July 27, 2017 – The Interim Cryogenic Propulsion Stage (ICPS) is the first segment for NASA’s Space Launch System (SLS) rocket to arrive at the agency’s Kennedy Space Center in Florida. It was transported from the United Launch Alliance (ULA) facility at Cape Canaveral Air Force Station, where it had been undergoing final testing and checkout, to the Space Station Processing Facility at the center.
The ICPS, a liquid oxygen/liquid hydrogen-based system, will be located just below the Orion capsule, at the top of the SLS. During the first integrated mission of Orion and SLS, known as Exploration Mission-1 (EM-1), the ICPS will provide the thrust needed to send Orion beyond the Moon before the spacecraft returns to Earth.
The ICPS was designed and built by ULA in Decatur, Alabama, and The Boeing Co. in Huntsville, Alabama. The ICPS is a modified version of Boeing’s existing Delta Cryogenic Second Stage, used on ULA’s Delta IV family of launch vehicles. Modifications included lengthening the liquid hydrogen tank, adding hydrazine bottles for attitude control, and making some minor avionics changes to meet the design parameters and performance characteristics NASA required to meet flight objectives.
The ICPS is powered by an Aerojet Rocketdyne RL-10B2 engine – also currently used on the Delta Cryogenic Second Stage.
The Orion capsule is being built by Lockheed Martin Space Systems of Littleton, Colorado. Orion will serve as the exploration vehicle that will carry crew to space, provide emergency abort capability, sustain the crew during space travel, and provide safe re-entry from deep space return velocities. As part of Lockheed Martin’s Deep Space Gateway, the Orion capsule, along with a habitat module, will be able to sustain crews in space for several months at a time.
The first flight test of the SLS will feature a configuration for a 70-metric-ton (77-ton) lift capacity and carry an uncrewed Orion spacecraft beyond low-Earth orbit to test the performance of the integrated system. An option for a second ICPS to be used on a crewed Exploration Mission-2 is also being considered.
For later long-duration missions in deep space, this interim stage will be replaced with a more powerful upper stage on SLS. This configuration will provide an unprecedented lift capability of 130 metric tons (143 tons) to enable missions into deep space.
Stacking of the rocket for EM-1 will occur in the Vehicle Assembly Building (VAB) at Kennedy Space Center. The propulsion stage will be cleaned and maintained and remain in the high bay at the Space Station Processing Facility and moved to the VAB when it’s time for stacking.
United Launch Alliance is headquartered in Centennial, Colorado.