It’s strange, looking back over all my space posts of the past 3 years I couldn’t find any that were dedicated to the European Space Agency’s cargo craft, the Automated Transfer Vehicle. Sure I mentioned it in passing back when JAXA sent its first HTV to the International Space Station but even its second flight, named Johannes Kepler, obviously wasn’t inspiring enough for me to take notice. The only good reason I can come up with is the maiden voyage happened well before I got into blogging, but that doesn’t excuse me ignoring the significance of the ATV.
The ESA’s ATV is the only craft that the ESA has that participates in the ISS program. It’s a derivative of the Multi-Purpose Logistics Module that the Shuttle used to carry up to the ISS and is meant to work alongside the Russian Progress craft that have been resupplying the ISS for years. Compared the Progress its something of a monster being able to deliver almost 4 times the payload although that’s offset significantly by the fact that it’s current launch rate is about once per year. The majority of the payload is taken up by reboost and attitude control propellant as the ATV is capable of reboosting the ISS, something which no other craft is currently capable of doing (the retired Shuttle was the primary reboost craft prior to this). The rest of the payload consists of crew and station consumables, roughly equivalent to the amount that a Progress craft would deliver.
Today sees the ESA’s 3rd ATV docking with the International Space Station:
Whilst it’s not pushing any boundaries or developing new capabilities the successful docking of the Edoardo Amaldi shows that the ESA can make the yearly launches of the ATV without incident. That’s quite an achievement in itself and means that the 2 currently planned ATV launches should go off without a hitch. With the upcoming flights from companies like SpaceX and Orbital Sciences to the ISS you might be wondering why we’d bother having a craft like the ATV, especially when something like the Dragon has similar capabilities whilst also being reusable. The answer, from my perspective is two fold.
For starters neither of the upcoming private craft have the ability to reboost the ISS. Now doing this is non-trivial so its unlikely that either craft will gain that ability in the near term and as far as I can tell there are no other craft, current or planned, that have that ability. That surprises me as the second argument for the ATV’s existence, redundancy in capabilities, doesn’t exist with ISS reboosting. It’s possible that the upcoming Space Launch System with the Orion capsule might be able to do this but I can’t find anything that states that.
The second reason, as I alluded to before, is that when it comes to maintaining a human presence in space it doesn’t hurt to have redundancy for different capabilities. Whilst you can argue that there will be much better ways of doing things in the future it never hurts to have a backup that you can rely on. The ATV, with its rock solid yearly launch schedule, makes for a good fall back for other re-supply missions should they encounter any issues. Now all that’s required is finding another means by which to reboost the ISS and then we’ll have full redundancy across most of our manned space program activities.