When we talk about space, we often mention big numbers – after all, space is vast. When it comes to space debris, the numbers may surprise you. The total mass of all objects in space is nearly 10 million kg, and a lot of this is simply debris. There are around 5,000 active and functional satellites orbiting Earth but around twice that number of dead and useless satellites that continue to orbit the planet.
There’s lots of little bits, too. The European Space Agency reports:
- 36,500 space debris objects greater than 10 cm
- 1 million space debris objects from greater than 1 cm to 10 cm
- 130 million space debris objects from greater than 1 mm to 1 cm.
The problem with space debris
Humans have been launching rockets into space since the 1950s, and now there is a vast amount of non-functional space debris – also called space junk – circling around Earth. Space junk can be made up of leftover rocket parts and non-functional satellites and any other machinery or debris left by humans.
Debris is a problem because useful machines orbiting Earth travel at very high speeds – the closer they are to Earth, the faster they orbit. Close to the Earth at an altitude of 100 km, a satellite needs to be moving at 28,000 km/h to stay in orbit. At higher altitudes, satellites do not need to travel quite as fast. Television communication satellites are at an altitude of 36,000 km and travel at 11,000 km/h. At those high speeds, a collision with even a fleck of paint can cause catastrophic damage. Fortunately, collisions in space are rare, but humans can’t go on filling space around Earth with machines forever.
International agreements
Since 2018, New Zealand has been bound by the Convention on Registration of Objects Launched into Outer Space treaty. This means we have agreed to keep a record of any objects we launch into space. In terms of kaitiakitanga, this is important – we need to be responsible for how we use space and how we contribute to its use. Furthermore, in 2021, New Zealand signed the Artemis Accords – an international agreement with NASA about how we can peacefully explore space. It covers multiple issues, including the sustainable use of resources, safe disposal of debris and not intentionally causing harm in other nations’ activities.
Tracking space debris
Dr Laura Pirovano from Te Pūnaha Ātea Space Institute at the University of Auckland compares small bits of space debris to bullets travelling at really high speeds. Laura and others at Te Pūnaha Ātea are interested in space situational analysis – keeping track of debris and predicting the paths it will take. This type of knowledge enables those who operate a satellite to manoeuvre it away from a potential collision – also known as a conjunction event. Moving a satellite is costly – it cuts into the satellite’s limited energy supply and sensors cannot collect data during the manoeuvre.
The New Zealand Space Agency has partnered with LeoLabs – a company that specialises in satellite collision avoidance. The company maps the location of operational low Earth orbit satellites, where new satellites will be placed, pieces of debris and where old satellites are removed from orbit. LeoLabs operates radar systems in different parts of the world. It established the Kiwi Space Radar complex in Naseby, Central Otago. The extra capacity from the Kiwi radar array enables LeoLabs to track an additional 250,000 objects down to 2 cm in diameter!
Cleaning up space junk
The next step beyond observing and directing space traffic is cleaning up the mess humans have created. Astroscale Japan launched the Active Debris Removal by Astroscale-Japan (ADRAS-J) satellite in February 2024. The Rocket Lab mission – named 'On closer inspection' – deployed the demonstration satellite into space from Launch Complex 1 on Māhia Peninsula. ADRAS-J will approach an old rocket body from a past launch and make observations of the debris. Inspections via cameras and sensors will help Astroscale Japan gain an understanding of how the old rocket body behaves. Phase 2 of the project will involve deorbiting the rocket body so it no longer clutters space, probably by altering its orbit so it heads towards Earth and burns up in the atmosphere.
The ability to actively remove satellites and debris from orbit at the end of their operational life will likely play a key role in ensuring a sustainable space environment for the future, so we’re delighted to enable Astroscale to demonstrate innovative new solutions in this field.
Peter Beck, Rocket Lab Chief Executive Officer
Related content
The article Space junk provides a historical look at this decades-old problem.
Space debris reduces the mauri of tuarangi. Find out how the space industry is increasing the mauri of the whenua in the article Tāwhaki – ecosystems restoration and aerospace opportunities.
The growing numbers of pieces of space junk is an increasing problem and harpoons, robots and lasers are just some ideas currently being investigated to capture defunct satellites and other space junk and bring them back to Earth.
Activity ideas
See if you have what it takes to clean up space – well, digital space – with the activity Making digital space debris clean-up games.
The need to limit space debris can form one of the tenets when students create a space treaty.
Useful links
The European Space Agency regularly updates its page on space debris by the numbers.
Outer space and high-altitude activities regulatory system from MBIE describes this regulatory system, lists the other government agencies involved in the system and main stakeholders.
You can view all of the space-related treaties that New Zealand is party to on the Ministry of Foreign Affairs and Trade website.
Read Dr Laura Pirovano’s opinion piece about the perils of space debris. Laura is a research fellow at the University of Auckland’s Te Pūnaha Ātea Space Institute.
Visit LeoLabs to learn more about collision avoidance and its global phased-array radar network.
See the NASA Orbital Debris Program Office (ODPO) website - the goal is to develop an improved understanding of the orbital debris environment and measures that can be taken to control debris growth.
See our space junk Pinterest board – a curation of articles and resources on space junk and the work looking into solutions happening here in New Zealand.
Acknowledgement
This resource has been produced with funding from the Ministry of Business, Innovation and Employment and the support of the New Zealand Space Agency.
