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What role do satellites, communication towers, GPS, etc, play in the operation, and specifically the landing, of a space shuttle?

If those and any other human-made things suddenly disappeared, could an astronaut in a shuttle in space still return to earth and land manually?

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    $\begingroup$ The key is going to be starting deorbit at exactly the right moment. Getting a position based on sighting stars is enough for large-scale positioning, but the shuttle needs to land in a very specific area with relatively little control. That is different from Mercury/Gemini/Apollo/Soyuz that can all land in a much larger area. $\endgroup$ – manassehkatz Oct 22 '18 at 2:21
  • $\begingroup$ Early shuttle flights used good old aviation radio beacons (1930s technology) to guide them in an S-curve from their deorbit vector to line them up to the runway. The angle of attack (the nose-up position) of the vehicle during most of descent made it very difficult for the pilots to see the runway until a few seconds before landing. $\endgroup$ – user535733 Oct 22 '18 at 3:40
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    $\begingroup$ Well, the space shuttle itself is a human-made thing. Can you clarify what stays there and what's not? $\endgroup$ – Ister Oct 22 '18 at 9:10
  • $\begingroup$ @user535733 Excellent information! Please put that in an answer, don't lose it as a comment. $\endgroup$ – a4android Oct 24 '18 at 4:49
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Well, the space shuttle could land quite effectively without GPS; we know that because the first space shuttle flights were in 1981, and the GPS grid wasn't active until 1995.

To be fair, the initial project by the US government to implement GPS in 1973, but it's not believed that the system was operational before 1995. In any event, although they didn't have to land like the space shuttle, the Apollo Missions wouldn't have had access to GPS in order to know where they were and they landed reasonably well in their (admittedly large) landing zone.

If you think of the space shuttle as a glorified plane (and you shouldn't, but for simplicity's sake), then once you've re-entered the atmosphere landing isn't that much different to what pilots did before radar, air traffic control, radio, etc. You do your own math, you observe your surroundings and line the plane up with your eyes rather than instrumentation.

That said, re-entry is the hard bit. You have to know how and when to get the shuttle to re-enter, you have to know the right angles to approach on, etc. It can be done by someone without ground support, but that person would have to be very precise, knowledgeable and perceptive about where their craft is in relation to the Earth. It wouldn't be easy. Ideally, you'd have a number of landing sites around the world to cover off every contingency, you'd make the craft more aerodynamic, give it emergency fuel loads so that it can achieve even limited powered flight in the atmosphere, and then hope like crazy that your pilot doesn't accidently re-enter with a landing vector right in the middle of the Pacific.

Ultimately, what all these satellites, comms and other tools do is allow for better precision, not for ACTUAL landing skill. That still comes into the hands of the pilot. Without them, your pilot has to be better than they have to be with a small army of ground support just a call away, and you need to be prepared for more contingencies. Once you do that though, the shuttle (in theory) can be landed without all that support, albeit with a level of risk that an organisation like NASA would find unacceptable.

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  • $\begingroup$ Oh, rather than a glorified plane you should call it a glorified glider. The main difference is you have no second try and as the L/D ratio was only 4.5 (very, very poor for a glider) you need to be close enough from any of the available landing spots. One of the bad things about space shuttles was that they needed extensively long runways to land (15000 ft). There were only about 40 landing sites for space shuttles so chances are you aren't close enough to any of those and then you'll have difficulty in a safe landing. $\endgroup$ – Ister Oct 22 '18 at 9:16
  • $\begingroup$ It's also worth adding that during a re-entry all communication from and to a space shuttle is cut off for something like 3-5 minutes. During that time the space shuttle has to do some rather precise maneuvers. So the communication is not essential, at least not during the whole process of landing. $\endgroup$ – Ister Oct 22 '18 at 9:19
  • $\begingroup$ Actually, your own reference says that the US military used GPS in 1990-1991, so it must have been (at least partially) operational before 1995. Full, non-precision (likely sufficient for Shuttle reentry use) service was available in late 1993. What happened in 1995, as per Wikipedia, was that the military higher-precision system became fully operational. $\endgroup$ – a CVn Oct 22 '18 at 12:13
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    $\begingroup$ ...but the point that GPS wasn't commercially available in 1981 when the first shuttle flights were still stands. $\endgroup$ – Steve Matthews Oct 22 '18 at 12:46
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    $\begingroup$ @DarrenRinger, I didn't know that. Anyway, the technique to re-enter without the communication had to be in place since it was used in the early flights. Anyway it all boils down to the answer it is technically possible to land with communication broken. $\endgroup$ – Ister Oct 22 '18 at 14:10
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"How would a real modern day space shuttle operate without satellites or any kind of communications signals?"

Very carefully. As long as the astronaut was capable of doing the math on his/her own, there's no reason they couldn't land safely. The issue is, once the astronaut lands (crashes into the water), there's no guarantee they will be found by their government. Fortunately, 71% of the surface is water. Even if he was guessing randomly, there's only a 29% chance he'd fail. That doesn't mean he can slack off though.

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    $\begingroup$ A space shuttle (if it has any resemblance to the original), lands on an airstrip as a very fat glider. $\endgroup$ – Karl Oct 22 '18 at 5:45
  • $\begingroup$ Sure, but the odds they'll find an airstrip aren't as good as the odds of finding ocean. No information, no communications... It's all beneficial to ensure a safe re-entry and landing, and without it, the risk increases. Having the shuttle land in water is a far safer bet so long as you can get out. Still gonna upvote that comment though. :P $\endgroup$ – Sora Tamashii Oct 23 '18 at 0:39
  • $\begingroup$ No communication, but I guess they're allowed to have a map, right? $\endgroup$ – Karl Oct 23 '18 at 18:45
  • $\begingroup$ What good is a map if you don't know whereabouts you're at? Even if you know what country you're in, that doesn't mean you'll be able to identify the province/county, let alone a safe place to land if at all. Or do you mean a GPS-style map? At which point, no communications means no GPS signal, therefore there's no way for the system to identify whereabouts you are. $\endgroup$ – Sora Tamashii Oct 23 '18 at 22:17
  • $\begingroup$ They know exactly where they are, also relative to the ground. Firstly thay can look down and check when they pass over the coasts along their orbit, and secondly they don't even need to, as long as they have a working clock and can do astronavigation. $\endgroup$ – Karl Oct 24 '18 at 6:33
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It is possible to land a space shuttle without communication. They can compute a flight path with their onboard computer, they have all the information necessary to do that.

Aiming precisely might be a bit harder as they lock on a radio signal, much like planes do, to precisely orient themselves and keep a level approach to the landing strip. Without that homing signal, it would be harder, though not impossible, to land at whichever of the few places worldwide that were made to accommodate the space shuttle.

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  • $\begingroup$ There are some quite famous plane landings on things that weren't designed to be runways and thus lacked ILS systems that provide the homing signal. The problem (one of the problems) with the space shuttle is that it has a poor visibility. But a skilled pilot might be lucky. $\endgroup$ – Ister Oct 22 '18 at 9:12
  • $\begingroup$ @Ister You don't need ILS to land a plane. ILS makes flying the approach easier from farther out, and more comfortable for the passengers, especially in IMC (instrument meteorological conditions) and when it allows a precision approach (horizontal and vertical guidance), but ILS is not necessary for a safe landing and even when ILS is available, the pilot may elect to not fly an ILS approach for various reasons. In fact, if the pilot is flying a stepped approach, it's very possible that they won't actually do the ILS intercept and capture until very late in the approach anyway. $\endgroup$ – a CVn Oct 22 '18 at 12:26
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If you are concerned for only the safety of the crew, and not about re-using the Shuttle, you don't have to do a precision re-entry. You can re-enter anywhere and then bail out once the shuttle is slow enough: http://mfwright.com/shuttlejump.html

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  • $\begingroup$ +1 I think if humanity has lost all radio communication, re-starting a space shuttle is really not on the list of things to do. $\endgroup$ – Karl Oct 24 '18 at 6:38
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You'd be surprised what they plan for, with such an expensive mission.

There's a famous story about Apollo 11 for this, which you can extrapolate to the shuttle. To save mass and complexity, Apollo spacecraft had a 3 axis gyro. Unlike their more advanced 4 axis cousins, 3 axis gyros can suffer from what is called "gimbal lock." This occurs in a particular orientation where 2 of the axes of the gyros get lined up. When this happens, you lose information about what direction you're pointing in (because you have 3 mechanical axes and 3 dimensions, but one of those mechanical axes just got doubled up, leaving 1 dimension unmeasured).

NASA had a solution, of course, they had a device which was designed to "kick" one of the gimbal axes out of the way before you get to that point. Without getting into the math, this is kind of like looking at an object from two points of view -- it works.

Or at least it usually works. In the case of Apollo 11, there was a computer glitch (a divide by 0), which took the computer that was responsible for this adjustment offline. Once that happened, Apollo 11 was fully capable of entering gimbal lock. If that happened, it would not be able to control which direction its thrusters pushed in.

They had a solution. NASA had calculated out the path. The astronauts could take sightings out of a few particular windows to the stars, and use that to align their gyros. The result was vastly inferior to the orientation information they would have gotten from having the gyros working the whole time. They wouldn't have been able to land on the moon after doing such an emergency realignment, but they would have enough control to get back home.

Now fast forward to the shuttle. The shuttle is more complex. There's many more systems that can break down. But the Apollo missions were crafted to deal with a gimbal lock destroying the single most important bit of information they needed -- their orientation. You can make guesses as to what sort of solutions the Shuttle has.

Apollo 11 managed to fly with the computer down without reaching any of the dangerous orientations which would cause gimbal lock. They landed on the moon successfully, as we all know.

After the Lunar Module had landed, Mike Collins aboard the Command Module joked "How about sending me a fourth gimbal for Christmas?"

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