During the lunar mission of Apollo 11, Armstrong and Aldrin descended to the moon’s surface in the lunar module while Collins remained in orbit in the command module. If the command module’s period was 2 hours and 20 minutes, how high above the moon’s surface did it orbit? (mmoon = 7.35 x 1022 kg, Rmoon = 1.74 x 106 m, and G = 6.67 x 10-11 N m2/kg2)