Let’s talk about space debris


This is part of a series of articles by satsearch called “Let’s talk about” – designed to help fulfill our mission of democratizing access to the space industry.

Astronauts are servicing the Hubble Space Telescope, while their shuttle is docked at the facility. While two perform a space walk in an attempt to fix a faulty transmission card they receive a message from Mission Control at Houston.

“Mission abort. Initiate immediate disconnect from Hubble, begin re-entry procedure. Debris from a Russian missile strike has caused a chain reaction hitting other satellites and creating new debris traveling faster than a high-speed bullet towards your altitude.”

Before the astronauts can try and take any action to avoid the catastrophe the debris destroys their shuttle killing one crew member. With all communication lost with Earth, the two astronauts now face the daunting task of trying to make it home safely; alone and unsupported.

Does this narrative sound familiar? It is taken straight from the early scenes of the blockbuster space movie Gravity which was released in 2013. And while it was fun to put on our 3D glasses and watch two fictional astronauts trying desperately to save themselves from a catastrophic space debris incident, the dangerous realities of this growing problem are becoming increasingly important for the industry to consider.

What is Space Debris?

ESA’s Space Debris Office defines space debris as;
all non-functional, human-made objects, including fragments and elements thereof, in Earth orbit or re-entering into Earth’s atmosphere.

Of the 22,300 artificial objects currently being tracked in Earth’s orbit only around 1,900 are actually functional satellites. The rest are space debris and the US Space Surveillance Network is the main source of tracking data on these objects, cataloguing various classes of debris using a variety of techniques.

However, the 22,300 figure doesn’t paint a true picture of the scale of this problem. This number only indicates trackable objects, which are anything over 2 inches. Debris below this size are very difficult to identify and track from Earth, but can still pose a significant threat to other objects in space.

Before we look into the problems space debris can cause, the following statistics provided by ESA’s Space Debris Office help to demonstrate the real scale of the issue:

Number of rocket launches since the start of the space age in 1957: about 5,450 (excluding failures)

Number of satellites these rocket launches have placed into Earth orbit: about 8,950

Number of these still in space: about 5,000

Number of these still functioning: about 1,950

Number of debris objects regularly tracked by Space Surveillance Networks and maintained in their catalogue: About 22,300

Estimated number of break-ups, explosions, collisions, or anomalous events resulting in fragmentation: more than 500

Total mass of all space objects in Earth orbit: More than 8,400 tonnes

Number of debris objects estimated by statistical models to be in orbit:

  • 34,000 objects larger than 10 cm
  • 900,000 objects ranging from from 1 cm to 10 cm
  • 128 million objects ranging from from 1 mm to 1 cm

As harmless as those 128 million tiny objects ranging from 1 mm to 1 cm might seem, many of them are present in Low Earth Orbit traveling at speeds of approximately 17,500 mph (20x faster than a bullet).

When even the smallest objects travelling at this speed collide with satellites or other technology, the results can be very serious. In 2016 for example a tiny object (likely a paint flake or small metal fragment) no bigger than few thousandths of a millimeter across caused a 7 mm diameter circular chip in the cupola window of the International Space Station (ISS).

Image of the circular chip in the window of the ISS
Image of the circular chip in the window of the ISS (image credit: ESA)

The ISS has debris shields deployed around the crewed modules composed of two metal sheets separated by about 10 cm. It also has the option to perform Collision Avoidance Maneuvers, which has been utilized in the past to avoid dangerous space debris. In addition, if there is no time to perform a maneuver the astronauts’ last resort is to abandon the station in a Soyuz escape craft that is standing ready.

The ISS is a manned facility, so these special precautions are very important. But for the average satellite there are far fewer options to guard against space debris.

And despite the extra capabilities of the ISS a small object still managed to collide with it, as shown above. Larger objects clearly pose an even more serious threat to space hardware and missions, and can even affect life on Earth. Severe damage to satellites could bring some aspects of our daily lives to a standstill as modern societies are so heavily dependent on them for communication and navigation.

In order to discuss how to address this problem, it helps to understand how it started.

How did we get here?

The problem of space debris has been decades in the making. Most agree that the space race officially started on 4th October 1957 with the launch of the Russian satellite Sputnik-1. It was launched on a rocket with reflectors covering its body, and was easily seen from Earth.

This rocket body can be considered as the first ever piece of space debris, and hence was the start of a new era in space. The launch of Sputnik-1 was followed by the US satellite Explorer-1 which added to the number of pieces of space debris in orbit.

By early 1961 the total number of artificial objects in near-Earth orbit was just over 50, a moderately small amount. But in June 1961 the Ablestar launch vehicle exploded in space just an hour after deploying its payload, the Transit 4A satellite, and this single explosion created about 300 debris fragments, most of which remained in orbit for a long time.

Accidental explosions, dead satellites and the spent upper stages of rockets are not the only ways in which space debris is created. Anti-satellite testing is also one of the primary causes of the enormous amount of space debris in Earth’s orbit.

The two countries mainly responsible for this activity are the former Soviet Union and the United States. The former Soviet Union conducted 20 anti-satellite tests between the year 1968 and 1982 which created over 700 catalogued items of space debris, some of which are still in orbit. Similarly, the United States tested its own anti-satellite technology in 1985, producing more debris as a result.

Collisions between satellites have also resulted in further problems. Debris from such collisions are small and hard-to-track, and can be dangerous both to other satellites and space missions.

The first known collision between two satellites took place in 1991. A retired Russian navigation satellite, Cosmos 1934, and a small piece from the satellite Cosmos 926 collided in orbit creating over 900 smaller pieces of untrackable debris each smaller than 1 centimeter.

Space debris in 1968 vs 2018
A comparison of space debris in 1968 (left) and 2018 (right) (image credit: NASA)

Satellites kept colliding and several rocket upper stages exploded during the next 15 years. However, two major events significantly increased the amount of debris in existence, and brought the attention of the international space community to the growing concern of orbital debris.

Interestingly, both events represent the two distinctly separate scenarios that are responsible for producing the majority of space debris: intentional destruction and accidental collision.

Anti-satellite test of Fengyun 1-C missile

On January 11, 2007, China tested an anti-satellite system. The Anti-satellite (ASAT) missile KT-2 was fired at the defunct Fengyun 1-C weather satellite and the resulting explosion creating a debris cloud which extended from an altitude of 200 to 4,000 kilometers, and is considered to be the single worst source of the contamination of low-Earth orbit.

The test must have been deemed successful as the ASAT missile destroyed Fengyun 1-C, fragmenting it into small pieces. However, the test also created an estimated 300,000 objects 1 cm or larger that threatened all future missions in that orbit. This also amounted to an increase in the volume of known debris in the Earth’s orbit by 75%, and the majority of the debris cloud still remains in orbit today.

ASAT missile KT-2 fired at Fengyun 1-C
The ASAT missile KT-2 fired at Fengyun 1-C (image credit: South China Morning Post)

The test also directly violated Space Debris Mitigation Guidelines that prohibited any anti-satellite testing which would produce space debris. As a result, the United Nations was forced to lay out a more stringent set of measures.

The Iridium-Cosmos Accident

The first major accidental collision between working satellites took place on February 10th 2009. An operational American communication satellite, Iridium 33, collided with the Russian satellite Cosmos 2251. The collision added more than 2,000 fragments of space debris into the catalogue of tracked objects.

Collision of Iridium 33 with Cosmos 2251
Collision of Iridium 33 with Cosmos 2251 (image credit: South China Morning Post)

The satellites slammed into each other at a relative velocity of 11 kilometers per second, colliding almost at right angles. As Cosmos 2251 had a larger mass than Iridium 33 it produced twice as much debris compared to its US counterpart.

The Cosmos 2251 – Iridium 33 collision remains one of the largest contributors of space junk into orbit. And every major collision like this can cause multiple additional effects, due to the Kessler Syndrome.

The Kessler Syndrome

One of the major problems with space debris is the speed with which it is traveling and the possibility that it might collide with another object in space. In the event that two sizable objects impact each other it would result in a massive debris cloud traveling at thousands of miles per hour.

This could then collide with other objects or satellites creating an even bigger debris cloud in the Earth’s orbit. This self-sustaining cascading collision of space debris in LEO is known as “The Kessler Syndrome” (named after the NASA scientist Donald Kessler).

Donald Kessler published a paper entitled “Collision Frequency of Artificial Satellites: The Creation of a Debris Belt” in 1978. He proposed that a chain reaction of exploding space debris could inevitably lead to a situation where it would be difficult for satellites to operate in their region and ultimately might put the whole space program in jeopardy.

Kessler’s paper was significant because at that time no one really was talking about the dangers of space debris in orbit. He emphasized the imminent dangers of space debris, and how this might lead to a future where, even if we stop launching new satellites and rockets to space, the debris might make it impossible for any space activity in orbit for a couple of centuries.

This is a bleak prospect and is increasingly a problem that space agencies are coming to terms with around the world.

What can we do to prevent such a scenario?

According to the ESA, the only effective long-term means of stabilizing the volume of space debris at a safe level is through the removal of mass (five to ten large objects per year) from regions with high object densities and long orbital lifetimes (source).

And this needs to being immediately NASA says; “in 2005, a study by Liou and Johnson using the LEGEND model showed that even if no future launches occurred, collisions between existing satellites would increase the 10-cm and larger debris population faster than atmospheric drag would remove objects.”

This is an alarming scenario and the Kessler syndrome shows that there’s an urgent need for the international community to begin tackling the problem of space debris more intensely on a global level. Let’s look at some of the initiatives currently in development.

Laws and mitigation measures

There is currently no single international law that aims to reduce the amount of space debris in orbit, or prevent nations and private organizations from disposing of dead satellites and rocket stages in space. However, efforts have been made by international organizations such as the United Nations, as well as by individual countries, to mitigate this issue.

Several international space laws have been created by the UN Committee on the Peaceful Uses of Outer Space (COPUOS), and although they do not directly address the issue of space debris and have not always been effective in reducing it, they do serve as a good starting point. Three relevant treaties that have been developed to-date are:

  • The Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, October 10, 1967 (the Outer Space Treaty);
  • The Convention on International Liability for Damage Caused by Space Objects, September 1, 1972 (the Liability Convention); and
  • The Convention on Registration of Objects Launched into Outer Space, September 15, 1976 (the Registration Convention).

The above treaties formed a basis for the UN’s Space Debris Mitigation Guidelines which were endorsed by the General Assembly in 2007.

Various countries and their national space agencies have also made an effort to create laws and guidelines to curb the growing threat of debris and reduce the volume of material already in orbit. The Inter-Agency Space Debris Coordination Committee (IADC) is one example of this activity.

This committee organizes meetings biannually which involve the ESA, the Russian Space Agency, NASA, and the space agencies of Japan and various other countries. The meetings are mainly focused on the technical aspects of space debris removal, and as far as the legal aspects are concerned, the Space Law Committee of the International Law Association has been studying orbital debris since 1986.

However, there’s no denying the fact that there is an urgent need for greater clarity in global international law to tackle space debris, and for countries to abide by more stringent rules and regulations. As such guidelines develop there are a number of private businesses taking the lead by developing innovative new technologies to deal with the problem.

NewSpace space debris companies and their exciting cleanup ideas!

The NewSpace revolution has led to the development of private companies working on all sorts of space applications in new and interesting ways. Here are some of the companies looking to address the issue of space debris:


Founded by Japanese technology entrepreneur Mitsunobu Okada in 2013, Astroscale’s primary mission is “To secure long-term spaceflight safety and orbital sustainability for the benefit of future generations.”

Astroscale is one of the leading orbital debris removal companies and has a clear plan to help mitigate the issue. It has raised $103 million in total to-date and expects to launch their first mission as early as 2020.

In a recent interview Alison Howlett, Public Affairs Specialist at Astroscale, explained the company’s motivation and future plans:

“Millions of pieces of debris, all human-made and ranging in size from spent rocket bodies and inoperable satellites as big as a city bus, to tiny paint chips a millimeter wide, are speeding around Earth at approximately 27,000 kilometers per hour, not only polluting space but endangering active satellite operations and future space missions. It is also anticipated that thousands more satellites will be launched in the next 10-15 years, up to three times the amount that have been launched in the past 60 years.”

“Our End-of-Life Services by Astroscale-demonstration (ELSA-d) is our first mission to demonstrate the core technologies necessary for debris docking and removal. ELSA-d, scheduled to launch in early 2020, consists of two spacecraft, a Servicer (~160 kg) and a Client (~20 kg), launched stacked together. The Servicer is equipped with proximity rendezvous technologies and a magnetic docking mechanism, while the Client has a docking plate which enables it to be docked. The Servicer will repeatedly release and dock the Client in a series of technical demonstrations proving the capability to find and dock with debris. Demonstrations include target search, target inspection, target rendezvous, and both non-tumbling and tumbling docking.”

With a launch scheduled for early next year, Astroscale currently has a workforce of 60 people, and plans to increase this to 100 as it expands to the U.S. and other global markets.


LeoLabs, a Silicon Valley-based startup, is also one of the leading companies working to solve the issue of space debris. It plans to map the low-Earth orbit, the region stretching from 160 km to 2,000 km above the Earth, in order to track about 250,000 objects bigger than a golf ball.

Founded in the year 2015 by Daniel Ceperley, John Buonocore and Michael Nicolls, LeoLabs tracks spacecraft and debris in low-Earth orbit with phased array radars in Midland, Texas and Fairbanks, Alaska. It also plans to install its next phase radar in New Zealand to help map the sky in the Southern Hemisphere as well.

On March 14th 2019, at the 62nd Annual Laureate Awards, Aviation Week & Space Technology named LeoLabs, Inc. a winner in the Space Operations category, honoring extraordinary achievements for innovation in operations and services for low-Earth orbit.

Morpheus Space

While some companies are directly producing systems to tackle space debris problems, there are others who are being mindful of the ways in which objects are put into space in the first place, so that the potential for further debris is reduced. Technology that enables prevention, as well as the cure, will be an important part of reducing space debris risks in all future missions.

Morpheus Space is an innovative new company seeking to revolutionize the nanosatellite industry by facilitating new capabilities and more sustainable missions. Morpheus’ core technology is a modular electric propulsion system suitable for small satellites called the NanoFEEP (Nano Field Effect Electric Propulsion).

“Our most important goal, which is also our mission statement, is to show the NewSpace industry that a sustainable approach to nanosatellite missions and constellations doesn’t just mean keeping the Low Earth Orbit clean by assuring a re-entry into the atmosphere.” Explained István Lorincz, co-founder of Morpheus Space.

The Morpheus MultiFEEP
The Morpheus MultiFEEP on a 3U CubeSat (image credit: Morpheus Space)

Morpheus Space has also developed what it calls the Agile Constellation system – an AI-driven platform used for collision detection and avoidance. Morpheus’ propulsion technology enables small satellites to make adjustments so they can move out of the path of obstacles, saving the system and reducing space debris.

The companies described above are just a few examples of the many businesses actively working on the problem of space debris. The technology created by these companies broadly falls into two categories: contact methods (such as robotic arms, tethers and nets that physically interact with debris) and contactless methods (such as lasers and ion beams). Some other examples of technology in development are:

Giant lasers: Laser Orbital Debris Removal (LODR) uses high-powered pulsed lasers based on Earth to create plasma jets that are fired at space debris in order to slow it down enough that it re-enters the atmosphere and burns up.

Space harpoons: one of the most direct ways of securing space debris is by using a capture mechanism such as a harpoon, net or robotic arm. In February 2019, a harpoon designed to capture orbital junk created by Oxford Space Systems was successfully tested in space for the first time as a part of a mission called RemoveDebris.

Solar Sails: solar sails push dead satellites to lower orbits so that they burn up on re-entry.

There are numerous other ideas that are being proposed to solve the problem of space debris. The number of different solutions shows that we are yet to find a single cost-effective method to reduce debris, but hopefully as more companies develop and test new ideas the leading prospects will emerge, and will be extended to address the issue at a global level.

What’s next?

Hopefully it is clear by now that space debris is one of the most pressing issues affecting the sector, not only in the short-term, but perhaps also for the next couple of centuries. According to a NASA study in 2008; even if all launches ceased tomorrow the risks of space debris would persist for a couple of centuries, and could even get worse if not dealt with properly.

Well, launches aren’t stopping tomorrow, and so they shouldn’t. Instead, the industry needs to continue to explore ways to tackle the problems effectively for the future, rather than taking a step back and contemplating reducing or even stopping launches.

With companies such as SpaceX and OneWeb aiming to launch mega constellations of satellites, the number of objects in orbit is soon expected to quadruple in number. However, both the companies have also been responsible enough to come up with plans to de-orbit them once the satellites becomes non-operational. SpaceX told the FCC it would de-orbit its satellites within five to seven years while OneWeb also explained that its deorbiting plans are [highly reliable and will take satellites out of orbit in five years](https://spacenews.com/oneweb-vouches-for-high-reliability-of-its-deorbit-system/ “”){:target=”_blank”}.

The above plans seem reasonable and effective ways of reducing the risks of creating space debris. In addition, getting companies to think responsibly and develop clear plans to de-orbit objects would prevent future legal disputes over who should remove debris produced by other countries or private organizations.

Once there is a system in place to limit any increases in new debris, space agencies and private companies can actively work on ways to bring down that already present. Developing this system will require a consistent and stringent international regulation.

The rules should be loud and clear: if you cannot take care of your own trash in space, you probably shouldn’t be launching!

And the further reading section for all the curious souls out there..

As we have done in the past with this series, we want to end this topic with a few cool facts and videos that will hopefully inspire the space junk nerd (space jerd?!) in you, and maybe even motivate you to bring out your own creative solutions to tackle this huge problem – that is surely going to affect everyone here on Earth if not dealt with. Happy reading!

Ad Astra!

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