SPOTLIGHT ON KESC – Kennedy Space Center, FL

NASA’s Space Launch System (SLS) Mobile Launcher Umbilical Qualification Testing is Nearing Completion KSC’s Launch Equipment Test Facility (LETF)

The testing phase of KSC’s Mobile Launcher (ML) umbilicals, which will be used to launch NASA’s new Space Launch System (SLS) Heavy Lift Vehicle, is nearing completion at KSC’s Launch Equipment Test Facility (LETF). As part of KSC’s development of SLS Ground Systems, the Mobile Launcher is being prepared to launch the new Heavy Lift Vehicle, which has a scheduled test launch, Exploration Mission 1 (EM-1), in 2019. Part of the ML development involves design, fabrication, testing, and installation of multiple umbilicals that will interface between the Mobile Launcher and the Vehicle. These include: the Aft Skirt Electrical Umbilicals (ASEU); the Orion Service Module Umbilical (OSMU); the Interim Cryogenic Propulsion Stage Umbilical (ICPSU); the Crew Access Arm (CAA); the Aft Skirt Purge Umbilicals (ASPU); the Core Stage Forward Skirt Umbilical (CSFSU); the Core Stage Inter-Tank Umbilical (CSITU); the Tail Service Mast Umbilicals (TSMU); the Vehicle Stabilizer System (VSS); and the Vehicle Support Posts (VSP).

Before installation on the Mobile Launcher, each umbilical must be tested at the LETF. Qualification testing verifies the umbilical performs as designed. To verify performance, the LETF simulates conditions that each umbilical will encounter: from the time it is mated in the Vehicle Assembly Building (VAB); during rollout to the Pad; during severe weather conditions at the Pad; and during lift-off. To simulate these conditions, the LETF uses a Vehicle Motion Simulator (VMS) and rain simulators. The testing usually consists of several phases. Phase One is used to test alignment and the ability to mate and de-mate in extreme coordinates. Phase Two testing is used to perform excursion testing, which simulates horizontal movements. Each umbilical is instrumented with load cells, strain gages, temperature, and many other sensors to record loads and other measurements that are monitored to verify performance. The main purpose of this phase is to verify the loads will not damage the vehicle or the umbilical. Phase Three testing usually involves primary and secondary liftoff testing without cryogenics. Primary liftoff testing uses a primary disconnect devise, such as a Collet Release Mechanism. Secondary liftoff testing involves programming the primary disconnect to fail, and the secondary release mechanism, such as lanyards, will engage and force separation. Again, it is critical to record the loads during this phase. High-speed video is also used during this phase to verify the umbilical is rotating and disconnecting properly. The last phase is a full-up disconnect test. Depending on the type of umbilical, this could include flowing cryogenics (LN2 or LH2) and rain simulation. Once the testing is completed, the data is analyzed, and if NASA determines that the umbilical performed as designed, it will be re-located to the Mobile Launcher for installation.

To date, the LETF has completed testing and delivered to the ML: the Orion Service Module Umbilical (OSMU); Core Stage Forward Skirt Umbilical (CSFSU); the Core Stage Inter-Tank Umbilical (CSITU); the Aft Skirt Electrical Umbilicals (ASEU); the Aft Skirt Purge Umbilicals (ASPU); and all ten Vehicle Support Posts (VSP). Currently, the LETF is testing Interim Cryogenic Propulsion Stage Umbilical (ICPSU), the LO2 Tail Service Mast Umbilical (LO2 TSMU), and the Vehicle Stabilizer System (VSS). Remaining umbilicals to be tested are the LH2 Tail Service Mast Umbilical (LH2 TSMU) and the Crew Access Arm (CAA). The LETF is maintained and operated by ESC managers, test conductors, engineers and technicians. Testing at the LETF is expected to last through February of 2018.


Rick VanGilder
Program Manager – KESC
Sierra Lobo, Inc.
Kennedy Space Center, FL

Orion Service Module Umbilical (OSMU) Mated to the Vehicle Motion Simulator. Photo Credit: NASA
Core Stage Forward Skirt Umbilical Mated to VMS #2 at the LETF. Photo Credit: NASA