From 1979 to 1986, he was chief test engineer and payload specialist for the McDonnell Douglas EOS commercialization project, having told company management that he was interested in flying in space if possible. Walker led the EOS laboratory test and operations team developing biomedical products. His contributions to the program included engineering planning, design and development, product research, and space flight and evaluation of the CFES device. Walker was involved with the program support activities at Kennedy Space Center, Florida, and at the Mission Control Center in Houston, Texas. He was responsible for training the NASA astronaut crews in the operation of the CFES payload on STS-4, STS-6, STS-7, and STS-8 shuttle flights during 1982 and 1983. In May 1986, Walker was appointed Special Assistant to the President of McDonnell Douglas Space Systems Company, working in Washington, D.C.
