The bulk of near-misses in orbit are caused by SpaceX’s Starlink satellite service. While the bulk of such events occur between Starlink’s satellites, the machines fly near 1km of other firms’ satellites 500 times every week on average.
Hugh Lewis, who serves as the head of Astronautics Research Group at the University of Southampton, said in a series of tweets in an interview with Space.com that we are seeing a “continuing (exponential) spike in the number of near approaches” where spacecraft comes within 1 kilometre of one another.
Lewis noticed that the number of near misses – also referred to as conjunction events – in orbit had risen dramatically in recent years while looking at the data from the Center for Space Standards & Innovation’s (CSSI) Socrates database.
Socrates reported 1120 sub-1km conjunctions each week in June 2019 and 28,000 below 5km conjunctions. By the close of July 2021, it had climbed to roughly 3500 sub-1 km and 60,000 conjunctions under 5 km every week.
The new satellite companies’ Low Earth Orbit (LEO) networks are responsible for much of this increase. Elon Musk’s company’s satellites are currently flying within 1km of other firms’ satellites 500 times every week, and its satellites even more frequently.
“I went back to May 2019 when Starlink initially debuted to grasp the load of all these mega-constellations,” Lewis informed Space.com. “Since then, the number of encounters detected by Socrates database has over doubled, and Starlink now accounts for half of all encounters.”
More than 14,000 times every week, Starlink accounts for almost 60% of all 1 kilometre or less conjunctions and approximately 40% of all 5 km or less miss distances. 2.5% and 3.5% of such incidents are attributed to OneWeb, respectively.
Even if you omit Starlink-on-Starlink events, the company’s machines account for 13.5% of all events within 1 kilometre – corresponding to approximately 500 for every week for the Starlink and 80 every week for OneWeb – and 17% of all events within 5 km, even if you omit Starlink-on-Starlink events. In 2019, the firm was responsible for about 2% of sub-1km incidents. When satellites crash in orbit at thousands of kilometres per hour, debris clouds form, damaging other spacecraft in orbit for years. Small satellites can be destroyed or badly damaged by even small particles 1-10cm in diameter.
The Russian military spacecraft Kosmos-2251 crashed with an Iridium 33 communication satellite in February 2009. The two-spacecraft collided at 26,000 miles per hour, resulting in a cloud of 1,800 enormous pieces of space debris, much of which is still being tracked in orbit today.