About a week ago, NASA scientists started a fire in one of their own cargo bays. Hold up, don’t freak out: NASA’s not dealing with rogue arsonist astronauts here. This was all part of the first Spacecraft Fire Experiment, a study constructed to figure out how flames behave in space—and how to put them out before making everything go kablooie.A fire in space is different than a fire on Earth. In microgravity, flames don’t taper like they do on your dinner table: They stay blobby and spherical. And without natural convection, flames spread differently, too—instead of rising, they just follow the spacecraft’s ventilation system. The standard smoke detector on the ceiling set up? Not going to work. If the fire is any bigger than an index card, though, scientists haven’t studied what will happen. What materials catch fire in microgravity? How fast does the fire spread? How hot does it get?