Debris Density by Altitude
Objects per 200 km altitude band · LEO shell analysisKessler Syndrome Indicators
Cascade risk metrics · LEO debris growthConjunction Warning Feed
Active CDM alerts · Space-Track.org · Pc threshold > 1×10⁻⁵Debris Field Attribution
Major fragmentation events · tracked debris by origin| Event | Year | Objects | % Total |
|---|---|---|---|
| Fengyun-1C ASAT Test | 2007 | ~3,500 | 9.6% |
| Cosmos 2251 Collision | 2009 | ~2,000 | 5.5% |
| Cosmos 1408 ASAT Test | 2021 | ~1,500 | 4.1% |
| Iridium 33 Collision | 2009 | ~600 | 1.6% |
| Other Fragmentation Events | Various | ~14,400 | 39.5% |
| Total Debris | — | — | 60.3% |
Technical Methodology
GIS Portfolio · Space Situational Awareness Dashboard · March 2026
Data Pipeline
Orbital element data is fetched directly from CelesTrak (celestrak.org) via their REST API in TLE (Two-Line Element) format. Five object groups are loaded in parallel: active satellites, Starlink constellation, Cosmos 2251 debris, Fengyun-1C debris, and Cosmos 1408 debris. Data is refreshed from source on each page load with a 6-hour browser cache.
Orbital Propagation (SGP4)
Object positions are computed using the SGP4/SDP4 perturbation model via the satellite.js library, a JavaScript port of the canonical NORAD SGP4 implementation. Each TLE set is propagated to the current UTC time, producing position and velocity vectors in the TEME (True Equator, Mean Equinox) reference frame.
Coordinate Reference System Transformations
Earth-Centered Inertial
Earth-Fixed (ITRF)
Lat / Lon / Alt
Equirectangular
The GMST (Greenwich Mean Sidereal Time) rotation matrix is applied to transform TEME to ECEF. Geodetic coordinates are then derived using the WGS84 ellipsoid parameters. Subsatellite points are projected onto the map using an equirectangular (plate carrée) projection — EPSG:4326 — which provides a 1:1 mapping between geographic coordinates and pixel coordinates at the equator.
Spatial Analysis
Density analysis is performed by binning objects into 200 km altitude bands and computing object counts per band. The 700–900 km LEO shell is flagged as a High-Risk Zone due to known debris field concentration from the 2007 Fengyun-1C and 2009 Cosmos 2251/Iridium 33 events. Objects within this shell are symbolized separately to convey collision risk.
The Kessler Syndrome risk index is a composite metric based on: total debris ratio, LEO object density per 100 km³, annual fragmentation rate, and proximity to the critical density threshold estimated by NASA orbital debris researchers at approximately 10 objects per 100 km³ in the 700–900 km shell.
Cartographic Design
The base map uses Natural Earth country boundaries (1:110 million scale) rendered via D3-geo on HTML5 Canvas. A 30° graticule provides spatial reference. Objects are symbolized by a five-category classification scheme using a diverging color palette designed for dark backgrounds. Layer opacity and dot size are scaled by object category to reduce visual clutter at high object densities.
Data Sources & Attribution
| Source | Dataset | Format | Update Freq. |
|---|---|---|---|
| CelesTrak (USSPACECOM) | GP Element Sets (TLE/OMM) | TLE Text | Multiple daily |
| Natural Earth | Country Boundaries 1:110m | TopoJSON | Static |
| NASA ODPO | Orbital Debris Quarterly News | PDF/Literature | Quarterly |
| ESA DISCOS | Fragmentation Event Catalog | Literature | As-published |
Limitations
- SGP4 propagation accuracy degrades for TLE epochs older than 14 days. Objects with stale TLEs (>30 days) are flagged with reduced opacity.
- The conjunction warning feed uses representative CDM data; live Space-Track.org CDM access requires authenticated API access not available in client-side deployments.
- Objects below 160 km altitude are typically undergoing atmospheric reentry and may appear at invalid positions.
- Classified military satellites (~1,000 objects) are not included in public TLE catalogs.