CAPE CANAVERAL: As the Space shuttle Columbia pierced a clear blue sky on its way to a 16-day low-earth orbit, the Russian space station Mir was having serious new problems with its air supply. The main device to remove carbon dioxide from exhaled air inside the space station is broken, and U.S. astronaut Jerry Linenger and his two Russian crewmates are relying on a backup air cleaning system composed of lithium-hydroxide canisters. Mir has only an eight-day supply of that gas, a NASA spokesman said. If Linenger and the two cosmonauts cannot repair the primary device, they'll have to stretch their resources until the Russian supply ship Progress can deliver more canisters. Progress is scheduled to blast off on Sunday, and reach Mir at the end of the week. Like a car whose odometer has long ago turned over, the 11-year old Mir is simply getting old, and this equipment failure is just the latest in a series. In early March, two oxygen generators broke, leaving the spacemen with a two-month supply of air. The 16-year-old Columbia, the oldest shuttle in the U.S. fleet, is getting a bit creaky itself. It regularly breaks its own record for scrubs per mission, and was delayed twice for quick fixes before today’s launch. The shuttle's 16-day mission will include 33 planned experiments, most investigating the effects of weightlessness on fire. The mission is primarily devoted to preparatory work for the future international space station, tentatively planned for launch in the year 2000.