Here's how sweat could soon help ships return to Earth

A new technology could revolutionize the way ships return to Earth. The principle is simple, but surprising: make the heat shield sweat. American researchers are testing this system to make spacecraft truly reusable.

The re-entry into Earth's atmosphere is one of the most dangerous moments of a space flight. Temperatures can exceed 1500°C, putting a strain on materials. During the return of a spacecraft like SpaceX's Starship, for example, the heat generated during reentry exceeds 1400°C, enough to melt some metals. Until now, heat shields were often single-use or required heavy maintenance. A situation that complicates the rapid reuse of spacecraft.

Researchers at Texas A&M University, in partnership with Canopy Aerospace, are developing a material capable of “sweating” to withstand these extreme temperatures. This system relies on transpiration cooling: a gas is released through the material, forming a protective barrier. It acts both as a thermal insulator and as a means of diverting the intense heat generated during atmospheric reentry.

This heat shield “sweats” gas to protect vessels during atmospheric reentry

This technology is based on a 3D-printed silicon carbide material. It is both robust against atmospheric pressure and porous enough to allow the gas to escape. Once activated, the latter forms a thin insulating layer between the surface of the vessel and the hot air. This principle is comparable to that of a down jacket: it is not the fabric that insulates, but the trapped air. Laboratory tests are underway to verify the effectiveness of this high-speed system.

If this technology works as expected, it could replace the ceramic tiles of the US space shuttle or the ablative shields used on capsules like Orion or Dragon, which must be changed after each flight. The goal is to make spacecraft more reusable, therefore less expensive and faster to relaunch. The project is funded by a $1.7 million grant, or about €1.58 million, from the US Air Force. The initial test results will determine the direction in which development continues.