ATV on track for 2007 debut
A final series of environmental and functional tests are being carried out in Holland on the European Space Agency’s (ESA) new vehicle, which will soon be carrying out re-supply missions to the International Space Station (ISS).
The ATV (Automated Transfer Vehicle) Jules Verne suffered major technical problems 2005, but is now on track to make its debut flight on top of an Ariane 5 launch vehicle, mid 2007.
The ATV will serve as an automated vessel, regularly launched by ESA to work alongside the Russian Progress re-supply, carrying food, clothing, fuel and experiments to the ISS, as the station grows in size and crew compliments.
Together with the Columbus laboratory, delivered to NASA this May, the ATV is one of ESA’s two major contributions to the ISS and was developed under the prime contractorship of EADS SPACE, as was Columbus.
On its outward journey, it will carry food, drinking water, oxygen, nitrogen, diverse scientific material and up to four metric tons of rocket fuel to maintain the Station in the correct orbit. On its return journey, after remaining docked to the Russian Zvezda module for six months, it will carry away 6.5 metric tons of waste produced on board the Station and undergo a controlled disintegration, together with its cargo, as soon as it reaches the outer limits of the Earth’s atmosphere
The ATV suffered a major setback in April 2005, when a small structural failure was deemed as too far reaching in risk management evaluations - thus requiring a major re-work and replacement of the ATV’s 48 valve-actuators in the Jules Verne’s fuel pipeworks of the propulsion system, buried deep in the then-completed ATV. This caused a delay of nearly half a year in the processing of the vehicle.
Another failure was spotted on the drive mechanism of the crucial solar arrays – forcing a back-up device to be installed.
However, testing in Noordwijk, Holland has been encouraging, as ESA’s most complex vehicle ever built starts to move closer to making its first jaunt into space.
‘With an unladen mass of almost 20 metric tons and equipped with flight software comprising nearly 10 times more lines of code than that of Ariane 5, the ATV represents the most impressive and complex space payload ever to have been built in Europe,’ explains Nicolas Chamussy, head of the ATV programme at EADS SPACE, speaking in an internal ESA bulletin
‘Alongside the functional tests currently under way at Les Mureaux, the set of mechanical and environmental tests being conducted at Noordwijk under the supervision of the teams from EADS SPACE, acting as the vehicle’s prime contractor on behalf of ESA, are of fundamental importance to the qualification and final acceptance of the space vehicle, and the essential prerequisite for its launch.’
The fully assembled ATV was tested in the acoustics chamber at ESTEC in mid-June, which saw the vehicle subjected three times to an acoustic load of up to 144 decibels, for a duration of thirty seconds on each test. These tests are vital to see how the spacecraft reacts to the acoustic vibration endured during launch on top of an Ariane 5.
‘We have an intense programme of activities to accomplish between now and the beginning of September, when thermal testing is due to start, but the teams from Bremen, Les Mureaux and Aquitaine are confident and looking forward to moving on to the next stage,’ reassures Marc Chevalier, in charge of the AIT and Launch Operations part of the ATV programme.
This will involve placing the ATV inside ESTEC’s Large Space Simulator, the largest vacuum chamber in Europe, for three consecutive weeks. The facility is capable of simulating the vacuum of space and reproducing the extreme fluctuations in temperature, varying from -130C to +150C depending on exposure to the Sun, which imitate the environment in which the ATV will have to operate during its six-month orbital mission.
Also being tested on the ATV is the state of the art software, tagged its ‘electronic brain’ by ESA. These tests – known as FSF (Functional Simulation Facility) – are being carried out at the EADS SPACE facility at Les Mureaux, on the outskirts of Paris.
‘Close to a hundred engineers are engaged in the task of rehearsing each phase of the ATV’s mission, on the basis of a hundred or so tests, from its release into orbit by Ariane 5 to its docking with the ISS, including the various booster phases to reposition the Station,’ noted Jean-Noel Monfort, the manager in charge of ATV qualification.
‘Our tests run through all predefined phases of the mission, but also include scenarios exposing the ATV to situations of critical failure that it might have to deal with.’
Safety precautions are also being tested, to ensure a malfunctioning ATV knows it will have to sacrifice itself, rather than attempt to dock with the ISS. The ATV has a dual failure protocol, with one failure switching on back up systems that will allow docking to continue. A second failure and the vehicle will give priority to the ISS, manoeuvring itself to a safe distance away from the station.
‘After devoting so many years to developing and perfecting the ATV, we have finally reached the operational phase and only have one objective in sight: that of seeing the ATV dock onto the ISS at a distance of 400 km above our heads. It will be a major premiÃ¨re for Europe,’ said Monfort, of ESA.
‘Following on from the delivery of the Columbus laboratory to the Kennedy Space Center in May, we have already proved that we are capable of reaching several important milestones in the ATV programme, which is a highly complex undertaking, and our teams have been working hard to meet the deadline of delivering Jules Verne to the Kourou Spaceport in early 2007.’
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