NASA’s Kennedy Space Center recently completed testing equipment that will provide electrical power and data connections to the Space Launch System (SLS) rocket until it lifts off from its launch pad.
The SLS will be the world’s most powerful rocket, launching the Orion spacecraft to send humans on deep space missions beyond low-Earth orbit. The SLS core with liquid fuel and two solid rocket boosters will provide the energy necessary to push the spacecraft to orbit.
The rocket and spacecraft will be put together in the Vehicle Assembly Building atop the mobile launcher platform, which will then carry the SLS out to Launch Pad 39B. A tower on the mobile launcher will have a series of lines connected to various stages of the rocket to provide the necessary power, fuel, and communications until launch. These umbilical lines must be able to provide the connections, release at liftoff, and retract to clear the way for lift off.
The Launch Equipment Test Facility (LETF) tested the first of two umbilicals that will connect to the rocket at the bottom outer edge of the booster, referred to as the aft skirt. The tests of the aft skirt electrical umbilical (ASEU) will confirm its design and function.
“This umbilical is the first of nine different types of umbilicals that will be put to the ultimate test before they are installed on the mobile launcher,” said Jeff Crisafulli, NASA LETF manager.
The umbilical underwent a series of tests using the facility’s Data Acquisition System and Vehicle Motion Simulator.
The Data Acquisition System is used to monitor and record about 80 channels of instruments during each test, including strain gauges, accelerometers, pressure transducers and load cells. The Vehicle Motion Simulator is a test structure capable of simulating all expected launch vehicle motions from rollout through about the first half-second of launch, when the umbilical is disconnected.
“This umbilical is especially critical because it acts like a telephone line and carries a signal to another subsystem on the mobile launcher called the Launch Release System,” said Martin Grashik, NASA mechanical engineer and test engineer for all of the SLS mobile launcher umbilical tests at Kennedy. “The Launch Release System distributes the signal to the rest of the umbilicals and the SLS boosters actually give the release command.”
Several other test objectives included gathering data for comparison to analysis models, running and revising operating procedures, and checking to ensure the umbilical worked as intended.
A team at Kennedy ramped up for the tests March 2, which began with some basic umbilical functions to exercise the umbilical’s systems and a functional check of the lifting and lowering actuators.
During the next couple of weeks, the team completed a simulated connection of the umbilical to the mobile launcher. The test was similar to the procedures that will be run in the Vehicle Assembly Building to connect the umbilicals during assembly of each SLS rocket.
Testing became more involved on the Vehicle Motion Simulator as the umbilical was attached to a representation of the flight umbilical carrier plate – the connection point on the booster — to test the range of motion of the umbilical’s compliance mechanism. The compliance mechanism allows the umbilical to accommodate differences in position between the umbilical that is permanently installed on the mobile launcher and the connection point on the booster’s aft skirt.
A series of launch and separation tests followed to simulate liftoff of the SLS.
Crisafulli said NASA also used the testing time in the facility to train the launch team on how to configure the launch accessories to support an SLS launch. After testing is complete, the umbilical will be installed on the mobile launcher.
The Ground Systems Development and Operations Program at Kennedy is overseeing the tests to verify that the umbilical meets all of the Space Launch System Program’s specifications for the entire umbilical system as NASA prepares for the first integrated launch of SLS and Orion, Exploration Mission-1.