spacetoday.net: Thrust transient cause of Falcon 1 failure

Posted: Thu, Aug 7, 2008, 7:41 AM ET (1141 GMT)
Falcon 1 3rd launch (SpaceX)

A thrust transient after the first stage main engine shut down is being blamed for the failure of the latest Falcon 1 launch, SpaceX announced Wednesday. The transient, created by fuel used to cool the engine and residual oxygen, pushed the stage forward and into the second stage after the two stages separated. The vehicle's design had already taken a thrust transient into account and put a brief pause between engine shutdown and stage separation, but the transient was longer than expected, and traced to the use of a regeneratively-cooled engine rather than a ablatively-cooled engine used in the previous two Falcon 1 launches. SpaceX said no design changes other than increasing the timing between engine cutoff and stage separation is needed to deal with the problem, and another launch, carrying no satellites, could take place as soon as late September.