In 2007, space debris punched a hole through the US space shuttle Endeavor's radiator panel. The shuttle program ended in 2011, but the debris problem has intensified as we launch more satellite constellations, telescopes, and spacecraft. Chinese scientists have devised a new aluminum material inspired by eggshells that could offer enhanced protection against debris fragments, according to a new paper in the Journal of Applied Physics.

Eggshells have long fascinated scientists for their mechanical properties. In 2012, MIT mechanical engineer Pedro Reis co-authored a paper demonstrating the link between an egg's ovoid geometry and its rigidity. Reis started studying eggshells after participating in a popular physics demonstration: walking on cartons of eggs without breaking them. The key was to align the eggs with their narrow tip pointing up and distribute weight over the entire surface area.

In the 1950s and 1960s, the aerospace industry found eggshells' resistance to shattering useful for failure analysis of metal shells in airplanes. An eggshell is mostly calcium carbonate crystals embedded in a protein matrix, bolstered by a thin collagen inner membrane. Earlier this year, Reis's MIT colleague Tal Cohen tested the assumption that dropping eggs vertically is best, finding that horizontal eggs absorb more energy and crack less frequently.

A NASA report from 2021 estimated about 34,000 pieces of debris larger than 10 centimeters in near-Earth orbit, 900,000 pieces between 1 cm and 10 cm, and 128 million pieces smaller than 1 cm. Even small debris can damage spacecraft due to high velocities. Spacecraft are typically protected by Whipple shields, but the new eggshell-inspired material could offer better protection.