STS-61-M

STS-61-M was a proposed NASA Space Shuttle program mission, planned for July 1986 but canceled following the Space Shuttle Challenger disaster.
The payload manifest was to have been TDRS-D, INSAT-1C, and EOS-1. EOS-1 was a payload developed by McDonnell Douglas that would have demonstrated the production in space of ultra-pure erythropoietin through electrophoresis. Robert Wood, a McDonnell Douglas engineer, was assigned as the payload specialist for EOS-1 with fellow engineer Charles D. Walker assigned as his backup.
If flown, this would have been Sally Ride's third spaceflight. After the Challenger disaster, Ride was named to the Rogers Commission investigating the disaster and left NASA afterwards in 1987.