Rosetta Comet Chaser on the move
18 August 1999It may not seem much of a journey compared with a multi-million kilometre space trek, but ESA's Rosetta spacecraft today completed its first small step along the road to a rendezvous with Comet Wirtanen in 2011. After a 2000 km hike across Europe, the Structural and Thermal Model (STM) platform structure of the Rosetta orbiter was safely delivered this morning to Alenia Aerospazio's Turin plant.
The 200 kg STM structure - the main skeleton of the spacecraft - was constructed and tested by Finavitec at Halli in Finland. On 13 August it was placed into a special Structure, Transport and Storage Container, 3.5 metres high, 3 metres wide and almost 6 metres long. It was then lifted by a mobile crane onto a lorry trailer and securely tied down for the rocky trip ahead. A low-load trailer with a mere 0.5 m metre road clearance was used so that the vehicle would safely pass under bridges and through tunnels.
In order to safely store the structure, the container was equipped with an active temperature control system which ensured its internal temperature stayed between -10°C and +25°C. It also had an active recording system which monitored accelerations as well as internal temperature and humidity.
Despite its bulk, the caravan-sized cocoon was small enough to allow transportation across Europe without a police escort. The first leg of the STM's journey was a short drive from the Finavitec plant to Helsinki. From there, it was taken by ferry to L|beck in northern Germany, where it stayed over the weekend. The precious load left L|beck on Monday, and headed south towards Turin. Using two teams of drivers, which allowed movement through the night, the STM eventually crossed the French Alps through the Frijus Tunnel near Chambiry.
On arrival at the Turin plant of Alenia Aerospazio, the container was unloaded straight away. Over the next few months, fuel tanks and spacecraft equipment will be added, while Structural and Thermal Models of the 12 scientific instruments and lander will also be installed.
The Rosetta STM comprises two main sections. At its heart is a 2.6 metre high central cylinder which is divided into quarters by vertical shear panels. More aluminium honeycomb panels are attached to the outside of this 1.2 metre diameter ring to create the familiar box-shaped structure which will eventually carry the solar panels and scientific instruments.