The reentry of a Soyuz rocket stage over southern Australia on August 7

click map to enlarge

 

On 7 August 2023 at 13:20 UTC, Russia launched the first of it's improved GLONASS-K2 navigation satellites from Plesetsk Cosmodrome. The launch employed a Soyuz 2.1b rocket with a Fregat upper stage. The payload and the Fregat upper stage were subsequently catalogued in 19156 x 19135 km resp 19182 x 19005 km, 64.8 degree inclined Medium Earth Orbits (MEO), as catalogue numbers 57517 and 57518.

Some 40 minutes after the launch, people from southern Australia and Tasmania were treated to a spectacular sight of a bright slow-moving, fragmenting fireball that crossed the sky. Many eyewitness video's were posted on social media and poicked up by the News media: for a few fine examples see here, here, here and  here. Immediate suspicions were raised that this was space debris.

Indeed, the fireball was the Soyuz 3rd stage reentering the atmosphere. A Navigational Warning for space debris connected to this launch had been published earlier (HYDROPAC 2502/23), for an area south of Australia and Tasmania:

021113Z AUG 23
HYDROPAC 2502/23(75,76).
TASMAN SEA.
WESTERN SOUTH PACIFIC.
TASMANIA.
DNC 05, DNC 06.
1. HAZARDOUS OPERATIONS, SPACE DEBRIS
   071300Z TO 071600Z AUG, ALTERNATE
   1300Z TO 1600Z DAILY 08 AND 09 AUG
   IN AREA WITHIN 35 MILES OF TRACKLINE JOINING
   43-10.00S 148-55.00E, 53-30.00S 163-20.00E.
2. CANCEL THIS MSG 091700Z AUG 23.

The time window matches well with the Australian reentry sighting. The area defined by the Navigational Warning matches a launch into a ~63 degree inclined parking orbit from Plesetsk:

click map to enlarge

 

The Soyuz 2.1b rocket consists of four side boosters ('stage 1'), a core stage ('stage 2') and a third stage. On top of that is (for this launch) the Fregat upper stage. The Soyuz rocket brings the Fregat upper stage and GLONASS payload in a low parking orbit. From there, a series of firings of the Fregat stage bring the payload to 19150 km Medium Earth Orbit (MEO). The Fregat upper stage is left on orbit, but the Soyuz stages deorbit downrange from the launch site: the last of these stages, is the stage that reentered over southern Australia about half a revolution after the launch.

GLONASS is the Russian equivalent of GPS.