Ariane flight 245: Bepi Colombo 

Late afternoon Tuesday June 5, I paid a visit to my ESA colleagues in S5, the biggest payload preparation building. During my ATV years I spent many months inside these offices and ATV certainly left it’s mark on the various doors.

Bepi-Colombo Team members

The facility is at the moment completely taken up by Bepi Colombo, the passenger on Ariane’s Flight 245 in October. It is misleading to speak about Bepi-Colombo as if it was one spacecraft. In reality it is three completely separate spacecrafts that will travel together from Earth to Mercury.

Orbital mechanics is one of the many factors driving their launch date. They have a launch window from early October to late November meaning they can launch any time inside that window. Should they miss it, for whatever reason, they have to wait 6 months until the planets are again lined up in a favourable position.

One of my ESA colleagues took me to the visitors room and explained some of the technical aspects using the model they have placed there.

Bepi Colombo model

There are actually three spacecraft stacked one on top of the other, each one with it’s solar panels, antennas, communication systems, propulsion systems etc. Two of them carry instruments (i.e. the “useful” part from the user perspective). These two are the Mercury Planetary Orbiter (MPO) built by ESA which will have an orbit close to Mercury, and the Mercury Magnetospheric Orbiter (MPO) built by Jaxa, which will have an orbit that takes it further out. (see the picture). At launch they are stacked on top of the third spacecraft, the Mercury Transfer Module, and it is this module that will pilot the stack from separation up to reaching the correct orbit around Mercury, a trip of about 7 years.

The mission page on has many more details on the Bepi-Colombo mission.

Bepi is currently the star attraction in Europe’s Spaceport and they will be seeing a lot of visitors in the coming months. I will certainly be one of the regular visitors.

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