▁more ▁than ▁ 5 – 1 0 ▁hours ▁it ▁would ▁buy ▁time ▁in ▁the ▁event ▁of ▁a ▁temporary ▁loss ▁of ▁all ▁three ▁fuel ▁cells . ▁Such ▁an ▁event ▁had ▁occurred ▁when ▁Apol lo ▁ 1 2 ▁was ▁struck ▁twice ▁by ▁light ning ▁during ▁launch . ▁ ▁Environment al ▁control ▁system ▁Cab in ▁atmosphere ▁was ▁maintained ▁at ▁ ▁of ▁pure ▁o xygen ▁from ▁the ▁same ▁liquid ▁o xygen ▁t anks ▁that ▁fed ▁the ▁elect rical ▁power ▁system ' s ▁fuel ▁cells . ▁Pot able ▁water ▁supplied ▁by ▁the ▁fuel ▁cells ▁was ▁stored ▁for ▁drink ing ▁and ▁food ▁prepar ation . ▁A ▁thermal ▁control ▁system ▁using ▁a ▁mixture ▁of ▁water ▁and ▁eth yl ene ▁g ly col ▁as ▁cool ant ▁dump ed ▁waste ▁heat ▁from ▁the ▁C M ▁cabin ▁and ▁electron ics ▁to ▁outer ▁space ▁via ▁two ▁ ▁radi ators ▁located ▁on ▁the ▁lower ▁section ▁of ▁the ▁exterior ▁walls , ▁one ▁covering ▁se ctors ▁ 2 ▁and ▁ 3 ▁and ▁the ▁other ▁covering ▁se ctors ▁ 5 ▁and ▁ 6 . ▁ ▁Communic ations ▁system ▁Short - range ▁communic ations ▁between ▁the ▁C SM ▁and ▁L M ▁employed ▁two ▁V H F ▁sc im itar ▁anten nas ▁mounted ▁on ▁the ▁SM ▁just ▁above ▁the ▁E CS ▁radi ators . ▁ ▁A ▁ste er able ▁un ified ▁S - band ▁high - g ain ▁anten na ▁for ▁long - range ▁communic ations ▁with ▁Earth ▁was ▁mounted ▁on ▁the ▁a ft ▁bulk head . ▁This ▁was ▁an ▁array ▁of ▁four ▁ ▁diameter ▁reflect ors ▁surrounding ▁a ▁single