Sweating Spacecraft May Be the Key To Greener Space Travel

Newsweek

01-05-2025

Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources.
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Space junk surrounds us. The European Space Agency estimates that there are approximately 130 million pieces of space junk from the over 6,800 successful rocket launches that have occurred since 1957. The South Pacific Ocean Uninhabited Area (SPOUA), a region near Point Nemo, is called the spacecraft cemetery as it is where those craft are routinely crashed at the end of their usefulness. Orbital debris falls into the Earth's atmosphere and burns up on its way back down.
Until recently, marked notably by the multiple successes by SpaceX, many spacecraft have been one-and-done use cases. The longest-serving spacecraft in history, the space shuttle Discovery, only flew a few dozen times before it was retired in 2011.
Scientists at Texas A&M University's Department of Aerospace Engineering are working to develop and test a 3D-printed material that aims to make spacecraft reusable and space travel greener in partnership with Canopy Aerospace.
The work is enabled by a $1.7 million Air Force Small Business Technology Transfer grant.
Reentering The Atmosphere
Reentering The Atmosphere
Photo-illustration by Newsweek/Getty
Spacecraft returning to Earth are subjected to intense heat. NASA's space shuttle experiences temperatures around 2,700 degrees Fahrenheit during reentry. NASA's Orion spaceship sustains even hotter temperatures, near 5,000 degrees Fahrenheit, the same temperature Apollo 13 reached during its reentry. Even higher temperatures are possible during hypersonic reentry.
Traditionally, spacecraft rely on heat shields or ceramic tiles to serve as a barrier from the extreme temperatures. SpaceX's Starship has an advanced heat shield, made up of approximately 18,000 hexagonal tiles.
The solution the partners are looking to prove out is a cooling method that acts as a heat barrier. Experts are testing transpiration cooling for spacecraft. This method features a layer of gas along the craft's surface that cools it and provides a barrier between the craft and extreme temperatures.
"The air around rockets becomes extremely hot as they reenter Earth's atmosphere — often exceeding 10,000 degrees Celsius. This requires heat shields to protect the rocket from overheating, which are not fully reusable. Upon mission completion, they need to be replaced or refurbished, which makes space travel astronomically expensive," Dr. Hassan Saad Ifti, assistant professor of aerospace engineering at Texas A&M University, told Newsweek.
"This technology creates a gaseous layer as the rocket 'sweats' or transpires a coolant gas, which acts as the heat shield. Once the mission is complete, the coolant gas tanks can be refueled for the next mission. This would make the rocket more reusable, and perhaps one day, we will have a fully and rapidly reusable rocket, just like the aircraft we fly today," he said.
This thermal effect is similar to how a puffer jacket works, Dr. Ifti explained. "This is why a puffer jacket is so effective. It traps air in these pockets, so it is the insulation from the air keeping you warm, not the solid part of the jacket."
The hypothesis is that when a vehicle uses the gas barrier as opposed to a single-use heat shield, flight times between missions could be reduced from years or months to days or hours, more similar to the turnaround time of a traditional passenger jet.
The gas barrier is not a new concept. Though the idea has existed for years, limitations in materials science, computational power and ground testing abilities have made it challenging to implement, Ifti said.
Testing rig development is being led by William Matthews, a fourth-year Ph.D. student at Texas A&M. "We should see that the material's surface is cooler at hypersonic speeds when the coolant flow is introduced than the baseline when no coolant is present," Matthews said. "Depending on how well the gas permeates the material, there are a lot of potential outcomes for this technology, and these tests should help us decide which direction we want to go."
Initial wind tunnel testing will take place at Texas A&M Engineering Experiment Station's National Aerothermochemistry and Hypersonics Laboratory. The results of that testing will determine if a full-scale testing mission is worth investing in ahead of any possible application for commercial use.
"I am optimistic about this technology," said Ifti. "If all goes well, we could see sweaty spacecraft in the sky by the end of our lifetimes."