NASA tests heat shield materials in 12 capsules aboard a departing cargo craft

NASA is using the disposal flight of a cargo spacecraft to try out materials for future heat shields, according to an article from the agency's Ames Research Center. When the Cygnus XL vehicle of Northrop Grumman's 24th resupply mission for NASA left the International Space Station, it held 12 small experimental capsules. NASA says the materials on board could become the basis for heat shields that keep astronauts safe on the way back from the Moon and Mars.

KREPE-3, short for Kentucky Reentry Probe Experiment, is the third mission of a series that NASA describes as low-cost and that collects data in the final moments of a cargo vehicle's life. It is run jointly by the University of Kentucky and the state of Kentucky together with NASA's EPSCoR program (Established Program to Stimulate Competitive Research), several NASA centers and further federal and commercial partners. Students at the University of Kentucky designed the capsules, which carry sensors for temperature, pressure, motion, magnetic field and light.

Before the Cygnus XL departed, astronauts loaded it with waste and switched the capsules on. The vehicle is planned to break apart in Earth's atmosphere; NASA says the capsules will then be ejected and record how each set of heat shield materials holds up, with live data relayed to researchers by satellite. Keith Peterson, a materials engineer at Ames, called the approach “a smart way to get flight data on materials that are still in development”.

According to NASA, the capsules carry established technology, for example the ceramic tile material flown on the space shuttle, alongside newer options such as a 3D-printed heat shield that NASA Johnson and Oak Ridge National Laboratory developed under the Additive Manufacturing of Thermal Protective Systems project. Ames contributed several materials, including two capsules with MERINO (Materials Engineered for Re-entry using Innovative Needling Operations), a family of coverings made of carbon and phenolic fiber layers stitched together much like felt. NASA says these are more flexible, quicker to produce and cheaper than traditional materials, which makes them candidates for Mars missions, where the thinner atmosphere means lower heat loads and allows lighter protection.

A third capsule, the Kentucky Instrumented Conical Hypersonic Experiment, has a dual-cone shape with a tungsten tip and an aft cone wrapped in MERINO, and is meant to check computer models against measured data. Another copies the shape of the aeroshell for NASA's upcoming Dragonfly mission to Saturn's moon Titan, tests the stability of that design and is covered in Phenolic Impregnated Carbon Ablator, a material developed at Ames that flew on Stardust, Mars Science Laboratory and Mars 2020. One more tests the umbrella-shaped Adaptable Deployable Entry and Placement Technology, and capsules from domestic and international partners include a heat flux sensor from Germany's University of Stuttgart.