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Practice Makes Perfect: Simulating Separation in Space in Near Zero Gravity

The LOFTID separation system ground test used air bearings, like an air hockey table, to simulate conditions in space. Credits: NASA/Gary Banziger

NASA engineers successfully completed ground testing of a system that will allow an inflatable heat shield to be tested in low-Earth orbit next year.

The Bernard Kutter Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) is the secondary payload on a United Launch Alliance (ULA) Atlas V rocket scheduled to launch in September 2022. It will fly as a rideshare with the weather-observing Joint Polar Satellite System-2 (JPSS-2), the third satellite of NOAA’s Joint Polar Satellite System series.

To get LOFTID to fit into the rocket, it will be packed inside the JPSS-2 payload adapter. The payload adapter is the structure used to connect JPSS-2 to the rocket. After JPSS-2 separates from the Atlas V, the payload adapter must be separated from the launch vehicle before LOFTID can start its demonstration mission. After it separates, it will demonstrate how the inflatable aeroshell, or heat shield, can slow down and survive re-entry through Earth’s atmosphere.

“This is a unique flight configuration,” said Sean Hancock, LOFTID payload adapter lead and aerospace engineer at NASA’s Langley Research Center in Hampton, Virginia. “Because of that, we developed a LOFTID-specific separation system.”

The LOFTID Payload Adapter Separation System (PASS) uses a series of springs, which release and initiate separation of the payload adapter from the launch vehicle. Then, like a reverse sling shot, the springs mounted to the payload adapter retract, pulling a net against the LOFTID re-entry vehicle, shooting the LOFTID payload adapter away from the re-entry vehicle.

That system was recently ground tested at NASA Langley.

Because actual separation will take place in zero gravity, testing on Earth requires some specialized hardware to simulate a space-like environment. The team used a flat floor with air bearings – like an air hockey table – which allows anything parallel to the floor to be near frictionless, imitating zero gravity in that direction. A mock-up of the LOFTID re-entry vehicle was attached to a wall, and a model of the payload adapter separated from LOFTID and glided on the floor using air bearings to test how well the system works.

The tests used an engineering development unit and were successful. Teams will perform additional testing in early 2022 using flight components.

The LOFTID project is a part of the Technology Demonstration Missions program within NASA’s Space Technology Mission Directorate. The project is managed by Langley with contributions from NASA’s Ames Research Center in California’s Silicon Valley, NASA’s Marshall Space Flight Center in Huntsville, Alabama, and NASA’s Armstrong Flight Research Center in Edwards, California.