NASA Standard Initiator explained

The NASA Standard Initiator (NSI) is a pyrotechnic device used to set off other pyrotechnic devices.It is the central multi-purpose component of a modular system of detonating cords, pyrotechnics and various other explosive charges with many different uses.[1]

The ignition charge of the device is a blend of zirconium, potassium perchlorate, Viton B and graphite, often abbreviated as ZPP.[2]

Uses of the device include:

Development

The NASA Standard Initiator (NSI) was developed from the Single-Bridgewire Apollo Standard Initiator (SBASI) which was itself based on the Apollo Standard Initiator (ASI).[3]

To provide additional redundancy and thus make the spacecraft more relieable, a double-bridgewire design was utilized, but during development of the Apollo Standard Initiator it was found that the original design responded unfavorably to RF frequencies. This resulted in a re-design with a single bridgewire which was approved in 1966. This new design introduced several other changes to improve resistance and give the device a longer shelf life, such as switching the Material of the body from 17-4 PH steel to Inconel 718.[4]
After the Apollo program ended, the Initiator was renamed and re-used on other spacecraft, such as the Space Shuttle.[3]

See also

Notes and References

  1. Book: 1 October 1963 . Proceedings of Electric Initiator Symposium - 1963 . Franklin Institute, Philadelphia, Pennsylvania . U.S. Army Materiel Command . 3-1 - 3-22 . https://archive.org/details/DTIC_AD0440764/mode/2up . 28 May 2018.
  2. Book: Thomas L. . Seeholzer . Floyd Z. . Smith . Charles W. . Eastwood . Paul R. . Steffes . 1 January 1995 . Applications catalog of pyrotechnically actuated devices/systems . Cleveland, OH . NASA Lewis Research Center . 66–67 . https://web.archive.org/web/20220822092153/https://ntrs.nasa.gov/api/citations/19950011972/downloads/19950011972.pdf . 22 August 2022.
  3. Book: 1 January 2009 . Apollo Spacecraft and Saturn V Launch Vehicle Pyrotechnics/Explosive Devices . Houston, TX . NASA, Johnson Space Center . https://web.archive.org/web/20220106185435/https://ntrs.nasa.gov/api/citations/20090015395/downloads/20090015395.pdf . 6 January 2022.
  4. Book: 1 March 1973 . Apollo Experience Report - Spacecraft Pyrotechnic Systems . Houston, TX . NASA, Lyndon B. Johnson Space Center . https://web.archive.org/web/20201212011306/https://ntrs.nasa.gov/api/citations/19730011151/downloads/19730011151.pdf . 12 December 2020.