SpaceX's Starlink communications satellite constellation is doing double duty as the company announces that it's moonlighting as the Stargaze Space Situational Awareness system that can track and manage traffic in low Earth orbit.
Currently, there are 9,600 Starlink satellites circling the Earth with a long-term goal of 42,000 satellites. That's a lot of hardware for providing high-speed, low-latency global internet connections, but SpaceX sees these birds as having more functionality than sharing penguin memes.
As part of its equipment, each Starlink is equipped with star-tracker cameras. It's a standard bit of space gear designed to keep the satellite properly orientated by using images of stars as reference points similar to how a sextant works. Nothing special about that, except when you've got nearly 10,000 of them scanning the skies at the same time.
What is special is that it helps to address a very serious problem that spacefaring nations and agencies see as a top priority. Space, as Douglas Adams said, is big, really big, and even the thousands of craft that have been fired into the void over the past 70 years amount to the tiniest drop in the cosmic bucket. Evenly distributed in the area between the Earth and the Moon, none of them should ever be aware of the other's existence.
However, space is like the sea, which is also pretty big, all things considered. You'd think that little things like ships would be safe as houses when it comes to collisions, but ships tend to concentrate in sea lanes and through various channels and other choke points. When I was making ocean passages outside of those lanes, the sea was lonely – scary lonely. But in the sea lanes, if I was sailing alone I'd be on constant lookout for cargo ships and praying that when I took a nap the watch on the other vessels would be paying attention and would pick up my radar reflector before I became a statistic.
It's the same in space. Most of the satellite traffic is confined to particular altitudes and orbital corridors. That greatly increases the danger of collisions and makes keeping track of what is where at any given moment a top priority.
Normally, such tracking involves the owners of satellites making public the orbital parameters of their craft and reporting any changes in trajectory – especially when it might endanger other vehicles. Added to this are ground-based radar and telescope networks scanning the heavens.
Unfortunately, neither is adequate. Operators often neglect to report changes and ground stations have only a limited ability to observe objects long enough or frequently enough to accurately calculate their orbits. Even if they can, it often takes several hours to get results. This isn't even taking into account forgotten bits of space flotsam and jetsam like disused rockets.
According to SpaceX, this is more than a potential problem. The company reports that in 2025 a third-party satellite was supposed to pass within 9,000 m (5.59 miles) of a Starlink unit but altered its trajectory to bring it within 60 m (197 ft). This could have been a disaster that would have resulted in a cloud of debris that could have endangered other satellites for months. However, SpaceX claims that its Stargaze system was able to provide a new trajectory projection that allowed controllers to maneuver the Starlink bird out of the danger zone.
SpaceX says that its constellation has about 30,000 tracking cameras that are capable of detecting and tracking objects on a continual basis, building up databases that make calculations much faster – minutes instead of hours. By incorporating this with a space-traffic management platform, close approaches between spacecraft can be predicted and appropriate action can be taken.
Stargaze has been tested in a beta version and the ephemeris it generates is available to the public and is updated every hour. However, SpaceX stresses that this tracking is no substitute for transparency on the part of satellite operators, who should remember to share data on any trajectory changes.
Source: SpaceX
