2025 Space Environment Report

Earth’s Crowded Orbit Raises Concerns About ‘Kessler Syndrome’

The European Space Agency (ESA) released its annual Space Environment Report in March with its Space Debris Office. Given how the Earth’s orbital environment is a “finite resource” with limited space, Kessler Syndrome (the Earth’s orbit becoming unusable due to increasing space debris) becomes a concern. The report provides an overview of global space activities, focusing on satellites, space objects, and space debris. Below are some key findings from the report.

1. According to ESA’s space debris environment model MASTER (Meteoroid and Space Debris Terrestrial Environment Reference), there were 54,000 space debris objects greater than 10 cm (4 in), 1.2 million space debris objects from 1 cm (0.4 in) to 10 cm, and 130 million space debris objects from 1 mm (0.04 in) to 1 cm in Earth’s orbit as of August 2024.
   

2. In 2024, there were 39,246 tracked objects orbiting Earth, an increase of 7,473 from the previous year. Payloads (or objects such as satellites and calibration objects with specific functions outside of launching something into space) occupied the highest share of the total, at 13,672 (34.8%). This was followed by unidentified objects at 7,967 (20.3%) and rocket fragmentation debris at 7,767 (20%).

   

   Key: Unidentified (UI, light grey); Rocket Mission Related Object (RM, dark orange); Rocket Debris (RD, dark red); Rocket Fragmentation Debris (RF, yellow); Rocket Body (RB, red); Payload Mission Related Object (PM, light blue); Payload Debris (PD, grey); Payload Fragmentation Debris (PF, blue); Payload (PL, dark blue)

   
   

3. There were about 13,579 tons of space objects orbiting Earth, an increase of 2,229 tons from the previous year. From the total, this was mostly from payloads, at about 9,707 tons—or 71.5%—followed by rocket bodies at about 3,727 tons (27.4%).
   

4. The number of re-entered objects into Earth’s atmosphere was 2,031 in 2024. Just over half were from payloads at 1,089 objects, followed by payload fragmentation debris at 515 objects (or 25% of the total).
   

5. There have been an estimated 656 fragmentation events in all of history, of which 220 occurred in the last 20 years. Fragmentation is a concern given how this increases the number of space debris objects, especially if it occurred unintentionally.
   

6. Nuclear power sources (including small fission reactors) are used in outer space for interplanetary payloads and planetary exploration. Eighty-two of such objects re-entered Earth’s orbit, of which seven are “asserted but not catalogued.”

Source:

• https://www.sdo.esoc.esa.int/environment_report/Space_Environment_Report_latest.pdf