There were no astronauts on Apollos 2-6, all were test missions that never left the Earth.

All 2-6 Apollos were made to test a new air mixture for the rockets. NASA stopped flight testing the Saturn 1B rocket because of the fire on Apollo 1. The fire was caused by the pure oxygen in the command module. The next Apollo flights 2 through 6 were all unmanned tests of different mixtures of oxygen and other chemicals to try to avoid the fire in the command module hazard. Apollo 1 and 7 were the only manned flights that used the Saturn 1 or 1B rocket.