 The shuttle program experienced five main engine shutdowns at LC-39, all within four seconds before launch; and one Abort to Orbit, STS-51-F on July 29, 1985.Shuttle missions during nearly 30 years of operations included deploying satellites and interplanetary probes, conducting space science and technology experiments, visits to the Russian MIR space station, construction and servicing of the International Space Station, deployment and servicing of the Hubble Space Telescope and serving as a space laboratory.The shuttle was retired from service in July 2011 after 135 launches.