A ball bearing of high thermal conductivity has been developed to provide conductive cooling for rotating optical devices at 2 rps. The bearings are made of pure copper which is silver coated. The bearing and hub are spring loaded to provide constant contact pressure even under changing temperature conditions. The bearing can cool a 310 g circular variable optical filter to 10K within 83 min. The bearing was utilized in a helium‐cooled spectrometer which was launched on a Black Brant VC rocket at Poker Flat, Alaska, on 22 March 1973, during a condition of post auroral breakup. Spectra were obtained form 185 km to about 40 km. Some 630 spectral scans covering the range of 6.75 to 23.3 &mgr; were telemetered. The special bearing performed well through all portions of the rocket trajectory.