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 centreroom 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 Centre 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.

The primary mission was the launch and deployment of the 7th Tracking and Data Relay Satellite (TDRS) by means of the two-stage Inertial Upper Stage (IUS) solid rocket. It was built by TRW and weighs about 2,200 kilograms (4,900 lb). The satellite was ejected from Discovery's cargo bay exactly on time at 2:55 p.m. CDT, approximately six hours into the flight. The release of the satellite was overseen by Mission Specialists Don Thomas and Mary Ellen Weber. About 15 minutes later, Discovery's Commander Tom Henricks fired the shuttle's engines to raise the orbit and move away from the vicinity of the satellite and the IUS. At about 3:55 p.m., the IUS fired the first of two burns that would put TDRS-G into its proper, 22,000-mile-high geostationary orbit above the central Pacific Ocean at 178 degrees West longitude.

The deployment operations utilized three separate control centers; the White Sands ground station controlled the TDRS, the JSC Mission Control Center (MCC) controlled the shuttle, and the Inertial Upper Stage (IUS) control center at Onizuka Air Force Base in Sunnyvale California controlled the booster stage. Once it reached its destination, the fully deployed satellite had a wingspan of 57 ft. The TDRS was the sixth placed in operational use. The first TDRS was launched aboard STS-6 on 1983-04-04 with a scheduled lifetime of seven years. The second satellite, TDRS-B, was lost aboard Challenger on mission STS-51-L. TDRS-3 was deployed from STS-26, TDRS-4 from STS-29, TDRS-5 from STS-43 and TDRS-6 was deployed by STS-54. The on-orbit TDRS network was rearranged and included two fully operational spacecraft occupying the TDRS East and West slots, one on-orbit fully functional spare, TDRS-1, which was nearly depleted having exceeded its planned lifetime, and the partially operational TDRS-3 spacecraft dedicated to supporting the Compton Gamma Ray Observatory and providing coverage an area that can't be seen by the other satellites known as the Zone of Exclusion.