
The EU Space Surveillance and Tracking (EU SST) has monitored the re-entry of large space object CZ-5B (2022-085B), the core stage of the rocket that launched Wentian – the second module of the Chinese large modular space station – on 24 July 2022. The EU SST network of sensors observed the object closely, and its radars narrowed down its re-entry window to 30 July.
Latest update: 2022-07-30 21:50 UTC+2
Based on EU SST analysis and external information, EU SST confirms that object CZ-5B decayed on 2022-07-30 16:45 UTC ±15 minutes.
EU SST contributing sensors confirmed that the object was tumbling. The below figure shows the Velocity Time Intensity (VTI) of the object during the pass observed by the MFDR radar, with a tumbling speed of 3.3 seconds per revolution, which suggested a fairly fast rotation. Due to its inclination (41.47 degrees), the object could re-enter within the latitude band ±41.47 deg. These predictions however came with uncertainties as the object was uncontrolled, and a better estimation was only possible a few hours before the actual re-entry.

Velocity Time Intensity (VTI) of the object detected by MFDR radar during the pass on 31 October, with a tumbling speed of 5 seconds per revolution.
The below figure shows the ground track for the last estimated re-entry window 2022-07-30 17:24:11 UTC ±58 minutes.

Map of the whole ground track.
Green lines: ground track during the re-entry window. Red lines: part of ground track over EU Member States. Marker: centre of the predicted re-entry window.
Note: possible re-entry locations lie anywhere along the green lines. The re-entry point was considered to be at an altitude of 80 km.
Object CZ-5B had a mass ranging from 17 to 23 tonnes and a size of about 30 m, which made it one of the largest pieces of debris re-entering in the near past and therefore it deserved careful monitoring.
Note: this article will be updated with the latest information provided by EU SST’s Operations Centres.