We got a quick confirmation from ESA’s ATV-4 Mission Manager Alberto Novelli on how Albert Einstein – at 20 235kg – weighs in as the heaviest spacecraft ever lifted by Ariane – more so than any of the three previous ATVs. Alberto wrote:
It’s important not to mix up the weight of cargo with the overall weight of the ATV.
In terms of cargo, we are slightly less than ATV-3 (on the order of 10kg) and definitely less than ATV-2. In terms of overall mass, we are heavier than any ATV and any satellite launched in Europe so far by about 200kg.
The reason is that we have a higher “tare” mass – including the cargo racks, adapter plates (e.g. to secure the Columbus water pump assembly during launch), etc. – this is included in the overall vehicle mass but it is not counted in the cargo mass that we actually transfer to the ISS.