A Delta II solid rocket motor
GPS IIR-1 was launched on a Delta II 7925-9.5 rocket, serial number D241, from Launch Complex 17A at the Cape Canaveral Air Force Station. The launch occurred at 16:28:01 GMT (11:28 local time), on January 17, 1997. Thirteen seconds later, the rocket's flight termination system was activated by its onboard computer. This detonated explosive charges aboard the rocket, causing it to explode. At the time of explosion, the rocket was 1,600 feet (490 m) above the launch complex. It was the lowest-altitude launch failure at Cape Canaveral since Atlas-Centaur AC-5 in 1965 and only the third total loss of a Delta in the previous two decades.
An investigation determined that the failure was caused by a crack in the casing of the number 2 GEM-40 solid rocket motor, which started to form at T+6 seconds and grew from there. At T+12 seconds, the SRB casing ruptured and debris struck the number 8 SRB next to it, causing that motor to fail as well. One second later, the range safety destruct charges automatically activated, causing the rocket to auto-terminate, which led to the self-destruction of the first stage and the detonation of the remaining SRBs. The upper stages were blasted free. At T+21 seconds, the Range Safety Officer sent a manual destruct command to terminate the upper stages for safety purposes, resulting in their destruction. The GPS satellite and payload shroud survived intact until impacting the ground. It could not be determined with certainty what had tripped the destruct system on the first stage; possible explanations including a lanyard being pulled, a shock wave from the rupture of the number 2 SRB, or heat generated by the event.
The booster had been damaged by pressure from a support in a new transportation system which had recently been introduced. Following the failure, the system was revised, and ultrasound inspections of boosters on future flights were introduced.