the infrared and microwave regions of the electromagnetic spectrum presently under development have already demonstrated their usefulness in agricultural experiments of this type. When used together with visual imaging, data from these new sensors, especially infrared, are expected to assist in a wide variety of interpretational studies, including identification of crop and timber species, analysis of crop vigor, estimation of crop production, and early detection of plant disease over wide areas of farmland and forest. Experiments in the microwave region indicate the utility of this spectral region for soil surveys. Infrared sensors have also been used in aircraft for forest fire detection and monitoring, while near infrared can aid in evaluating crop response to fertilizers, insecticides, and pesticides. There is every reason to believe that these kinds of sensors will be equally effective in earth orbit. Multispectral sensing can also disclose important changes in soil moisture and salinity. The principal need at this early stage is for improved identification of the "spectral signatures" of various crop and tree species; i.e., the distinctive ways in which such plants reflect and emit energy at various wavelengths. The difficulty of such a program should not be underestimated. Both seasonal and diurnal changes in growing plants will greatly complicate efforts to determine spectral signatures; interestingly, agricultural scientists believe that as they gain experience interpreting data from space, such changes will assist their understanding. Various conditions of temperature, illumination, and weather will also affect data collection. The multitude of variables, however, presumably will be manageable assuming development of appropriate sensors and techniques of interpretation. While some work has been done in the laboratory and from aircraft flying over "ground truth" sites at which all surface phenomena have been carefully measured and recorded, additional research and experimentation of this type is required to associate various identifiable spectral signatures with agricultural objects of interests on the surface. In any event, there is reason to be encouraged that an earth resources satellite will someday provide data from which land-use maps may be constructed, soil surveys may be made, cropping practices and range conditions may be assessed, and agricultural yields may be predicted. There is also considerable evidence that infrared imagery will permit early detection of diseased crops. All such information will become more critical as mankind attempts to increase food production so as to keep pace with population growth. With respect to forests, a satellite system is the only practicable way to mount a continuous watch over vast wooded areas so as to provide warning of insect infestations and diseased trees. Furthermore, infrared devices in orbit will be capable of sensing incipient forest fires and then providing timely information to firefighting crews. Such instruments can also delineate the boundaries of full-fledged forest fires through smoke and haze, both day and night, thereby permitting firefighters to dispatch equipment to the most appropriate places expeditiously. For continuous monitoring, of course, a satellite would need to be placed in geosynchronous orbit. Oceanography More than 70 percent of the earth's surface is covered by water, and the broad expanses of the oceans, taken together with the dynamic nature of such large bodies of water, have made it entirely impracticable to undertake continuous broad-scale surveillance by conventional methods. In point of fact, most of the world's oceans are never seen by man, while areas of special interest are checked only intermittently by ships or aircraft. Remote sensing from space appears to be the only feasible way to monitor the major oceanographic features such as sea state, distribution of sea ice, ocean surface temperatures, current patterns, and marine biology. Since the bulk of the world's international commerce is transported by ship, information on sea state and distribution of sea ice are of major importance to the shipping lines in the routing of vessels around dangerous and turbulent areas. For purposes of measuring sea state, experiments conducted in aircraft have demonstrated that radar can illuminate the ocean's surface and the reflected energy will produce different images according to the roughness and height of the waves. This is a potential 24-hour, all-weather system, for radar can penetrate clouds and storms, and is not dependent upon sunlight. Television pictures and infrared data obtained from Nimbus meteorological satellites have already been used by the shipping industry to determine the distribution of sea ice, a major hazard to navigation; icebergs are of special interest, of course. Microwave scanners may also prove useful in producing sea ice data from orbiting spacecraft. In addition, infrared sensing can be used to trace the temperature outlines of ocean currents and upwellings; and since there is a correlation between ocean temperature and the location of large schools of fish, this type of data should be valuable to the fishing industry. Surface temperature measurements help to identify the places of highest plankton concentration, the prime source of food for fish, suggesting preferred locations of the fish population. Small spotter planes have been used by the commercial fishing industry to locate fish visually for many years. In the future, remote sensing from orbit should also provide current information of considerable value to the fishing fleets both by locating fish and by determining their migration habits. Geology Modern industrial society is using up certain natural resources at an unprecedented rate. It has been reported, for example, that the United States, in the past 30 years, has used more coal and oil than the people of the entire world in all previous history; and the process is accelerating. As world population expands, and as industry continues to grow, the location and exploitation of new mineral and fuel resources will become increasingly critical. It also follows that more efficient use, management, and conservation of resources known to be limited in quantity, will be imperative. As Dr. William T. Pecora, Director, U.S. Geological Survey, has said: If our ability to find and efficiently utilize resources does not accelerate, and accelerate rapidly, the industrial civilization we now enjoy will crumble within a few decades, for the economic status of any nation is almost always a direct function of the use it makes of available natural resources. Put in another way, natural resources are the nonhuman inputs to the economy, and economic growth results in large part from new discovery and effective use of these resources. Geologists have discovered that certain relationships exist between concentrations of mineral and fuel resources on the one hand, and particular geologic features, on the other. Petroleum deposits, for example, are frequently found near structural features such as folds or faults. Many metallic mineral deposits are also found near or along faults. Aerial photographs have been used to identify such features, but pictures from orbital altitudes have proven to be superior for viewing the larger linear geologic features some of which are continental in length and rather subtly expressed. Specifically, Gemini photographs revealed certain large-scale geologic features, which, partly because they were enhanced by shadows and uniform illumination, were visible in these pictures taken from orbital altitudes, but had not been earlier detected in the relatively small-area photographs produced from aircraft. Geologic fractures and faults are even more obvious in radar images than in visual pictures, and radar penetrates clouds and haze, and can be used during nighttime. Therefore, radar may prove to be most valuable to geologists. In any case, the unique observation capabilities of satellites, particularly the synoptic view which reveals large-scale geologic features and surface patterns fully in context, would seem to assure the future use of satellites in petroleum and mineral exploration as well as for scientific investigation. In addition to viewing the earth's crustal formations, satellite observations may prove to be useful to geologists in other ways. There is evidence to the effect that some mineral deposits yield significant quantities of heat through the process of oxidation. Repetitive satellite observations of the melting patterns of snow may point to the existence of such deposits, and thereby aid in mineral prospecting. Infrared imaging will also indicate temperature differences at or near the earth's surface indicating possible sources of geothermal power and volcanic activity, both subjects of interest to geologists. Repetitive observations in the visible and infrared regions may disclose crustal movements and thermal anomalies which will provide timely data on which to base predictions of natural disasters such as earthquakes, volcanic eruptions, and landslides. Hydrology An adequate supply of fresh water is indispensable to economic progress. As everyone knows who lives in the arid States of the Southwest United States, too little water greatly inhibits agriculture and industry. Inhabitants of the world's great river basins, on the other hand, will testify that too much water in one place can be even more destructive of man's well-being and plans. The problem has to do with forecasting the supply and controlling distribution. And the problem is becoming more acute as population grows and the tendency toward urbanization continues unabated. Experiments conducted to date in aircraft indicate that water resources are susceptible to a certain degree of management using data produced by remote sensors. In the future, through repetitive observations from space in the visual, infrared, and microwave regions of the spectrum, snow and ice accumulation and melting patterns will be monitored during the various seasons of the year over areas too large to monitor by conventional means. More accurate predictions of runoff can thereby be made, and these forecasts, in turn, will provide the basis for hydrologists to regulate the impounding and release of water in reservoirs. Improving their ability to make such decisions will have measurable economic consequences. Programs such as flood control, irrigation, and power production, as well as water for urban and industrial consumption can thus be more intelligently managed. Surveillance of surface water in lakes, rivers, and ponds can also be done from space, amounts estimated more accurately, and hydrological maps, needed for conservation, can be greatly improved. More to the point, they can be made current for the first time. Infrared imaging can be used to trace fresh water discharge into salt water, and pollution discharge into fresh water, based upon discernible temperature differences. Plans for the conservation of fresh water can thus be aided, the sources and distribution of pollution can be identified and assessed, and the design of pollution abatement systems can be made more effective. In summary, hydrology is a data-dependent natural science. Current observational techniques are incapable of producing the types of information needed for effective management of water resources. Space technology promises global, synoptic, repetitive, realtime coverage of major aspects of the hydrologic cycle. HISTORY OF THE ERS PROGRAM NASA's Aircraft Program NASA's earth resources program has been largely limited to the testing of a variety of instruments in aircraft flights conducted by the Manned Spacecraft Center, Houston, Tex., over 166 different mission sites located largely in the continental United States, but including sites in Iceland, Labrador, Puerto Rico, Bermuda, the Gulf of Mexico, and the Atlantic Ocean. The data obtained are analyzed by user agencies and cooperating scientists, and the results compared with the known resources phenomena and conditions at the test site. The aircraft flight program got underway in November of 1964 utilizing a Convair 240A which had been acquired for testing of various electronic systems for the Apollo Program. A Lockheed P-3V was acquired on loan from the Navy in December 1965 and became operational early in 1967. It is presently undergoing modification, but is expected to return to full operational status in March 1969. These two aircraft have been used to acquire data from low and intermediate altitudes. An agreement has been reached with the Air Force for utilization of flight time aboard an Air Weather Service RB-57F reconnaisance aircraft for the high altitude phase of the program to begin in May 1969. The Convair 240A is soon to be phased out and replaced by a Lockheed Hercules C-130B in order to provide for greater ranges, altitudes, and payloads. Initial flights of the C-130 are scheduled for April 1969. Instruments flown to date have included mapping cameras, a multiband camera, infrared scanners, an ultraviolet scanner, a microwave radiometer, a microwave imager, and radar scatterometer. Procurement is underway for the acquisition of a package of instruments for the RB-57, and additional instruments for the P-3V and C-130 airplanes. Approximately $1 million is being expended during the current fiscal year for experiment instrumentation feasibility studies. The aircraft program has been a relatively minor activity at the Manned Spacecraft Center during the past 4 years. In fiscal year 1965, only nine missions were flown; the following year, only 12. In fiscal year 1967, this activity was approximately doubled to include 25 flights, and in fiscal year 1968 the number dropped back to 19 missions. Essentially, all the funding for this program has come from the Office of Space Science and Applications' supporting research and technology budgets. For the most part these funds have been utilized to pay for the acquisition of instruments, aircraft modifications and integration of instruments, data processing, and instrument studies. Funds expended for these purposes are summarized as follows: Fiscal year 1965....... Fiscal year 1966.. Fiscal year 1967. Fiscal year 1969 (to date). $200, 000 840, 000 2,700,000 5, 971, 000 7,995, 000 Another measure of the scope of the aircraft program at the Manned Spacecraft Center is the number of civil service and contractor personnel involved in this activity. The figures below represent approximate full-time man-years. The prime responsibility for the aircraft program rests with the Office of Space Science and Applications at NASA headquarters. The role of the Manned Spacecraft Center is essentially that of implementation and operation. In carrying out these responsibilities, the Manned Spacecraft Center has established interfaces with user agency representatives and the scientific community. Well-defined programmatic procedures have been established for mission planning and scheduling. According to officials at the Manned Spacecraft Center, the aircraft mission schedules are established by regular mission planning sessions held quarterly, at which time representatives of the various Government user agencies request the sites to be overflown and the specific instruments to be operated. The U.S. Geological Survey is responsible for the geology, geography, and hydrology disciplines. The U.S. Department of Agriculture is responsible for the agriculture and forestry disciplines, and the Naval Oceanographic Office is responsible for the oceanographic disciplines. |