Space Balls of Fire

When you light a candle on Earth, its flame rises into the shape of a teardrop. But in space, flames act differently. Without the force of gravity pushing down, the flames expand into round domes that don’t flicker. Researchers recently completed a series of experiments on the International Space Station (ISS) exploring how these rounded flames behave in a near-weightless microgravity environment.

The team ignited more than 1,500 flames to better understand combustion—a chemical reaction that produces heat and light. “Even though we’ve been using fire for millennia, the detailed chemistry is very complicated,” says Dennis Stocker, a scientist at NASA’s Glenn Research Center in Ohio.

Learning how materials burn aboard spacecraft can help make vehicles safer for astronauts. These experiments can also help scientists improve the efficiency of processes on Earth that rely on combustion—like furnaces and power plants.