EX02 — Ground Access

Tags: propagation · ground access · contact windows Input: ground-access.yaml · Runtime tier: quick · Recommended views: 2D, Analysis

Purpose

Determine when a constellation can see selected ground sites and inspect the range, elevation, azimuth, and sampled contact-window evidence behind the answer.

Setup

The example uses 12 satellites in three planes and three sites—Madrid, Singapore, and Honolulu—over six hours at a two-minute cadence.

astraeus run astraeus-resources/examples/user/ground-access.yaml

Use the 2D view for the moving geometry and Analysis for access windows and site metrics.

RunSpec Focus

The distinctive input is the explicit ground segment. Each site carries its own minimum-elevation constraint; the geometry stage turns those constraints into sampled access windows.

ground:
  sites:
  - site_id: MADRID
    latitude_deg: 40.4168
    longitude_deg: -3.7038
    min_elevation_deg: 10.0
  - site_id: SINGAPORE
    latitude_deg: 1.3521
    longitude_deg: 103.8198
    min_elevation_deg: 10.0

Results

The reference run completed successfully in 0.25 seconds. Across 181 timestamps, 12 satellites, and three sites, Astraeus found 36 sampled contact windows. All azimuth samples were defined; the geometry arrays have shape 181 × 12 × 3.

Artifacts To Inspect

Artifact	What it shows
geometry/geometry_summary.json	Site and satellite counts, sampling policy, shapes, and window total
geometry/access_windows.parquet	Start, end, duration, peak elevation, range, and azimuth for each window
ground_track_map_data.json	Map-ready satellite tracks and configured ground sites

Interpretation

The 36 windows describe geometric opportunity under the configured elevation masks and two-minute sampling. The range and elevation histories can feed later RF and transport studies. Continue with EX03 to aggregate opportunity over an area.