The Science of Collisions: Protecting Spacecraft from Space Junk

Space junk is a huge problem in our orbit. After 50 years of space exploration, the debris is piling up--aluminum, steel and nylon are all contributing to the problem. As we move forward to the future, this trash can pose a danger to manned and unmanned spacecraft, which means that shielding ships from this debris is crucial. Researchers are now looking into the science of impacts.

Currently, there's about 21,000 pieces of space junk roughly the size of a baseball in orbit, and there are also about 500,000 pieces roughly the size of a golf ball. With all of this trash floating around, it becomes more and more likely for it to impact a spacecraft. In space, this junk can be faster than a bullet--and can drastically impact walls and shields by punching holes through them. In fact, a piece of space debris recently impacted the International Space Station's solar panels, leaving behind a bullet-sized hole in one of them.

In order to better understand these impacts, scientists ran hundreds of simulations on supercomputers at the Texas Advanced Computing Center. This allowed them to create ballistic limit curves, which predict whether a shield will be perforated when hit by a projectile of a certain size and speed. This gives NASA the tool it needs to design future spacecraft.

"If a spacecraft is hit by orbital debris it may damage the thermal protection system," said Eric Fahrenthold, professor of mechanical engineering at The University of Texas at Austin, in a news release. "Even if the impact is not on the main heat shield, it may still adversely affect the spacecraft."

The simulation framework employs a hybrid modeling approach. This captures both the fragmentation of the projectiles and the shock response of the target. This, in turn, allows researchers to determine exactly what materials will work best.

The simulations don't just have applications for space, though; they could also have applications for materials research. Items like body armor could benefit from these models. The simulations could open up a whole new way to design materials.

The findings were published in the journals Smart Materials and Structures and International Journal for Numerical Methods in Engineering.