"The crew was never in any danger," NASA spokesman Josh Byerly told NBC News. "They worked to keep the freezers going. ... They're fine for the near future."
Byerly said engineers think the problem was caused by a malfunctioning flow control valve for the station's ammonia coolant. Mission managers are trying to determine whether a software fix can get the valve working again, or whether a spacewalk will be required. Sorting through the issues might take a couple days, or as much as a couple of weeks.