The Landsat 7 mission - Terrestrial research and applications for the 21stcentury

The Landsat Earth observation approach introduced in 1972 created a new way of monitoring land cover and land use globally. The Landsat 7 mission, suc cessfully launched on April 15, 1999, continues those observations and demo nstrates significant progress in precise numerical radiometry, spectral dif ferentiation, and seasonally repetitive monitoring. Substantial improvement s in calibration procedures, both prior to launch and during normal operati ons, have also been made to ensure long-term stability in the acquired spec tral radiometry. Landsat 7 data acquisitions are being driven by a long-ter m data acquisition plan that was designed to ensure that substantially clou d-free, seasonal coverage would be recorded and archived in the US for all land areas of the globe. NASA competitively selected a Landsat Science Team , consisting of representatives from US universities and government agencie s, to exploit the Landsat 7 record for global change research. This team is addressing the technical and analytical means to process and analyze the c ore of this observation record, and for the first time in the history of th e Landsat mission, the technical and operational aspects of the mission are being driven by the goals of the US science community. The expected outcom e of these efforts is a rapid improvement in understanding the Earth system , as well as conceptual knowledge that will underpin significant advancemen ts in the application of this technology for commercial, operational, educa tional, and research purposes. Pathways to achieve effective Landsat contin uity in the early decades of the 21st century are also being given careful attention, and there is no question that the lessons teamed from the Landsa t 7 mission will strongly influence these next-generation sensor systems. ( C) 2001 Elsevier Science Inc. All rights reserved.