2 ms·Engine relighting in zero gravity is routinely done these days. All current upper stages do this.by HarryHirsch 6y agoEngine relighting in zero gravity is routinely done these days. All current upper stages do this.Gwypaas 6y agoThey also generate their own gravity using ullage motors. This gives us very different profiles regarding the time constraints.DennisP 6y agoIf the landing maneuver put the engines and fuel tanks in zero-g, that might be relevant.