Delta IV Heavy
Launch vehicle Delta IV Heavy (inaugural flight)
Launch site Cape Canaveral Air Force Station, USA
Date/Time 2004-12-21 21:50
Description First stage performance shortfall
Cause Faulty sensor readings
Payload Demosat (test payload), Ralphie, Sparky (experimental nanosatellites)
Desired orbit near geosynchronous


The partial failure of Boeing's first Delta 4 Heavy seems to have been caused by faulty sensor readings on all of the the rocket's three Common Booster Cores (CBCs), which together form the first stage.

According to U.S. Air Force preliminary investigation results, the right and left CBCs shut down eight seconds early after sensors wrongly indicated they had run out of fuel. The same error occurred on the centre CBC, which continued its flight after the two strap-on CBCs were jettisoned -- it shut down nine seconds early.

As as result, the second stage was left approximately 460 km/s short of the planned velocity, and thousands of kilometers short of its target. Despite the second stage's attempts to compensate for the first stage underperformance, the two student nanosatellites Ralphie and Sparky were released at a too low altitude. They failed to achieve orbit and burnt up in the atmosphere.

The primary payload, Demosat, was released into a 19,000 km x 36,400 km x 13.5 degrees orbit after the second stage ran out of fuel during its third and final burn. The apogee was about 17,000 km lower than planned, and the inclination 3.5 degrees higher.

Last modified: 08 January 2005

Launch Failures Chronology