STS-41-F was a planned Space Shuttle mission that was to have been flown by the Space Shuttle Discovery, however it was cancelled due to the June 26 launch attempt of STS-41-D. This would have been the second flight of Discovery. Because of the cancellation, STS-41-D later took the payloads from that flight and mixed them with the maiden voyage's payloads.
During the Space Shuttle program, several missions were canceled. Many were canceled as a result of the Challenger and the Columbia disasters. Many early missions were canceled due to delays in the development of the shuttle. Others were canceled because of changes in payload and missions requirements.