Space Debris 101
Space junk poses an existential threat to modern life and our possibilities for a sustainable future beyond earth. Start here to learn the basics about that risk and what we can do about it.
What is it?
Space debris is a broad term used to refer to material from human activity in orbit about the Earth that no longer serves a useful purpose. This can include anything from spent rocket stages to defunct spacecraft, decommissioned satellites, and metallic fragments from past collisions.
How much is out there?
We currently know of approximately 27,000 pieces of space debris, but the actual figure is estimated to be much higher when considering that much of this material is too small to be monitored with current technology.
How big is space debris?
Space debris can be categorized into three distinct categories:
The largest category makes up much of the 27,000 pieces of trackable debris and includes debris larger than 10cm in diameter. Most of the defunct rocket boosters, satellites, and larger fragments of other spacecraft fall into this category.
The second category covers debris 1cm in diameter and larger, about the size of a marble, and features an estimated 500,000 fragments.
Not to be outdone, the smallest category includes any debris larger than 1mm, roughly the size of a grain of salt. Here NASA estimates about 100 million pieces of debris, which despite their size are still quite capable of causing severe damage to operating spacecraft.
What’s the danger?
All debris has the potential to pose a significant risk to satellite operations and human space activity. Regardless of size debris moves at incredibly high speeds exceeding 17,500 mph. For perspective, a marble-sized debris fragment traveling at typical speed would have the energy equivalent to an SUV moving 70mph down the interstate.
The largest debris items -- such as abandoned boosters and satellites -- can be easily tracked and avoided but have the ability to create more additional debris through collisions, explosions, and breakups with other defunct objects. Smaller pieces can puncture spacesuits and inflict mission-critical damage on spacecraft windows, hulls, and external systems.
Considering that most of this debris can’t be tracked and that we rely primarily on predictive analytics to avoid collisions, we really do play a dangerous game as we continue to increase satellite launches and human activity in space.
Where is the debris located?
Space debris is spread across Earth’s three orbital zones: LEO, MEO & GEO. Most of the debris population is located in LEO (low Earth orbit), which is approximately 160-1,000km above the surface. Consequently, this is where the majority of satellite and human space activity takes place. Defunct satellites that are too large to burn up in the atmosphere are sometimes sent to a disposal orbit in GEO (geostationary orbit) over 35,000km from the Earth’s surface.
Have we had collisions before?
Yes.
These collisions are considered debris-producing events and can significantly contribute to the debris population in orbit. The crash between an active Iridium and a defunct Cosmos satellite in 2009 is considered the most notable example and created 1/6th of the current trackable debris in orbit. Anti-satellite tests involving the intentional destruction of satellites have also contributed to the debris problem and have been conducted as recently as 2019.
Why is this a problem?
With more objects being launched into orbit this decade than the prior sixty years combined, the operating risk in Earth orbits posed by debris could become high enough to fail a basic cost-benefit analysis. The Kessler Syndrome, a theoretical scenario in which the amount of orbital debris reaches a threshold that produces a cascade of collisions that becomes self-sustaining, originated in 1978 and warned of the consequences of unchecked human activity in space. Over 40 years later, and with exponentially more spacecraft and debris in orbit, such a phenomenon legitimately threatens humanity’s access to technologies such as weather monitoring, GPS, communications, and other services that have become ubiquitous with modern society.
What’s being done to fix it?
Managing the debris problem focuses on two functions: mitigation and remediation. Mitigation efforts seek to limit the creation of additional debris through the tracking of space objects to avoid collisions and implementation of post-mission disposal standards for spacecraft at the end of their useful lives. A major shortfall here is the lack of enhanced tracking capabilities for smaller objects and a lack of enforcement on proper disposal methods. Current regulations require disposal 25 years after an object becomes inoperable, however with the exponential growth of space activity this policy will see many defunct spacecraft occupying disposal orbits for a significant amount of time, creating too many opportunities for collisions, mechanical failures, and human operator errors during the disposal of this debris.
Remediation initiatives seek to remove debris from orbit to reduce the risk of collision, a process called active debris removal (ADR). Many efforts are underway from government-led initiatives by the European Space Agency to companies such as Astroscale, however, none of these projects have advanced to a stage where they are market-ready. Clean Orbit’s goal is to raise awareness of these efforts and funds to support them so that they may be implemented as soon as possible.
Why do we need to do more?
The UN’s Committee on the Peaceful Uses of Outer Space (COPUOS) offers debris mitigation guidelines, however, they are not legally binding under international law. NASA’s own internal report issued by the Office of the Inspector General in January 2021 found that mitigation-only measures are no longer effective in stabilizing the debris environment in space.
Government policies and procedures to address this issue, commensurate with the increase in launch activity, are constantly being outpaced by emergent technologies and commercial ventures. Projects with active debris removal (ADR) technology have yet to advance beyond the development phase. The result is an orbital environment congested with new satellites, defunct hardware, and material debris. The risk of debris collision and challenges it poses to operation is so great that the on-orbit insurance market is failing, causing the cost of this risk to be passed along to us -- the consumers.
Clean Orbit advocates for proactive, sustainable solutions to the growing threat of space debris in low earth orbit. Follow our newsletter for the latest developments in Space Traffic Management (STM), Active Debris Removal (ADR), and orbital close-calls.
Routine space operations create countless pieces of space junk that pose mission-critical risks to humanity’s future in space. At this crucial time for space exploration, utilization, and development, Clean Orbit is dedicated to mitigating the risks that could jeopardize safe access to space.