Background

Early 2022 October, Russia released a range of navigation warnings for a satellite launch from Plesetsk. The areas covered and relative times reflected a similar set issued for a launch in April that year. The earlier mission was a test flight of the Angara 1.2 launch vehicle.


2022 April 29 Launch

The Angara rocket departed Plesetsk at 19:56 UTC. The nature of the payload was not announced but it was a military satellite and acquired the name "Cosmos 2555". It performed no orbital manoeuvres and re-entered naturally as the result of air drag on May 17.

Angara's configuration was as a three stage rocket. The two Angara stages were supplemented by an orbit insertion stage that performed two jobs. The first of was to act as the third stage provide the final thrust to orbit where it deposited the satellite at 278 x 293 kilometres, 96°.45 inclination. The two Angara stages re-entered above the Barents Sea and the eastern Pacific Ocean.


On-orbit Activity

The second task of the insertion stage was unconnected with the satellite. On other launches such as with a Soyuz-2 1v rocket, the insertion stage generally completes a further Earth circuit after satellite release and is sent to re-entry on it's next pass over the Pacific Ocean. In the case of April's Angara mission, the navigation warnings indicated that the insertion stage would make nearly two circuits from that point.

What was more, once the initial orbit of the satellite was known, it pointed to the stage making a significant manoeuvre. Without a manoeuvre, the ground track would not have passed over the disposal area indicated in the navigation warnings. That track would be 200-300 kilometres to the east of the zone.


Amateur Observation

On April 30, stories were circulating of a diffuse cloud being observed from the UK the previous evening, following a satellite-like track from south to north across the night sky, shortly after 23:00 UTC. It was 5-10 minutes later than when the payload would have been expected. It was flagged through the Seesat-L visual observers' discussion group by Nick James who provided a rather nice video.


Analysis of the Observations

The observed cloud was similar to what is often seen when a rocket stage is venting propellant and this is what the Nick James video shows. It was the Angara orbit insertion stage but over 800 kilometres above the Earth rather than the less than 300 kilometres of the satellite. It had not long finished firing its engine to send it into the Earth's atmosphere above the disposal area.

Putting the position against the star background together with the re-entry zone information pointed to the orbit being in the region of 279 x 855 kilometres at the same inclination as the satellite. Perigee appeared to be around 50° - 60° south latitude.

The effect of the orbit change was to increase the orbital period from the 90 minutes of the satellite to 96 minutes. It then completed nearly two circuits in the higher orbit before the re-entry engine firing. That meant it would be about ten minutes behind the satellite when it reached the latitude of the disposal area. In that time, the Earth would have rotated by 2°.5 eastward to place the disposal zone underneath the ground track.


2002 October 14

The navigation warnings for this event shows similar restricted zones to those for Cosmos 2555. What it tells us is that the orbit insertion stage will probably fly a similar profile to April flight. It is not possible to forecast it in detail but it will result in the insertion stage being be similarly 'late' in reaching its re-entry zone.

The launch time is mid-evening UTC. Given its similarity to previous launches, it's likely to be 19:50 - 20:00 UTC.

The map above lays out the mechanics of the April flight but is only a guide to what MAY happen for this mission. However, the insertion stage re-entry zone location restrains the launch vehicle mission duration to about 215 minutes.

Amateur observations from Europe are not going to be possible this time. April's launch was after the Spring Equinox, and the north polar area at 800 kilometres was illuminated by the Sun - hence visibility of the cloud.

This launch is on the 'wrong' side the Autumnal Equinox and the north polar area is unfortunately not illuminated. In fact the whole ground track is badly placed for observation as it passes over inhabited areas either in darkness or it misses them entirely, spending its time over the Oceans.


Navigation Warnings

These warning is for the Drop Zones of the Angara first stage (Area A) and the payload shroud (Area B):

HYDROARC 315/22(42,43).
BARENTS SEA.
RUSSIA.
DNC 22.
1. HAZARDOUS OPERATIONS, SPACE DEBRIS
1900Z TO 2130Z DAILY 14 THRU 17 OCT
IN AREAS BOUND BY:
A.
71-55.00N 032-28.00E, 70-54.00N 033-44.00E,
70-44.00N 032-29.00E, 71-44.00N 031-08.00E.
B.
74-26.00N 028-46.00E, 73-17.00N 030-36.00E,
73-05.00N 029-11.00E, 74-14.00N 027-15.00E.
2. CANCEL THIS MSG 172230Z OCT 22.

This warning is for the Drop Zone of the Angara second stage (Area A) and the insertion stage re-entry (Area B) at end of mission:

NAVAREA XII 752/22(19,83).
NORTH PACIFIC.
1. HAZARDOUS OPERATIONS, SPACE DEBRIS:
A. 1900Z TO 2130Z DAILY 14 THRU 17 IN AREA BOUND BY
15-45.75N 131-30.97W, 15-57.41N 132-39.92W,
11-30.37N 133-27.00W, 11-18.34N 132-19.33W.
B. 2230Z TO 2350Z DAILY 14 THRU 17 OCT IN AREA BOUND BY
40-05.66N 173-03.92W, 40-30.17N 175-21.75W,
33-27.17N 177-13.67W, 33-04.50N 175-08.00W.
2. CANCEL THIS MSG 180050Z OCT 22.