1 Author: Bakhtigarayev N.S. (Institute of Astronomy of the RAS), Chazov V.V. (SAI MSU)

Title: Is the “Kessler Syndrome” Emerging in Geostationary Orbit? Results of the October Space Debris Observation Session

Abstracts: 
A recent observation session of space debris was conducted at the Terskol Observatory using the Zeiss-2000 telescope in October 2024.

The initial impression from this session raises the question: is the “Kessler Syndrome” beginning to manifest in geosynchronous orbit? For the first time, numerous (over 100) debris fragments were observed in geostationary orbit, characterized by near-zero orbital inclinations and low eccentricities.

A comparison of the results from this session with previous observations is presented. Preliminary findings indicate that, as of now, the newly detected fragments do not pose a critical threat to the operation of active spacecraft. However, there are many yet-undetected fragments, suggesting that the risk is likely to increase.

2 Author: Kuzin S.P. (Institute of Astronomy of the RAS)

Title: Study of geocenter motion series obtained as a result of DORIS RINEX measurements processing

Abstracts:
The report presents a harmonic analysis of weekly series of geocenter motion obtained by processing of DORIS RINEX measurements. The time series of geocenter motion were obtained by processing DORIS RINEX data of the eight active satellite missions (Cryosat2, HY2C, HY2D, Jason3, Saral, Sentinel3a, Sentinel3b and Sentinel6a satellites) over the time interval of 2022 – 2024.5. In addition, a harmonic analysis of weekly oscillations of the geocenter series was performed for a combined solutions including six satellite missions (Cryosat2, Jason3, Saral, Sentinel3a, Sentinel3b and Sentinel6a satellites) over the interval of 2023 – 2024.5. The harmonic analysis of geocenter oscillations was carried out using a software package written by the author of the article.

 As a result of the linear regression analysis, the offset, trend, amplitudes and phases of the annual and semi-annual harmonics of the geocenter motion, which are present in almost all of the above-mentioned satellite missions, were estimated. The estimated amplitudes of the annual components of the geocenter motion vary within 0.7–9.8 mm, 0.9– 11.5 mm and 2.3–36.3 mm for X, Y and Z components respectively. The amplitudes of the semi-annual harmonics vary within 1.8-7.6 mm, 2.7-10.6 mm and 1.3-20.8 mm for X, Y and Z components respectively.

In addition to the above-mentioned harmonic components, the series of geocenter variations also contain high-frequency harmonics with periods from 2 weeks to 3-4 months with amplitudes sometimes comparable with the annual and semiannual components.