[Reading Science] Musk's Starlink Is Currently Performing Aerobatics

Rapid Increase in Collision Avoidance Maneuvers
1 Million Maneuvers in 6 Months by 2028
Experts "Safety Concerns, Satellite Numbers Must Be Limited"

Elon Musk's space development company, SpaceX, has launched Starlink satellites for space internet service, which have become a cause for concern. Their sheer number threatens other satellites in Earth's orbit and interferes with astronomers' star observations. Recently, the number of avoidance maneuvers conducted by the rapidly increasing Starlink satellites to evade potential risks has surged dramatically. In the past six months alone, more than 25,000 avoidance maneuvers have been performed. The number is doubling every six months, and it is projected to reach one million by around 2028. Experts are calling for limits on the number of satellites in orbit.

On the 7th, space news outlet Space.com reported this citing data submitted by SpaceX to the U.S. Federal Communications Commission (FCC) on the 30th of last month. From December 1, 2022, to May 31, 2023, SpaceX activated thrusters more than 25,000 times over six months to change course and avoid potential collision risks with other satellites or space debris. This figure is about twice as high as the previous six months. Since SpaceX first launched Starlink satellites in 2019, the total number of avoidance maneuvers has exceeded 50,000.

Experts have expressed concerns that the exponential increase in avoidance maneuvers could lead to an uncontrollable state in Earth's orbit. Hugh Lewis, an astronomy professor at the University of Southampton in the UK, told the outlet, "The number is doubling every six months, and the problem with this exponential trend is that it reaches an enormous scale at a very rapid pace."

According to Professor Lewis, SpaceX conducted 2,219 avoidance maneuvers in the first half of 2021, 3,333 in the second half, 6,783 from December 2021 to June 2022, 13,612 in the second half of last year, and 25,299 from December last year to May this year. If this trend continues, about 50,000 maneuvers are expected in the second half of this year, and over one million by 2028. Moreover, the number is unlikely to decrease easily. SpaceX has only deployed about one-third (around 4,000) of its planned 12,000 first-generation Starlink satellites. It continues to launch approximately 800 Starlink satellites annually. Additionally, it plans to launch 30,000 second-generation Starlink satellites, some of which have already received FCC approval.

To make matters worse, the launch of small clustered operational satellites by other companies and countries is also rapidly increasing. Jeff Bezos's Amazon, a rival of Musk, is building a space internet network through the Kuiper Project, planning to launch thousands of small communication satellites similar to Starlink. China is also conducting the Guowang Project for the same purpose. Globally, the number of satellites registered by countries with the International Telecommunication Union (ITU) under the United Nations (UN) has reached a staggering 1.7 million. Although not all of these satellites will be launched as planned, concerns about the safety of Earth's orbit are justified.

Professor Lewis said, "If 100,000 satellites are in orbit by the late 2020s, operators will have to perform an enormous number of maneuvers to avoid collisions," adding, "It would be like changing direction every 10 meters while driving on a highway to avoid collisions, which would never be safe."

According to the European Space Agency (ESA), there are currently about 10,500 satellites orbiting Earth, of which approximately 8,100 are operational. However, congestion has recently become a serious problem. In 2019, there were only 2,300 active satellites in Earth's orbit. But with the launch of many small satellites operating in clusters like Starlink, the number is rapidly increasing. In addition to new satellites, space debris such as broken satellites, abandoned rockets, and fragments is also increasing sharply, causing difficulties for satellite operators.

Of course, SpaceX's high safety standards for operating Starlink are also a cause of these frequent avoidance maneuvers. SpaceX performs avoidance maneuvers if the probability of collision with an approaching object is greater than one in 100,000. However, organizations like NASA require avoidance maneuvers when the collision probability exceeds one in 10,000, which is ten times higher. Jonathan McDowell, a researcher at the Harvard-Smithsonian Center for Astrophysics, said, "SpaceX is confident it can handle the increasing burden of avoidance maneuvers, but that may not be the case," adding, "It is questionable whether they are adequately prepared for the possibility of a bad outcome like a collision caused by independent and unpredictable problems combined."

Starlink satellites are equipped with an automatic collision avoidance system. They track the orbits of approaching objects and send advance warnings several days ahead. However, this system is not always accurate. Moreover, when the atmosphere at high Earth altitudes thickens due to solar wind, lift and air resistance increase, which may cause satellites to deviate from their intended orbits.

Professor Lewis warned, "Although the possibility is low, collisions could occur in situations where maneuvers are not possible, generating an enormous amount of uncontrollable space debris that would surround Earth's orbit," and emphasized, "Regulatory authorities need to limit the number of satellites in orbit."