Hack-A-Sat 4, taking place live at DEFCON on August 10 in Las Vegas, will be the first-ever hacking contest staged on a vehicle in orbit.

In previous years, the contests used genuine working satellite hardware but running safely on the ground. Hack-A-Sat 4 is an attack/defend contest in which teams compete to hack each other's systems while defending their own.

It is being staged by the Air Force Research Laboratory and the US Space Force. More than 380 teams signed up for the qualification round in April, and the eight top-scoring ones, which include contestants from Australia, Germany, Italy, and Poland, and the U.S., will participate in the finals at DEFCON.

Contest organiser Steve Colenzo said: "We always knew our objective was to do this in space  but in 2020, organizers asked satellite operators if they could stage a hacking contest on their space assets, the answer was always no."

Hack-A-Sat organizers realized that, if they wanted to reach their objective of staging such a contest in space, they would have to launch their own satellite, Colenzo said.

The Moonlighter satellite was launched on a SpaceX rideshare rocket to the International Space Station by the US government-backed non-profit The Aerospace Corporation. It's a foot-long toaster-sized cubesat satellite with extendable solar panels.

If all goes according to plan, Moonlighter will be deployed into orbit early in July. Moonlighter is designed to be hacked and there are numerous safety measures in place.

The first thing that we said was that propulsion was off the table. Moonlighter can't change its own orbit, which might make it a hazard to other satellites. And its ground controllers have the ability to reboot the system, kicking out any intruders and restoring their control.