however Polyus failed to correctly perform the orbital insertion. Due to the termination of the Buran program the Energia program was concluded after only two launches, and further the payload on the first launch did not perform the final boost properly. The legacy of Energia/Buran project manifests itself most visibly in form of the RD-170 family of rocket engines, and the Zenit launcher, with the first stage roughly the same as one of the Energia first-stage boosters. Launch history First launch (Energia–Polyus) The Energia was first test-launched on 15 May 1987, with the Polyus spacecraft as the payload. An FGB ("functional cargo block") engine section originally built as a cancelled Mir module was incorporated into the upper stage used to insert the payload into orbit, similarly to Buran and the US Space Shuttle performing the final orbital insertion, since the planned "Buran-T" upper stage had not yet progressed beyond the planning stage. The intended orbit had 280 km (170 mi) altitude and 64.6° inclination. The Soviets had originally announced that the launch was a successful sub-orbital test of the new Energia booster with a dummy payload, but some time later it was revealed that in fact the flight had been intended to bring the Polyus into orbit. The two stages of the Energia launcher functioned as designed, but due to a software error in its attitude control system, Polyus's orbital insertion motor failed to inject the payload into orbit. Instead, the Polyus reentered the atmosphere over the Pacific Ocean. Second launch (Energia–Buran) The second flight, and the first one where payload successfully reached orbit, was launched on 15 November 1988. This mission launched the uncrewed Soviet Shuttle vehicle Buran. At apogee, the Buran spacecraft made a 66.7 m/s burn to reach a final orbit of 251 km × 263 km. Discontinuation and potential revival Production of Energia rockets ended with the end of the Buran shuttle project in the late 1980s, and more certainly, with the fall of the Soviet Union in 1991. Since that time, there have been persistent rumors of the renewal of production, but given the political realities, that is highly unlikely. While the Energia is no longer in production, the Zenit boosters were in use until 2017. The four strap-on liquid-fuel boosters, which burned kerosene and liquid oxygen, were the basis of the Zenit rocket which used the same engines. The engine is the four combustion