It's a hydrogen/oxygen engine (https://en.wikipedia.org/wiki/BE-3 https://en.wikipedia.org/wiki/BE-3), the exhaust is basically water or maybe hydrogen peroxide

It's a hydrogen/oxygen engine (https://en.wikipedia.org/wiki/BE-3 https://en.wikipedia.org/wiki/BE-3), the exhaust is basically water or maybe hydrogen peroxide. https://space.stackexchange.com/questions/16821/what-is-the-cause-of-the-blue-light-from-lh2-lox-rocket-engines https://space.stackexchange.com/questions/16821/what-is-the-...