In 2008, NASA Astronaut Don Pettit was on the space station, pondering a uniquely space-based problem: So many of Earth’s basic cultural rituals—clinking glasses together, for example—just don’t translate in near-zero gravity. “You can smash your juice bags together, but it doesn’t have the same human connection,” he says.

Seven years later, the first gravity-defying coffee cups have arrived at the space station. Pettit describes their odd, curvy shape as the “kind of bulbous thing you might find on a rare orchid.” They work using capillary action: Simply press your lips to the rim, and you get a sip, whether you want one or not.

Pettit and his co-designer, mechanical engineer Mark Weislogel of Portland State University, join us to talk about this unique design challenge.