Astronomy:Built-in hold
From HandWiki
A built-in hold is a period in a launch countdown where the countdown clock is stopped. The hold serves as a milestone in the countdown and may be of a fixed or variable duration. Criteria for exiting that hold and restarting the countdown may be based on a fixed time, the completion of a checklist of work items, or a go/no-go decision from mission management.[1] For example, space shuttle launch countdowns included seven holds at T-27 hours, T-19 hours, T-11 hours, T-6 hours, T-3 hours, T-20 minutes, and T-9 minutes.[2]
References
- ↑ Evans, Ben (2009). Escaping the bonds of Earth : the fifties and the sixties (Online-Ausg. ed.). Berlin: Springer. ISBN 978-0-387-79093-0.
- ↑ "NASA - Countdown 101". http://www.nasa.gov/mission_pages/shuttle/launch/countdown101.html.
 |  |
