Rosetta breaks the sound barrier
23 May 2002Europe's comet chaser has not yet left the planet, but the Rosetta spacecraft has already broken the sound barrier during preparations for its launch nextJanuary.
At the beginning of May, the spacecraft was subjected to a series of deafening acoustic tests that would impress even the most dedicated fan of heavy metal music. Placed in a giant chamber, a barrage of sound was directed at Rosetta from a huge amplifier in order to simulate the noise expected during lift-off.
Soaring to a maximum of 135 decibels - many times louder than Concorde at take-off - the sound levels were so severe that anyone straying within the chamber would have been killed within seconds.
Following these not-so-good vibrations, Rosetta returned to the clean room to complete a rock and roll turn on a giant shaker in order to simulate its ride into orbit aboard an Ariane 5 rocket.
Attached to a table capable of moving the 3 tonne spacecraft from side to side like a metallic rag doll being mauled by a mastiff, Rosetta was severely shaken, first vertically and then horizontally over a wide range of frequencies. Over two hundred accelerometers on the structure were used to monitor the spacecraft's performance during each one-minute simulation.
"These environmental tests were essential to show that the spacecraft will survive the stresses of launch," explained John Ellwood, Rosetta project manager.
"The spacecraft was powered in its launch mode with the Lander, the high gain antenna and the solar arrays all in their launch configuration," he said. "Even the propellant tanks were filled with 'dummy fuel'."
"I'm pleased to say that the spacecraft performed very well and no significant problems were identified," he added.
Once the engineers at the European Space Research and Technology Centre at Noordwijk in the Netherlands have verified that all of the spacecraft's electronics were still working nominally, they will prepare for this week's deployment test involving Rosetta's huge and unique solar arrays and booms. This check-out will show whether each of the two 15-metre-long arrays and the delicate instrument booms have survived their potentially shattering ordeal intact.
Rosetta is expected to be shipped to the spaceport in Kourou, French Guiana, during September 2002. The launch is scheduled for the night of 12-13 January 2003.