From 09:00:00 to 19:30:00, a sleep period was scheduled. The astronauts slept well, but complained of being woken by non-English transmissions. Scott theorized that they were possibly in Chinese. The highlight of the second day in orbit (March 4) was three SPS burns. The initial burn, at 22:12:04.1, lasted 110 seconds, and including swiveling or "gimbaling" the engine to test whether the autopilot could dampen the induced oscillations, which it did within five seconds. Two more SPS burns followed, lightening the SM's fuel load. The spacecraft and engine passed every test, sometimes proving more robust than expected. The performance of the CSM in remaining stable while the engine was being gimbaled would in 1972 help cause McDivitt, by then manager of the Apollo Spacecraft Program, to approve the continuation of Apollo 16 when its CSM was experiencing an unstable gimbal after separation from its LM in lunar orbit.