The ATV will mark several firsts for Europe's launcher: it will be carrying a payload of up to 21 tonnes, injecting it into an inclined 51.6° circular orbit at an altitude of 260 kilometres and reigniting its upper stage twice after a long ballistic coast phase. The first firing will deliver 30 seconds of additional thrust to circularize the orbit. The second, lasting 15 seconds, will slow the upper stage so that it falls 115 back into the atmosphere and breaks up over the Pacific to prevent any chance of falling on populated areas. Combining proven elements from other versions, Ariane 5 ES-ATV features the EPC main cryogenic stage of the Ariane 5 ECA (with a lift capacity into GTO of 10 tonnes), topped by the EPS reignitable storable propellant stage of the Ariane 5 GS and two higher-thrust EAP solid booster stages. For the ATV, new Ariane flight software had to be defined and the launcher was modified to withstand higher loads. Finally, the carbon fibre structure of the vehicle equipment bay has been strengthened and the attitude control system adapted for a longer flight. As a precaution, the upper stage's liquid propellants are heated to 27-33°C before launch to stop them getting too cold during the ballistic phase. Lastly, the new launcher trajectory requires a dedicated network of tracking stations.
