Rosetta runs hot and cold
19 March 2002Like a hardy mariner preparing for a marathon journey from the tropical shores of Brazil to the icy waters of Cape Horn, the mettle of ESA's Rosetta spacecraft has been tested to the limit in recent weeks.
After being alternately baked and frozen in a large thermal vacuum chamber at the European Space Technology and Research Centre (ESTEC) in Noordwijk, The Netherlands, Europe's comet chaser has come through with flying colours.
Imprisoned in the giant, airless chamber, the Rosetta orbiter, its Lander and their complement of 20 scientific instruments were exposed to the conditions of extreme heat and cold that they will experience during their 10-year, 5 billion kilometre mission to Comet Wirtanen.
In order to simulate the warmth of the inner Solar System, the exterior of the spacecraft was heated to a sizzling 150°C. During subsequent tests, the temperature was allowed to plummet to minus 180°C. Sensors indicated that the spacecraft's insulation and heat control systems enabled Rosetta to survive these thermal tortures in fine shape, with internal temperatures restricted to between 50°C and minus 20°C.
"These tests show that Rosetta can survive the tremendous temperature contrasts it will endure as it flies from the vicinity of the Sun to the orbit of Jupiter," said John Ellwood, Rosetta Project Manager. "This gives us great confidence that the spacecraft will be able to survive its long exposure to the harsh environment of space."
Rosetta's punishing pre-launch programme is not over. Later this week it will be prepared for the next set of environmental tests. Once the high-gain antenna and huge solar arrays are mounted in early April, the spacecraft will be moved into an acoustic and then vibration chambers where it will be mercilessly shaken in order to check whether it can survive the stresses of a rocket launch.
These intensive trials will play a vital role in ensuring the success of Rosetta's unique mission to unravel the mysteries of Comet Wirtanen.
During its 10-year, 5 billion kilometre mission of exploration, Rosetta will travel from the benign environment of near-Earth space to the dark, frigid regions beyond the asteroid belt. During three circuits of the Solar System, the amount of light and heat radiation reaching Rosetta will vary by as much as 25 times.