NASA decided to launch TDRS-M satellite on the top of the Atlas V from SLC-41 at Cape Canaveral, before Dragon CRS-12 on the top of the Falcon-9 from LC-39A at Kennedy Space Center.
Recently during last preparations before encapsulation of TDRS-M under the payload fairing of Atlas V, satellite was seriously damaged. Problem caused delay of the TDRS-M mission. originally planned for August 3, 2017. Launch was put under the question on July 14, when service teams caused damage of Omni-S antenna. These antennas are installed on the bottom of the satellite and are facing to Earth during mission of the spacecraft. These antennas are sending to Earth telemetry data, tracking and receive commands from ground control centers. Omni-S are one of the smallest from set of different antennas at TDRS-M.
Boeing, manufacturer of the satellite managed to repair antenna and NASA decided to launch Atlas V with TDRS-m on August 10, 2017. This means that CRS-12, resupply mission of SpaceX Dragon, was delayed in time to at least August 14. Dragon's mission was planned originally for August 10 with docking probably two days later to Unity or Harmony nadir docking ports. Vehicle will deliver 1258 kg or unpressurized cargo and 2052 kg of pressurized cargo.
TDRS-M Satellite was built on Boeing BSS-601HP satellite bus and will improve communication between ground control stations, International Space Station and various NASA satellites. TDRS-M represents third generation of data relay satellites which have been launched by NASA since 1983. It is thirteenth TDRS satellite launched by NASA and third designed and manufactured only by Boeing (previous were result of cooperation between Hughes and Boeing and first seven were designed and manufactured by TRW).