Page last updated at 00:59 GMT, Friday, 16 April 2010 01:59 UK

Europe prepares to ship second ATV space freighter

By Jonathan Amos
Science correspondent, BBC News, Bremen


Up close with a giant space truck

Europe's next space truck is nearly ready to be shipped to its launch site.

Dubbed "Johannes Kepler" after the famous German scientist, the vehicle is expected to fly to the International Space Station (ISS) in November.

It will take more than six tonnes of fuel, air, food and equipment to the orbiting outpost, acting as a temporary store room on the back of the platform.

The unmanned spacecraft will also use its thrusters to push the ISS higher into the sky.

The freighter - also known by its generic name of Automated Transfer Vehicle (ATV) - will be the second such craft sent to the ISS. The first, "Jules Verne", had a near-flawless flight to the station in 2008.

Front of ATV Jules Verne (Nasa)
The robotic ship provides critical logistics support to the ISS, especially post-shuttle
It will have the biggest refuelling and waste elimination capability for the space station
ATV will push the ISS higher into the sky once the shuttle's height limitations no longer matter
It is the only vehicle on the current timeline able to de-orbit the ISS when it is retired

The European Space Agency (Esa) trucks are now coming off the end of what could be described as a production line at prime contractor EADS Astrium's Bremen facility in Germany.

ATV-3 is already part built, and as soon as Johannes Kepler goes out the door in May, integration of ATV-4 will begin.

"I'm not sure Henry Ford was talking about the same cadence as we have it here because we are delivering [just] one ATV per year, but considering the huge dimension of the vehicle, it's a production line, yes," observed Michael Menking, Astrium's head of orbital systems and space exploration.

The freighter is part of the barter arrangement Esa has with its international partners on the ISS project.

Instead of handing over cash to cover station running costs, Europe has taken on the major responsibility of resupplying the platform; and in return it gets residency rights for its astronauts.

Five freighters have already been ordered to fulfil the commitment through 2013; and with the ISS now expected to fly until at least 2020, discussions will soon begin on procuring ATV-6 and ATV-7.

And there could be even more to follow if space station operations are extended deep into the 2020s. What is for sure is that at least one additional ATV will have to be built just to de-orbit the space station at the end of its life.

Only the European freighter has the fuel capacity, combined with the propulsive might, to carry out such a task.

Wide view of Johannes Kepler (EADS Astrium)
In two parts: Solar panels and thermals blankets are yet to be attached

Johannes Kepler currently stands into two parts at Bremen - one end contains its propulsion and avionics units; the other end is the pressurised module which will hold the cargo.

The two sections will only be joined once they are at the Kourou spaceport in French Guiana prior to their attachment to an Ariane 5 rocket. Engineers and mission managers are working to a timeline that would see a launch in perhaps late November with a docking at the ISS in mid-December.

The astronauts will certainly be very pleased to see another ATV visit. The additional room in 2008 proved very popular, not least because its position on the end of the station made it a very quiet place.

"I believe it's true that two Russian crewmembers slept in the ATV, however it's not qualified for that," observed Nico Dettmann, Esa's ATV-2 mission manager.

One of the major aspects for the future is to see how far we can advance the capabilities of ATV
Michael Menking, EADS Astrium

"In order to have a real sleeping module, you have to fulfil certain requirements on radiation and those radiation requirements are different for a module that you spontaneously just ingress and egress to load and unload cargo."

Making the modifications to give the ship added radiation protection has not been carried out on Johannes Kepler. Indeed, very few changes have been made to the vessel, such was the smoothness of Jules Verne's mission.

The board which reviewed ATV-1 made some 130 recommendations, of which about 30 were picked up for implementation. A number affected the spacecraft, others related to the operation of its ground control segment.

There were only two significant hardware issues on the ATV's maiden voyage.

One, early in the flight, saw the vehicle's propulsion system switch to a back-up chain when anomalous pressure readings were detected in the complex network of pipes and valves that feed the engines. The other saw segments of thermal blanket on the exterior of the craft lift away from their Velcro fittings.

Both issues have been addressed and neither event is expected to repeat itself.

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: 1.1bn euros; Mission cost: 400-450m euros

Esa wants Johannes Kepler to be viewed as part of a "reliable recurring service". This means the ship's voyage to the ISS will be much shorter this time.

"For Johannes Kepler, the mission profile will be very different," explained Olivier de la Bourdonnaye, Astrium's ATV programme manager.

"For ATV Jules Verne, it was a kind of qualification flight, which meant that before docking ATV had to demonstrate in flight its capabilities. There were a series of 'demo days'. For Johannes Kepler, nothing like that will occur. We will join the vicinity of the station and then dock directly."

The robotic truck's sophisticated capabilities - it can find its own way to the ISS and attach itself without any human intervention - have prompted Europe to consider upgrading the freighter into an astronaut crew ship.

Esa has asked Astrium to scope out the design of a return capsule that could be fitted to the ATV's propulsion and avionics section instead of the present pressurised unit.

It is envisaged this Advanced Return Vehicle (ARV) would be used in the first instance to bring just cargo safely back to Earth from the ISS.

However, the capsule would be developed in such a way that life support systems for astronauts could be incorporated at a later stage if European member-states decided to pursue the option.

"One of the major aspects for the future is to see how far we can advance the capabilities of ATV. Currently, it is filled full of waste and then burnt up through re-entry. To bring cargo back to Earth, it has to have a capsule," said Dr Menking.

To go to the next level would be a big step for Europe.

"The ability to transport crew is first, let's say, a political decision," the Astrium boss observed.

ARV (EADS Astrium)
ATV could be fitted eventually with a return capsule

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