Rosetta STM arrives at ESTEC
5 December 1999After a five day journey across Europe, the Structural and Thermal Model(STM) of the Rosetta spacecraft has arrived safely at the European SpaceResearch and Technology Centre (ESTEC) in The Netherlands.
"This is a significant step towards meeting the very tight launch window of January 2003," said Rosetta project manager, Bruno Gardini.
Over the past three and a half months, the STM has been painstakingly assembled by technicians at the Turin plant of Alenia Aerospazio. The next stage in its progress towards launch was transportation to ESTEC for a series of environmental tests.
Nothing was left to chance for the long-distance drive. Cocooned inside a pressurised protective container filled with nitrogen gas, the 1.4 tonne STM was gingerly lifted onto a trailer last Monday.
Illuminated by flashing neon lights, the lorry meandered for more than 1000 km through Italy, France, Belgium and Holland, accompanied all the way by a police escort. With several drivers operating in shifts, the slow-moving vehicle and its precious load mostly travelled at night to minimise traffic congestion.
On arrival at ESTEC, in driving rain and wind, the STM container was unloaded and placed in an airlock. Once the spacecraft was retrieved, it was then moved into a large integration room, ready for its high gain antenna to be added in 10 days time.
The STM will remain at ESTEC for the next six months, where it will undergo a series of environmental tests. The first of these will be a series of acoustic tests to find out if the spacecraft will survive the noise and vibrations of an Ariane 5 launch. Early next year, the STM will undergo thermal vacuum tests to check out its performance in the harsh temperature and vacuum conditions of outer space.
2.8 metres high and more than 2 metres wide, the STM is practically identical in size and shape to the spacecraft which will set off for Comet Wirtanen in 2003. It has the same thermal blankets that will protect the flight model against the temperature extremes of deep space. The scientific instruments, although not functional, are high fidelity replicas of the flight hardware.
However, there are some significant differences. For example, there is only one 16-metre-long deployable solar array (the other is a dummy), the electronics boxes are empty and only one attitude thruster works. Although the fuel tanks can be pressurised, they will be filled with water instead of propellant during vibration testing.