Plotting a course for Europe's space freighter
It was a big moment in every sense. When the Ariane 5 shook and lifted skyward, it marked not only the heaviest payload carried into orbit to date by Europe's premier rocket but the 200th mission of the launcher series initiated back in 1979.
Point perfect: Ariane delivered Johannes Kepler precisely into the 260km-high orbit demanded
Wednesday night's beefy passenger was the . Nicknamed Johannes Kepler for this mission, the robotic truck tipped the scales at 20,062kg.
I've discussed the capabilities of the ATV on a number of occasions, especially its very smart rendezvous and docking technology that allows it to find its own way to a destination and attach itself without any human intervention.
The current ship is the second such vehicle (the first, "", went to the launch pad 600kg lighter than Kepler). Three more ATVs are in various stages of construction.
The freighters are a kind of subscription that Europe has to pay to be a member of the International Space Station "club". Instead of handing over cash to the Americans to get access to the orbiting laboratory for its astronauts, Europe has instead bartered a logistics role for itself.
So long as ATVs keep turning up at the station with several tonnes of food, water, air, fuel and equipment, European astronauts can claim a place on the platform for six months out of every 24.
The ATV production line requires a decision now on any future orders
The supplies that will fly on the next three ATVs should see Europe meet its end of the bargain through to about 2016. But as we know, the station now looks as though it will fly until at least 2020, and perhaps beyond.
So how should Europe continue to pay its subscription?
It's a very timely question right now because European industry has told Esa that if the production line for the freighters is to be kept open and economical then fresh orders must be placed very soon.
For a long time, the expectation was that Esa would request simply an ATV-6 and ATV-7, with little significant change in the basic design concept.
Then the idea was floated of having a return capability added to at least one of these vehicles.
At the moment, the ATVs are destroyed at the end of their mission by being commanded to burn up in the Earth's atmosphere with all the refuse off-loaded from the space station.
Feasibility work has been done to assess the implications of adding a re-entry capsule, one that could be used in the first instance to bring cargo safely down to Earth and then maybe, sometime in the future, even astronauts.
But this option, known as the Advance Re-Entry Vehicle, does not appear to have the momentum it once had.
Adding a return capsule to an ATV may not be the best option in a common transportation plan
Driving the thought process now is the need for a global transportation policy, the idea that the different partners in the space station club bring capabilities that enhance the overall effectiveness of their endeavours in orbit.
In other words, on space transportation they should all play as a team. And with a number of return capsules already in development in the US (such as Dragon, Boeing CST-100, etc), does Europe really need to be duplicating this function?
Should it instead try something different, something new? Shouldn't the next series of ATVs look to take that clever automatic rendezvous and docking technology into new roles?
Simonetta Di Pippo is the director of human spaceflight at Esa. She told me that Esa was looking at re-defining the ships:
"The idea is to procure up to ATV-5 and then to develop a new system. We want something new in order also to keep the expertise in our industry.
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"We're discussing that in the context of the extension of ISS up to 2020 and beyond with our member states. It would be something that is a derivative of the ATV, with the requirements to be discussed with the station partners. Because whatever we develop, it has to be done on the basis of a common understanding of what is needed for the future.
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"With the new commercial systems coming out, we need to revisit the overall picture; and this has to be done together with the partners. In the past, we've had co-ordination but not a common plan. Now we want to develop a common plan that allows us to co-operate while at the same time being autonomous in certain technologies.
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"[The future vehicle] needs certain requirements. The space station needs to be de-orbited at a certain point; we need probably also on the longer term to be able to send some pressurised modules to the station, because we do believe that more space will be needed in the years to come; and it would need to have some features like a service module that could act as a tug.
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"In June, we should have the requirements on the table, jointly agreed with Nasa and the other partners."
So, some new roles for the European space freighter are being defined and we'll find out what they are very shortly.
The issue of de-orbiting the space station is an interesting one. Currently, we've no clear idea when that might happen; it could be quite late in the 2020s if the modules receive the necessary certification or/and are updated.
But what is clear is that of all the vehicles out there at the moment, only the ATV has the propulsive might to bring the 400-tonne structure down into the atmosphere and a controlled burn-up.
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