An orbit of this height is not sustainable for very long due to friction with the Earth's atmosphere, but the crew would only spend three hours before reigniting the S-IVB third stage to put them on a lunar-bound trajectory.

About 485 lb (220 kg) of liquid oxygen (LOX) was lost through an open vent of the S-IVB after the rocket was pitched down too quickly after cutoff.

One of the windows of the Apollo 15 CSM was specifically designed to transmit ultraviolet radiation, permitting the crew to acquire UV photographs of the Earth and the Moon.

As such, it was required for the CSM to separate from the S-IVB, travel a short distance, turn 180 degrees and then dock with and extract the lunar module.

First the CSM , Endeavour, separated, taking ten minutes to turn, come back and hard dock.

About half an hour later, after pressurizing the lunar module and checking the integrity of the docking latches, the crew extracted Falcon from the S-IVB.

It was sometime during the transposition and docking that the "SPS Thrust" light on the entry monitor system part of the control panel came on.

One of the reasons for the success of the Apollo program was the redundancy of critical systems—in the case of the SPS, there were two independent valve systems for the engine.

The burn allowed Mission Control to confirm that the SPS would only be ignited accidentally if the faulty switch was armed.

The engine burn itself was good enough, adding 5.3 ft/s (1.62 m/s) to their speed, that Mission Control cancelled the planned second and third course corrections.

After venting the atmosphere of the lunar module overboard (in case there was some contamination in the spacecraft), and then replenishing it from the CSM, the crew removed the hatch between Endeavour and Falcon and entered the LM.

The experiment involves the crew facing in the same direction, wearing blindfolds and having placed shades over the windows.

It is thought that the flashes were caused by Cherenkov radiation from high energy cosmic rays passing through the eyes.

During this period, the spacecraft passed the point when the lunar gravity becomes stronger than that of the Earth's as felt by Apollo 15.

As with all the LOI performed during Project Apollo it was perfect, the SPS burned for 6 minutes and 38 seconds, placing them into a 169 by 59 nautical miles (313 by 109.3 km) orbit.

This burn placed them into a 58.8 by 9.5 nautical mile (108.9 by 17.6 km) orbit, with the low point over Hadley Rille landing site.

From Apollo 14 onwards, it was done by the CSM as a way of conserving fuel on the LM, allowing it to land with more equipment and consumables on board.

Mission Control predicted that by the time the crew awoke the next "morning", the lowest point of their orbit, perilune, would have dropped to about 8.6 nm (16.1 km) but this turned out to be an underestimate.

The spacecraft was kept in a perfect attitude for the instrument which was designed to investigate the extremely tenuous lunar atmosphere.

The "Apollo 15 Preliminary Science Report" said that most of the measurements of gas made by the spectrometer were actually caused by the spacecraft itself.

The crew spent the period behind the Moon activating the LM and general housekeeping in preparation for the undocking.

They also updated the guidance computer on the LM and made landmark sightings to improve the accuracy of the known position of the landing site.

Undocking was meant to come at the end of their eleventh orbit of the Moon, but was delayed by an improperly attached umbilical that sent the signal to the docking probe to disengage.