By Jonathan Amos

Science reporter, BBC News

The propulsion unit of Johannes Kepler is taking shape

"It's clear from space history that often it was not the prototype that experienced the problems; it was the mission that came later. That's why specific attention has to be paid to what we do now." Nico Dettmann is in charge of producing the European Space Agency's (Esa) next space freighter. THE ATV - THE FIRSTS The ATV is the first completely automated rendezvous and docking ship to go to the ISS The ATV is the largest and most powerful space tug going to the ISS over its mission life It provides the largest refuelling and waste elimination capability for the space station It is the only vehicle on the current timeline able to de-orbit the ISS when it is retired He knows the near-flawless maiden voyage of the Automated Transfer Vehicle (ATV) last year does not mean the second flight is guaranteed to turn out the same way. Attention to detail is everything. The follow-up ship - dubbed Johannes Kepler - is in the process of being assembled. Its propulsion and avionics units are being prepared in Bremen, Germany. Its pressurised module which will hold the cargo - air, water, scientific equipment, food, and clothing - to be taken to the space station is being built in Turin, Italy. The various segments should come together in September, into a single line of assembly that will lead to a launch in November 2010. Thereafter, ATVs will fly every year for three years. The vehicle is no longer an experimental spacecraft; it is a production spacecraft. And to emphasise the point, if you walk through the cleanroom at EADS Astrium in Bremen, you can already see ATV-3 components. "The whole integration process, from the first day until launch, is 28 months. So if you want to launch every 12 months, obviously you have to produce in parallel," explained Esa's Mr Dettmann. The brains of ATV - its parallel computers - are inside the avionics bay

The space freighter has huge significance for Europe. On one level, it is the "subscription" Europe must pay to be part of the International Space Station "club". If Europe can deliver about six tonnes of supplies a year to the platform, it is guaranteed six-month residencies at the ISS for its astronauts. But ATV has also been a test of European competency. It is the biggest, most sophisticated vehicle the bloc has ever flown in space. Its automatic rendezvous and docking technology allows it to find its own way to the station and attach itself without any human intervention. Please turn on JavaScript. Media requires JavaScript to play. The European Space Agency believes the vehicle's capabilities will feed into many other exploration activities, at the Moon, Mars and other Solar System destinations. Esa is even looking into the possibility of upgrading the robotic truck so that it can carry people - an independent European crew transportation system. Astrium Bremen is in sole charge of manufacturing Johannes Kepler. The company's Les Mureaux plant in France had a bigger role on the previous vehicle (known as Jules Verne) but with the switch to routine production, it was felt the lines of responsibility should be simplified. "In the past, we had one organisation dedicated to development and one to production. At the end of Jules Verne, it was decided to have just one organisation in order to have maximum consistency going forward," said Astrium's ATV project manager, Olivier de la Bourdonnaye. "All of what we did on the Jules Verne adventure belonged to the development of ATV; and it finished a couple of months ago with the post flight analysis." Please turn on JavaScript. Media requires JavaScript to play. Germany carries about 50% of the production effort; and all the sub-contractors - including Europe's other major space concern, Thales Alenia Space - are reporting direct to the German centre. Very little is having to be changed on ATV-2, such was the success of Jules Verne. There were only two significant hardware issues. One, early in the flight, saw the vehicle's propulsion system switch to a back-up chain when anomalous pressures were detected in the complex network of pipes and valves that feed the engines. The other saw a segment of thermal blanket on the exterior of the craft lift away from its Velcro fittings. Neither event affected the mission and should be easily remedied on Johannes Kepler. The pressurised cargo module is being prepared by Thales in Turin

Perhaps more significant was the slight mismatch that occurred in the advanced GPS systems used on ATV and the Russian Zvezda module on the ISS to align the vehicles prior to docking. Had the discrepancy been more serious, Jules Verne could have been triggered into aborting its approach to the platform. It wasn't - and a software correction on the Russian side should fix this issue before Johannes Kepler arrives in 2010. The ship will be heavier this time - by some 600kg. This will take it over 20 tonnes, making its launch the heaviest payload in the history of Esa missions. The supplies ATV-2 carries will be gratefully received: with six permanent residents now living on the platform, Europe's logistics effort is paramount (the US shuttle should be close to retirement by November 2010). Its role in boosting the ISS will be significant, also. With no shuttle visiting the station, the ATV's power will be needed to lift the platform higher into the sky to avoid the drag from residual air molecules at the top of the atmosphere. "We're supposed to lift the station significantly because after the shuttle retirement the ISS will raise its average altitude from 330-350km to almost 400km to produce less drag," said Mr Dettmann. "Today the ISS altitude is linked - let's say - to low shuttle performance. After shuttle is gone, ISS can fly higher but ATV will have to deliver a major part of that altitude increase." Total cargo capacity: 7.6 tonnes, but first mission flew lighter Mass at launch: About 20 tonnes depending on cargo manifest Dimensions: 10.3m long and 4.5m wide - the size of a large bus Solar panels: Once unfolded, the solar wings span 22.3m Engine power: 4x 490-Newton thrusters; and 28x 220N thrusters Development cost: 1.3bn euros; Subsequent missions: 400m euros

Jonathan.Amos-INTERNET@bbc.co.uk



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