Increased risk of collision in space

SGGP July 22, 2023 11:38

According to data from the German company Statista, before the US company SpaceX was born in 2019, there were only 2,300 satellites in Earth's orbit. To date, this number has reached 10,500 satellites, of which 8,100 are still active. SpaceX's Starlink telecommunications network alone currently has about 4,700 satellites in orbit.

Satellites for SpaceX's Starlink network

In a report submitted to the US Federal Communications Commission at the end of June, billionaire Elon Musk's company said it had had to perform more than 50,000 collision avoidance operations since deploying the Starlink network in 2019, of which more than half were in a 6-month period (from December 1, 2022 to May 1, 2023). This shows that the risk of collision between satellites has increased dramatically, with an average of nearly 140 collision risks per day. According to Professor of Aerospace Hugh Lewis of the University of Southampton (UK), the number of collision avoidance operations has increased 10-fold in just 2 years. It is predicted that this number will be 50,000 in the next 6 months, 100,000 in the next 6 months.

Meanwhile, the number of satellites launched into space continues to increase. SpaceX plans to launch up to 12,000 satellites for the first generation of Starlink. The second generation of Starlink could have up to 30,000 satellites. Amazon with its Kuiper project or China with its GW project are planning to launch many satellites into orbit. According to estimates by aerospace experts, by the end of this decade, the number of space objects orbiting the Earth could reach 100,000.

SpaceX has a collision alarm system that automatically commands satellites to take evasive action when the probability of hitting another object in their path exceeds a threshold of 1 in 100,000. This threshold is considered more stringent than the 1 in 10,000 threshold used by other space companies. However, the calculations in the alarm system are not completely accurate because of the influence of changes in space weather, such as electromagnetic storms, which can skew the calculations. In addition, the more objects in orbit, the higher the risk of collision.

In addition to satellites, there are currently many pieces of debris in space with different sizes and the number is also increasing rapidly, making it more difficult to ensure the safety of satellites. According to Professor Lewis, if there are no better management measures, the situation will become uncontrollable. According to the European Space Agency, there are currently 36,000 pieces of debris larger than 10cm and one million small pieces (larger than 1cm) flying at a speed of 28,000km/h around the Earth. At such a terrible speed, any collision, even with the smallest piece of debris, can cause serious damage.

Faced with this prospect, many technologies have been developed to monitor the flight paths of satellites and debris, using radar, optical or electromagnetic means. For example, the American company LeoLabs has built many radar stations that can detect objects as small as 2cm in low orbit. With this technology, they can predict the risk of collision 7 days in advance and thus can carry out operations to avoid accidents.

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