Aster vs. Landsat Satellite Imagery Comparison
(Click Here for Landsat 8 - Sentinel-2 Comparison)
Aster satellite imagery, like Landsat, is free. It launched in 1999 and has 15 x 15 meter pixel resolution (as opposed to 30 x 30 meter resolution for Landsat). Unlike Landsat, data was not acquired at regular time intervals over the same location. Aster imagery was acquired when and where requested by authorized personnel; as a result, there is less likely to be imagery for a particular location for a certain time in the past. The images below show a comparison between Aster NIR (left) and Landsat 7 ETM+ NIR (right) for the same day (September 1, 2005) and the same spatial extent (brighter shades correspond to higher reflectance). For comparison purposes, a higher-resolution true color image with the same extent is included below each - this image is from 2010, however. The images are from the Corn Belt, USA, where for the September 1st date, the predominant features on this landscape with relatively high, medium, and low NIR reflectance are soybean, corn, and harvested fields, respectively.
(True color aircraft-based image has the same extent as the satellite images but is from 2010 as opposed to 2005.)