Apollo 13 more immediate and visible warnings of anomalies. Because Apollo 13 followed the free-return trajectory, its altitude over the lunar far side was approximately greater than the orbital altitude on the remaining Apollo lunar missions. The Moon was almost at apogee during the mission (as it also was during the flights of Apollo 10 and Apollo 15), which also increased the distance from the Earth. The combination of the two effects ensures that Apollo 13 holds the absolute altitude record for a manned spacecraft, reaching a distance of from Earth on 7:21 pm EST, April 14, 1970. The A7L spacesuit intended
Apollo 21 in orbit. Some people have speculated that tentative plans of an "Apollo 21" might have been made assuming availability of the extra Saturn V that would have left, although by the time NASA resumed planning manned missions using this numbering sequence (defined on April 24, 1967), the dual-Saturn IB plan had been replaced with the single Saturn V. There is no evidence NASA ever planned an eleventh Moon landing mission. Apollo 21 "Apollo 21" is an apocryphal reference to an eleventh manned Moon landing mission of NASA's Apollo program. Apollo contracted for the construction of fifteen Saturn V launch vehicles