He was a NASA engineer, IIRC. Helped engineer&send the Mars Rover to its current location, I believe.
His entire channel is full of cool stuff. He blew up a canned air bullhorn/foghorn to like 20x the size, using a huge, vertical air compressor tank that must have been at least 60 gallons, then building the actual horn himself. It must have been 8' by 10'. They set it up, his buddy hit the air while holding a walkie talkie so they knew when to start the timer, and then waited for it to get to them like 2 miles away while they timed how long it took. They were out in the middle of the desert. It was pretty freaking cool, IMO.