5 Sites for Free Satellite Imagery

High resolution imagery offers the option of research and analysis of on-the-ground realities, in as close to real-time as possible for some cases, without the need for travels to locations that may not be easily or readily accessible. They closely represent the actual situation on the surface, and sometimes beneath it, at up to a global extent, and the with the data being freely available to the public, anyone can use and manipulate it in mapping applications to study both small- and large-scale changes. Very high-resolution satellite can provide images of up to 30 centimeters.

The disadvantages of high-resolution images is that they sometimes are only available from commercial sources, which means access to the data can cost. Additionally, the better the resolution, the less total ground area may be covered because even a small bit of area may result in very large file sizes.

USGS Earth Explorer

The United States Geological Survey (USGS) Earth Explorer provides free digital USGS data, including Landsat, LiDAR, and hyperspectrial images; aerial photos; elevation models, and more. Imagery resolution for both satellite images and aerial photography are available in high resolution, but can also vary according to satellite source and imagery type. As an example, images from the Global Land Cover Survey, a joint operation between USGS and the University of Maryland, are also available, at 30-meter resolution using Landsat 7 ETM+ data.

2013 Global Forest Change Project
2013 Global Forest Change Project

NOAA Data Access Viewer

The U.S. National Oceanic and Atmospheric Administration (NOAA) Data Access viewer offers satellite, aerial, and LiDAR imagery. It also contains elevation and land cover data for the coastal U.S. and territories. Like the USGS Earth Explorer, resolution varies according to type of imagery and source. For example, this image of the southeastern coast of the U.S. from the Office for Coastal Management has a resolution of 30 meters.

NOAA Data Access Viewer
NOAA Data Access Viewer

University NavStar Consortium (UNAVCO)

UNAVCO is a non-profit consortium of universities, sponsored by the National Science Foundation and NASA, that supports scientific research by offering free access to geodesy data. Data types include GPS/GNSS, SAR and Lidar/SfM, strain and seismic borehole data, and Tropospheric data, from foreign and U.S. space agencies. High resolution images are available for most areas.

GPS stations in South Africa and surrounding countries
GPS stations in South Africa and surrounding countries

Bhuvan Indian Geo-Platform of ISRO

The Bhuvan Indian Geo-Platform of ISRO contains images obtained from satellites managed by the Indian National Remote Sensing Centre. Resolution ranges from 24 meters (Linear Imaging and Self Scanning Sensor, or LISS) to 56 meters (Advanced Wide Field Sensor, or AWiFS) to 500 meters from the IMS1 (as shown in this image).

Instituto Nacional de Pesquisas Espaciais (INPE), Brazil

Brazil's National Institute for Space Research (INPE) data library contains images from China-Brazil Earth Resources (CBERS), a joint satellite program that focuses on collection and analysis of South America and Africa observational data. High resolution images are available, like this multispectiral image of São José dos Campos at 20 meters.