Welcome to the United States Geological Survey's (USGS) Earth Resources Observation Systems (EROS) Data Center, or EDC. The EDC was established in 1971 to receive, process, and distribute data from NASA Landsat satellites, as well as aerial photographs gathered for the USGS and other agencies. The original 115,000-square-foot building was completed in 1973 for $6 million. In March 1996, the Center completed a 65,000-square-foot addition for $9 million to house equipment and people for NASA's Earth Observing System Program and Landsat 7 data handling.

Elements of our work here potentially affect millions of lives. We supply data--the raw material of science--to a worldwide community of users. Scholars, engineers, and land managers use our data to study a growing list of environmental issues such as resource development, global change, and land use planning. In addition to maintaining earth science data, EROS scientists constantly work to discover new ways to use this information.

• images formed from satellite data
• images formed from aerial data
• images formed from elevation data
• images formed from map data
• images formed from land cover data

The USGS EROS Data Center purchased this rotating globe in the early 1980's. One inch on this model represents about 100 miles.

The Large Format Camera, housed in the EDC's long, skylit atrium, is a remote sensing system used aboard the Space Shuttle Challenger mission of 5-14, 1984.

Engineers designed this device to shoot photographs for precision mapping projects, involving the exploration of minerals and fossil fuels such as oil and coal.

The 2,100 photographs acquired by this instrument help document the natural and human changes that continue to shape the Earth's surface.

The EDC operates two of the largest computer complexes within the Department of the Interior. In a computer room that supports USGS projects and activities, a robotic mass storage system holding approximately 6,000 cartridges, or 15,000 separate images, makes much of the EDC's satellite information immediately available to scientists at desktop workstations.

Online access to the EDC's Earth science data bases and other centers worldwide is available through Earth Explorer.

The USGS uses the resources of the EDC to put ever greater amounts of earth science data online. This work is forming the foundation of a national spatial data infrastructure, an immense electronic library of information on the land surface, the processes acting on it, and their effects.

The computer equipment in the middle of the room is used by the EDC to transfer earth Science data, including satellite images, aerial photographs, and derivative products, to compact discs and other magnetic and optical media for distribution to customers. During the first 5 months of 1998, the EDC copied data to 30,000 compact discs. The room is staffed 24 hours a day, 5 days a week.

This computer room was associated with NASA's Earth Science Enterprise initative. The robotic mass storage systems hold approximately 5,500 cartridges, or 920,000 separate images. These units also make much of the EDC's NASA satellite information immediately available to scientists working at desktop workstations here and around the world. One robotic mass storage system holds 5 years of Landsat data.

A major part of NASA's Earth Science Enterprise initative is the Earth Observing System, or EOS, which will collect data required to measure changes in the Earth system. Beginning in 1999, and running for at least the next 15 years, the EOS will collect data through a series of satellites and field experiements to observe the Earth.

In the back part of this room are computer systems associated with Landsat 7 -- the latest in a series of Earth observation satellites first launched in the early 1970's. Launching early in 1999, Landsat 7 records improved images of the Earth's land surface on the order of 250 scenes per day.

The Advanced Very High Resolution Radiometer (AVHRR) sensor flown aboard NOAA weather satellites has a resolution of 1,100 meters. The most common product from AVHRR data are 10-day global area coverage composites that show the density and health of vegetation on the Earth's surface.

Every day the AVHRR sensor measures the amount of energy reflected by plants, soil, and water on the Earth's surface. By merging data over a period of several days, 10 in this case, it is possible to acquire a nearly cloud-free observation of North America.

Analysis of the amount of reflected energy enables scientists to measure the condition, or "greenness," of the vegetation. The vegetation condition is computed as an index value ranging from zero to one.

The EDC's Photographic Laboratory processes pictures 18 hours a day, 5 days a week. Annually, the lab produces more than 350,000 products. These products range from 16 mm film to 40-inch-black-and-white and 50-inch color prints. The lab uses vertical and horizontal enlargers, autododging contact printers, and roll-to-roll printers, along with digital high-resolution film, and paper printers.

The processing bay houses 10 processors capable of black-and-white and color film and paper productions. Two chemists ensure that processors maintain process control, regenerate chemicals, and monitor the discharge.

The lab uses approximately 20,000 gallons of water each day. In accordance with Environmental Protection Agency standards, safe photographic processing chemicals that cannot be recycled are piped to recess ponds behind the Center. Four ponds filter the water before it is released into Lake EROS. By the time it reaches the lake, the water is purified. Ninety-nine percent of the silver in the waste photo chemistry is reclaimed and sold to the highest bidder.

Packaging and Shipping

From 25,000 annual inquires, Customer Services staff provide roughly $10 million in products and services to other Federal agencies, private industry, academia, and the public. All of the hardcopy data produced at EROS are shipped through the Dissemination area.

About 25 percent of the products are shipped outside the country. Data managed at the EDC are sold for the cost of reproduction, and distribution.

Analysts at the USGS EROS Data Center take traditional map information and combine it with images acquired by sensors on satellites or aircraft to produce image maps. These products give scientists and decision makers a sense of what things are (for example, vegetation types ) and how they relate to one another.

A digital satellite image is made up of picture elements called pixels. Arranged horizontally and vertically, each pixel represents the minimum size of an area on the ground that is detectable by a remote sensing device. The spatial resolution of a Landsat multispectral scanner image is approximately 80 meters, while the spatial resolution of a Landsat Thematic Mapper (TM) image is 30 meters. The TM image above is of southeastern South Dakota with both the city of Sioux Falls and its airport enlarged. Each pixel is represented by a number that indicates the amount of reflected light encoded by the satellite sensor. The higher the number, the greater the amount of reflected light recorded.

This shows how a pixel of Landsat TM data would fit on a football field.

Photographic chemicals may be reused after the silver has been removed (approximately 250 Troy ounces of silver are collected each month) and after the chemicals have been treated for reuse.

Recycling photographic chemicals extends their life, reduces the amount of chemicals discharged through the Center's waste management system, and saves on chemical costs. Photographic chemicals are broken down before they are finally released to the Data Center's holding ponds.

The chemical management system has more than saved $1 million in chemical costs. This figure includes the funds put back into the system through the sale of recovered silver.

Image mapping combines satellite images with traditional map information to form a product that is visually appealing and informative as well as geographically accurate. This TM image map covers Florida from the Orlando area south to Key West. Vegetation is green and dormant vegetation and harvested croplands are reddish-brown; water varies from blue to black; cities are identified by purple tones and rectangular street patterns.

South Dakota Mosaic

WET vs. DRY

These two TM scenes of South Dakota cover the James River Valley from Mitchell to just below Aberdeen. Ipswich is in the northwest, while to the northeast are Watertown and the glacial lakes region. To the southeast are Lake Thompson and Vermillion River drainage, and in the southwest are Fort Thompson and the Missouri River. The May 25, 1993, image shows a normal spring, where unplanted fields are reddish tones. Growing vegetation is green and water is black. In contrast, the May 15, 1995, image shows a wet spring. Note the dramatic increase in the amount of water in the region. The James River is flooding, every pothole is full, and many of the fields are saturated. Image data such as these are provided to the State of South Dakota and the Federal Emergency Management Agency to support natural disaster declarations for the affected counties.

Mississippi River Valley Floods

This three-scene TM montage shows extensive loss of farmlands in the floodplain of the Missouri River during the record flooding of 1993. The September 1991 image shows field patterns that indicate almost total use of the floodplain for agriculture. The July 1993 image shows the inundation of the floodplain. By October 1993, the waters have receded, but fertile soil has been washed away, replaced by sandbars and gravel deposits. The EDC housed the interagency Scientific Assessment and Strategy Team following the 1993 flooding. The scientists and engineers gave advice to policy makers and officials responsible for flood recovery and river basin management in the Upper Mississippi River Basin.

Types of Media Available at EROS

The EDC has been archiving, managing, and distributing land remote sensing data and other Earth surface data for more than 25 years. Stored in environmentally controlled areas, the digital archives contain collections, including data from Multispectral Scanner (MS) and Thematic Mapper (TM) sensors carried aboard the Landsat satellite series and data from the advanced very high resolution radiometer (AVHRR) sensor carried aboard NOAA weather satellites. By the year 2005, the EDC's holdings, including both its film and digital archive, will expand exponentially with additions of several data types.

EDC employees manage an archive of 4 million frames of worldwide satellite images and 8 million high-altitude aerial photographs. This massive and ever-expanding collection includes more than 30 years of satellite data and 50 years of photographs.

The EDC is home to an office affiliated with the United Nations Environment Programme Global Resources Information Database, known as GRID-Sioux Falls. Since 1991, GRID-Sioux Falls has functioned as a partnership among UNEP, the USGS, and NASA. GRID-Sioux Falls makes environmental data available to developing countries and so frequently is host to scientists from these countries. The extensive archive of satellite images and other data housed at the Center, GRID Sioux Falls helps other countries achieve sustainable development.

The Don Lee Kulow Memorial Library is a technical reference source for EDC scientists, students, engineers, and professional staff to help perform their work and keep up to date in their disciplines. The library also is a source for other people around the world of information on land remote sensing and global environmental change.