NASA is testing new heat shields with 12 small capsules placed on the Cygnus XL cargo vehicle leaving the International Space Station. The KREPE-3 experiment, announced by the institution on October 9, will collect data of different protective materials by taking advantage of the vehicle’s planned atmospheric entry. However, the capsules will operate in the vehicle containing the waste brought from the station and measure flight conditions without requiring a separate launch.
Before leaving the station, the astronauts activated the capsules and prepared them for temperature, pressure, motion, magnetic field and light measurements. According to NASA’s KREPE-3 statement, the capsules will come out when the cargo vehicle disintegrates and transfer the data they collect to researchers via satellite. On the other hand, this experiment developed by University of Kentucky students constitutes the third flight of low-cost atmospheric entry studies.
Options in the capsules include a three-dimensional printed heat shield developed by NASA Johnson and Oak Ridge National Laboratory. In addition, the two capsules carry the MERINO material, which combines carbon and phenolic fiber layers in a felt-like manner. NASA states that this material is more flexible than traditional options and can be produced faster and at lower cost.
In addition, another capsule will examine the stability of the shape during flight, which resembles the protective shell of the Dragonfly vehicle that will go to Titan. On the other hand, the institution does not yet share the measurement results of this experiment or the success evaluation of all shields in its new announcement. The purpose of the flight is to obtain real atmospheric entry data as well as laboratory measurements for materials in development.
Flight experiment of small capsules complements ground heat testing of Dragonfly
Separate work on Dragonfly’s actual heat shield took place at Sandia facilities in New Mexico in June. NASA’s description of the Dragonfly heat test states that hundreds of mirrors directed the Sun’s energy to the shield samples, creating temperatures of approximately 2500 degrees. However, researchers evaluated not only the temperature but also the effect of the pressure applied with high temperature on the material.
On the other hand, the tests included samples representing the curved edges of the shield and parts where the researchers specifically added defects. This study tested the behavior of a carbon fiber and resin lightweight protective material called PICA-D developed for Dragonfly. In addition, the material constitutes a new variant of the PICA family used in missions such as Curiosity and Perseverance.
This mechanism in the laboratory tries to represent together the heat and pressure expected to occur during entry into Titan’s atmosphere. Therefore, sample tests on the ground do not mean testing on the same scale or for the same purpose as the flight of small capsules. Researchers continue their evaluation of the final design of the flight shield with new data by comparing their results with computer models.
In addition, NASA’s Dragonfly plan envisages that the vehicle, to be launched in 2028, will arrive at Saturn’s moon Titan in 2034 and operate on the surface. Therefore, the protective shell is required to safely complete atmospheric entry before the rotorcraft can begin its science work. The similarly shaped capsule in KREPE-3 aims to measure the stability of this shell in flight on a smaller vehicle.