40 votes
Accepted

Challenger Shuttle: could the crew have survived?

One of the major errors in the Space Transportation System (STS) design was the lack of a crew escape system usable from launch to landing. Escape systems are costly, take up mass allowance that can ...
Organic Marble's user avatar
32 votes

Could the Apollo lunar ascent stage have separated from the descent stage before touchdown in an emergency?

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 ...
Organic Marble's user avatar
31 votes
Accepted

Was the LES used in the MS-10 abort?

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 ...
Ghedipunk's user avatar
  • 1,167
25 votes
Accepted

How did the attitude system of the uncrewed Soyuz 7K-OK No.1 fail on the launch pad in 1966, killing ground staff as LES was activated?

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 ...
Russell Borogove's user avatar
20 votes
Accepted

Why didn't Saturn V have grid fins? Long March and Soyuz do!

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 ...
Hobbes's user avatar
  • 127k
20 votes
Accepted

Why are launch escape towers jettisoned early?

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: ...
DylanSp's user avatar
  • 1,958
20 votes

Does a fully loaded Starship really have a thrust to weight ratio less than 1 at sea level?

Yes. It's not unusual for a second stage to have a TWR less than 1:1 at ignition; when it stages, it will have plenty of upward velocity imparted by the first stage, and as fuel is consumed the TWR ...
Russell Borogove's user avatar
17 votes

Challenger Shuttle: could the crew have survived?

Similar systems certainly exist but not at this scale Some spherical cow approximations - a parachute for a 70kg human weighs 14kg, giving 0.2kg of parachute per kg of payload. The dry mass of the ...
GremlinWranger's user avatar
17 votes

Why were ejection seats used in Project Gemini instead of a tower escape system?

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 ...
Russell Borogove's user avatar
12 votes
Accepted

When have astronauts been launched without launch escape system (tower)?

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 ...
Organic Marble's user avatar
12 votes

Could the Apollo lunar ascent stage have separated from the descent stage before touchdown in an emergency?

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-...
Uwe's user avatar
  • 48.9k
11 votes
Accepted

Does Soyuz LES take the service module?

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;...
Russell Borogove's user avatar
10 votes

Why not turn off the main engines while using the launch escape system on liquid fuelled engines?

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 ...
Organic Marble's user avatar
9 votes

Why doesn't the BFR/Starship have a launch escape system?

You are not the first to raise this question! It's worth reviewing Tim Dodd's accessible and detailed evaluation of escape systems: https://everydayastronaut.com/starship-abort/ He draws attention to ...
SusanW's user avatar
  • 383
8 votes

Why was Dragon sent to the isolation room?

Apparently, they also do electromagnetic interference testing inside what looks to be the same chamber, as just said by Elon Musk:
Lukas_Skywalker's user avatar
8 votes
Accepted

Escape tower details of Mercury spacecraft

They "...ensure(d) that exhaust from the combustion chamber was distributed equally within these three nozzles." by test and redesign. The first test on March 8, 1959 of a three-nozzle ...
Organic Marble's user avatar
7 votes
Accepted

Is a low-altitude, stable glide really absolutely needed to bail out of the space shuttle?

The escape pole / hatch jettison system was only certified to work in a controlled gliding flight situation. See Mode VIII Egress in the Crew Escape Workbook That doesn't mean that the crew couldn't ...
Organic Marble's user avatar
7 votes
Accepted

Were ejection seats on the Space Shuttle a practical safety system?

The seats were ineffective above 80K feet on ascent due to the expansion of the SRB plumes - if you ejected after that, you would pass through the plumes making a bad day worse. A call was made at ...
Organic Marble's user avatar
6 votes

Why don't unmanned launch vehicles include launch escape system for payload?

Another difference between human spaceflight and uncrewed launchers that isn't mentioned in the other answers: Capsules for human spaceflight are used for both ascent and return, so are designed to ...
djr's user avatar
  • 1,705
6 votes
Accepted

Does a launch escape system have any lateral propulsion?

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 “...
Russell Borogove's user avatar
5 votes
Accepted

Why doesn't the BFR/Starship have a launch escape system?

If Superheavy fails during launch (or even fails to launch in an unsafe way) the Starship itself might well be able to just light its engines and fly a suitable suborbital trajectory to a safe landing ...
Steve Linton's user avatar
  • 19.6k
4 votes

Launch escape trajectory

In the Apollo system the LES was comprised of three solid rocket motors. In an emergency two were used. These were solid motors so once started there was no LES control; only initiation. They did ...
tckosvic's user avatar
  • 2,262
4 votes
Accepted

Riding out an exploding rocket

This actually kind of happened during SpaceX CRS-7. The Falcon 9 booster exploded 136 seconds into the flight. The Dragon capsule was thrown from the disintegrating vehicle and plummeted back to the ...
Jörg W Mittag's user avatar
3 votes

Dragon launch escape: is nose cone ejected for parachute deployment?

Dragon’s landing parachute is stowed roughly in the nose cone hinge area, and this leads me to believe the nose cone has to open for the chute to deploy. That belief is incorrect. Other than both ...
Jörg W Mittag's user avatar
3 votes

Why is ISRO Launch Escape System so SLOW?

The official video appears to show the ignition of the Launch Escape System in slow-motion and unfortunately doesn't include a time stamp for reference. The motion of the exhaust/dust on ignition and ...
Jack's user avatar
  • 9,976
2 votes

Are there any Pusher Launch Escape Systems in actual use?

The proposed, but never completed and flown, Gemini B spacecraft might have used its solid-fuel retrorocket package, normally used for de-orbiting the spacecraft, for early launch aborts. The NASA ...
Russell Borogove's user avatar
2 votes

Why didn't the Space Shuttle have a launch escape system?

In order to obtain additional political support for STS, NASA essentially convinced lawmakers to force the Air Force/NRO to replace Titan with Shuttle as the launch vehicle for KH-11 spy satellites ...
Evan Finch's user avatar
2 votes

Why is ISRO Launch Escape System so SLOW?

The linked footage of the ISRO LES test is in slow motion. Look at how slowly the exhaust flame and smoke plumes propagate compared to Mercury, Dragon, Soyuz, etc LES launches.
Justin Braun's user avatar
  • 2,275
2 votes

Dragon Launch Escape: Attitude Control?

The SpaceX In-Flight Abort webcast (3:14 in vid, T+2:45) announcer says that the Dragon capsule uses its Draco attitude thrusters to re orient the vehicle after the trunk has separated. I think this ...
BrendanLuke15's user avatar
2 votes

How safe are launch escape systems?

Normally there are very safe and well tested and the Crew could abord safely at any time. But there are of course exceptions like the Space Shuttle which didn't have a Launch escape system. But of ...
Dragongames DEV's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible