Launch of a space shuttle mission is governed by a countdown. 2 clocks are maintained, the unofficial, but sometimes mentioned, L (launch) clock represents the time remaining before the scheduled launch in real time and the more often referred to T (test) clock includes several built-in holds where additional verifications are made. Built-in holds may be extended if mission parameters allow for additional checks or to correct issues.
| Attributes | Values |
|---|---|
| rdfs:comment |
|
| foaf:depiction | |
| thumbnail | |
| is rdfs:seeAlso of |