Interactive lab · Research estimates
Which objects in orbit matter most?
This lab runs the model from the Space Debris Credits paper on real catalogue data. It ranks every intact object in low Earth orbit by a simple risk measure, shows what removing a few of them would achieve, and lets you rate an object or mission of your own.
R = M × L × Pc
Mass × the share of the next 25 years the object stays in orbit × its chance of colliding with another catalogued object in that time. R is a proxy for how much debris an object could create. It is not a probability of disaster, and a high R is not a removal order.
Every number here is an illustrative research estimate. No official rating or credit exists. Data: GCAT, Jonathan C. McDowell, update of 11 October 2026, CC BY 4.0.
Loading 18,036 objects from the catalogue…
Method
How the numbers are made
Mass (M) comes from GCAT, with a ±10 % range, or ±20 % where GCAT marks the mass as an estimate.
Persistence (L) comes from drag decay through the NRLMSIS 2.1 model atmosphere, at low, moderate and high solar activity. On 404 rocket bodies that have already reentered, the predicted range held the real lifetime for 96 % of them.
Collision probability (Pc) uses the density of all 29,188 catalogued objects along the object's orbit, a relative speed of 7–13 km/s and the object's average cross-section.
The exposure rating (SDER) is a weighted sum of seven factors. Its persistence and congestion tables are calibrated from the same data. Its weights are still placeholders, and it has a known flaw: it puts a 1.3 kg derelict cubesat in the same band as a 9-tonne rocket stage.
Not included: debris smaller than about 10 cm, which no public catalogue tracks, and conjunction data, which needs non-public covariance information.
This page runs a browser copy of the open reference code, and a test checks it against the Python original on more than 400 cases.