NASA's gas gun shoots pellets at 5 miles per second to test space shields

Micrometeorites that travel at speeds of up to 50 miles per second can cause catastrophic damage to space missions.

At those speeds, "even dust could cause damage to a spacecraft," explained Bruno Sarli, NASA engineer at NASA’s Goddard Space Flight Center, Greenbelt, Maryland, in a new report from the space agency. Sarli, alongside a team of engineers, is developing shields to protect NASA's Mars Earth Entry System from space rocks traveling at incredible speeds.

They recently conducted a high-speed experiment in which they recreated dangerous space impacts on the system, which will be used for NASA's Mars Sample Return mission currently slated for the 2030s.

NASA's 2-stage gas guns

Sarli recently traveled to the Remote Hypervelocity Test Laboratory at NASA’s White Sands Test Facility in Las Cruces, New Mexico. The facility has been used to test components since the Space Shuttle era, and it has also been used for tests related to the Artemis program and the International Space Station.

Inside the laboratory, 2-stage gas guns accelerate objects to incredibly high speeds to simulate micrometeorite and space debris impacts on spacecraft shielding.

The first stage uses gunpowder like a standard gun, while the second stage uses highly compressed hydrogen gas. This gas is pushed into a small tube to increase the pressure in the gun, similar to a car piston. According to NASA, "the gun's pressure gets so high that it would level the building if it were to explode," meaning scientists have to observe from a bunker.

Simulating micrometeorite impacts on Earth

The NASA team behind the experiment prepared for three days for what was eventually only a one-second-long experiment using the lab's mid-sized high-pressure (50-caliber range) 2-stage light gas gun. During the experiment, small pellets were shot at shielding material at speeds of 5 miles per second.

"At that speed, you could travel from San Francisco to New York in five minutes," said Dennis Garcia, the .50-caliber test conductor at White Sands.

While that is incredibly fast, micrometeorites in space travel six to seven times faster, meaning Sarli and his team have to go beyond these experiments. They also use computer models to simulate the impacts at higher speeds. By comparing the accuracy of their computer model to the real-life experiment at the White Sands Test Facility, they can then use it to simulate higher-speed collisions.

What is NASA's Mars Sample Return mission?

The Mars Earth Entry System will be used to carry Mars soil samples collected by NASA's Perseverance rover into Earth's atmosphere as part of NASA's Mars Sample Return mission.

NASA is currently developing the technology to bring Mars samples — most collected by its Perseverance mission — back to Earth at some point in the 2030s. The space agency describes the Mars Sample Return mission as "one of the most ambitious endeavors in spaceflight history, involving multiple spacecraft, multiple launches, and multiple government agencies."

This ambitious undertaking will allow scientists back on Earth to use state-of-the-art analysis techniques on carefully-selected Mars samples to ascertain whether life once existed on the red planet.