Mars Express enters orbit around Mars, December 25, 2003
Data as of 2026-10-14
The instant
- Instant (UTC)
- December 25, 2003, 03:17:32 UTC
- Distance from the centre of Mars
- 4,379 km
- Speed relative to Mars
- 4.42 km/s
This is the first instant at which Mars Express, inside the sphere of influence of Mars, no longer has the energy to escape its pull. An orbit insertion announced by an agency is a manoeuvre that lasts; this instant is a point within it, not necessarily its start.
The manoeuvre
A manoeuvre detected on the same trajectory, by another method (the trajectory departing from a coast under gravity alone), falls 13 min before this instant.
In Galaxy
Open Mars Express at this instant, at true scale
Pages of the spacecraft and of the body:
How it is measured
The position and velocity of the spacecraft relative to the body are read from Horizons every hour across its stay in the sphere of influence, then every minute and every second around the first hour at which its energy, half the square of its speed minus the mass of the body times the gravitational constant over its distance, is negative. The mass is the one Galaxy displays for the body.
Source
NASA/JPL Solar System Dynamics, Horizons System. Read on October 14, 2026.
Trajectory solution cited by Horizons: MEX_merged