Lunar day around the Sun at the same time, the Moon must travel further to return to the same phase. On average, this synodic period lasts 29 days, 12 hours, 44 minutes, and 3 seconds. This is the mean figure since the speed of the Earth–Moon system around the Sun varies slightly during a year due to the eccentricity of its elliptical orbit, variances in orbital velocity, and a number of other periodic and evolving variations about its observed, relative, mean values, which are influenced by the gravitational perturbations of the Sun and other bodies in the Solar System. As a result,
Pioneer 3 direct ascent trajectory, the odds of hitting the Moon were slim. However, a lunar flyby rather than impact would still be considered a successful mission. The flight plan called for the "Pioneer 3" probe to pass close to the Moon after 33.75 hours and then go into solar orbit. The Juno II lifted from LC-5 at 12:44 AM on December 6. Launch went entirely according to plan until first stage cutoff, when the engine cut off 3.7 seconds early due to a failure of the propellant depletion sensors, leaving a velocity shortfall of several hundred feet per second. The injection