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The launch escape system is part of the Crew Dragon spacecraft, which has not entered service yet, and would probably not be used to deliver satellites anyway b
by obi1kenobi 10y ago
The launch escape system is part of the Crew Dragon spacecraft, which has not entered service yet, and would probably not be used to deliver satellites anyway because its crew-carrying capabilities add significant weight and cost.
Rocket launches have gotten fairly reliable in recent years -- launch success rates have been hovering around ~95% since the 1970s. [1][2] A 5% chance of killing 7 astronauts is unacceptably high at essentially any cost, hence the launch escape system on the Crew Dragon. However, for an unmanned launch, the entire launch escape and recovery system would have to add little more than 5% extra cost on top of the satellite and launch vehicle for it to be a sound purchase.
A Falcon 9 rocket costs about $62M. A very complex satellite can cost over $200M, so for easy math, let's say that the entire system costs $300M, 5% of which is $15M. Those $15M have to cover the following:
- powerful launch escape engines (e.g. SuperDracos) that are not recovered if the satellite reaches orbit
- hydrazine fuel for those engines (highly toxic and reactive, has to be handled with great care)
- carrying all that extra weight to orbit
- parachutes and their deployment systems
- hardening the payload to survive the physical stresses experienced during landing
- refurbishing the payload after it falls into corrosive salt water
Given all this, I am skeptical that a launch escape system for unmanned payloads is economically feasible.
[1] http://space.stackexchange.com/questions/1659/what-is-the-success-rate-of-nasa-launches/12319#12319 http://space.stackexchange.com/questions/1659/what-is-the-su...
[2] http://planet4589.org/space/log/launchlog.txt http://planet4589.org/space/log/launchlog.txt
- dTal 10y ago>A 5% chance of killing 7 astronauts is unacceptably high at essentially any cost Not that I disagree, but I find it interesting that this is "only" three times riskier than the Space Shuttle's empirical loss rate of ~1.5%
- obi1kenobi 10y agoIndeed -- and the ~5% chance is averaged across all launches (manned and not) across many countries' launch systems. So that shows how "little" the billions of dollars' worth of redundancies and backups actually improved the safety bottom line, and also how far we are willing to go to prevent loss of life.