with user agencies at both federal and state levels. Because of the high qualtiy of the data from the recently flown ERTS-1 satellite and the favorable results of the investigators' early analyses of this data, there is a feeling of cofifidence that the use of space technology will play an important role in the monitoring and control of the Earth's resources.

The national importance of this undertaking was recognized in early 1972 by the creation of the Federal Earth Resources Survey Program under the guidance of an Interagency Coordinating Committee. Membership is composed of representatives from NASA, the Departments of Agriculture, Commerce, Defense, Interior, and State; the Corps of Engineers (Civil Works) and the Environmental Protection Agency.

The determination as to the role of space technology in earth resources applications requires direct and indepth contact with the widest possible population of potential users. This wide contact has been achieved by appointing "principal investigators" to analyze and report on the potential uses of the data received from our first earth observations satellite (ERTS-1). As shown in figures 358 and 359 (see p. 1024), these investigators come from almost every

state in the nation and from 36 foreign countries. Figure 360 (see p. 1024) lists Some of the subjects of their investigations and shows just how varied and how detailed their interests are.

Because ERTS-1 could not accommodate all types of instruments which hold promise for useful applications, a package of complementary earth sensors has been placed aboard Skylab for its flight in 1973. Since the data collected from space must be verified, NASA has an earth observations aircraft program which provides experimentors with supplementary data for this purpose. It also is used as an early test of instruments being developed for space use. The development of the instruments, sensors and interpretative techniques themselves is one of the most important elements of NASA's program and is carried out in two steps. Interesting new concepts and techniques are funded under a research program. A second program carries the development of the more promising ones to a point where they are considered ready for development into spaceflight instruments. In addition to these traditional research and developmental programs, the earth resources survey program supports specific users in demonstration programs which are carried out as field tests of a total observation system-including, in some cases, the use of data from spacecraft, aircraft and ground stations. These programs are discussed in more detail below.

DISTRIBUTION OF FOREIGN INVESTIGATORS
FOR USE OF ERTS 1 DATA

EARTH RESOURCES TECHNOLOGY SATELLITE

The ERTS-1, launched July 23, 1972, with its payload of special earth sensors, is well into its one-year mission of observing selected regions of the earth every 18 days. The quality of the photograph-like images is excellent. Early results of data interpretation indicate that a unique and highly successful demonstration of the ability to meet the desired information needs is underway. Each of the images taken by ERTS-1 depicts a square one hundred miles on a side (10,000 square miles) of the surface of the earth. The large area covered by these images is a unique and valuable aspect of the ERTS-1 data since it al lows the recognition of surface features which are too subtle to be found on even the best mosaic pictures. Coverage and detail exceed our expectation. Linear

features such as roads, pipe lines, canals, etc. can easily be seen. The images are taken at uniform lighting conditions which is of great importance in their interpretation and are geometrically correct to commonly used mapping standards which makes their translation into usable map products rapid and economical. The images are obtained in four bands of light-two visible to the naked eye, essentially a green and a red, and two infrared bands. By combining these different color images in different ways, the image can be analyzed to provide information about the quality, condition, and kinds of objects in the scene in much more detail than can be obtained from normal photography. In fact, one of the most promising uses of the technique is the development of automated processing systems which will permit the direct translation of the satellite data into maps or charts defining land use categories and the areas devoted to each, i.e. crop types and acreages, forest areas, urban boundaries, etc. The ease with which ERTS-1 is obtaining accurate, detailed, and useful information about large regions of the earth every 18 days is unprecedented and establishes a new capability which must be evaluated against other forms of data collection. During the first four months, the North American continent was covered many times and large portions of all other continents, coastlines, and polar regions were observed at least once, with repeat coverage continuing as the investigation requirements dictate. One of the general objectives of the investigations is to determine how often data should be collected for each of the more promising applications. On the average, about 6 million square kilometers were mapped daily by the satellite's sensor system. Preliminary analyses of these data show excellent performance of the sensor systems and indications are that the data is extremely useful.

The investigations being conducted to assess the utility of the data cover a wide range of application as shown in figures 361 and 362 (see p. 1026). The participation of foreign and domestic agencies illustrates the scope of interest in the ERTS-1 data. In addition to sending the data to these principal investigators, the data is also made available for other users by general sale through the Department of the Interior, EROS Data Center in Sioux Falls, South Dakota; and

NOAA's Data Center at Suitland, Maryland. Purchase orders for data have recently been averaging over 170 per week at these centers.

While the examination of the data is still in its earliest stage, many enthu siastic and favorable comments have been made by the user/experimentors similar to that expressed by Dr. David Sweet, Director of the Department of Development and Community Affairs for the State of Ohio, who noted the following: "The ERTS program is a unique opportunity for Ohio State Government to put its house in order in terms of improving natural and man-made resource management."

Another example of the impressions created by an initial examination of the ERTS products is illustrated in the following excerpts from a Brazilian report shortly after the first imagery of their country became available. As a result of a quick analysis of the ERTS-1 images of Brazil, such as the one shown in figure 363, it was possible for Dr. Fernando de Mendonça, General Director of Brazil's National Space Institute, to say, "The ERTS-1 imagery over the Amazon region has indicated to us some extraordinary conclusions." He continues by listing the following examples:

"The course of the tributaries of the Amazon River are very different from the ones shown in the most recent available charts . . . Islands with more than 200-km2 area exist which are not shown on maps. . . Small villages and towns are located wrongly on the maps by several tens of kilometers.

"The drainage systems of some areas are entirely wrong and this has caused. among other things, the construction of roads (Manaus-Porto-Velho for instance) with extra expenditures for bridges. In fact, the mentioned road is placed wrongly (by more than 20 km) in recent maps (1971).

"The entire Amazonian region was covered last year with Side Looking Airborne Radar (SLAR). The completed controlled photo-mosaics will not be ready for at least another year. Over 150 people are working on the SLAR project, which has cost Brazil about 20 million dollars. The cost of ERTS imagery per square kilometer is about two orders of magnitude less than the SLAR if the satellite operates for the expected lifetime of one year."

Results of ERTS-1 data analyses from the planned program of investigations are now being reported, and some significant applications have already been demonstrated. The following are examples of early results selected to illustrate the broad range of activity to which the ERTS-1 data have so far been successfully applied.

AGRICULTURE AND FORESTRY RESOURCES

Repeated inventory of crops to estimate yield are made during the year by the Department of Agriculture. The announced forecast guides the agriculture industry in planting, selling, storing, and distributing farm produce. Improvements in the speed and accuracy of such inventories using ERTS data are being investigated. Crop and forest species can be discriminated by analysis of data being acquired by the multispectral scanner. Crop calendars can be developed and crops identified. The image shown in figure 364 (see p. 1028) shows a partial analysis of the crop and forest species in the San Joaquin Valley of California. Conditions of damage in forest areas have been detected. This information is important since it is expected to provide for better management of our forest resources by indicating when and where cutting should be undertaken.