 They each flow 290 kg (637 lb) of anhydrous ammonia through three heat rejection radiators.The S1 truss was launched on STS-112 in October 2002 and the P1 truss was launched on STS-113 in November 2002.Detailed design, test and construction of the S1 and P1 structures was conducted by McDonnell Douglas (now Boeing) in Huntington Beach, CA.