A galley water heater is being blamed for smoke aboard the International Space Station.

Russian astronauts reported smoke and a burning smell in their main compartment Tuesday. There wasn't enough smoke to activate the alarms or to warrant the use of masks by the six-man crew. The smoke came from a vent and dissipated within a half-hour or so.

Commander Steven Swanson says there was only a small amount of smoke and everyone was fine.