An analysis of close approaches and probability of collisions between LEO resident space objects and mega constellations

ABSTRACT

With the undergoing and planned implementations of mega constellations of thousands of Low Earth Orbiting (LEO) satellites, space will become even more congested for satellite operations. The enduring effects on the long-term space environment have been investigated by various researchers using debris environment models. This paper is focused on the imminent short-term effects of LEO mega constellations on the space operation environment concerned by satellite owners and operators. The effects are measured in terms of the Close Approaches (CAs) and overall collision probability. Instead of using debris environment models, the CAs are determined from integrated orbit positions, and the collision probability is computed for each CA considering the sizes and position covariance of the involving objects. The obtained results thus present a clearer picture of the space operation safety environment when LEO mega constellations are deployed. Many mega constellations are simulated, including a Starlink-like constellation of 1584 satellites, four possible generic constellations at altitudes between 1110 km and 1325 km, and three constellations of 1584 satellites each at the altitudes of 650 km, 800 km, and 950 km, respectively, where the Resident Space Object (RSO) spatial density is the highest. The increases in the number of CAs and overall collision probability caused by them are really alarming. The results suggest that highly frequent orbital maneuvers are required to avoid collisions between existing RSOs and constellation satellites, and between satellites from two constellations at a close altitude, as such the constellation operation burden would be very heavy. The study is not only useful for satellite operators but a powerful signal for various stakeholders to pay serious attention to the development of LEO mega constellations.

KEYWORDS:

• Resident space object
• mega constellation
• close approach
• collision probability

Acknowledgments

The authors are grateful to anonymous reviewers whose constructive and valuable comments greatly helped us to improve the paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research has been supported by the National Natural Science Foundation of China [Grant No. 41874035], the National Natural Science Foundation of China [Grant No. 12103035], the Natural Science Foundation of Hubei province, China [Grant No. 2020CFB396], and the Fundamental Research Funds for the Central Universities, China [Grant No. 2042021kf0001].

Notes on contributors

Yan Zhang

Yan Zhang is currently working toward a PhD degree in geodesy and surveying engineering with the School of Geodesy and Geomatics, Wuhan University. His research interests include space traffic management, satellite collision warning, and collision probability.

Bin Li

Bin Li received the MS and PhD degrees 2013 and 2017, respectively. He is currently an Associate Research Fellow with the School of Geodesy and Geomatics, Wuhan University, Wuhan, China. His research interests include space object surveillance and catalog, orbital mechanics, orbit determination and prediction, uncertainty propagation, and machine learning.

Hongkang Liu

Hongkang Liu is currently working toward a PhD degree in geodesy and surveying engineering with the School of Geodesy and Geomatics, Wuhan University. His research interests include orbit mechanics, machine learning and uncertainty quantification and propagation.

Jizhang Sang

Jizhang Sang received the BS and MS degrees in geodesy from the Wuhan Technical University of Surveying and Mapping (now part of Wuhan University), Wuhan, China, in 1983 and 1986, respectively, and the PhD degree in satellite navigation from the Queensland University of Technology, Brisbane, QLD, Australia, in 1997. From 1998 to 2013, he was a Senior/Principal Research Engineer with EOS Space Systems, Canberra, ACT, Australia. Since 2013, he has been a Professor at the School of Geodesy and Geomatics, Wuhan University, Wuhan, China. He has published widely in geodesy, satellite navigation, and space debris orbit determination. His research interests include space debris surveillance, orbit determination, atmospheric mass density modeling, space geodesy, and satellite navigation.