I should say! I hadn't looked at the counter since this morning. Wow, folks.
 
Good stuff. So I'm clear - repairs to Skylab have been more successful than OTL?

Just as successful, actually. The big problems were the loss of the solar shield and the jamming of the one (surviving) solar panel. There wasn't much else that was actually wrong with the station as such.
 
I do happen to know Eyes Turned Skyward has Winchell's Official Atomic Rockets Seal of Approval though:

"It's the sort of thing I'd be writing, if I was a real engineer, instead of just playing one on the internet."--Winchell Chung

Close enough. :)

I hadn't run across Silverbird Astronautics before - nice site!
 
I often feel guilty not commenting in threads I really like; sometimes I fall silent because I think things are really going well and I have nothing to add. Then again sometimes I yammer away anyway.

All I have to say at this point--you guys, E of Pi, Truth is Life--you know how they say "TV Tropes Will Ruin Your Life?" You're ruining my life! (Well, to an extent all of AHC does that). But just lately---

I've been trying to figure out if something like a NERVA rocket would be any good in any stage of achieving orbit. It isn't so much this thread as this one that sent me down this primrose path. Me, the "let's avoid nuke if we can" guy--you're luring me over to the Dark Side, is what!

Well fortunately the lame potentials of a NERVA type engine for an orbital launch mission help keep me from going there. From what I've found (including some 100 page PDF of the actual research program engines) we could get a fantastic specific impulse of 800 (the last actual test engine built would have been more like 700 though). With specific impulse nearly doubled over the 420 or so of the hydrogen-oxygen SSME type engines, couldn't we get either dramatic reductions of the launch weight for a given payload or greatly increased payloads for a similar launch weight?

Well, as you guys probably know better than me, sadly not. The "nominal NERVA" I've got in my head now (with numbers adjusted for convenience of mental calculation) can take 40 kilograms a second of hydrogen and boost it to 8000 meters/sec effective exhaust speed, for a thrust of 320,000 Newtons. That sounds impressive until you divide by 10 to get a force equal to the Earth surface weight of a 30 ton mass, and realize that something like the Shuttle Orbiter masses 100 tons. And the "engine mass" in my head from the various versions I've skimmed is, for that sort of output--30 tons. In other words, if we could get that thrust while having Scotty teleport the fuel continually into the engine, it could just barely lift itself--just itself, no infrastructure, fuel, tanks, let alone payload--to hover on the launch pad.

At that in assuming 40 kg mass flow I cheated a bit, kicking it up from the best figures I'd ever seen for a convenient number.

And I hope the "engine mass" of 30 tons includes the whole thing--reactor, shielding, plus the engine nozzle and pumps and coolant loops and so forth.

Such an engine might accomplish great things in slowly but efficiently boosting an already-orbiting deep space vehicle into an interplanetary trajectory. It obviously can't boost anything into orbit.

Plus another drawback of the NERVA is that those high ISPs are for operating in vacuum. All engines designed for vacuum thrust will be worse off trying to thrust in air; the high density of surface air will impede the flow. Well, the penalty for typical liquid fuel chemical rockets seems to be in the ballpark of 25 percent or so--bad news to be sure, but basically the engines still work. But some reference I can't cite at the moment mentioned a much more dramatic reduction of a NERVA rocket's thrust in atmosphere--something like 5/6! On Earth then that bare NERVA being fueled magically could not even come close to lifting itself!

But wait! All is not lost! After all the Shuttle itself did not rely on its vaunted 420 ISP hydrogen/oxygen engines to take off the launch pad either! Nope, it used much lower ISP solid fuel boosters that taken together massed about half the mass of the whole launch pad weight of the craft.

So I was reasoning, could the NERVA be the engine that completes orbital insertion, a final stage, and could the efficiency of its thrust result in propellent savings so great they offset the dead weight of that 30 ton engine? I was actually running the rocket equation in reverse, working backwards from a circular orbit, estimating how far a time-reversed ascent turned into a descent (not an actual descent, I'm assuming mass increases as it backs down, running the film of a launch backwards, not a re-entry) would fall under that feeble thrust and how fast it would be "falling" as it "entered," then asking what sort of boost it would take to supply the implied (upward, in real, non-reversed life) vector; the NERVA stage would be after and above that.

Well, I figure that around the time we'd have "slowed" down 1000 meters/sec or less, the rocket would be in the upper stratosphere and coming "down" at 500 meters a second or so. So only something like 1/8 or 1/9 the total mission delta V could be provided. The good news is, that means only about say 10 tons of propellent would be needed for the upper stage.

So last night I took these speculations to the Silverbird calculator. After getting a feel for what the inputs mean (and making some spectacular mistakes--I overlooked that the thrusts specified for the stages are supposed to be kiloNewtons and so was blithely proposing 3000 G acceleration engines:eek: for instance--I started playing around with putting this thing on top of a SSME type set of lower stages.

Well, the calculator worked fine and showed me some attractive figures, so I tried shifting propellent mass from the lower stages to the nuclear one, expecting to have the calculator tell me when the payload fell again to zero, due to the nuclear upper stage simply not having time, with its feeble thrust, to build up to orbital speed before it comes crashing down first.

But it did no such thing! It blithely let me transfer more and more fuel to the 300KNewton propelled upper stage, giving me rosier and rosier scenarios for payload to orbit the more massive I made that last stage!

for quite some time I happily took the answers, figuring I must have overlooked something that made this make sense. But then I looked at how long it would take to expel these hundreds of tons of hydrogen, and realized it would take hours or even days!

I wound up going to bed around 2:30, when I was supposed to wake up at 4:30.

So now I'm back to the conclusion that actually, just using hyrdo-oxy combustion engines all the way to orbit is the smart thing to do.

And I can't trust the Silverbird calculator with anything weird apparently.:(
 
I often feel guilty not commenting in threads I really like; sometimes I fall silent because I think things are really going well and I have nothing to add. Then again sometimes I yammer away anyway.

All I have to say at this point--you guys, E of Pi, Truth is Life--you know how they say "TV Tropes Will Ruin Your Life?" You're ruining my life! (Well, to an extent all of AHC does that). But just lately---

*snip*

I wound up going to bed around 2:30, when I was supposed to wake up at 4:30.

So now I'm back to the conclusion that actually, just using hyrdo-oxy combustion engines all the way to orbit is the smart thing to do.

And I can't trust the Silverbird calculator with anything weird apparently.:(
Yeah, if you're really interested you should read through the paper where Shilling lays out the method. It's a relatively short PDF and explains the assumptions and particularly the corner cases where they are not valid.
I've always thought of the various 'atomic rockets' as being more for transfer orbits (Earth-Mars, say) than for digging your way out of the gravity well in the first place.

That is roughly my thinking as well, but even there the high engine mass means you may not see an improvement in payload. After all, the burnout mass in the rocket equation is payload plus the rocket mass. For instance, an ISP increase from 420 s to 900 s in an Earth Departure Burn with delta-v of 4 km/s will see a mass ratio drop from 2.59 to 1.56. However, if the atomic engine craft masses anything more than 1.66 times the chemical engine craft (which is well within the range of the possible) then the chemical craft will actually have a smaller initial mass in LEO for the same payload to the transfer orbit. The higher burnout mass of the atomic engine cancels completely the benefits of the higher mass ratio.
 
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Post 8: Apollo-Soyuz Test Project I, Skylab 3, 4, 5, and Skylab End-Of-Mission
Well, it's once again turned into Wednesday, so once again, here's a new ETS post. When we left off, Skylab 2 had succeeded in performing basic repairs to save the Skylab station. This week, it's time to put it to use.

Eyes Turned Skyward, Post #8:

With the completion of the first manned Skylab mission, Skylab (and indeed NASA’s entire station-focused program) had been saved from failure. It now fell to the later missions to fully utilize the station. Skylab 3 and 4, launched in June and November of 1974 respectively, would complete repairs to the station and then use the station’s capabilities to perform observations of the Earth, the Sun, and other astronomical bodies, as well as performing biological observations on the effects of microgravity on humans and other living things. Every Skylab flight was intended to beat the record of the previous mission in terms of time in space, culminating with Evans, Gibson and Pogue’s 84-day Skylab 4 flight. In addition to this data, the feedback of the astronauts on the realities of long-term spaceflight from food to sleeping to scheduling to use of space were being monitored and incorporated into planning for the follow-up spacecraft (Block III Apollo and the AARDV) and the modification of the backup Skylab-B into a a follow-up station, Spacelab, which was to play host for the second phase of the Apollo-Soyuz Test Project.

As these plans and preparations were being finalized and put into action, the first ASTP mission was carried out in 1975. On this flight, the Russian Soyuz 19 conducted rendezvous and docking in low Earth orbit, exchanged gifts and performed the first international joint operations in space, including several precision formation flight maneuvers, including using the Apollo spacecraft to occlude the sun to enable the Soyuz crew to image the sun’s corona. In addition to being the fourth flight of veteran American astronaut Thomas Stafford and the second for Alexei Leonov (the first spacewalker in history), this flight was the first flight for both Bruce McCandless and Mercury 7 member Deke Slayton, who at 51 was the oldest astronaut to fly to that point. However, despite its politically valuable joint operations successes and personnel records, failures of the Apollo hardware during descent and splashdown nearly cost the crew their lives. The CSM’s RCS was accidentally left active during entry, leading to the cabin being flooded with toxic nitrogen tetroxide fumes. Additionally, airbags in the nose designed to prevent the capsule from coming to rest in a nose-down attitude failed to deploy. Thankfully, the capsule did not require this assistance as it touched down successfully nose-up, but it was a less-than-stellar end to the last flight of a Block II CSM with two failures that put the crew at risk.

Although the splashdown of the ASTP-II marked the end of an era with the retirement of the Block II Apollo, it was not the last flight for the Saturn 1B. The new Saturn 1C intended for Spacelab crew and cargo flights was delayed into 1978, so planning for Spacelab called for flying the first tests of the Apollo Block III CSM and the Aardvark logistics spacecraft on three surplus Saturn 1B boosters, including the new Skylab 5 mission. Following a successful first flight of the Aardvark in January 1976 during which maneuvers similar to those required to rendezvous and dock with Skylab were demonstrated under ground control, the Skylab 5 mission was launched in May 1976.

The Skylab 5 mission plan was a variant on a mission that had been discussed for several years. Essentially, the crew were to dock with the orbital workshop (testing out the Block III CSM in the process), spend 20 days checking out and securing the station, then receive an Aardvark. Using supplies from the Aardvark, the crew could then extend their stay another 40 days before departing the station and leaving the Aardvark attached. Finally, the Aardvark’s engines (commanded from the ground) would be used to de-orbit Skylab, demonstrating orbital control techniques that would be used on Spacelab for the re-boost of the station. In the event of an Aardvark failure, contingency options included falling back to an earlier plan to use the Apollo’s SPS engine to perform this de-orbit burn. It was an important step in the transition from Skylab’s orbital outpost to Spacelab’s international base in space, proving many of the techniques and technologies needed for the long-term supply and operation of the future station.

The Skylab 5 crew consisted of the backup crew from the Skylab 3 and 4 missions, Rusty Schweickart as commander, with Vince Lind as Pilot and William Lenoir as Scientist-Pilot. Skylab 5 was Schweickart’s second flight, having served as CMP and performed EVAs on the Apollo 9 flight that first tested the Lunar Module in Earth orbit. During that flight, his EVA had almost had to be cancelled due to Schweickart’s issues with microgravity adaption. Post-flight, he had spent extensive time working with flight surgeons on the causes of space sickness, and the further study of this was to be a goal on Skylab 5. Skylab 5 was the first flight for both Lind and Lenoir, though both had extensive experience as backup crew and in the support of experiments from past flights.

In addition to the purely technical aspects of the mission, there was other importance--the flight would (if the AARDV was successful) overlap with bicentennial celebrations on July 4, 1976. In honor of this, NASA worked to arrange a special event on Skylab. The event would begin with a call from President Ford to the station astronauts. Next, NBC, ABC and CBS reporters including the venerable Walter Cronkite would have the chance to conduct the first live interview with astronauts in space. Finally, NASA would be covering the landing of Viking 1, hoped to be the first successful Mars landing. In addition to these activities in space, NASA also played host to a science and technology exhibit in a series of geodesic domes in the parking lot of the Vehicle Assembly Building. The keystone exhibit consisted of the Skylab test article (as ongoing modification work rendered Spacelab unfit for display), mockups of Apollo Block III and the AARDV, the Pioneer H space probe, and a mockup of the Viking 1 lander. At the event, the Pioneer H was officially transferred to the Smithsonian, though it would not be moved to the museum until 1977.

Beyond the bicentennial events, the Skylab 5 mission was a complete success, achieving all major objectives. The Block III Apollo and the Aardvark both performed well, and the re-docking maneuver of the CSM to make room on the station’s MDA for the Aardvark was executed perfectly, a prelude to the common use of such port swaps on future stations. The transfer of supplies and equipment into the station from the Aardvark was achieved, and though microgravity added some wrinkles that had been unanticipated, they were not showstoppers. Finally, the ground-commanded de-orbiting of the station using the Aardvark’s engines went perfectly, verifying that re-boost of Spacelab and future stations would be possible using the Aardvark’s engines, a key element in the plans for Spacelab. The station entered on-time and on-target over the Pacific Ocean to avoid debris falling onto populated areas. The Skylab program was officially complete, having generated information about long-duration spaceflight that were critical to the preparations and plans for Spacelab.
 
So things are going rather well for NASA right now - besides a few small issues. They managed to control the de-orbit of Skylab and thus avoid a hefty littering fine from the Australian Government, which they still haven't paid OTL. Deke Slayton finally got his flight in space, so that's the same as OTL. Block III Apollo CSM and Aardvark Resupply Craft work well. Viking and Pioneer or going well. All in all, a good run for them so far.

My questions - as usual - involve the other key players. ESA and CCCP.

IIRC, by this time, the SU has managed to get their UR-500 up to an acceptable reliability rating following its disasterous initial run as a direct result of its crash-development run in the mid-60s. So I suspect they will either improve on it further, possibly for larger manned spacecraft and continuation of their Salyut programme, which by Salyut 4, was working well enough. Or use what they've learned from their constant failures and the ASTP to redesign their entire approach setup - as they did OTL. The main reason Energia/Buran was able to work properly on its first and only flight, thanks to all the ground tests and de-bugging of system prior to flight. How close to the mark am I?

As for ESA. With Europa able to work thanks to identification and correction of faults. It's gonna see some use, and perhaps some upgrades. Thought the only ones I see happening are contant diameter stages - all 3.05m - and use of booster stages, perhaps two more Blue Streaks. That, IIRC, should allow for 7,500Kg to LEO max, but would require some substantial upgrades for it to work. If I could find the source again, I'd link it. :(

In any case, I'm certain all these questions are gonna be answered soon enough.

BTW, congrats on the Official Atomic Rockets Seal of Approval! That's quite an achievement IMHO! :D
 
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So things are going rather well for NASA right now - besides a few small issues. They managed to control the de-orbit of Skylab and thus avoid a hefty littering fine from the Australian Government, which they still haven't paid OTL. Deke Slayton finally got his flight in space, so that's the same as OTL. Block III Apollo CSM and Aardvark Resupply Craft work well. Viking and Pioneer or going well. All in all, a good run for them so far.

So far, yeah. There are some difficulties, largely with the new first stage for the Saturn IC, which is actually the main delaying factor for Spacelab at this point--they have the station mods well-underway, they have the craft to fly crew and supplies to the station, they have the last Saturn V to launch the station...but without the Saturn IC they have no way to launch Aardvarks or Apollos.

My questions - as usual - involve the other key players. ESA and CCCP.

IIRC, by this time, the SU has managed to get their UR-500 up to an acceptable reliability rating following its disasterous initial run as a direct result of its crash-development run in the mid-60s. So I suspect they will either improve on it further, possibly for larger manned spacecraft and continuation of their Salyut programme, which by Salyut 4, was working well enough. Or use what they've learned from their constant failures and the ASTP to redesign their entire approach setup - as they did OTL. The main reason Energia/Buran was able to work properly on its first and only flight, thanks to all the ground tests and de-bugging of system prior to flight. How close to the mark am I?

We're not as focused on Russia as we are on the US and unfortunately Truth is our Russia "expert," not me, so I have to stay quiet on a lot of this for now. As Abe Lincoln said, beter to keep one's mouth closed and be thought a fool than to open it and remove all doubt. I can say that they're doing better than OTL, and one thing that never succeeded OTL will here: Soyuz will be retired in favor of a manned TKS launched as you guess on Proton. No Energia/Buran to steal the thunder of a new manned vehicle means that TKS gets its chance. The Russians really seem to have ADD when it came to replacing Soyuz. First there was TKS, then Buran came just as TKS was being finished and successfully tested unmanned, then the USSR collapses and they have no money to replace it, then Klipper is tossed around but with not real money behind it, and now there's another new replacement program. It really is a long story of trying to do anything but Soyuz, and constantly failing.

As for ESA. *snipped* In any case, I'm certain all these questions are gonna be answered soon enough.

Perhaps sooner than you think? ;)

BTW, congrats on the Official Atomic Rockets Seal of Approval! That's quite an achievement IMHO! :D
Thanks. :) I'm pretty proud of having earned it, and I wish I had room in my signature for his blurb as well. Winchell's site is a lot of why I decided I have a chance at being a rocket scientist one of these years, so I owe him a lot more than just thanks for this.
 
We're not as focused on Russia as we are on the US and unfortunately Truth is our Russia "expert," not me, so I have to stay quiet on a lot of this for now. As Abe Lincoln said, beter to keep one's mouth closed and be thought a fool than to open it and remove all doubt. I can say that they're doing better than OTL, and one thing that never succeeded OTL will here: Soyuz will be retired in favor of a manned TKS launched as you guess on Proton. No Energia/Buran to steal the thunder of a new manned vehicle means that TKS gets its chance. The Russians really seem to have ADD when it came to replacing Soyuz. First there was TKS, then Buran came just as TKS was being finished and successfully tested unmanned, then the USSR collapses and they have no money to replace it, then Klipper is tossed around but with not real money behind it, and now there's another new replacement program. It really is a long story of trying to do anything but Soyuz, and constantly failing.


Ah. Well - for Truth - have you sorted the critical failure mode of TKS? Namely that the heat shield has a hole in it, needed to get the crew from the Reentry Capsule to the Habitation/Service Module. Not very confidence-inspiring for me, even if I'd feel safer in an unmodified UR-500 than an Ares 1.

Finally found some Europa links here and here. After two months of searching, and that's it? Talk about thin. Hope you got more links, 'cause I'd really like to know more about Europa. And yes, I know there's plenty here. Just looking for some more.
 
Ah. Well - for Truth - have you sorted the critical failure mode of TKS? Namely that the heat shield has a hole in it, needed to get the crew from the Reentry Capsule to the Habitation/Service Module. Not very confidence-inspiring for me, even if I'd feel safer in an unmodified UR-500 than an Ares 1.
You and me both on that last bit. As for the hatch holes...they apparently had some concern with it as well, which would be why they flew a bunch of the re-etry capsules unmanned OTL, both on dual-manifested independent flights and with the unmanned TKS-to-Salyut flights. None failed. And it's not like hatches in heat shields haven't been done other places--the landing gear on Shuttle deployed through hatches in the heat shield. So, yeah. It was tested, it worked fine, and it's not too different from something that was used IOTL for 30 years. (For the record, Truth is swamped with grad school stuff, so may not be able to offer his opinions for a while, which is why I'm catching your comment directed at him.)

Unfortunately, as you say information about Europa evolution paths is really thin on the ground, especially compared to, say, the reams and reams about prospective evolution of Titan, Saturn, and whatever else. It's like the whole thing was an embarrassment they just wanted to forget.
 
Unfortunately, as you say information about Europa evolution paths is really thin on the ground, especially compared to, say, the reams and reams about prospective evolution of Titan, Saturn, and whatever else. It's like the whole thing was an embarrassment they just wanted to forget.

Definately seems that way. Though IIRC, the management was worse than at the N1 project, and we all know how well that went! Best thing I can see you doing is designing it yourself. Best I can do is some rough sketches and basic number-crunching. Which doesn't bode well for the TL I'm trying - and not really succeeding at - to develop.
 
Definately seems that way. Though IIRC, the management was worse than at the N1 project, and we all know how well that went! Best thing I can see you doing is designing it yourself. Best I can do is some rough sketches and basic number-crunching. Which doesn't bode well for the TL I'm trying - and not really succeeding at - to develop.

The Silverbird calculator is great for that, particularly if you have some idea of similar vehicles or engines to base thrust, mass, and orbital information on. Our calculations for Saturn IC's capabilities have been done on that calculator, checking the changes in capabilities compared to the Saturn IB. I'd be willing to offer further advice in PM or email or whatever, but I'm reluctant to do more--last time I did, I ended up a co-writer on this timeline you might have heard of. :)
 
The teaser is hilarious, considering the conventional wisdom of our OTL space-fans who post here that the Shuttle was in retrospect, evil and dumb and everything would be so much better if we only didn't get caught by that tar-baby!

It's amazing how much greener the grass is in some other timeline!:p

Those people aren't especially in favor of building space stations either.
 
So sorry not to have kept up in realtime; between work and volunteerism-related exhaustion and an Internet freeze-up this morning, I haven't looked at AH at all since I believe Tuesday night.

I've been refining my Timberwind-based evil plan for the Single-Stage-to-orbit thread (BTW, I think if those things work, and no one worries about the various potentials for disaster, they could serve as bases for a real SSTO vehicle--but I still think that overall it would still prove far more sensible to use the same technologies to put payloads into orbit much more efficiently using disposable stages--however, recovering the nuclear engines, at least for reprocessing and waste disposal purposes!)

However I can't find my calculator, so I've been learning to estimate exponentials in my head. Typically I have neither scrap paper, reliable pens, nor time to even write things down--and when I do much of it is literally on the backs of envelopes! Then my pens die, this seems to be either a consequence of living in a high semidesert (Washoe County Nevada) or a personal jinx.

OK, so I continue to enjoy this TL while spectating. I think if there had been a real live active space program with American astronauts in orbit between my middle school and high school years--well, who knows, maybe I'd have been more focused on actually going to work for NASA. As things were OTL while waiting for the Shuttle my mentality was more soft-focused on the fantastic ships we ought to have eventually and the message was that the huge pointy rockets of my childhood were now old hat and obsolete.

So, a question inspired by some remarks in a product of those doldrum years of OTL--in Stardance Spider Robinson made the theme of people who can really make the full mental transition to operating in zero g (OK, I know it's technically "microgravity" everywhere but the dead center of mass of the object and that's only if there's no air drag or solar wind--sue me, it's effectively zero g on a human scale) being rather rare. He mentioned Owen Garriot of IIRC Skylab Mission 2 as an example, perhaps the only one to that date, of a person who became completely comfortable operating without visual cues implying a local (and uncontradicted) vertical, and freely shifting between differently oriented zones and having no problem with two or more rival "verticals." Garriot, said Robinson, quite enjoyed zero G and "three-dimensional thinking." (The book later ended with the hope that given time--years, decades--in zero G far larger numbers of people would eventually learn to make the same transition).

I believe your Skylab missions that correspond to ours OTL had the same crews; Garriot presumably had his good times on your second mission.

With more astronauts kicking around Skylab, do you suppose there'd be more insight into the nature of human mental adaptation to zero G?

For that matter in 1978 of OTL, when I believe Stardance was evolving from a short story to a novel, while a number of Soviet space stations (all smaller than Skylab) had flown and some cosmonaut missions had been extended to many months, information from those missions would not have flowed freely, and with less space to kick around in in any of the Salyuts I suppose the Russians had fewer chances to observe variations in human adaptation, and were focused on the obviously crucial questions of physical adaptation (and for the most part, how to stop it!) But in this timeline, a few more missions of US astronauts made it to Skylab and shared its spaces, most of which had been designed to provide a particular vertical reference. So they'd know more by the late 70s than we did.

So OTL with Mir and the ISS, have there been signs of this diversity of human response, with some people like poor Schweickart having an especially hard time, a norm of people who can handle it as long as there are visual cues that there is still some sort of up and down, and more cases like Garriot showing up who sometime in the course of the mission find they can do just fine without pretending some direction is up and are mentally at ease?

It seems to me that the modular nature of Mir and ISS tends to make it easy and automatic to design in local verticals--for one thing, the modules are not only designed but assembled on the surface of the Earth, where just for practical reasons of layout during construction we'd impose the actual vertical on the module. Then, when the modules get linked up, there may well be a deliberate policy of lining up the visual verticals of each module so that as much as possible, any line of sight even through several (and from footage I've seen, one can typically only see two or three at once--the one you are in plus the next ones up and down the chain) would be consistent. People would tend to think of the ISS as a flat array of modules laid out on the "ground" on pretty much one level--kind of like Bag End--"no going upstairs for the hobbit!"

Still there must be junctions where different visual verticals clash, and the way Mir was laid out this must have been more of an issue there.

In fact, do we get these 3 "tribes" of people, the ones who really dislike not having real gravity, the ones who get by with visual verticals (but probably would be uncomfortable where these clash and either avoid the locations where this happens or arrange visual screens to minimize the problem) and finally the ones who just start caroming around freely and find virtual verticality at best an irrelevance, and perhaps an annoying restriction? With I forget how many men and women spending some time up there, what has been the verdict? Do people tend to evolve out of the spacesick phase at least into comfortable-as-long-as-it-looks-Ok phase, given time, and given time do some of that middle majority get more adventurous and comfortable with orienting any which way that happens to be momentarily convenient?
 

Hnau

Banned
Just like to let you guys know I am following the timeline and liking its direction. I'm not too science/math-savvy and the space race is not my forte, so, sorry if I can't give more constructive criticism.

e of pi said:
That is roughly my thinking as well, but even there the high engine mass means you may not see an improvement in payload. After all, the burnout mass in the rocket equation is payload plus the rocket mass. For instance, an ISP increase from 420 s to 900 s in an Earth Departure Burn with delta-v of 4 km/s will see a mass ratio drop from 2.59 to 1.56. However, if the atomic engine craft masses anything more than 1.66 times the chemical engine craft (which is well within the range of the possible) then the chemical craft will actually have a smaller initial mass in LEO for the same payload to the transfer orbit. The higher burnout mass of the atomic engine cancels completely the benefits of the higher mass ratio.

So, sorry to go a little off-topic with this, but is there any situation in which building a nuclear thermal rocket would be cost-effective? Or is it really just a waste of investment? Is there any way the space race could have seen them?
 
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