We got the "Key & Peele" star Tuesday in Bev Hills leaving The Palm and asked if he'd caught the launch of SpaceX's Falcon Heavy rocket -- which was historic for lots of reasons.

He says he missed it, but sounds pleased with the results. Then he hits our camera guy with a little bit of a hot take -- humans aren't stepping foot onto Mars anytime soon ... despite the Tesla Roadster and the mannequin spaceman zipping toward the red planet.

Keegan thinks the car is cool, but there's something that Martians may find more useful.

He makes a solid point ... that a private citizen with a passion for space exploration might be better suited to tool around the galaxy than NASA.