The KREPE-2 mission, designed to test different heat shield materials under real re-entry conditions, featured capsules developed by students at the University of Kentucky. Funded by NASA's Established Program to Stimulate Competitive Research (EPSCoR) within NASA's Office of STEM Engagement, each capsule survived re-entry temperatures exceeding 4,000 degrees Fahrenheit.
These football-sized capsules also successfully transmitted data via the Iridium satellite network during their fiery descent. This valuable data collection is being assessed to aid future spacecraft design and support the improvement of re-entry technologies.
"These data - and the instruments used to obtain the data - assist NASA with designing and assessing the performance of current and new spacecraft that transport crew and cargo to and from space," said Stan Bouslog, a thermal protection system expert at NASA's Johnson Space Center in Houston and technical monitor for the project.
Experiencing Hypersonic Flight: A Test in Real Conditions
"The only way to 'test like you fly' a thermal protection system is to expose it to actual hypersonic flight through an atmosphere," Bouslog explained.
The self-contained capsules launched in January 2024 aboard an uncrewed Northrop Grumman Cygnus spacecraft. Once the cargo craft detached from the International Space Station on July 12, it initiated its planned re-entry over the south Atlantic Ocean. As the Cygnus craft disintegrated, the KREPE-2 capsules detected key signals - such as temperature increases or shifts in acceleration - and began recording data before being released at approximately 16,000 miles per hour from an altitude of around 180,000 feet.
During the re-entry event, the University of Kentucky team and its advisors tracked the capsules' descent. A team aboard an aircraft near the Cook Islands in the south Pacific Ocean closely monitored the return of the Cygnus spacecraft, a flight coordinated in collaboration with the University of Southern Queensland in Australia and the University of Stuttgart in Germany. Alexandre Martin, professor of mechanical and aerospace engineering at the University of Kentucky and principal investigator for the experiment, was on board.
"We flew in close to the re-entry path to take scientific measurements," Martin explained, adding that cameras and spectrometers helped capture detailed observations of re-entry. "We now have a much better understanding of the break-up event of the Cygnus vehicle, and thus the release of the capsules."
Back at the University of Kentucky's Hypersonic Institute, team members awaited real-time updates as KREPE-2 data streamed in via email, confirming all five capsules successfully transmitted data during their descent.
"It will take time to extract the data and analyze it," Martin noted. "But the big accomplishment was that every capsule sent data."
Analyzing the incoming information, the University of Kentucky team aims to reconstruct the capsules' flight environment digitally, providing essential insights for future heat shield modeling and design.
Building on Prior Success
This experiment builds on the achievements of KREPE-1, which launched in December 2022 with two capsules that recorded temperature data during re-entry and relayed it back to Earth.
For KREPE-2, the team collected a broad set of data, including heat shield temperatures, pressure, acceleration, and angular velocity. A spectrometer was also tested, capturing spectral data on the shockwave in front of a capsule.
"KREPE-1 was really to show we could do it," said Martin. "For KREPE-2, we wanted to fully instrument the capsules and really see what we could learn."
The project is slated to continue with KREPE-3 in 2026, providing ongoing learning opportunities for University of Kentucky students, from undergraduates to PhD candidates, who are gaining hands-on experience in spaceflight technology development.
"This effort is done by students entirely: fabrication, running simulations, handling all the NASA reviews, and doing all the testing," Martin said. "We're there supervising, of course, but it's always the students who make these missions possible."
Related Links
Established Program to Stimulate Competitive Research (EPSCoR)
Rocket Science News at Space-Travel.Com
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