Orbital Debris: Exploring Innovative Solutions for Space Junk Removal
Last Updated: April 4, 2023
Space is incomprehensibly big, and yet we already need to start thinking about how we treat it, and what we put into it. Since the beginning of the Space Race, we’ve been adding debris to the area of space around Earth, and it’s a growing problem that we need to address before it’s too late.
Let’s discuss orbital debris, a.k.a. space junk: what it is, what are the concerns, and what are the potential solutions.
Debris In Space
When traveling in space there are many concerns we have to think about, including the various physics calculations, mechanical innovations, and unknown hazards of space that could harm the spacecraft, its instruments, and any potential occupants. One of those hazards is actually fairly ordinary, something we encounter when moving: collisions with other objects. Even if we are walking, an unexpected object in our path can cause issues.
Increase our speed and that risk increases. If you hit something while traveling in your car going 20 mph, it is a very different scenario (even though it can still be bad) than if you hit something going 65 mph.
While space is a vacuum, it is imperfect, and there are not only small clusters of molecules, but objects in space including small rocks such as tiny meteoroids and asteroids. If one of these hits a spacecraft in space, things can go very, very wrong, but they are no longer the only debris we have to worry about in orbit around Earth.
History of Human-Created Debris in Space
In 1957, humanity entered space by launching Sputnik 1, the first artificial satellite, into orbit and has continued doing so ever since with increasing rates. These satellites provide a variety of benefits ranging from engineering experiments to providing communication, Internet, real-time tracking data of Earth, and more. We assumed space was big and therefore didn’t worry about the stuff we were sending into space, both the actual satellites themselves and the pieces large and small that would be lost in orbit during launch.
We figured it would take a while for that to add up, but as we have figured out with our pollution of this planet, we’re slowly but surely filling up the area around Earth with junk that highly increases the risk of collisions.
Briefly, let’s review the different levels of space around Earth to better understand this environment and future discussion by establishing the definitions of different levels of orbit:
- Low Earth Orbit (LEO): below an altitude of 2,000 km above sea level
- Middle Earth Orbit (MEO): between 2,000 and 35,786 km above sea level
- Geostationary Earth Orbit (GEO): a circular geosynchronous orbit at a constant altitude of 35,786 km above Earth’s equator
In 1978, orbital debris produced by human space exploration activity was acknowledged formally as a problem thanks to the research of Donald Kessler who brought this creation of a debris belt around Earth created as an unintended side effect of space flight to the public eye.
He proposed that like the collisions in the asteroid belt, the proliferation of debris around Earth would not just increase the chance of one satellite colliding with another, but that one collision will lead to another and another, increasing exponentially as each collision creates more free-floating debris. These types of collisions have been dubbed Kessler-style collision events.
What has changed since this problem was brought to our attention? Unfortunately, much like efforts to reduce pollution here on the surface, not much. Too little, but hopefully not too late.
Governments and, more recently, private companies such as SpaceX have continued to fund space exploration with little emphasis and few meaningful strategies for handling debris caused by these actions. By 1994, the debris in LEO already caused more concern and hazards than natural meteoroids. While advancements have been made, is it enough?
What are the concerns of this debris today and into the future?
The Concerns Of Space Junk
Hitting something while traveling can be bad, especially in space where there are countless other variables to worry about and often no rescue crew on the way. But, what exactly is the concern? How much junk have we added to the space around Earth? What can happen in a collision?
Space junk consists of active and inactive satellites and their payloads, intact rocket bodies and mission-related objects (MRO) (such as rocket exhaust materials, objects released in deployment and spacecraft operations, and trash from crewed missions), and fragmentation debris.
Active and Inactive Satellites
There is a growing number of satellites in orbit, particularly from the broadband internet access push using LEO satellite networks like SpaceX which means the risk of collision, while currently not high, is increasing rapidly.
With the number of satellites in orbit expected to increase from 9,000 today to over 60,000 by 2030, and more than 3,000 defunct satellites that are now inoperable, these technological innovations that have helped humanity grow, are certainly beginning to clutter LEO. While Sputnik burned upon re-entry into the atmosphere, the Vanguard 1 satellite launched a year later is still in Middle Earth Orbit despite dying 6 years after its launch, making it the oldest piece of artificial space junk.
Satellite collisions are not a future concern. In 2009, an American satellite collided with a defunct Russian satellite, which resulted in over 2,300 pieces of trackable debris. The concerns of space junk and orbital debris are real today and will only increase unless changes are made.
Debris from launches, old satellites, and collisions
In addition to current and active satellites, we have plain old debris to worry about, in various sizes from launches and past collisions. These pieces of debris from launches range from those as big as a school bus to those down to the size of a screw and even paint flecks, which cannot currently be detected.
It is currently estimated that there are over 100 trillion untracked pieces of old satellites and other space exploration materials with tens of millions of pieces of debris left over from launches and over 34,000 pieces of debris larger than 10 cm.
Now, debris the size of a school bus would obviously cause a lot of damage, but even those tiny, untrackable screws and paint flecks cause concern. Why? While car crashes from speeds of 65 mph can cause catastrophic impacts, those speeds are nothing compared to the speeds of space. While reports vary, space junk can be traveling at speeds of 15,700 mph to 17,500 mph (25,267-28,163 km per hour) and up to 22,000-33,000 mph (35,405-53,108 km per hour).
At that speed, these tiny, minuscule pieces of debris can cause immense damage to existing and future satellites and space stations, ripping holes through structures and systems. While the ISS, like other space crafts, is shielded, with extra shields on the areas that have been prone to collisions, even one stray screw could depressurize the station, damage vital equipment, or even strike an astronaut on an EVA.
The longevity of orbits
While spacecraft in low-Earth orbit will eventually fall into the atmosphere, it takes an incredibly long time to happen naturally. If the dinosaurs had launched a satellite hundreds of millions of years ago to the furthest geostationary orbit at 35,786 km from the surface, it would still be there today. These pieces of debris won’t just go away.
Debris from launches, old satellites, and collisions
Based on simulations both of the asteroid belt and Kessler collisions, collisions will continue to happen as more and more debris is left in orbit. Debris will collide with other debris and create more debris to continue causing collisions.
This would continually make launching spacecraft more and more hazardous until, eventually, a mini asteroid belt of debris material would form around Earth, potentially grounding any spacecraft due to safety concerns over collisions.
This will take time, but again, with a projected 600% increase in satellites in the next seven years, this will happen sooner than we could imagine or predict if we don’t do something to stop it.
Solutions Past, Present, and Future
Since we’ve known about the future problems of leaving space junk in orbit around the Earth since 1978, what solutions have been proposed and utilized? Which show promise?
Cataloging and tracking debris helps us to know where hazards lie so that we can avoid those paths. Currently, we are using ground-based radar and other more advanced technologies including
- the US Space Surveillance Network (SSN) for the Department of Defence for objects greater than 10cm in LEO and out to the GEO
- the Haystack Ultrawideband Satellite Imaging Radar (HUSIR), HAX and Goldstone radars by NASA to detect smaller objects in LEO
- the Michigan Orbital Debris Survey Telescope (MODEST) and other visual aids to track smaller objects in GEO, but these aren’t usable in tracking and simply used in modeling to help understand the state of that area of space in the future.
The more debris we can track, the better we can plan missions and flight paths to reduce the chance of hitting space junk. While tracking has continually improved, allowing us to see smaller and smaller pieces, the trillions of predicted untracked debris can cause potentially catastrophic problems.
With tracking, we are able to shift the flight path of currently operating spacecraft to avoid larger debris. In fact, hundreds of flight path adjustments are made every year by operating spacecraft, satellites, and even the ISS to avoid debris.
In fact, in 2019, the ESA performed its first satellite maneuver to narrowly avoid crashing into SpaceX satellites and this wasn’t the first time satellites have had to change their course to avoid another satellite, just the first involving SpaceX. This will only continue to increase as more debris is accumulated.
The standard method for decades now is that some pieces are designed to fall back to Earth, burning up in the atmosphere or land back on Earth mainly in the oceans (such as the “Spacecraft Cemetery” in the Pacific). This basic idea of the object falling out of orbit is a major solution currently and a part of many proposed future solutions.
Since we know that they will burn up in the atmosphere if they enter at the right trajectory, it provides a viable option, especially as a planned end to the spacecraft. If we can bring them back to Earth, at least they are here instead of up there, and some of the resources might be able to be reused/ recycled if they are recovered.
However, there are concerns. Pollutants can be added to the atmosphere when spacecraft burn up as well as to the ocean or land when they return all the way. In addition, if something changes the trajectory, it could either not burn up completely or not land where it was planned to, causing concerns of it will fall on a populated area.
Life Extension and Active Removal
Life extension services to inactive or aging satellites and active debris removal are both newer methods to attempt to solve the issue of existing and future space junk. If we can continue to use the satellites and therefore track them, we can reduce the chance of them, or broken parts of them, colliding with something.
There are many current and proposed active debris removal options including:
- Graveyard/ junk/ disposal orbits have been utilized to deliberately move defunct spacecraft into an orbit further away from Earth. However, it doesn’t actually solve the issue and just moves the problem to a slightly different area that will also eventually fill up and cause problems with debris collisions.
- Anti-satellite missile tests had been a relatively common answer in the past. If it was clogging up space, removing it would solve the issue, yes? The US, Russia, China, and others set out to test this theory (as well as to destroy enemy spy satellites or satellites that were at risk of falling back to Earth) primarily in the late 2000s, but reaching up to present times. The answer? Just as if the satellite had collided with another satellite or piece of debris, the result was thousands upon thousands of much smaller, and harder-to-track pieces of debris, which only accelerates the problem, but hope is on the horizon; see more in International Guidelines and Policy below.
- Giant nets have been proposed for years to capture and remove space junk from orbit either to burn up in the atmosphere or deliver it back to Earth. In 2018, Surrey Satellite Technology’s RemoveDEBRIS successfully tested its giant net and have continued testing its orbital debris removal technology, working with SpaceX and the European Commission.
- Lasers have long been proposed as a way of actively removing debris, originally along the same idea as launching missiles at them. However, based on the continual data that shows that blowing up debris will only cause more, harder-to-track debris, the use of lasers has shifted in this effort. Instead, they are being used for tracking currently and are also proposed to help nudge debris into deorbiting.
- Drag sails increase the overall area of the satellite which increases the gradual air drag acting on it from atoms at the top of the atmosphere, speeding up its atmospheric re-entry. In late December 2022, the ESA deployed the Drag Augmentation Deorbiting System Nano (ADEO-N) on the ION Satellite Carrier to deorbit it into Earth’s atmosphere to burn up. The 38.7-square-foot (3.6 square-meter) aluminum-coated polyamide membrane attached to 4 metallic struts launched in 2021 and deployed from a box measuring 3.93 X 3.93 X 3.93 inches (10 X 10 X 10 centimeters). The sail unfurled in February, immediately began the atmospheric descent of the satellite platform, and is expected to re-enter the atmosphere in about a year and three months as opposed to the 4-5 years it would have taken otherwise. This test is the final qualification test for proof of concept of the program.
Debris removal robots have long been proposed as a method of cleaning up space, moving satellites and other debris out of orbit. As part of their Clean Space initiative, the ESA’s been working on 4-armed debris removal robots named “e.Deorbit” that will grab satellites up to 10 meters large using nets and harpoons and drag them to the atmosphere.
The first test, scheduled for 2026, will be to remove the upper stage of the VEga Secondary Payload Adapter (VESPA) launched in 2013. If successful, the robots will be charged with cleaning up debris in LEO, spearheading the way for global debris removal.
Planning and economics of spaceflight
There has also been research into adapting our thinking of the whole process of sending something into space. The idea of a circular economy has been proposed for space focusing on risk reduction, resource efficiency, added employment, and climate chate knowledge, science, and monitoring.
This would rework the current set-up and lifecycle of spacecraft missions to help ensure efficient use of resources and sustainability throughout the project from the planning phase to the end of the lifecycle and beyond to reduce the presence and possibility of space junk.
International policy and guidelines
While likely not your first guess when it comes to solutions to clean up the space around Earth, international policy and guidelines help immensely in creating change when drafted well and enforced because they can allow more of the world to enact better procedures and ideally be held accountable to and responsible for them. Below are a few historic and recent prominent changes in international affairs of space exploration that affect space junk and orbital debris.
This is certainly not a comprehensive list but provides some varied examples and particularly recent changes.
- The Committee on the Peaceful Uses of Outer Space (COPUOS) presented a list of orbital debris mitigation guidelines that were accepted by the United Nations (UN) General Assembly in 2007 that should be considered in mission planning, design, manufacturing, and operational phases of both the spacecraft and launch vehicle. These guidelines in concert with the mitigation guidelines of the Inter-Agency Space Debris Coordination Committee (IADC) recommend a maximum lifespan of defunct objects, and active removal on a regular basis to help provide a meaningful effect, especially in response to the ever-growing space industry. However, they are simply guidelines, not enforceable policies as of yet.
- Scientists and even agencies like the ESA are calling for a legally-binding Zero debris policy which would essentially state that if you bring a spacecraft into orbit, you have to remove it. This would ensure that a spacecraft’s end is determined during the planning phases to help ensure that we are all being responsible for what we put in space.
- Scientists are calling for a legally–binding treaty to restrict the number of satellites launched into low-Earth orbit as the space industry expands, mirroring the historic High Seas Treaty to protect 30% of the high seas by 2030 earlier this month, March 2023. Scientists hope to do what we can for space now as opposed to the decades-long wait to clean up the oceans, to learn from our past mistakes and enact change before runaway effects progress to catastrophic outcomes.
In December 2022, the U.N. approved a ban on anti-satellite testing with 155 nations voting in favor of the resolution, 9 voting against it, and 9 abstaining. This was actually spearheaded by the US. Just last April (2022), VP Kamala Harris, as chair of the National Space Council announced that the U.S. would be the first country to ban missile tests on satellites, acknowledging the dangers caused by it and calling for others to do the same.
There are, unfortunately, often negative side effects to scientific and technological advancements. Many of these couldn’t be foreseen and even when they are identified, the charge to take action can be stymied by the allure and even benefits of progress.
Just as we are finally learning to take active roles in cleaning up and protecting our environment here on Earth, such as in our oceans, we are learning to do the same in space. While satellites and other space exploration efforts have fundamentally changed our understanding of the universe and improved life on Earth in various ways, the proliferation of debris in Earth’s orbit will only continue to exponentially raise the risk of collisions.
Earth-based conservation efforts can provide a blueprint for the clean-up of space in orbit around Earth, especially if we learn from the past and start soon with dedicated efforts across various fronts including technological advancements, a revised planning process focused on sustainability and conservation, and legally-binding international policy changes.
The longer we wait, especially with the increase of satellites, the quicker we speed up the timeline for Kessler collision events that would lead to more hazardous conditions for spaceflight. A focus on both sustainability and active clean-up will help prevent a run-away effect and even work to mitigate the existing problem.
There are many new recent initiatives, both in the form of technology and policy that show the potential of human ingenuity in achieving this goal.
Written by Sarah Hoffschwelle
Sarah Hoffschwelle is a freelance writer who covers a combination of topics including astronomy, general science and STEM, self-development, art, and societal commentary. In the past, Sarah worked in educational nonprofits providing free-choice learning experiences for audiences ages 2-99. As a lifelong space nerd, she loves sharing the universe with others through her words. She currently writes on Medium at https://medium.com/@sarah-marie and authors self-help and children’s books.
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