 |
| click map to enlarge |
At the end of the first week of September, the North Korean military reconnaissance satellite Malligyong-1 (2023-179A) made an orbit raising manoeuver again, as I predicted in June.
The raise can be seen as sudden altitude jumps at the righthand side in the diagrams below, that plot the change in the satelllite's apogee and perigee altitude over time. The first diagram shows Malligyong's orbital evolution since launch in 2023, with three orbit raising events, one in February 2024, one in June 2024 and now one in September 2024 (the gradual sinusoid trends are due to natural orbit decay and
periodical evolution of the orbital eccentricity: the sudden stepped
"jumps" are manoeuvers). The second diagram is a detail and shows the current September orbit raise, in five distinch daily steps:
 |
| click diagram to enlarge |
 |
| click diagram to enlarge |
As was the case for the orbit raising manoeuvers in February and June 2024, the raise was performed in five incremental steps, one per day. The first manoever was on September 6, the last on September 10. It raised the average orbit by 5.9 km, similar to the altitude raise in June, to 504 km (see diagram below), slightly above the initial orbit insertion altitude from the launch in November 2023. While the June manoeuvers raised both perigee (slightly) and apogee, this time only the apogee was raised, from 499 km to 511 km, a raise of 12 km (see diagrams above).
 |
| click diagram to enlarge |
As a result of the manoeuver, the value for the daily RAAN precession is now slightly under, but still very close to, the ideal sun-synchronous value, with the match improving over time (se diagram above)
From the pre- and post-manoeuver orbital data, I reconstruct these five sequential nominal manoeuver times (for an explanation of how these times were determined, see my earlier analysis of the February manoevres in The Space Review of 8 April 2024):
# DATE UTC LAT LON ORBITS USED FOR ANALYSIS RAISE
M1 06 Sep 2024 13:12 36.9 N 137.4 E 24250.58978379 24251.57588172 1.17 km
M2 07 Sep 2024 14:24 48.6 N 122.4 E 24251.57588172 24252.49645891 1.18 km
M3 08 Sep 2024 14:01 60.6 N 133.0 E 24252.49645891 24253.21993764 1.19 km
M4 09 Sep 2024 13:43 55.0 N 134.8 E 24253.54879868 24254.20668986 1.20 km
M5 10 sep 2024 13:32 26.0 N 130.6 E 24254.20668986 24254.93046907 1.19 km
These nominal positions correspond to the crosses in the map below, with the lines showing the trajectory from 10 minutes before to 10 minutes after the nominal manoeuver time:
|
| click map to enlarge |
As can be seen, and as was the case in February and June, all manoeuver times correspond to passes within direct line-of-sight range of the Pyongyang General Satellite Control Center (PGSC) in North Korea (the red oval in the map is the geographical area where the satellite will be above the horizon as seen from Pyongyang). And as was the case in February and June, all manoevers were done on late evening passes, between roughly 13 -14 UTC (10-11 pm local time in Pyongyang).
The manoeuvers started three days earlier than I had predicted. In June, I had predicted the next manoeuver to start either Sept 9, Sept 16 or Sept 23. That was based on the time between previous manoeuvers, and the fact that these were initiated on Mondays. This time however, the series of manoeuvers started on a Friday.
We can expect the next orbit raising manoeuver to happen mid-December 2024, most likely somewhere around December 13-16, on local late evening passes (13-14 UTC) within direct range of Pyongyang.
No comments:
Post a Comment