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Satellite Imagery Sources and Access

3 min read Created Aug 10, 2026 Last updated Aug 10, 2026

Overview

Overhead imagery splits into free government and open programmes, which are unlimited but capped in resolution or refresh rate, and commercial providers, which offer sub-metre resolution and tasking for a fee. Match the source to the question: footprint confirmation needs resolution, activity monitoring needs frequent revisits.

Free High-Resolution Base Layers

For confirming a footprint, the best free imagery is the composite base layer in mapping platforms:

  • Google Earth and Google Earth Pro, the highest-resolution free imagery for most populated areas, with a historical timeline.

  • Esri World Imagery, sub-metre in many regions, with a companion Wayback archive of past versions.

  • Bing Maps aerial and Yandex Maps satellite, which sometimes hold a clearer or differently dated frame than Google for the same spot.

Free Medium-Resolution, Frequent-Revisit Programmes

When recency matters more than resolution, the Copernicus and Landsat programmes deliver fresh imagery on a fixed cadence, free and openly licensed:

  • Sentinel-2 optical at 10 m, revisiting every few days. Access through the Copernicus Data Space Ecosystem and its EO Browser.

  • Sentinel-1 radar, which sees through cloud and at night.

  • Landsat 8 and 9 at 15 to 30 m through USGS EarthExplorer.

  • NASA Worldview for near-real-time daily global coverage at coarse resolution.

Query the Copernicus catalogue programmatically to find scenes covering a point within a date window. The STAC API returns matching Sentinel-2 products:

┌──(kali㉿kali)-[~]
└─$ curl -s "https://catalogue.dataspace.copernicus.eu/stac/search" \
-H "Content-Type: application/json" \
-d '{"collections":["SENTINEL-2"],"datetime":"2025-06-01T00:00:00Z/2025-08-31T23:59:59Z","intersects":{"type":"Point","coordinates":[$LON,$LAT]},"limit":5}' | jq '.features[].id'

Commercial Providers

When free coverage is too coarse or too old, commercial imagery offers 30 to 50 cm resolution and, at a price, tasking of a fresh capture:

  • Maxar, the highest publicly available optical resolution, with an open data programme releasing imagery over major disaster events.

  • Planet Labs, whose PlanetScope constellation images the entire landmass daily at around 3 m, with SkySat tasking at 50 cm.

  • Airbus, offering Pleiades and SPOT products.

Choosing Resolution Against the Question

Resolution decides what a pixel can answer. At 10 m Sentinel-2 shows the presence and outline of buildings and large vehicles. At sub-metre commercial resolution individual cars, their type, and ground activity become distinguishable. Do not pay for resolution the question does not need, and do not expect a 10 m pixel to answer a question that requires counting vehicles.

References