On July 15, 2015, United Launch Alliance (ULA) conducted successful launch of Atlas V 401 launch vehicle with GPS IIF-10 satellite into a medium Earth orbit of approximately 20,200 km altitude from Space Launch Complex (SLC)-41 at Cape Canaveral Air Force Station, Florida.
GPS IIF-10 mission marked the 55th Atlas V launch since the vehicle's inaugural launch in 2002, and the 27th flight of the 401 configuration. Also, hashtag #GPS20 was widely used in social media, meaning that the very same day marked the 20th anniversary of full operational capability of GPS system. Every operational GPS mission has launched on a ULA or heritage rocket.
GPS Block IIF, or GPS IIF, is an interim class of GPS satellites, which will be used to keep the Global Positioning System operational until the GPS Block IIIA satellites become operational. They were built by Boeing under the contract with the US Air Force for a total of twelve Block IIF satellites. The spacecraft have a mass of 1,630 kilograms and a design life of 12 years.
GPS satellites serve and protect US warfighters by providing navigational assistance for military operations on land, at sea, and in the air. Civilian users around the world also use and depend on GPS for highly accurate time, location, and velocity information.
“Congratulations to the US Air Force and the entire mission team on today’s successful launch of the 10th GPS IIF satellite! In just a few days, on July 17, the Global Positioning System will celebrate the 20th anniversary of GPS achieving fully operational status. ULA is very proud to play a role in delivering these satellites to orbit, with Atlas and Delta rockets having launched all 58 operational GPS satellites.” Jim Sponnick, ULA vice president, Atlas and Delta Programs
Global Positioning System utilizes 24 satellites, in six different planes, with a minimum of four satellites per plane. The satellites continuously transmit digital radio signals pertaining to the exact time (using atomic clocks) and exact location of the satellites. With the proper equipment, users can receive these signals to calculate time, location, and velocity. The signals are so accurate that time can be measured to within a millionth of a second, velocity within a fraction of a mile per hour, and location to within feet.
As we mentioned above, the mission utilized Atlas V booster in 401 configuration, where '4' means a 4-meter-diameter payload fairing, '0' stands for no solid boosters at the first stage, powered only by two Russian-made RD-180 engines, and '1' is for a single Aerojet Rocketdyne RL10A engine that powers Centaur upper stage.
This was the second of three GPS missions scheduled for 2015. On March 25 Delta IV Medium+ (4,2) rocket orbited GPS IIF-9 navigation satellite. ULA's next launch is Delta IV M+ WGS-7 mission for the US Air Force, scheduled for July 23 (UTC) from Cape Canaveral.