by SpaceX reported that the number of close encounters between its satellites and other orbiting objects has not increased over the past six months despite the growth of constellations.
Space sustainability experts say the development is good news but warn that the decline in evasive maneuvers is likely just a departure from a longer-term trend.
Twice a year, SpaceX reports to the US Federal Communications Commission (FCC) how many times its satellites have had to change their paths to avoid potential collisions with other spacecraft and space debris. The company introduced its latest rocket “Semi-annual report on constellation status” on December 29, 2023, which will cover a period between June 1, 2023, and November 30, 2023.
In that period, Starlink satellites had to make 24,410 maneuvers to avoid collisions, which equated to six maneuvers per spacecraft. In the previous reporting period which was the six months before May 31, 2023, the constellation’s satellites had to move 25,299 times. The data suggest that while the Starlink constellation has grown by about 1,000 spacecraft over the past six months, its satellites have made fewer evasive maneuvers in that period than in the previous half year.
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Previously, the number of maneuvers had doubled every six months as the constellation grew, a trend experts expected and worried would continue.
Hugh Lewis, a professor of astronomy at the University of Southampton in the United Kingdom, who has been studying the effects of mega-constellations on orbital safety for several years, told Space.com that the apparent departure from the previous trend could be due to natural . “variability” and improvements in the accuracy of satellite positioning data available to satellite operators.
“We’ll have to wait until the next reporting period to see what’s going on, but it’s good news,” Lewis said. “However, if we look at the numbers per year as a whole, we can see that they had to do around 50,000 maneuvers, still a very high number, and slightly higher than the value for the previous year.”
Starlink satellites make autonomous transition decisions based on information provided by the US Space Force and commercial US space situational awareness company LeoLabs. When the available data shows that a Starlink satellite has a less than 1 in 100,000 probability of hitting another spacecraft or piece of space debris, the satellite will move. SpaceX emphasizes that its approach is much stricter than that of most other operators who only move their spacecraft when the collision risk exceeds 1 in 10,000.
Dan Oltrogge, chief scientist at US space company COMSPOC, told Space.com that he expects the number of evasive maneuvers to increase as more satellites are planned to be launched in the coming years.
“We’ve seen a fairly significant increase in the close approach we’ve seen over the last five years,” said Oltrogge. “It was a five-fold increase, in general, and contact rates will continue to climb as more satellites are added to the mix and more debris survives in the space population.”
SpaceX currently operates more than 5,250 Starlink satellites, less than half of its first-generation constellation of 12,000 spacecraft. The company wants to eventually expand its fleet to over 40,000 satellites.
Lewis added that while his previous predictions indicated that Starlink satellites may need to be maneuvered more than a million times per year as early as 2028, the new data suggests that growth has been much milder for about a century. a thousand maneuvers in six months required at last. the ten years.
“He still has a lot of maneuvers to do,” said Lewis. “I’m still concerned about whether we can operate that many satellites safely. The risk is there because there are so many of them [close approach] events, some of which could lead to a collision at some point.”
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Orbital collisions are a major threat to humanity’s ability to safely use space technology. Each collision can produce thousands of fragments, which can remain in orbit for a long time and threaten other spacecraft.
Experts, however, praise SpaceX for its tough attitude and for sharing information publicly with other operators. They hope other spacecraft operators will follow suit.
“We have to tackle this in every aspect,” said Oltrogge. “We need to try to get the most accurate data possible about the positions of satellites, dead payloads and all the other debris in space. We need to share our data between operators as much as possible, because This improves everyone’s location awareness so we can get rid of the evasive maneuvers we didn’t need in the first place.”
