36

TL;DR: The low technology readiness, the very, very low thrust, and the need for a catalyst bed means this was and still is the wrong technology for the intended purpose of a launch abort system and maneuvering in low Earth orbit. Low technology readiness SpaceX began working on Dragon V2 over five years ago. At that point, AF-M315E had a rather low ...


34

Providing crew escape for all phases of flight of the Space Shuttle, given its design architecture, was simply not practical. Keep in mind you have up to 7 crew members on two decks. Keep in mind that the flight regime consists of large ranges of altitude and velocities. Keep in mind that it would have to cover launch, landing, and several abort modes. ...


31

Yes, the launch escape system was used, contrary to earlier reports based on assumptions and ignorance of Soyuz hardware. However, it was not the tower that we are familiar with on Mercury and Apollo era manned rockets that was used. The Russian launch escape system, SAS (Система Аварийного Спасения, or Sistema Avariynogo Spaseniya, meaning emergency ...


28

Yes. There is a lot of good information in this presentation from the June 1966 Apollo Lunar Landing Mission Symposium relative to landing flight design including abort planning. The crucial figure is this one: which shows the capability of the ascent engine to abort all the way down to landing. It assumes a 4 second delay to separate the landing stage. ...


26

Rocket guidance systems generally use a fixed inertial platform based on gyroscopes to determine their orientation in space; an accelerometer solution would be useless to determine orientation (though helpful for position determination) as soon as the rocket was in motion. https://en.wikipedia.org/wiki/Inertial_platform Once operating, the platform's ...


25

14G sounds like a lot. To put it in context: the acceleration you can endure depends on the force vector. The position in which we can withstand G-forces best is forward (using the directions from the XKCD diagram), so spacecraft seats are placed to take advantage of this. When the rocket sits on the pad, the astronauts lie on their back. fighter pilots ...


19

While the launch escape system (LES) is important for getting the crew away on ascent there are other thing required for human-rating a craft/launch system (and you do need to pay attention to the entire system and mission, not just the rocket during ascent). Specifically for Atlas V they needed to: space.com upgrade the emergency detection system (your ...


18

Escape towers get jettisoned once they're no longer necessary, usually when the spacecraft can abort under its own power or using an intact upper stage. Using the Apollo abort modes as an example: The pad abort (before launch) and modes IA/IB/IC (between launch and escape tower jettison) would use the escape tower. Mode II (after escape tower jettison, ...


18

The Apollo capsule was allowed to tumble after being pulled away by the LAS. This tumbling would continue until the first drogue parachute was deployed, which would stabilize the capsule. The LAS and command module shroud have to be separated from the CM. There's a second set of rockets on the LAS that takes care of that. This can be done even if the ...


16

Soyuz 10 used the launch escape tower from the pad.


14

While a number of sources say the motivation for using ejection seats instead of LES is to save weight, a tower launch escape system can be jettisoned relatively early in flight, while ejection seats have to be carried all the way into orbit. Depending on the exact masses and time of tower jettison, this can be a wash or even slightly favorable to a tower ...


12

Proposed Russian spacecraft, for Mars, Lunar, or orbital tug missions that would have used a nuclear reactor, did provide escape tower like functionality for the reactor. But the issue is that the entire payload stack, is usually too big to save with an escape tower (and still have any payload left to go to orbit, due to weight of escape system). In the ...


12

From Encyclopedia Astronautica (emphasis by me): This configuration was selected only after considerable engineering angst. From the point of view of pulling the capsule away from the rocket in an emergency, positioning the capsule at the top of the spacecraft was ideal. But to use this layout with the living module concept, a hatch would have to ...


12

That is an anechoic chamber. An anechoic chamber ("an-echoic" meaning non-reflective, non-echoing or echo-free) is a room designed to completely absorb reflections of either sound or electromagnetic waves. They are also insulated from exterior sources of noise. The combination of both aspects means they simulate a quiet open-space of infinite ...


11

You'll have to define 'pad abort' as you are talking about both Apollo, Soyuz and the Space Shuttle. Apollo/Soyuz and Space Shuttle are vastly different vehicles, hence they have vastly different definitions of aborts. There were five RSLS (Redundant Set Launch Sequencer) aborts during the STS programme (on STS-41-D, STS-51, STS-51-F, STS-55 and STS-68). ...


11

US Gemini capsules had ejection seats, not escape towers. Shuttle had ejection seats (commander and pilot only) for the first 4 flights (albeit with limited useful envelope: close to launch and landing). And after STS-51L the shuttle had a bailout system (although it was useful in only a minuscule number of possible scenarios.) Shuttle bailout testing ...


11

The Soyuz LES takes only the orbital module and reentry module with it, in order to maximize acceleration away from the launch vehicle. The diagram you link to in the question implicitly confirms this; the proportions of the separated section are such that the OM and RM fit neatly, and there’s no room for the SM. Per russianspaceweb: In 1965, developers ...


9

That maneuver was called "fire in the hole". See the wikipedia article. According to this NASA paper there was an extra "fire-in-the-hole shield". During Apollo 5, 9 and 10 there was a test of "fire-in-the-hole", see 1 , 2 and 3. The LM test of Apollo 5 was done unmanned. The insignia of the mission Apollo 5 was designed by Grumman engineers to show the ...


9

When I worked with Vladimir Titov on STS-86 he was fine after experiencing such an abort years earlier. If your question is could an injury happen, sure, anything can happen.


8

Weight is a major factor... every item on the vehicle has to have a good reason to be there. Rather than trying to save an expensive payload in the event of a launch failure, it may be simpler/cheaper to maximize the reliability of the launch system, and accept the cost of losing the entire vehicle and payload in the (presumably rare) event of failure. Even ...


8

It's simple economy. Unmanned payloads can and usually are insured against loss due to launch complications. The insurance costs less than the additional cost to install a launch escape system.


7

While Dream Chaser is, indeed, based on HL-20, one of the few significant changes was removing the launch abort adapter and replacing it with an integrated abort system. This was made possible by using a pair of liquid bipropellant engines (though originally the plan was to use hybrid motors) as the spacecraft's main propulsion system. The same engines could ...


7

Since Dream Chaser is based on the HL-20 lifting body design, I presume it would have same or similar Launch Escape System (LES). What follows are to the question the most relevant excerpts from the Launch Pad Abort of the HL-20 Lifting Body journal article (including diagrams). JOURNAL OF GUIDANCE, CONTROL, AND DYNAMICS Vol. 17, No. 6, November-December ...


7

Besides reasons mentioned by others - humans are more durable against "impact" type stress than usual orbital payloads are. The satellites are calculated to withstand the sustained several g of rocket acceleration, but not a single ~80g shock of hitting the ground. That means their emergency system would have to be far more advanced - provide much more ...


7

@Philipp has nailed it in his answer in my opinion, and we've, in a sense, discussed the economic viability of such payload escape systems versus insurance cost before in our main chat room, too. Technical and economic feasibility studies of such payload escape systems have however been done before, one such good example is Fred E. Wagner's thesis on ...


7

Great idea! The Apollo designers agreed. The Emergency Detection System / Abort Sequencer would indeed shut down the engines when the appropriate abort was called. Shutdown of the engines was inhibited for the first 40 seconds after liftoff so that the vehicle wouldn't fall back onto the pad. The subsystem is activated automatically by the ...


6

No. Dragon V2 will likely be the first capsule with a built in "pusher" LES, an array of SuperDraco engines. The reason it has never been done is because the LES is usually considered dead weight once the craft has reached orbit. Jettisoning the LES as early as possible saves payload mass. The reason SpaceX and Dragon keep it is twofold. Falcon 9 v1.1 is ...


6

Consider the Soyuz spacecraft vs the Apollo spacecraft. Both are 3 man spacecraft originally designed for the lunar mission. Both use tractor rocket escape systems for launch abort. In the Apollo spacecraft, the reentry craft, living area and docking functions are combined into the same module. The Soyuz separates those functions into two modules. The ...


6

Is there some form of lateral propulsion that moves the crew capsule out of the way of the booster? Yes. The Saturn-Apollo LES, for instance, has a solid rocket mounted sideways at the tip, the “pitch control motor”. In abort mode Ia, used for low altitude aborts when the booster is still flying nearly vertically, this fires briefly along with the main ...


5

Apparently, they also do electromagnetic interference testing inside what looks to be the same chamber, as just said by Elon Musk:


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