Landsat Imagery: A Unique Resource
Landsat satellites provide high-quality, multi-spectral imagery of the surface of the Earth. These moderate-resolution, remotely sensed images are not just pictures, but contain many layers of data collected at different points along the visible and invisible light spectrum. These data can be manipulated to reveal what the Earth’s surface looks like, including what types of vegetation are present or how a natural disaster has impacted an area (Fig. 1).
|Figure 1. Landsat images before (2007) and during (2008) flooding along the Wabash River along the Indiana-Illinois (USA) border (L: June 9, 2007, R: June 12, 2008). Source: http://landsat.usgs.gov/gallery.php.|
Currently, there are two Landsat satellites producing imagery: Landsat 8, operational since early 2013, and Landsat 7, operational since 1999. While many other satellites provide imagery, Landsat images are unique in three ways:
They provide global coverage on a regular basis.
They are now available for free.
Landsat’s image archive reaches back to 1972 (Fig. 2).
No other satellite imagery has that combination of attributes, which makes Landsat imagery of particular value to the global community. Understanding the value of the imagery provided by Landsat satellites is essential as future land-imaging initiatives move forward.
|Landsat Time Span Imagery|
|Figure 2. Landsat images of change in the Mississippi Delta, USA, over a 30-year time span (L-R: 1973, 1989, 2003). Source: http://landsat.usgs.gov/gallery.php.|
The Landsat Study
In a project initiated by the U.S. Geological Survey’s Land Remote Sensing Program, the USGS Fort Collins Science Center’s Policy Analysis and Science Assistance Branch (PASA) is conducting a study to investigate the users, uses, and benefits of Landsat imagery. The goals of this study are to (1) identify and classify Landsat imagery users, (2) better understand the specific uses of the imagery as well as the extent to which it is used, and (3) determine the value of Landsat imagery to the users. The study has two main components:
These investigations have so far demonstrated the myriad types of users and uses, as well as the substantial value of Landsat imagery to users.