Space debris — also called space junk or orbital debris — refers to any non-functional human-made object in Earth orbit. This includes defunct satellites, spent rocket stages, fragments from collisions and explosions, and even items lost during spacewalks.
The Numbers
| Category | Estimated Count | Total Mass |
|---|---|---|
| Objects >10 cm (estimated) | ~54,000 | ~15,800+ tonnes (total all objects) |
| Objects 1–10 cm | ~1,200,000 | Included above |
| Objects 1 mm – 1 cm | ~140,000,000 | Included above |
| Defunct satellites | ~3,500 | Varies widely |
| Spent rocket bodies | ~2,300 | Often 1–8 tonnes each |
These numbers, sourced from ESA and NASA, represent best estimates as of 2025–2026. The actual population is constantly changing — new objects are added through launches and fragmentation events, while atmospheric drag gradually removes objects from lower orbits.
Biggest Sources of Debris
Fengyun-1C ASAT test (2007): China's deliberate destruction of a weather satellite created over 3,500 trackable fragments and remains the single largest contributor to the catalogued debris population.
Cosmos 2251 / Iridium 33 collision (2009): The accidental collision between a defunct Russian satellite and an active Iridium communications satellite created over 2,000 trackable fragments.
Kosmos 1408 ASAT test (2021): Russia's destruction of a defunct satellite created over 1,500 trackable fragments at an altitude threatening the ISS.
Together, fragments from these three events account for a substantial fraction of all tracked debris below 1,000 km altitude.
Speed and Impact Energy
Objects in low Earth orbit travel at roughly 7.8 km/s (28,000 km/h). At these speeds, even a 1 cm fragment carries the kinetic energy of a hand grenade. A 10 cm object can completely destroy a satellite. This is why tracking and conjunction assessment are so critical — there is no practical shielding against debris at orbital velocities.
Trends
The tracked debris population has roughly doubled over the last decade, driven by fragmentation events and the sheer increase in orbital activity. However, active debris removal missions are beginning to emerge, and newer satellites are increasingly designed to deorbit at end of life. Whether these measures can keep pace with growth remains an open question.
Explore the debris environment visually on Orbital Radar's live globe — use the debris filter to isolate debris clouds from major events and compare them against active constellations.