Emma Louden is an astrophysicist and science communicator.

This essay and Forecasting the Evolution of the Space Debris Population by space systems engineer Kostas Konstantinidis offer diverging perspectives and forecasts on space governance questions from the Sagan Space Tournament.

Satellites and the global space economy

Approximately 7,300 active satellites are orbiting in the sky above you right now. These satellites are critical infrastructure for communication, finance, and navigation in the 21st century. But they represent only 10% of the material hurtling at 16,000 mph around the Earth. The other 90% is debris ranging in size from a paint fleck to a school bus. Every active satellite has the potential to become another piece of debris when it becomes defunct — or thousands of pieces of debris if it collides with another satellite or is shot by an anti-satellite missile. The orbital environment is a chaotic web of space junk intermixed with critical satellites. There is no solution to this global problem in sight. And yet, 2100 satellites are predicted to be launched yearly in the coming decade. Why is there so much interest in satellite launches? Who is investing money in an environment that is becoming increasingly unstable, and why?

In 2022, the global space economy was valued at 386B. Of that, 279B was in satellite services, and 13.7B was in satellite manufacturing. 80% of satellites are used for communications. The remainder are used for remote sensing (9%), technology development (9%), scientific purposes (1%), and unknown uses (1%). While other sectors within the space economy are growing (launch being prime among them), analysts predict that satellite services and manufacturing will continue to dominate. 

Satellite Utilization in Daily Life

The impact of investment in satellites appears in our everyday lives. The cellphone, likely within five feet of you right now, may soon not require a cell tower to make a call. Phone companies are moving beyond the cellphone tower model and making satellite coverage for phones the standard. Built on the expansive infrastructure of the Starlink satellites that offer high-speed internet to the Earth's most remote regions, SpaceX and T-Mobile provide a joint service using antennas in space to send and receive signals from phones with a 5G modem. In 2022, Apple announced a partnership with Globalstar, an established satellite service provider with a worldwide network. Globalstar satellites will connect to a new directional antenna in the iPhone 14 and 14 Pro phones allowing them to function as satellite phones while the satellite passes overhead. While this system is only intended for emergency coverage for now, the $450M investment set the stage for the telephone-to-satellite connection to become the industry standard.

For frequent travelers, satellites are the source whenever you connect to the internet on a Delta or Alaska Airlines plane. While airlines previously offered internet via antennas in their airplanes (effectively making them a hotspot), some have now partnered with Intelsat and Viasat to provide satellite-based internet on all their flights. This is better for the consumer as the internet is 20 times faster, and it's more reliable because the connection is not dependent on cell tower density. It is also a strategic business proposition for the satellite service providers beyond the first-order profit because this model uses satellites that were previously undersubscribed during the trans-oceanic leg of their orbits. 

Satellites also appear in our lives via GPS-satellite-to-phone connections that enable run tracking and personalized weather alerts. They are critical to banking infrastructure: ATMs, cash registers, and the New York Stock Exchange all rely on ultra-precise timestamps determined with a combination of general relativity and satellites to execute trades, catch fraud, and process payments.  The electric grid uses the data from satellites to ration power to high-demand areas without causing surges. Hedge funds also use satellites to estimate changes in specific commodity prices based on satellite imagery of regions related to said commodities. For example, they use images of drilling sites to track if the rigs are active. Insurance companies use satellites to track flooding and set insurance premiums based on that data. You can even buy satellite images of where you will be at a given time to mark a special occasion.

Having a clean and functional orbital environment is critical to the functioning of our society, and satellites will only increase in number. With that increase comes an increased risk of satellite debris, potentially wiping out this critical infrastructure.

Satellite Debris Creation 

First, let’s talk about how debris is created. The two main mechanisms are anti-satellite (ASAT) tests and random fragmentation/collisions, explosions, and anomalies. ASAT tests are a globally controversial military action. Only four countries, the U.S., Russia, China, and India, have destroyed their satellites in ASAT tests, and no one has used an ASAT missile offensively.  

My prediction: 15% chance. I predict a fairly low probability given the US policy on ASAT weapons tests and the reluctance of other countries (due to extension of mutually assured destruction to their satellites). However, as more space actors come online and conflicts increasingly include space-based capabilities, the probability becomes higher.

In April 2022, Vice President Kamala Harris committed to ending U.S. ASAT missile tests. This came in response to a Russian ASAT test in the fall of 2021 that created thousands of pieces of debris and sent the astronauts into safety mode on the ISS as the models predicted possible collisions with the space station. The U.S. committing to end ASAT tests sets a new standard for countries with a serious stake in the space environment to manage debris creation proactively.

My prediction:  Two per year plus tests that have already occurred in the past. There will be no more US tests per the recent policy statement from the Biden Administration. I predict that it is unlikely for there to be a significant change in business as usual for other countries that currently have this capability. However, I predict more tests will be initiated by countries seeking to demonstrate new abilities.

The breakup of and collisions between satellites also create debris. Even a fleck of paint can cause damage to a satellite when traveling at 16,000 mph. While satellites are deliberately placed in particular orbits related to their purposes, they are subject to drag forces in the atmosphere. That drag seeks to change their trajectory and ultimately lower the satellite’s altitude until it either burns up in the atmosphere or crashes on the Earth’s surface. To stay in orbit, satellites need to counteract drag. The International Space Station fires thrusters at regular intervals to ensure the stability of the orbit. For satellites without thrusters or that run out of fuel, the end of their functionality often means an increased risk of collisions as their orbit deteriorates. Further compounding the issue is that once a satellite becomes defunct, the precision orbit tracking abilities are also limited.  

My prediction: Combining the high rate of conjunction events for small satellites in LEO (the population most likely to grow by the highest rate in the next decade) with the normalized number of fragmentation events per launch year, a back of the envelope calculations produces 0.08 collisions per launch, which yield  approximately 1200 events by 2030, in addition to the 600 that have occurred already. This higher number of events comes from the combined growth rate of LEO satellites and their high conjunction rate. I predict that we will see more satellite collisions, which will cascade into other collisions at a higher rate than previously seen.

All satellite positions have a margin of error. That error is magnified for smaller pieces of debris, and current limits mean debris less than 2cm in size is almost impossible to track. Altering orbits that are challenging to predict precisely produces an increased risk of accidental collision. On February 10, 2009, one of these catastrophic collisions occurred when Iridium 33, a commercial communications satellite, and Cosmos-2251, an obsolete Russian military satellite, collided and produced over 2000 pieces of debris. Maintaining precise orbital locations of satellites and providing operators sufficient warning to maneuver and prevent collisions is central to avoiding the theoretical Kessler Syndrome.  

What will be the total quantity of space debris orbiting earth in each year?

My prediction: Increasing at an accelerating rate for the next 4-5 years and then increasing at a slowing rate as more STM/SSA companies become viable and deploy their products. There is a growing long tail to the right that accounts for the Kessler syndrome probability.

Investments in Solutions to Space Traffic Management 

Solutions to this challenge are part of the massive space industry investment; they include satellite servicing missions and deliberate reentry to remove debris. Satellite servicing missions refuel satellites and collect, move, and track waste. Currently, there are over 50 companies focused on satellite maintenance and refueling, and one company has even proposed being a “gas station in space.” Debris can also be removed as satellites reenter the earth’s atmosphere and burn up. SpaceX has does this with defunct Starlink satellites: After alerting relevant authorities, they set aside fuel for reentry and allow the satellite to pass through lower orbital shells before burn-up. The FCC prefers this controlled reentry, and new rules require that satellites be deorbited within five years of finishing their mission. While this solution may appear ideal on the surface, it comes with risks, including unknown atmospheric effects and fatalities from falling satellites.

Conclusion

Space debris is a critical challenge of the 21st century. It is an issue with an impact on our daily lives and the infrastructure upon which our society depends. While debris management is daunting given the increasing debris creation rate, strategizing about removing and mitigating debris is an opportunity for innovation and creativity, both from a technology and a policy perspective.