You know how it is: One minute you’re sitting in the pub and someone says, “Let’s launch a paper plane into space.” Next, you’re standing on a Spanish mountaintop filling a meteorological balloon and strapping a Playmobil astronaut into an aircraft made entirely from A4-size paper. Your finished rig should include a 1,500g meteorological balloon, a recovery parachute, a styrofoam “payload” box containing all the electronics and a release mechanism, and a paper airplane. Whatever you do, resist the calls to use hydrogen instead of helium: Simply respond, “Hindenburg.” — As told to Ashlee Vance