The majority of the crew's approximately 53 hours in low Earth orbit was spent conducting systems tests. Despite the scheduling impact of efforts to image "Columbia"'s TPS by utilising external assets, these were all accomplished. They included: Crew Optical Alignment Sight (COAS) calibration, star tracker performance, Inertial Measurement Unit performance, manual and automatic RCS testing, radiation measurement, propellant crossfeeding, hydraulics functioning, fuel cell purging and photography. The OMS-3 and OMS-4 burns at 006:20:46 and 007:05:32 MET respectively raised this orbit to (compared to a planned circular). These two firings were single engined utilising the crossfeed system. The crew reported a cold first night on board despite acceptable temperature indications. They found the second night comfortable after settings were adjusted.