At last month's Defcon, the United States Air Force invited pre-selected hackers to attempt to sabotage an F-15 fighter-jet data system:

And after two long days, the seven hackers found a mother lode of vulnerabilities that — if exploited in real life — could have completely shut down the Trusted Aircraft Information Download Station, which collects reams of data from video cameras and sensors while the jet is in flight.

Pleased with the results, the USAF has announced that next year's Defcon will feature an assault on a satellite. There will again be a pre-screening and qualifying process:

Sometime soon, the Air Force will put out a call for submissions. Think you know how to hack a satellite or its ground station? Let them know. A select number of researchers whose pitches seem viable will be invited to try out their ideas during a "flat-sat" phase—essentially a test build comprising all the eventual components—six months before Defcon. That group will once again be culled; the Air Force will fly the winners out to Defcon for a live hacking competition.

The tentative plan is to allow the hackers to try to take control of an orbiting satellite:

"What we're planning on doing is taking a satellite with a camera, have it pointing at the Earth, and then have the teams try to take over control of the camera gimbals and turn toward the moon"

You can find information about Defcon 28 here.