Central Florida as seen by Landsat 7. Photo: NASA

A year after its April 1999 launch, Landsat 7 continues to serve a wide variety of "Earth customers" with its spectacular data. Since being declared operational last July, Landsat 7 has gathered more than 90,000 images, covering most of the Earth's surface multiple times in stunning detail.

"The resolution and absolute calibration of the imagery collected by the Landsat 7 'Enhanced Thematic Mapper Plus' instrument are better than what has been provided by previous Landsat sensors," said Dr. Darrel Williams, Landsat 7 Project Scientist, at NASA's Goddard Space Flight Center, Greenbelt, MD. "These enhancements permit users to more easily register the image data to maps, to resolve smaller features in the imagery and to more confidently compare current results with those derived from analyses of data acquired by earlier Landsat sensors."

Landsat 7 is the latest in a continuous series of Earth observation satellites that began with Landsat 1 in 1972. Unlike its predecessors, Landsat 7 can create global maps of the Earth in record time due to technology advances developed by NASA.

The Kennedy Space Center and Cape Canaveral Air Force Station, Florida. Photo: USGS

Landsat 7 has provided images of most major U.S. cities, as well as timely images of the recent devastating floods in Mozambique, the flood damage in North Carolina from Hurricane Floyd, and the drought conditions that plagued the eastern U.S. last summer. The imagery also has been used to monitor volcanic eruptions in Alaska, Hawaii, Italy, Mexico and Central America. The satellite has documented changes over time, such as receding glaciers in Alaska and the Alps, deforestation in the tropics, and wildfires in Siberia and the outback of Australia.

Farmers and commodity brokers have used the data to assess and predict crop yields locally, regionally and on a global basis. A group of scientists, led by Dr. Susan Moran of the U.S. Department of Agriculture, is using Landsat 7 data help farmers and land managers increase crop yields and cut costs while reducing environmental pollution.

Scientists from NASA's partner agency in the Landsat 7 mission, the U.S. Geological Survey (USGS), are using Landsat 7 to determine the amount and condition of dry biomass on the ground, a potential fuel source for wildfires that can threaten humans, animals and natural resources. In addition, USGS scientists have used Landsat 7 to provide a synoptic view of the landscape simultaneously with the outbreak of infectious diseases -- most recently in the outbreak of the West Nile Virus, a mosquito-borne disease that caused encephalitis in some residents of New York City last summer.

"Landsat 7 is already proving to be a major source for information about the land mass of the planet, and building on previous satellite data provides us a long-term record of information about the Earth," said USGS Landsat program manager, R. J. Thompson.

Liberty, Ellis and Governors Islands of New York City. Photo: USGS

The USGS Earth Resources Observation Systems (EROS) Data Center in Sioux Falls, SD, processes, archives, and distributes all Landsat data to researchers and the public. Every 16 days, Landsat 7 flies over the same geographic area and can document the ground-cover conditions of the entire globe on a seasonal basis. Everyday, Landsat 7 collects and downlinks 250 scenes of data to be archived at the EROS Data Center. An additional 200 unique scenes are sent down to nearly a dozen international ground-receiving stations located around the world.

The spacecraft is controlled from a mission operations center at Goddard. NASA controllers will continue to operate the spacecraft until Oct. 1, 2000, when control will be turned over to the U.S. Geological Survey. The U.S. Geological Survey currently provides Landsat 7 image products to hundreds of customers each week through an Internet site that allows visitors to preview imagery before purchase.

Landsat 7 is part of NASA's Earth Science Enterprise, a long-term global research program studying human-induced and natural changes in the Earth's global environment.