Comparisons of fresh complex impact craters on Mercury and the Moon: Implications for controlling factors in impact excavation processes

•We compare crater exterior structures for lunar and mercurian complex craters.•Lunar craters have larger continuous ejecta deposits but smaller secondary craters.•Some mercurian and few lunar craters have more circular, less clustered secondaries.•The results are consistent with predications from crater gravity-regime scaling laws.•Impactor velocity and target properties are less important in the excavation stage.