8

NASA always appears to use pyrotechnic devices (NASA standard initiators for explosive bolts, frangible nuts, etc.) to release elements (spent stages, fairings, etc.) where SpaceX appears to be using pneumatic latches and pushers.

Some obvious pros and cons are that the SpaceX approach favors re-use (no expendable parts, no risk of debris damage to recoverable components), and assuming the pyrotechnic fires, it definitely fires. Reading some of the literature available on-line, it appears the NASA devices, while apparently designed to be highly reliable are also very complex bits of technology.

My question is: if SpaceX is having success with their approach, do NASA standard pyrotechnics still hold any advantage, or are they on the way out in newer designs?

DrSheldon
  • 47,946
  • 12
  • 162
  • 329
Anthony X
  • 17,510
  • 1
  • 61
  • 99
  • Suggest splitting into 2 questions. I could probably answer one but not both. – Organic Marble Feb 25 '18 at 21:12
  • 1
    Pyrotechnics on spacecrafts have a long history. Each Apollo mission used more than two hundred of them. Not a single failure, see. – Uwe Feb 25 '18 at 21:13
  • Split the "related question" here: https://space.stackexchange.com/questions/25684/how-was-enterprise-held-released-from-the-carrier-747-for-the-shuttle-approach-a – Anthony X Feb 25 '18 at 23:25
  • 1
    There was an incident on shuttle mission STS-112 where one of the (redundant) pyro systems that released the shuttle from the launch platform didn't fire. More at https://space.stackexchange.com/questions/17579/how-does-a-simple-construction-keep-a-firing-rocket-on-the-ground/17580 – Organic Marble Feb 26 '18 at 02:12
  • 1
    Also on shuttle mission STS-51 there was an incident where too many of the pyros fired on a deployable upper stage and blew a hole in the payload bay aft bulkhead. http://www.spacefacts.de/mission/english/sts-51.htm – Organic Marble Feb 26 '18 at 02:17

1 Answers1

8

For a rocket or spacecraft not to be reused, pyrotechnics should be more reliable, less weight and less components. No need for pressure tanks, regulators, hoses, valves and pistons. Redundant detonators are easy and were used with success. Redundant valves are more difficult and increase weight.

There are decades of experience using pyrotechnics with success.

Uwe
  • 48,975
  • 4
  • 121
  • 206