Air conditioning eventually reach the upper atmosphere. Once the refrigerant reaches the stratosphere, UV radiation from the Sun homolytically cleaves the chlorine-carbon bond, yielding a chlorine radical. These chlorine radicals catalyze the breakdown of ozone into diatomic oxygen, depleting the ozone layer that shields the Earth's surface from strong UV radiation. Each chlorine radical remains active as a catalyst until it binds with another radical, forming a stable molecule and quenching the chain reaction. Prior to 1994, most automotive air conditioning systems used R-12 as a refrigerant. It was replaced with R-134a refrigerant, which has no ozone depletion potential. Old R-12 systems
Journey of Apollo 15 to the Moon 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. These photographs began as soon as they reached Earth orbit and would continue throughout the mission. During times when they were not using the window, Mission Control had them place a cover over the window that blocked the