Mars Express
Europe's long-lived Mars orbiter, which has made the closest flybys of the moon Phobos.
Key facts
- Agency
- European Space Agency (ESA)
- Type of mission
- Orbiter
- Target
- Mars and its moon Phobos
- Launched
- 2 June 2003
- Status
- Operating
Mars Express went into orbit around Mars on 25 December 2003 and has been working for more than two decades. Its small British-built lander, Beagle 2, was lost on landing, but it was found in 2015 in pictures from another orbiter, with its solar panels only partly unfolded.
Minerals and water
The orbiter's OMEGA spectrometer mapped the minerals of the Martian surface. It found clays in the oldest terrains and sulphate salts in younger ones, which pointed to a change from a wet, mild early Mars to an acidic and then dry one. Its radar, MARSIS, measured the thickness of the ice caps and reported signs of liquid water beneath the southern ice in 2018, a claim that is still debated. Its spectrometers also detected traces of methane in the air.
Phobos
Because its orbit is elongated, Mars Express passes Phobos regularly. In March 2010 it flew just 67 kilometres from the moon, closer than any other spacecraft, and measured its gravity. Phobos turned out to be only about 1.9 times as dense as water, so it must be very porous, perhaps a pile of rubble. Its pictures and colour data are being used to plan the MMX sample return.
Why it matters to meteorites
Orbital maps of Mars's minerals are compared with the Martian meteorites to search for their launch sites. Young volcanic regions with suitable fresh craters are the leading candidates for the shergottites.
Key dates
| Date | What happened |
|---|---|
| 2 June 2003 | Mars Express launched on a Soyuz rocket. |
| 25 December 2003 | Entered orbit around Mars; Beagle 2 was lost on landing. |
| 3 March 2010 | Flew 67 km from Phobos, the closest pass of any spacecraft. |
| January 2015 | Beagle 2 was found on the surface in images from a NASA orbiter. |
See where this mission fits among all the others in the mission timeline.
Did you know?
Mars Express was built quickly by reusing designs from the Rosetta comet mission, which is how it got the word Express.
Beagle 2 was named after the ship on which Charles Darwin sailed.
Related pages
Comets connected with this mission: Comet 3I/ATLAS. See all comets.