Earth Observation/Remote Sensing Satellites
Weather satellites form another major segment of remote sensing satellites, typically operating in GEO or polar LEO orbits. These systems are primarily operated by national governments for forecasting near-term weather patterns. Delays and funding issues could endanger the robustness of some weather satellites programs, as several existing polar satellites are operating near or beyond their design life and are in need of replacement. One program in particular, the Joint Polar Satellite System (JPSS), is set to replace the aging Polar-orbiting Operational Environmental Satellite (POES) fleet.
Land imaging satellite performance is described using a variety of characteristics, including differences in spatial resolution (as measured by how many pixels compose an object), positional accuracies (as measured by the extent to which objects are represented accurately), and spectral capabilities (as measured by wavelengths of light captured, including visible and beyond-visible spectra). High-resolution land imaging satellites have resolutions below 1 meter (3 feet) per pixel, allowing users to distinguish cars from trucks, for example.
The German Federal Armed Forces operate a ##-satellite LEO fleet called SAR-Lupe, which provides radar imagery with one-meter (3-foot) resolution for surveillance purposes.
Funding is a serious concern for government-supported remote sensing satellite endeavors. Europe’s Global Monitoring for Environment and Security (GMES) program is facing difficulties because of the global economic climate, which is forcing many space programs around the world to cut costs. In November 2011, the European Commission (EC) proposed moving funding for operating the GMES space segment from the 27-member commission to the individual EU member states.
Two major players in satellite-based Earth imagery are U.S. companies DigitalGlobe and GeoEye. Both companies provide imagery to widely used applications such as Google Earth. In August 2010, the U.S. National Geospatial-Intelligence Agency (NGA) awarded 10-year contracts to the companies, valued at $## billion for GeoEye and $## billion for DigitalGlobe, under the agency’s EnhancedView procurement. The NGA specializes in mapping and imagery intelligence, and played a key role in the raid on Osama bin Laden’s compound in May 2011 by providing satellite imagery, geospatial and targeting analysis, and modeling support to plan the successful mission.
In June 2010, Israel launched the OFEQ-9 reconnaissance satellite which joined ## others already in operation. China’s utilization of space for military purposes is even harder to gauge due to the country’s lack of transparency in its space programs. In 2010, the country launched ## Yaogan satellites with the stated purpose of engaging in scientific experiments, land survey, crop yield assessment, and disaster monitoring. Many space analysts believe that the true mission of these satellites is for reconnaissance or other military purposes.
Concerns about global climate change have led to the use of remote sensing satellites to measure the potential impact of humans on the environment. NASA employs more than a dozen Earth science spacecraft measuring a variety of environmental factors, including sea level, the amount of aerosols in the atmosphere, and changes in the size of the Earth’s ice sheets. The United States and Taiwan have partnered to develop the six-satellite FORMOSAT fleet, used to collect atmospheric data for weather prediction and for ionosphere, climate, and gravity research.
Two major U.S. commercial providers of satellite-based Earth imagery are DigitalGlobe and GeoEye. Both companies provide imagery for widely used applications such as Google Earth. In August 2010, the companies were awarded separate 10-year, $## billion contracts from the U.S. National Geospatial-Intelligence Agency under that agency’s EnhancedView procurement. These contracts make it possible for both companies to finish procurement and launch of new advanced satellites capable of discerning objects on the Earth’s surface as small as 25 centimeters (9.75 inches) in size.
NASA operates or participates in more than a dozen remote sensing satellites and international programs. The Jason satellite, a joint mission between France and the United States that follows the highly successful TOPEX/Poseidon altimeter mission, has measured an increasing rate of sea level rise. Data from the Ice, Cloud, and land Elevation Satellite (ICESat) and Gravity Recovery and Climate Experiment (GRACE) satellites have shown rapid changes in the Earth’s ice sheets.