LOS ANGELES AIR FORCE BASE, El Segundo, Calif. — While securing the DSP-23/Delta IVlaunch vehicle after the Wet Dress rehearsal held on 28 February, two structural cracks were observed in the metallic Launch Table. The cracks appeared on the bottom of the launch table’s starboard and center bays; roughly underneath the liquid oxygen servicing equipment for the starboard and center booster cores. There was no damage to the heavy launch vehicle.

A combined ULA and Air Force investigation team, supported by the Aerospace Corporation, has been making structural assessments, and working to determine the root cause and corrective actions for the problem. The team completed initial inspections and strength analyses and determined that the launch pad structure is safe for normal crew access. The launch vehicle is currently in a safe, secure configuration.

Based on findings to date, the investigation team has determined that a liquid oxygen leak inside the launch table most likely led to the fracturing of the low carbon construction steel plates from cryogenic temperatures. The origin of the leak appears to be from the vacuum jacketed liquid oxygen propellant lines inside the launch table, which are used to fill the booster tanks. These lines were replaced in 2006 with a new design with a longer predicted service life. Specific cause of leakage from the new lines has not yet been identified.

Replacement of the liquid oxygen lines will require de-erection of the launch vehicle for access considerations. De-erection is planned for late March. In parallel, the investigation team is determining the extent of structural repairs required for the launch table. The preliminary repair plan envisions removing any cracked sections from the load path by adding external plates and stiffeners. A new launch date for DSP-23 will be established pending the launch table repair assessment and schedule.

The Space and Missile Systems Center, located at Los Angeles Air Force Base, Calif., is the U.S. Air Force’s center of acquisition excellence for acquiring and developing military space systems including six wings and three groups responsible for GPS, military satellite communications, defense meteorological satellites, space launch and range systems, satellite control network, space based infrared systems, intercontinental ballistic missile systems and space situational awareness capabilities. SMC manages more than $60 billion in contracts, executes annual budgets of $10 billion and employs more than 6,800 people worldwide.