• Include a research and development component to improve data products based on core measurements and to develop new measurement methods and consider evolving requirements.
For the Sustained and Enhanced Land Imaging Program to be successful, program responsibilities should be divided between USGS and NASA such that the agency responsible for balancing science requirements with mission complexity and cost is also provided with the necessary budget. Both agencies should participate in an iterative process to design missions that meet the needs of research and operational communities, but final decisions should be made by the agency that has been given the budget.
The committee recommends key elements of a successful Sustained and Enhanced Land Imaging Program (SELIP) no matter where the federal government decides it should reside.
TECHNICAL CHARACTERISTICS OF THE CORE PROGRAM
SELIP would provide a core set of capabilities and measurements that continue to support operations and scientific investigations and maintain and enhance continuity with the information available since 1972. Landsat has provided an unequaled record of moderate-resolution (30-100 m) multispectral measurements of Earth’s surface, the long-term continuity of which is critical for quantifying ecological, environmental, and land-use change. Preserving program continuity requires a satellite system and launch schedule that provides a continuous stream of land images and data and at the same time implicitly requires strategies to contend with future instrument or launch failures. Risk mitigation strategies could range from instruments ready to launch to securing agreements with international partners for data access. A “hot spare” on orbit or available for quick launch—as weather satellites have been managed historically—is not required.
The core scientific and operational requirement for the SELIP is the capture and distribution of global, moderate-resolution, multispectral data calibrated sufficiently to allow the rigorous comparison of future image products with previous collections, easily accessible by all users, and free. Ensuring continuity of the ongoing data stream does not require continuing to fly the same sensor, nor does it require that all measurements be made from a single space platform. The section “Findings,” in Chapter 2, presents a detailed list of user requirements. These include spatial resolution no coarser than 30 m, except in the thermal band; spectral coverage from the visible through the thermal infrared; and temporal coverage at 7-to 10-day frequency.
The top priorities for the Sustained and Enhanced Land Imaging Program (SELIP) should be to ensure that the core program provides for continuity of Landsat products and coverage on a secure and sustainable path.
The SELIP should take advantage of technological innovation in sensors, spacecraft, and data management and analysis to improve system performance, allow for new analyses that better exploit the data and meet future needs. Because future measurements will derive from both current and new technologies, new implementations of existing data products derived from a multispectral sensor should be cross-calibrateable with Landsat legacy products and be essentially interchangeable for scientific and operational purposes.
To better meet these primary goals, the committee recommends that the program should
• Systematically monitor users and uses of Landsat data so that the program can evolve with changing user requirements and
• Consider alternative implementations that continue to enable the collection of global, moderate-resolution data with the full range of spectral capabilities.
ENHANCING A SUSTAINED LAND IMAGING PROGRAM
Landsat has been the cornerstone of U.S. land imaging, but it has never comprised the totality of that effort. Although the core program of SELIP is a set of measurements and data products that preserve the continuity of