Where every tracked satellite and piece of space junk is right now, and why it matters.
See where tracked satellites and space debris are right now, and why the crowding matters.
Radar and telescopes on the ground, mainly the US Space Surveillance Network, watch objects as they pass overhead. Analysts fit an orbit to those observations and publish it as a short set of numbers called orbital elements (a TLE or OMM). CelesTrak redistributes these elements for free. To find where an object is at any moment, OrbitWatch feeds its elements into SGP4, the standard model made for this data. SGP4 accounts for Earth's bulge and air drag.
Speed, not size, makes debris deadly. Two objects in low orbit typically meet at about 10 km/s, which is ten times faster than a rifle bullet. Kinetic energy is ½ × mass × speed², so a 1 cm aluminium ball weighing 1.4 g carries about 70 kJ at 10 km/s. That is roughly the energy of 17 g of TNT. Objects smaller than about 10 cm usually are not tracked at all, and ESA estimates there are around a million fragments between 1 and 10 cm.
| Regime | Altitude | One orbit takes | Used for |
|---|---|---|---|
| LEO, low Earth orbit | up to 2,000 km | about 90–127 min | space stations, Earth imaging, Starlink, most debris |
| MEO, medium Earth orbit | 2,000–35,786 km | 2–24 h (GPS: 12 h) | navigation: GPS, Galileo, GLONASS, BeiDou |
| GEO, geostationary orbit | 35,786 km over the equator | 23 h 56 min, one Earth turn | weather and TV satellites that stay above one spot |
| HEO, highly elliptical | swings from low to very high | varies (Molniya: 12 h) | coverage of far-north regions |
In 1978 NASA scientist Donald Kessler warned that once orbits get crowded enough, collisions create debris faster than air drag removes it, and each collision makes the next more likely. Two events in this data show how fast clouds form. In 2007 an anti-satellite missile test destroyed the Fengyun-1C weather satellite. In 2009 the working Iridium 33 and the dead Cosmos 2251 collided by accident, the first collision between two intact satellites.
Communications: satellite internet, TV and phone links for ships, planes and remote areas. Navigation: GPS gives position and precise time to phones, banks and power grids. Weather: polar and geostationary weather satellites feed every forecast and storm warning. Climate and Earth observation: crops, wildfires, ice and sea level are monitored from orbit. Exploration: astronauts on the ISS have had to move the station out of the way of debris many times. If key orbits fill with fragments, all of these get riskier and more expensive.
Positions from public elements are approximate: typically around a kilometre off when the elements are fresh, and drifting by kilometres per day as they age. Each object panel shows its element age. Solar activity changes air drag, which is the biggest source of error in low orbit. Some objects are not in public data, and most debris is too small to track. OrbitWatch loads only some CelesTrak groups, so its counts are a subset of the catalog. Clouds on the globe are decorative, and dots are not to scale.