CNN) -- Things didn't go quite according to plan for astronaut Heide Stefanyshyn-Piper during her spacewalk outside the International Space Station on Tuesday.
Astronaut Heide Stefanyshyn-Piper maneuvers by the tail of the docked space shuttle Endeavour.
Stefanyshyn-Piper and Steve Bowen were outside the space station on the scheduled six-hour spacewalk, the first of the space shuttle Endeavour's stay at the station.
After completing a few preliminary tasks, Stefanyshyn-Piper was beginning the job of cleaning and lubricating the gears of the station's malfunctioning starboard Solar Alpha Rotary Joint, or SARJ, when she discovered the grease gun leak and then lost the bag.
Cleaning and lubricating the starboard SARJ is a time-consuming job, and will take several spacewalks to complete. When finished, the joint should be partially functional again. More extensive repairs are planned for the future.
Stefanyshyn-Piper was able to share tools with Bowen, and NASA mission controllers expressed confidence that the lost tool bag would not be too much of a problem for the duration of the spacewalk.
Mission controllers were also tracking the lost bag, which they say is floating well clear of the station and drifting further away.
Stefanyshyn-Piper is a member of the crew of the Endeavour shuttle that docked at the ISS Sunday to help install more living areas and upgrade amenities at the station(c) CNN 2008