km³/s²
cubic kilometer per second squared
Standard gravitational parameterexact by definition
The cubic kilometre per second squared is exactly 10⁹ m³/s², an exact decimal relation. It is the unit almost all published ephemerides and mission-planning software use, since spacecraft work is done in kilometres: Earth is 398 600.4418 km³/s² and the Sun is 1.32712440018 × 10¹¹ km³/s².
Watch out: Mixing kilometre-based \(\mu\) with metre-based positions is a classic and expensive error, because the cubic relation means the mismatch is a factor of 10⁹ rather than 10³. Keep the entire orbital calculation in one length unit.
| 1 km³/s² | 1 km³/s² |