The Most Important Space Shuttle Mission Never Happened

hello it's scott manley here today i want to talk a bit about space shuttle history so over 30 years and over 100 missions the space shuttle showed a lot of different capabilities it broke ground in your space construction and satellite servicing missions things like repairing the hubble space telescope simply would not be possible in any other human rated spacecraft but there's one mission plan which drove the design of the space shuttle more than any other and in the end it never flew during the 1970s it was known as shuttle reference mission 3b and there was a closely related mission 3a so during early development of the shuttle program they actually had you know hard to get political support and it came within a single vote of being cancelled so nasa sort of played the political game and they made a deal with the department of defense they would redesign the shuttle to accommodate a wish list of requirements and well nasa pretty much paid for this and in exchange they got support from the dod but even before this happened there had actually been influence of the design from the military for example early shuttle designs had a blunt reentry with very little wings and the air force flight dynamics laboratory said you know we would prefer delta wings because those will perform more across a much wider range of air speeds and give you control all the way down giving you better cross-range capability but the actual military requirements for the space shuttle in exchange for the political support they were much more onerous on the design so the payload bay became a massive 15 feet long about a wide by 60 feet long that's about four and a half meters by 18 meters and that made it able to carry the new generation of reconnaissance satellites nasa was fine with this too because hey it helped them with their goals it certainly served them well when they were building the international space station however this large payload bay meant that the orbiter no longer had room for massive fuel tanks and that necessitated the large disposable external tank and of course the foam and its various problems the delta wing design actually also required a much more capable heat shield since it would spend more time flying like an aircraft at hypersonic speeds but anyway reference mission 3b that would be the plan that set just how big those wings needed to be transforming the shuttle orbiter from a winged space capsule to a fully fledged space plane 3b involved a single orbit rendezvous and capture of a spacecraft in near polar orbit followed by an immediate landing back in the launch site so for this the shuttle would launch from a site at vandenberg payloads to polar orbits generally have to use the west coast launch site to avoid the risk of dropping spent stages on land the vehicle would launch southwards in a carefully designed trajectory which would take 12 minutes to reach orbit and finish with the shuttle on an intercept course with a target satellite now normally when the shuttles go into orbit they're initially in a low orbit with the perigee still inside the atmosphere so they can dump the external tank and that will re-enter and then they can use the ohms orbital maneuvering system to push them into a proper orbit but this plan had to put them on the same orbit as the target likely a lot higher up and that also had to bring the tank up with them to get there fast in this design the tank would also include a small solid rocket motor that would be used to deorbit the tank quickly but this never made it into the shuttle final shuttle design so normally after reaching orbit you would then dump the excess propellant in the external tank and you do this dumping it through the engines and vents and things like that this usually takes a couple of minutes but because the time is critical in this mission they wanted to skip as much of this as possible which meant another modification to the launch design so the shuttle launch trajectories they're usually designed to be as efficient as possible to make sure that when you get to orbit you have as much propellant left over as possible and that means that you have excess available if there's an emergency but instead for this rapid rendezvous they wanted to minimize the amount of time they spent dumping propellant so they would adjust their trajectory to maximize the propellant that would be used and make sure they ended up with the minimum amount left in the tank so it was a less efficient trajectory but it saved them time overall so after dropping the tank and moving away the orbiter opens the payload bay doors and it starts preparing for rendezvous and capture it would be chasing the target about 10 nautical miles below it and seven nautical miles back behind it would be an elliptical trajectory which is designed to intercept the target in about 20 minutes so over the next 20 minutes the spacecraft is basically taking measurements off the target and making adjustments to its approach the vehicle maintains an attitude which keeps the target above the payload bay because that's where the rendezvous sensors are appointed uh there would be limited contact with ground control during this operation so they had to be able to do this of performing all the trajectory analysis on board with the onboard computer all the maneuvering on approach is performed using the small reaction control thrusters rather than the large orbital maneuvering thrusters so yeah initially the approach speed is about 30 meters per second and while the shape of the orbit will naturally slowly approach to some extent there's lots of brute force maneuvering to reduce the speed down to about three meters per second once they're within a hundred meters and less than 32 minutes after liftoff they would be station keeping within 30 meters of the target and at that point they would have about 20 minutes to capture the spacecraft presumably with the manipulator arm and then put it into the payload bay to store it stow it securely for the return to earth now you have to remember the shuttle is an aircraft and getting the center of mass just right is critical to the flight dynamics so they can't just throw it in there i don't know how they would actually be able to do this because on all the shuttle missions where they flew that did actually capture something from space they were way more caches cautious and took their sweet time in these kind of operations also by the way if you needed astronauts to help you i presume they would have to be suited up and ready to go and they'd have pre-breathed oxygen before launch and they'd maybe run straight to the airlock as soon as possible or maybe they would just like have no airlock doors and have everyone wearing pressure suits point is i don't think evas would be done for this kind of mission it wouldn't make sense with the time they had so anyway after this act of magic making the satellite disappear into the shuttle they would close the payload bay doors and perform the de-orbit burn as they cross the equator going north over africa now the deep orbit burn on this mission it is only supposed to use one of the ohms pods presumably because this is a one orbit mission and they wanted a big safety margin in case one of the olms pods failed so if you work with the principle of one working then you're guaranteed to be able to do it in time so that they're descending and entry interface occurs over europe and they begin to perform re-entry over like greenland the north pole and at this point they're aiming to touch down at vandenberg but because of the rotation of the earth the launch site has actually moved eastwards and it's about 2 000 kilometers east of their orbit track which means they have to make this long slow turn well slow it's a big wide curve turn at hypersonic speeds and this is the maneuver that sets the cross-range capabilities of the shuttle and therefore the small wings that were originally envisaged for the shuttle grew into these large delta wings so the shuttle would fly down the west coast of the us dropping sonic booms on towns along the west coast like san francisco and then it would touch down uh and come to a halt about one hour and 50 minutes after taking off so anyway mission 3a used essentially the same flight path but it was deploying a satellite into orbit so it didn't need the fast rendezvous or capture or stowing of the satellite instead it was a much easier deployment also during the re-entry it wouldn't have had the mass of the satellite on board so the wing size constraint was smaller for the 3a so 3b set the size of the cargo bay the performance of the thrusters the performance of the wings it was critical to the design of the shuttle as we knew it now if you look at the mission plans for this you'll notice that the flight path doesn't pass over the soviet union or any of their territories so this mission would be really hard for an adversary to observe and many people then took or look at this mission and they assume that this must be some sort of sneaky plan to grab some soviet satellite from orbit but i highly doubt that this was the case since they could only reasonably capture and store a satellite in the 20-minute window if it was designed for this and it cooperated the documents specify a 25 000 pound satellite in a 100 nautical mile orbit with 104 degree inclination for both launch and recovery so given the low orbit and the identical parameters i presume that it's a reconnaissance satellite probably a lot like those in the corona program but instead of returning the film via re-entry capsules the entire spacecraft is just captured and returned to the ground the size and the mass of this payload are pretty close to that of the kh9 hexagon which flew in 1971 or first flew in 1971. if you take off the mapping camera it'll just fit into the shuttle payload bay so it's possible that they were considering an evolved version of this which would fly on the space shuttle and get rid of those um re-entry capsules maybe at some point we will find some more declassified documents that will reveal the truth behind this anyway planning for these single orbit missions had apparently stopped by 1977. i think it's probably the time constraints were just too tight to make the plan feasible and at the time they were also seeing the first electro optical satellites in development so it might have been a hard sell to pursue a new film-based system at that time so without the single orbit requirements the large wings on the space shuttle were no longer needed but by that time nasa was committed to the shuttle design we all know and love of course the idea of launching the shuttle from vandenberg into polar orbits did live on and they did begin building out a launch facility at vandenberg the site was to be space launch complex 6 which had originally been planned for the titan iii carrying the gemini uh mar the manned orbiting laboratory but that never came to fruition and it never flew as a shuttle launch facility it was quite different from what we saw on the east coast there was no large vehicle assembly building and a crawler transporter instead the vehicle was assembled inside on a pad inside the service structure and then when they were getting ready for launch they would roll the structure back and reveal the vehicle there are actually photos of this facility during fit tests with the enterprise test vehicle on it so you can actually get an idea of what it would have looked like but it was never used because after challenger disaster the dod stopped working in the vandenberg facility for various other reasons and it wasn't possible to fly these kind of polar launches needed for reconnaissance from florida now sts-36 was a classified dod mission and that was the one that pushed the shuttle to the highest inclination higher than any other and to do this they had initially to fly out you know along a normal launch azimuth for safety reasons and then they dropped the solid rocket boosters and made a left turn going north to get into their target orbit so that was the end of the story of shuttle at vandenberg but it wasn't the end of the story for a space launch complex six uh they they initially tried to reallocate it to titan four but that quickly was cancelled then lockheed came along with their athena launch vehicle and they actually flew four times out of this site the rocket had to sit on a dinky little milk stool or sorry a milk stool to raise it up to the servicing height and currently delta iv flies out of there and i guess that's where it's been most successful although there is only two flights left it is kind of cool to look at it it's still very much recognizable as the original shuttle facility built back in the era when the us envisaged a fleet of space shuttles being able to do everything needed in space i'm scott manley fly safe [Music] you

Channel: Scott Manley

Views: 289,435

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Id: _q2i0eu35aY

Length: 13min 26sec (806 seconds)

Published: Mon Nov 23 2020

Reddit Comments

[u/RetardedChimpanzee]

Link to NASA’s report on this

SPACESHUTTLESYSTEM BASETINEREFERENCMEISSIONS VOTUMEIII-MISSION3A AND MISSION 3B

[u/rocketsocks]

This basic design choice (flaw, really) probably cost the Columbia crew their lives as the Shuttle as it existed had much larger wings that it ever needed in practice, which meant it needed a much larger area of extremely vulnerable wing leading edge material than it would have otherwise, an area that eventually a piece of foam/ice found during liftoff and smashed through.

It also, incidentally, is why you can tell that the Buran shuttle is somewhat of a copy of the US Shuttle. Nobody in the Soviet Union had a mission 3A or 3B profile for the Buran, but the Soviet leadership wanted a vehicle that matched the US Shuttle's capabilities as closely as possible, because they didn't know what the US was planning on using it for. Ultimately the Buran was an expression of the very high caliber of Soviet engineering and technical capability, and in some ways its design was superior to the US Shuttle. But there can be no mistake that fundamentally it was born out of an attempt to copy the US Shuttle as closely as possible, which it did so. Those that claim that somehow the Buran/Shuttle airframe is simply an inevitable result of optimizing for the job have no idea what they're talking about. The peculiar design of the US Shuttle was due to a bizarre mission profile that by chance happened to be extremely demanding and for a brief blip in time seemed to be important enough to twist the entire program around to accommodate it, but due to the vagaries of history was essentially abandoned as unnecessary and impractical before the first launch, though it left its mark regardless.

[u/Jetfuelfire]

What a giant clusterfuck. Compare to a dude smoking dope and tweeting memes and spreading the plague and shit, and he's doing a better job making rockets.