STS-70 was the 21st flight of the Space Shuttle Discovery, and the last of 7 shuttle missions to carry a Tracking and Data Relay Satellite (TDRS). This was the first shuttle mission controlled from the new mission control center room at the Johnson Space Center in Houston. STS-70 was also the first flight of the new Block 1 orbiter main engine, designed to improve both engine performance and safety. The mission was launched from Kennedy Space Center in Florida on 13 July 1995, only six days after the landing of sister ship Atlantis, marking the fastest turnaround between flights in the history of the program.