Russian Moon Lander Crashes

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Wow - an "over burn" where the motor didn't shutdown and burned about 150% of planned.
I've not heard of this kind of failure before.
Will be interesting to hear how they managed that.
 
Wow - an "over burn" where the motor didn't shutdown and burned about 150% of planned.
I've not heard of this kind of failure before.
Will be interesting to hear how they managed that.
A propellant feed valve being stuck open seems like a simple possible scenario.

There's also always the possibility of a software issue when you have computer-controlled autonomous devices such as space probes.
 
Wouldn't it take two valves to stick open?
Depends upon what type of propellant and/or motor was being used in the probe to take it to the required altitude.
If it were a Hybrid motor, for example, only one valve would need to stick.
 
Wouldn't it take two valves to stick open?
Otherwise they are just venting.

Must have been SW.
Venting propellant can still produce considerable thrust if the back pressure is high enough. LOX venting from a stuck valve can produce about 8000 lbs of thrust in an RD-181 engine. Nowhere near its full thrust but enough to be a huge problem when it pushes on an empty first stage.
 
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