Closer Look: Satellites versus Science

by | October 25, 2023, 9:14 PM | Rockets

Bluewalker 3 over Kitt Peak

In this week’s closer look, we go where I haven’t really wanted to go before: we are going to look at the impacts of the growing number of satellites, like star links, on our ability to safely live and do astronomy.

This closer look is brought to you by an FAA report that I found while doom-scrolling.

According to the FAA, given the expected growth in satellites coupled with the fact that satellites do, very literally, fall out of space through the atmosphere and sometimes fall all the way to the Earth… given all these things, we can expect 1 person could be killed or injured every 2 years by satellites falling out of the sky.

Folks, I did not have “Satellite Debris” on my list of possible ways to die. Turns out, I lack imagination.

The Report, delivered to Congress on Sept 22, is titled “Risk Associated with Reentry Disposal of Satellites from Proposed Large Constellations in Low Earth Orbit”, and per its executive summary, it “informs Congress of ways that the FAA’s launch and reentry licensing process may be leveraged to address the risk from reentering space debris.”

Put another way, they are explaining how they hope to do their best to prevent people from getting killed by space debris, and that may mean companies can’t do exactly what they would like to do. They are also explaining why their best really isn’t enough given that more nations than the US are filling space… and a company can always just go elsewhere.

I want to read you a section of the report. It is utterly dry, but the meaning is alarming, “By 2035, if the expected large constellation growth is realized and debris from Starlink
satellites survive reentry, the total number of hazardous fragments surviving reentries each year is expected to reach 28,000, and the casualty expectation, the number of individuals on the ground predicted to be injured or killed by debris surviving the reentries of satellites being disposed from these constellations, would be 0.6 per year, which means that one person on the planet would be expected to be injured or killed every two years.

“Some debris fragments would also be a hazard to people in aircraft. Projecting 2019
global air traffic to 2035 and assuming that a fragment that would injure or kill a person on the ground also would be capable of fatally damaging an aircraft, the probability of an aircraft downing accident (defined in the Aerospace report as a collision with an aircraft downing object) in 2035 would be 0.0007 per year.”

These are extremely low odds, but… this is information we didn’t have before, and as we assess the need for multitudes of competing companies launching greater multitudes of tiny, potentially killer satellites… it is important to ask… can’t we all work together?

I know the answer is no… but as a scientist who has seen the success of international collaborations like CERN, I’m going to ask the question… and then move along…

While the FAA was doing their report on how both the rockets that launch satellites and the satellites themselves can potentially do random humans harm, astronomers have been busy specifically looking at how different constellations can wreck our ability to do survey science… like all that cool stuff I’m anxious to see Rubin Observatory do.

BlueWalker 3 threatens to step on science

Consider the upcoming BlueWalker 3 satellite. Developed by AST SpaceMobile, it is a prototype for a new constellation of BlueBirds satellites that will provide cell signals with normal ground-based phones. This is possible thanks to the satellite’s remarkable size, which allows it to generate significant amounts of power it can use to send out astronomically strong 3G cell signals.

The large size of these satellites means they are bright. During 130 days, an IAU observing campaign monitored the brightness over 130 days. At the brightest point in its orbit, the satellite appeared as bright as the brightest stars in the sky.

These observations are described in a new paper in the journal Nature led by Sangeetha Nandakumar.

AST SpaceMobile has requested permission to operate 243 satellites in 16 orbital planes.

This combination of an extremely bright visual appearance and a powerful cellular transmitter has the potential to hit astronomy in both the optical and radio wavelengths. Images that contain the satellite – images that may be many minute exposures – will have to be thrown out. This means more images will need to be taken to accomplish the same science.

According to the research paper, “The expected build-out of constellations with hundreds of thousands of new, bright objects1 will make active satellite tracking and avoidance strategies a necessity for ground-based telescopes.”

To many, the concerns raised by these satellites go well beyond just the science and the potential danger. Dave Clements, who was part of the campaign to observe BlueWalker 3, explains, “The night sky is a unique laboratory that allows scientists to conduct experiments that cannot be done in terrestrial laboratories. Astronomical observations have provided insights into fundamental physics and other research at the boundaries of our knowledge and changed humanity’s view of our place in the cosmos. The pristine night sky is also an important part of humanity’s shared cultural heritage and should be protected for society at large and for future generations.”

The benefit of constellations

When people start invoking the importance of something for future generations, it is important to ask, where is the good?

In this case, that means trying to balance the potential benefits of low-earth orbit satellite communication against the potential harm of those same satellites.

There is clearly a need to have some kind of a service that can provide internet to remote locations at a cost that a mountaintop forestry service station or a remote town’s library can afford. We are better off when more people have access to the internet. From education to ecommerce, to disaster mitigation, there is a clear good served when small villages can have the same bandwidth as large cities.

So how do we balance the good of internet access against the bad of a light-filled sky.

I can’t pretend to know all the answers. This is a new era with new problems we are just starting to try and get a handle on. The first StarLinks only launched in 2019, and we were all pretty distracted by the pandemic for a while.

But while we don’t have answers, there are hints at things to look at.

Mitigating potential problems

The FAA Report points, without actually pointing, at one place to start. While the FAA can’t control the licenses on launches from other nations, we can, as a planet, work together to not create too much orbital chaos. There are already international agreements about registering vehicles, and there are suggested guidelines on how spacecraft should have end-of-mission plans so we don’t fill space with defunct hardware. These guidelines are a start, and it may be time for tough talk to start on how we navigate forward as humanity instead of as myriad spacefaring nations and companies.

Yeah, I know, right now there are harder problems that need to be sorted… but we need to pay attention and make sure we don’t let space get completely filled before we sort out how to launch things safely. Right now, that means making sure this upcoming problem stays on the to-solve list, even if it is stuck down toward the bottom.

The other thing we need to work on is mitigation techniques.

Currently, there are over 50,000 pieces of orbital debris being actively tracked, as well as 170 million smaller pieces that cannot be tracked and can endanger anything they hit. If we’re just going to keep launching satellites by the hundreds, we need a way to start cleaning the current debris and preventing future debris.

We’ve talked in the past about potential missions that will grab satellites and debris to clean up space. The catch is that those missions need to know – very precisely – where the debris is located.

Helping provide that extra information is a planned swarm of small satellites that will fly together and have a distributed suite of instruments that allow them to measure the earth’s changing atmosphere, magnetic fields, and more. By measuring how space weather affects the swarm, we should be able to better predict how satellites in general will have their orbits modified by the space environment. Just like knowing rain will slow your commute home, these satellites will help us know how drag might lower a satellite and change when it passes overhead.

Rules, observations, information, collaboration… it’s all going to be needed.

And finally, we also need to make sure there are actual penalties when companies screw up. In early October, the FCC fined Dish Network $150,000 for failing to move a satellite into an appropriate graveyard orbit. By leaving a dead satellite in a frequently used part of orbit, they increase the potential of collisions. While $150,000 doesn’t represent that much money to a company with nearly $17 billion in revenue per year, at least there was a penalty. It’s a start.