The goal of the current Landsat mission is to acquire annual data sets of optical band digital imagery of the landmass of the Earth. Ground spatial resolutions for the panchromatic, reflective and emissive bands are 1 5, 30 and 60 meters, respectively. The design life for the Enhanced Thematic Mapper Plus (ETM+) imager on the Landsat-7 satellite is five years. The satellite was launched on April 15, 1999. The mission builds on the 27-year continuous archive ofthematic images ofthe Earth from previous Landsat satellites. Early results from the ETM+ instrument, the spacecraft, and the ground processing indicate that the image quality is as good as expected and all systems are working. Partial Aperture Solar Calibrator (PASC) 100-day radiometric background stability is Full Aperture Solar Calibrator (FASC) 2-day stability isMid-scale per pixel noise isOperational collection of Landsat's Long Term Acquisition Plan (LTAP) started June 29th. NASA Goddard Space Flight Center (GSFC) is responsible for the instrument, spacecraft, launch, flight operations and science team investigations. On October 1 , 2000 USGS EROS Data Center (EDC) takes over flight operations while continuing archiving, monitoring quality, and distributing the imagery without restrictions on reprocessing and redistribution.
The rise of the commercial space industry has resulted in the development of megaconstellations that promise to provide global broadband. These constellations capitalize on advancements in technology, improved modeling capabilities, and reductions in launch cost. One of the significant open questions is whether these constellations will significantly increase access for uncovered and underserved communities, in addition to serving existing markets. This paper analyzes which constellation characteristics provide the best global coverage at the lowest operational cost. First, we present the demand model that assesses the number of under-served and uncovered users in a given region. Then, we present a genetic algorithm used to identify potential constellations. Finally, we conclude by identifying which characteristics are the most promising for broadband constellations, as well as predictions of how the market will develop in the coming years. Our analysis has found that geostationary (GEO) and medium Earth orbit (MEO) satellite constellations have the highest likelihood of profitability. LEO networks are on average 27% more expensive, but if designed wisely, they can be competitive. Our work shows that there are diminishing returns with large constellations, and that it is more cost effective to have a small number of highly capable satellites, rather than many low complexity satellites. Key technologies like high frequency bands and miniaturization of components can lead to further cost reductions and increase the competitiveness of LEO constellations.
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