In case any problems arise during the lengthy cruise, backup systems have been added to ensure that the spacecraft can remain operational during critical mission phases.
 
 
Hot and Cold
 
Temperature control was a major headache for the designers of the Rosetta spacecraft. Near the Sun, overheating has to be prevented by using radiators to dissipate surplus heat into space. In the outer Solar System, the hardware and scientific instruments must be kept warm (especially when in hibernation) to ensure their survival.

This is achieved by using heaters located at strategic points (e.g. fuel tanks, pipework and thrusters), placing louvers over the radiators, and wrapping the spacecraft in multi-layered insulation blankets to cut down on heat losses.
 
 

Close-up of a single solar-array cell

Solar Power
 
Rosetta will be the first space mission to journey beyond the main asteroid belt and rely solely on solar cells for power generation, rather than the traditional radio-isotope thermal generators. The new solar-cell technology used on the Orbiter's two giant solar panels allows it to operate over 800 million km from the Sun, where sunlight levels are only 4% those on Earth. Hundreds of thousands of specially developed, nonreflective, silicon cells generate up to 8700 W in the inner Solar System and around 400 W for the deep-space comet encounter.