A technical challenge that NASA is working to solve is how to maintain very cold liquid propellants to be used as fuel for deep space missions. Heat intercept concepts such as advanced insulation blankets, foam insulation and vapor-based cooling will be evaluated with the Structural Heat Intercept Insulation Vibration Evaluation Rig or SHIIVER, which arrived Aug. 10 at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for application of its first round of insulation.
“We need to get to a point where we can preserve cryogenic liquid propellants for months to enable higher performing systems for deep space travel. The state-of-the-art on-orbit storage of a liquid hydrogen tank is a few hours, meeting our current needs for low-Earth orbit. We will need much more capable systems for deep space travel,” said Arthur Werkheiser, Marshall integration manager for the Evolvable Cryogenics Project (eCryo), a collaborative project between Marshall and NASA’s Glenn Research Center in Cleveland, Ohio. SHIIVER is responsible for testing technologies to extend the storage time of these propellants in a cold enough environment to remain liquids that are usable as fuels. The tank was manufactured by Didion’s Mechanical in Bellevue, Ohio and is managed by the eCryo project.
Cryogenic propellants are gases such as hydrogen, that when chilled to subfreezing temperatures and condensed, form highly combustible liquids that can be used to propel space vehicles. Any introduction of heat, including heat radiating from a test stand, can raise the temperature of the propellants and cause them to boil. In normal upper-stage operations, boil-off is considered lost propellant because it must be vented from the vehicle to prevent the tank from over-pressurizing.
“If you want to get to Mars, you must prevent boil-off, or when you get there, you won’t have enough fuel left to get back,” said Werkheiser. Until now, boil-off hasn’t been a problem because the space shuttle and Apollo missions only needed to retain cryogenic propellants in flight for minutes or hours instead of the months or years that will be required for deep space missions.
While at Marshall, the tank will have sensors installed to measure the heat that gets into the tank. The team will then apply spray-on foam insulation (SOFI) to the 13-foot-long tank in Marshall’s Thermal Protection System Facility. A rotisserie-style fixture allows for even spraying of large objects. Following SOFI trimming, the tank will undergo a white-light scan to measure its final dimensions to assist with eventual multi-layer insulation (MLI) application. The SOFI and MLI will reduce future propellant storage tank heat leak while on the launch pad where it is subject to atmospheric temperature and pressure conditions.
“Glenn and Marshall share expertise in cryogenics and have worked on several of these projects together,” said Lauren Ameen, eCryo testing and validation cost account manager and SHIIVER deputy lead engineer at Glenn. “We are looking to develop cryogenic fluid management technologies that can be used in a future in-space cryogenic stage.”
After the spray-on foam insulation application, the tank will travel to NASA’s Plum Brook Station in Sandusky, Ohio, which is managed by Glenn, for assembly, integration and testing in the B2 test chamber. The assembly will first undergo thermal vacuum testing with only SOFI on the tank surface. This will be the baseline heat load from which to assess future improvements. Then, the tank will be insulated on the top and bottom domes with MLI over the layer of SOFI and will undergo further cryogenic testing.
When the eCryo project testing is complete, the SHIIVER test tank will be retained as an asset for NASA that can be used for future cryogenic testing needs.
The eCryo project is led by Glenn, managed by the Technology Demonstration Missions Program and sponsored by NASA’s Space Technology Mission Directorate.
For video footage of the SHIIVER tank and arrival at Marshall:
https://images.nasa.gov/#/details-SHIIVER_Interview_And_Move.html
To learn more about NASA’s Space Technology Mission Directorate, visit: