ENERGIYA PAD TESTS

When it came to testing the whole stack on the launch pad, NASA and the Russians had different strategies because of the presence vs. absence of main engines on the spaceplane. With the US Orbiter being an integral part of the Space Shuttle stack, all pad-related tests were carried out with the Orbiter in place. In 1979 NASA performed fit checks on the pad of a stack consisting of OV-101 Enterprise and a mock-up External Tank and Solid Rocket Boosters. Pad tests of the main engines were conducted during 20-second “Flight Readiness Firings” several weeks prior to the maiden flight of a new Orbiter (except Endeavour).

Since Buran lacked main engines and was only one of several possible payloads for Energiya, most of the early pad testing at Baykonur focused only on the rocket. Various specially adapted experimental versions of the rocket were rolled out without any payloads attached to undergo dynamic tests, fueling tests, and engine test firings at the Universal Test Stand and Launch Pad (UKSS). Only at a later stage were full-scale mock-ups of Buran used for pad tests of the complete stack.