What impact did the Buran Energia and Interkosmos programs have on the development of space technology?

by TrekkiMonstr

Were they mostly just catching up with the US, or did they lead to developments we might not have made otherwise (at least as soon)? And I know they're different programs, this is really two questions.

CatnipFarmer

The RD-170 engines that were developed for Energia are arguably the most advanced kerolox (kerosene and liquid oxygen fueled) rockets engines ever created. They generated approximately the same thrust as the F-1s that were used on Apollo but had a 20% better specific impulse (fuel efficiency, to over-simplify what SI is).

The RD-170s were only used a couple of times, but a half-sized version called the RD-180 has been used for 15+ years on the American Atlas V. ULA buys those engines because the US has no kerolox engines that can match their thrust and efficiency.