Is this a disco ball or a spacecraft part?

This beauty may look like the love child of a flying saucer and a disco ball, but is actually a key component of Europe's most powerful rocket launcher.

The image was taken in Les Mureaux, near Paris, France, where the Ariane 5 rocket is built by the company EADS for Arianespace, a launch service provider. The saucer forms the inside top part of a cryogenic tank that holds the liquid hydrogen fuel for the upper stage of the Ariane 5.

That stage is powered by the same engine as the one used successfully more than 100 times between 1988 and 2003 in the Ariane 4 launcher.

In its successor, Ariane 5, the engine in the upper stage is used to deliver the additional energy required to put a satellite or payload into a target orbit.

Overall, Ariane 5 can loft over 20 tonnes into low Earth orbit, at an altitude of about 400 kilometres. Alternatively, it can boost a payload of about 10 tonnes into geostationary orbit, at around 36,000 kilometres.

The latest launch, the fifth this year by an Ariane 5, was scheduled this week from Kourou, French Guiana, a dedicated commercial spaceport.

The upper stage carried two satellite passengers: on top was the Arab Satellite Communications Organization's 4.6-tonne Arabsat 5C communications satellite, and loaded beneath it the 3.2-tonne SES-2 communications satellite, which will serve North America.

SES-2 will also carry an experiment for the US air force. The Commercially Hosted Infrared Payload will test the potential of wide-field-of-view infrared sensors to detect missile launches for the US's ballistic missile defence system.

Image: Vincent Founier/Gallery Stock. This post originally appeared on New Scientist.