HESSI has not had an easy path to launch. During testing it was vibrated at 20G instead of 2G, later the US mililtary rescued it from a flood and problems with the launch vehicle resulted in many months of delay. The launch involved a Pegasus rocket being dropped from a converted air-liner over the Atlantic. Although it was ultimately successful there was a moment of drama when the dreaded word's "abort" came over the speakers. Luckily the problem (launch control couldn't hear the pilot on the plane!) was minor and the rocket was dropped on the second pass. Video of the launch and a mission science briefing can be downloaded from the NASA Pegasus/OSC launch web page.