ATV-4. Credits: NASA

ATV-4. Credits: NASA/ESA

Mission director Mike Steinkopf sent this update from ATV-CC:

We just finished our internal briefing: all ATV-4 systems are nominal and we are GO for reentry.

A first deorbit boost DEO1 is planned at 08:35 GMT (09:35 CET) with a decreasing ATV-4’s speed by about 26 m/s for a duration of about 7 min. The second and last boost (DEO2) is planned for 11:28 (12:28 CET) and will decrease its speed by 88.4 m/s for about 23 min.

This is the biggest-ever boost of all ATVs because of ATV-4’s special reentry flight plan that will be observed from the International Space Station. Albert Einstein will aim for an orbit that puts it -70 km below sea level (a -70 km perigree) whereas previous ATV’s aimed at 0 km. 

In other words ATV-4 will enter our atmosphere at a steeper angle over the South Pacific Unpopulated Area safety zone compared to its predecessors.