According to the European Space Agencysome 35,000 Space debris objects larger than 10 centimeters orbit the Earth, more than 1 million greater than 1 centimeter and hundreds of millions of very small fragments of between 1 mm and 1 cm, all adding up to a mass of more than 14,500 metric tons and moving at a speed of 8 kilometers per second. Now, a study presented last Friday at the International Astronautical Congress of Sydney points out the most worrying space debris objects in low Earth orbit. The majority correspond to launches made in the 20th centurymostly inactive rocket stages who were left wandering through space after concluding their missions.
‘Objects left before the year 2000 remain the majority of the problem. He 76% of the objects in the Top 50 were deposited last century, and the 88% They are rocket bodies. It is important to highlight this, especially given some worrying trends that we are seeing now,’ he stated. Darren McKnightlead author of the study.
The 50 objects identified in the study are the more likely to generate new space debris in low Earth orbit (LEO) due to collisions with other fragments. They orbit the Earth in a busy area of the LEO located between 700 and 1,000 kilometers altitude.
An impact with even a small object at orbital speed could generate countless fragments, causing a chain reaction of collisions that would saturate low orbit with more and more debris. It is the call Kessler syndrome.
The most dangerous space debris objects
Russia and the Soviet Union top the list with 34 objectsfollowed by China (10), United States (3), Europe (2) and Japan (1). Russian rockets SL-16 and SL-8 are the most common among them, with 30 of the 50 positions. The top 10 are:
- Russian rocket SL-16 launched in 2004.
- Envisat European Satellite launched in 2002.
- Japanese H-II rocket launched in 1996.
- Chinese CZ-2C rocket launched in 2013.
- Soviet rocket SL-8 launched in 1985.
- Soviet rocket SL-16 released in 1988.
- Russian satellite Kosmos 2237 launched in 1993.
- Russian satellite Kosmos 2334 launched in 1996.
- Soviet rocket SL-16 released in 1988.
- Chinese CZ-2D rocket launched in 2019.
The study also analyzes how the risk would decrease if some or all of these objects were eliminated. According to McKnight, removing all 50 would reduce the potential for low-orbit debris generation by 50%while removing only the top 10 would reduce the risk by 30%.
China and the 25-year threshold
McKnight states that ‘the bad news is that, since January 1, 2024, they have been abandoned 26 rocket bodies in low orbit that will remain there for more than 25 years‘.
The 25-year threshold is important because it is the guideline set by the Interagency Space Debris Coordination Committee (IADC) which includes the major space powers: USA, China, Russia, Europe, India and Japan. If an object is left in a low enough orbit, it will re-enter before that time.
The United States and Europe force launch companies to deposit upper stages at altitudes that guarantee natural reentry in less than 25 years or to actively deorbit them. For example, SpaceX usually makes the upper stages of its rockets re-enter Falcon 9 over unpopulated areas of the ocean. The rule does not apply to missions that place satellites above low orbit.
China The deployment of its constellations began last year Guowang and Thousand Sailssimilar to starlink from SpaceX, which will add thousands of communications satellites in low orbit. However, most of the rockets used for these launches have left their upper stages in orbit. McKnight noted that nine Chinese stages abandoned after Guowang and Thousand Sails missions They will remain in space for more than 25 yearsviolating international standards.
Since 2000, China has accumulated more dead rocket mass in durable orbits than the rest of the world combinedand in the last two years the pace has accelerated.
‘Launching these megaconstellations will require hundreds of rockets. If they continue like this, they will leave more than 100 bodies above the 25-year limit. The trend is not good‘ says McKnight.