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 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.
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One cubic kilometer per second squared in every standard gravitational parameter unit
| 1,000,000,000 | cubic meter per second squared (m³/s²) | |
| 1 | cubic kilometer per second squared (km³/s²)this unit | |
| 0.00000250878 | terrestrial mass parameter (GMearth) | |
| 7.53509e-12 | solar mass parameter (GMsun) | |
| 2.22972e-15 | cubic astronomical unit per square day (AU³/d²) |