Satellite Sensing Systems

Satellite data provide an important source of information for characterizing and monitoring land-cover and land-use change. In some regions it is the only feasible way to provide timely and reliable land-cover assessments and identify areas of rapid change. Recent land-cover history also provides a point of departure for modeling land-cover change.

NASA Current Missions For LCLUC Research

NASA currently has sensing systems at high, medium and low resolution, which meet the LCLUC program observation needs. NASA satellite systems supplement operational satellites providing systematic measurements to study long-term trends. For example, the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments on the EOS Terra (AM) and Aqua (PM) platforms have significantly improved on the capabilities of the operational NOAA/METOP Advanced Very High Resolution Radiometer (AVHRR). These coarse resolution data are used to classify and characterize land-cover at the global scale and to detect land-cover change at the regional scale. They also provide daily monitoring of land surface characteristics such as surface temperature, LAI and fire activity, which are often an indicator of land-cover change.

NASA as part of the Integrated Program Office contributed to the design of the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument launched in 2011 which provided  a transition from MODIS class observations into the operational domain. Together with MODIS, the VIIRS instrument has continued the long-term data records of vegetation indices, land-cover and fire. The NASA S-NPP Science Team is establishing data continuity between MODIS and VIIRS products. New products derived from VIIRS important for LCLUC science have include the nighttime lights product providing moderate spatial and temporal resolution data to supplement and improve upon the operational Defense Meteorological Satellite Program which has also been used by LCLUC-funded research. Additional products such as finer-resolution active fire products have also been developed with the VIIRS sensor.

Landsat 7 has provided the systematic moderate resolution observations necessary to map and quantify land-cover changes at the local to regional scale for nearly 2 decades. The Landsat class observations are a critical underpinning for LCLUC research. The global acquisition strategy provided increased coverage with multiple cloud-free scenes each year, facilitating land-cover studies around the world. The LCLUC program has been pioneering methods for regional analysis of Landsat class observations setting the stage for periodic continental and global assessments of land-cover change. In this regard, the combination of systematic moderate and high resolution satellite remote sensing provides the opportunity for global scale studies and forms the basis for a global land observing system. Landsat 8 launched in 2013 has been providing improved moderately-fine resolution imagery building upon the success of the previous Landsat missions. It has included more refined bands than Landsat 7, including bands developed for cloud cover and aerosols. All bands have improved radiometric resolution making Landsat-8 sensor more sensitive. 

The NASA Harmonized Landsat Sentinel (HLS) Project in partnership with the LCLUC Program has developed a co-located, normalized Landsat 8 and Sentinel 2 product, which provides increased temporal frequency of moderate resolution coverage. The NASA MuSLI Projects funded by the LCLUC Program are using multiple sources of data to  develop higher-level co-located satellite products for applications such as inundation mapping, burned area mapping, and forest cover mapping. This innovative project integrating moderate to high spatial resolution imagery from multiple NASA and non-NASA satellites.

Over a number of years, NASA has participated with NGA in providing access to fine resolution data through a commercial data archive and the NextView License. Fine spatial resolution data with 1-3m resolution from sensors such as IKONOS, Quickbird, and Worldview have been used by LCLUC PI’s to provide detailed validation of high resolution products. With the increase in commercial fine resolution data, NASA has undertaken an activity to evaluate the utility of commercial data for science through a Commercial Smallsat Data Acquisition Program. A number of PI’s in the LCLUC Program are participating in this evaluation.

Experimental measurements of limited duration are needed to better understand processes and to test new sensor technologies. For example, the Earth Observer 1 (EO1) system  provided a test-bed for new sensor technology and spaceborne hyper-spectral remote sensing. Similarly the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor has provided coarse resolution thermal data collocated with MODIS data for improved surface characterization and validation of MODIS thermal products. More recently the ECOSTRESS  thermal instrument on board the International Space Station (ISS) was developed to reduce the cost and risk for the thermal infrared radiometer on the future Hyperspectral Infrared Imager (HyspIRI) mission. HyspIRI is one of the system concepts being considered for the Surface Biology and Geology (SBG) Designated Observable identified by the most recent NASA Decadal Survey. The GEDI instrument also on ISS is providing the first satellite based Lidar data for studying the 3-D Structure of vegetation.

NASA LCLUC research in the microwave part of the Spectrum had been limited by the absence of a current US microwave sensing system until recently. Various SAR systems have been used including airborne platforms such as UAVSAR which can be deployed as a fully polarimetric system with high spatial resolution to any given location in the world. Microwave satellite sensors operated by Europe (e.g. ERS-1/2) and Japan (JERS-1) have also been used by LCLUC PI’s for mapping the extent of wetland areas. Currently NASA collaborates with the European Space Agency for sharing of Sentinel-1 C-Band SAR which is available for public download with a wide array of SAR data from the Alaska Satellite Facility

NASA Future Missions For LCLUC Research

Landsat 9 development is currently underway as a partnership between NASA and the USGS to continue the decades-long legacy of Landsat sensors and associated historical record. It will prove useful for land resources mapping, monitoring land cover and land use change consequences including ecosystem function and services with implications on human health, the economy, and society. Landsat system of sensors have helped stakeholders across the world to the better manage farm resources, wildland fire control, drought monitoring, flood mapping, and much more. Landsat 9 is planned for launch in late 2020 and will include the OLI-2 and TIRS-2 science instruments with a design life of 5 years and is in essence a rebuild of Landsat-8 which may allow for a much quicker and safer launch and prolonged lifespan.

NASA is currently developing a SAR system in collaboration with the Indian Space agency. The system is called NASA-ISRO SAR Mission (NISAR) planned for launch in 2020. It will be the first earth orbiting satellite with dual-band frequency (S-band and L-band) SAR with applications for hazard monitoring, global environmental change, and more.

Additional information on NASA’s planned mission details are available here

Through the international reach of the LCLUC Program, we have been interacting with the international scientists and Space Agencies to advocate for increased availability of free and open sharing of data from satellites that are relevant to LCLUC research.