As you read this story, you will learn the following:
-
As more internet satellites are launched each year, scientists are increasingly concerned about the rising risk of collisions.
-
The Collision Clock is a new predictor of how long it would be before a collision occurs if a solar storm knocks out power and immobilizes satellites.
-
Currently, the maximum time we have to get a satellite back operational before an almost inevitable crash is only 5.5 days, and this time may be shortened in the future.
More than a thousand miles above land, low-Earth orbit is becoming increasingly crowded as constellations of internet satellites fill the sky. What started out as an effort to bring affordable internet to much of the world has turned into a proliferation of metal robots that only seem to be increasing.
SpaceX recently announced plans to launch a constellation of 7,500 second-generation Starlink satellites in 2031, while the company also plans to lower the orbits of its 4,400 existing satellites before they collide with each other and become space debris. Starlink is already required to double its collision avoidance drills every six months and currently conducts about 41 a year. Several Chinese companies recently submitted applications to launch up to 200,000 internet satellites in the early 2030s (shortly after the government criticized Elon Musk’s Starlink business). Every 22 seconds, two satellites pass within less than 62 miles (1 km), which happens every 11 minutes for Starlink satellites.
The number of research spacecraft far exceeds. More than ever, light pollution is plaguing astronomers. The risk of collision has risen sharply since the pre-constellation scenes, which could be a sign of coming satellite disasters.
Astrophysicist Sarah Thiele is particularly concerned about the rapid crowding of low-Earth orbit, especially in the case of solar storms, which would prevent satellites from moving away from Earth. These craft are vulnerable to being shut down every time a solar flare or coronal mass ejection occurs. The hot stream of charged particles causes the air to expand, giving satellites more atmospheric drag, causing them to burn more fuel to prevent them from veering off course and crashing into other objects. In addition to the problems satellites have to deal with in space, satellite navigation and communications systems can also be knocked out by solar storms, cutting them off from Earth.
To address these growing problems, Tiller and her colleagues developed what they now call the Collision Realization and Significant Injury (CRASH) clock.
“Colliding clocks [gauges] “Without satellite maneuvering or severe loss of situational awareness, the time scale over which a catastrophic collision could occur would be stressful,” the team wrote in a study recently uploaded to a preprint server. arXiv. “Our calculations show a current collapse clock of 5.5 days, indicating limited time to recover from a large-scale damaging event such as a solar storm.”
Before the Starlink constellation, a spacecraft would take 164 days to recover before hitting anything causing serious damage. But that was 2018. Less than a decade later, that grace period has shrunk to less than a week. The collision clock takes into account everything in low Earth orbit – even defunct satellites, spent rocket stages and debris floating around – and according to the team, being shut down due to a solar storm means the spacecraft only has five and a half days before an almost inevitable crash.
This is not a far-off science fiction question. As the Gannon storm of 2024 demonstrates, the potential for this phenomenon is truly disturbing. Over the course of three days—dangerously close to current collision limits—almost half the satellites in low-Earth orbit needed to maneuver to survive the sudden, intense drag. While this was an important flare, it had little to do with the 1859 Carrington Event, which lasted for several days with one storm after another (at least there were no spacecraft orbiting the Earth at the time).
While maneuvers (when we can effectively communicate with satellites to perform them) appear to be a reliable solution to the collective collision problem, they come with their own risks. For one, they create uncertainty in satellite positions, and many times, inaccuracies are observed immediately after maneuvers are performed. On the other hand, an increase in the number of maneuvers means that the ability to prevent collisions can suffer lapses—from inaccurate tracking of satellite positions, which can cause satellites to deviate from their designated orbits, to communication errors during maneuvers, which can lead to disaster. Breakdowns like this have already happened. In 2019, for example, a SpaceX warning system malfunctioned, preventing operators from seeing a higher likelihood of a collision, and an ESA satellite was forced to move out of the way to allow a Starlink satellite to pass.
The issue has attracted so much attention that the United Nations declared low-Earth orbit a limited resource. Every satellite launched into the limited space around Earth automatically consumes resources, while space junk does so without any additional benefit. On top of that, satellites throw scrap metal debris into the upper atmosphere, which is a frustrating source of light pollution for astronomers trying to discern extremely faint and distant objects.
“The collision clock is, in part, a measure of how much space is being consumed in Earth’s orbit and how sustainable it is,” she said. “Increases in track density or collision cross-section will both reduce collision times on the track and reduce the margin of error for safe operation.”
You may also like