The second test flight was originally scheduled for January 2007, but was delayed because of problems with the second stage. Before the January launch date, SpaceX had stated earlier potential launch dates, moving from September 2006 to November and December. In December the launch was rescheduled for 9 March, but delayed because of range availability issues caused by a Minuteman III test flight which would re-enter over Kwajelein. The launch attempt on 19 March was delayed 45 minutes from 23:00 GMT because of a data relay issue, and then scrubbed one minute and two seconds before launch at 23:45 because of a computer issue, whereby the safety computer incorrectly detected a transmission failure caused by a hardware delay of a few milliseconds in the process. The 20 March attempt was delayed 65 minutes, from an originally planned time of 23:00 because of a problem with communications between one of the NASA experiments in the payload, and the TDRS system.
The launch attempt on March 21, 2007 was aborted at 00:05 GMT at the last second before launch and after the engine had ignited. It was however decided that another launch should be made the same day. The rocket was launched successfully at 01:10 GMT on 21 March 2007 with a DemoSat payload for DARPA andNASA.