HPC Tier Module
SGP4/SDP4 Orbital Propagator
Browser-native satellite orbit propagator.
This tool runs inside GDBS HPC. What it computes and the authorities it applies are below.
What it is
Browser-native satellite orbit propagator. Paste a NORAD two-line element set (TLE) and get the TEME-frame position and velocity (km, km/s) across an ephemeris window, an ephemeris table, a 3D orbit track drawn over a reference Earth, and a JSON export. Add a second TLE for a conjunction assessment - closest-approach distance and time by coarse grid then golden-section refinement. Near-earth SGP4 is implemented faithfully from Vallado (AIAA 2006-6753); deep-space objects (period >= 225 min) are detected and reported honestly rather than propagated with the wrong model. Deterministic, entirely client-side, wall-time shown on every run.
Honest scope
Deterministic and citation-backed: every figure is exact arithmetic or a cited rule. Any year- or jurisdiction-indexed value is a confirmable input, never an eternal hardcode. This is a computation tool, not professional (legal, tax, medical, or financial) advice - confirm against the controlling authority for your context.
Authorities cited
- D. A. Vallado, P. Crawford, R. Hujsak, T. S. Kelso (2006). Revisiting Spacetrack Report #3. AIAA/AAS Astrodynamics Specialist Conference, AIAA 2006-6753. The reference SGP4/SDP4 implementation and the SGP4-VER verification cases. https://celestrak.org/publications/AIAA/2006-6753/
- F. R. Hoots and R. L. Roehrich (1980). Spacetrack Report No. 3: Models for Propagation of NORAD Element Sets. The original SGP4/SDP4 specification and TLE format.
- WGS-72 gravity constants (mu = 398600.8 km^3/s^2, R_e = 6378.135 km, J2 = 0.001082616, J3 = -0.00000253881, J4 = -0.00000165597). SGP4 mean elements are fitted in this model; SGP4 must propagate in it.
- T. S. Kelso, CelesTrak. TLE format documentation and current element sets. https://celestrak.org/
Get an email when tools like this one change
Leave your email and we will tell you when we add or update Aerospace & Defense tools like this one, at most once a month.
We email you once to confirm. After that, unsubscribe from any issue in one click. Your address goes to VaultSync only (privacy).
Run it on your own data
Open it inside GDBS to save runs to Sandbox, attach results to a Worklog case, or share through a Gate client portal - all in the browser, nothing uploaded to anyone’s cloud.