A brief update from ESA’s Thomas Beck, Mission Director responsible for reboost operations at ATV-CC.
The first reboost of the of the ISS by ATV-4 has just finished and was fully successful. Two OCS (orbital control system) thrusters (engines 2, 4) functioned flawlessly during the burn that started at 15:05 CEST and lasted 407 sec. ATV provided the ISS with a change in velocity (delta-v) of 1.0 m/sec.
The next propulsive support, using just the ACS system (attitude control system, i.e. thrusters) is planned during the EVA next week (24 June) during which ATV’s propulsion system will be used to ‘desaturate’ the ISS control momentum gyroscope (CMG).
Desaturation means, essentially, that ATV takes over attitude control for the ISS while the the gyroscope wheels are off-loaded.
Today’s burn sort of looked like this; well, only two engines were used instead of the four shown here – but you get the idea! More details on ATV propulsion via Astrium.