The Best Free Satellite Imagery for Alaska
Sentinel-2, Landsat, NAIP — a practical comparison for Alaska mapping and analysis.
For Alaska, no single free imagery source is perfect. Here’s how they compare.
Sentinel-2. 10–20m resolution, 5-day revisit. Good for change detection and vegetation. ESA’s Copernicus program, free and open. Cloud-free mosaics are possible with enough scenes. Our default summer basemap.
Landsat. 30m resolution, 16-day revisit. Longer archive (back to 1972), good for historical comparison. Free from USGS. We use it for temporal analysis and older coverage.
NAIP. National Agriculture Imagery Program. 1m resolution, flown periodically. Excellent for visible terrain — but Alaska coverage is patchy and often outdated. When available, we serve it as a premium layer.
Radar (Sentinel-1). All-weather. Penetrates cloud. Different look — no true color. We’re experimenting with it for winter and cloud-prone regions.
TrueTopo’s stack. Users can switch basemaps. We default to the best available for the view and season. Pro users get NAIP and custom mosaics where we’ve processed them.