The Skylab Earth Resources Experiment Package is an integral part of the NASA Earth Resources Survey program which was developed in collaboration with the Departments of Agriculture, Interior, Commerce and Navy, the National Academy of Sciences-National Research Council, several universities and many segments of the aerospace industry. The purpose of this effort is to use our space capabilities to gain knowledge applicable to some of man's most pressing resource and environmental problems, such as weather, crop deterioration, pollution of air and water, flooding, erosion, and the depletion of mineral resources. Space platforms allow scientists to observe and analyze entire regional systems, such as mountain ranges, river basins, and belts of crop production, opening the way to new understanding of man's interaction with his environment. More specifically, the program will develop the means for comprehensive and timely collection of earth resources data and its rapid dissemination and interpretation. Other elements of the Earth Resources Survey program are the unmanned Earth Resources Technology Satellite, a flight program for sensor and technique de elopment using research aircraft, and a comprehensive program of ground research. Man's unique capabilities to observe a large scene and to discern unusual features cannot be duplicated in current automated systems. However, it is recognized that when operations reach the stage of regular, systematic data acquisition, they can be efficiently accomplished with automated systems. Direct on-board control by the crew in selective data acquisition, the operation of microwave sensors whose physical characteristics and scan requirements are not compatible with the Earth Resources Technology Satellite, and the broader spectral coverage of the Skylab sensors are unique contributions that Skylab will make in the Earth Resources Survey Program, ML 70-6216A. This will be the only near term opportunity for this country to gain the practical experience with manned operations that is essential to sound, factually-based recommendations and decisions on both operational and developmental flight systems of the future. The Skylab Earth Resources Experiment Package ML 70-7504, includes five sensors, a control and display console, recording equipment, and a viewfinder and tracking system which is boresighted with a spectrometer instrument. These systems, summarized in Table 3 (ML 71-5110), are installed in the Multiple Docking Adapter and on adjacent structure. The Multispectral Camera Facility ML 71-5205, contains an array of six high precision 70mm cameras with precisely matched lenses. The facility has been designed to provide precision multispectral photography in the visible and nearinfrared portions of the spectrum for a wide range of studies. Three of the six band have been chosen to correspond to bands selected for the Earth Resources Technology Satellite. The Multispectral camera has evolved from the photographic experiments conducted during Apollo missions. The spatial resolution and spectral coverage, however, will be a considerable improvement over early space photography obtained in space. The crew will install special filters for evaluating the effectiveness of different film/filter combinations and will be able to service the cameras. The Infrared Spectrometer ML 71-5204, will be used to evaluate the utility of specific regions of the infrared spectrum to Earth resources investigations and to determine quantitive effects of atmospheric attenuation on radiation from ground sites. This instrument is a cryogenically cooled filter wheel spectrometer capable of accurate continuous measurements in the visible, near infrared and thermal infrared regions, allowing observation of thermal characteristics of ground areas for analysis similar to the use of infrared scanning in medical diagnosis. Using a tracking viewfinder the crew will locate and manually point the spectrometer to examine small sites approximately 1,300 feet in diameter: typically agricultural areas, geological features, and population centers. Simultaneously with the orbital observations similar data are to be recorded with an indentical sensor aboard high altitude aircraft and instrumentation at the ground site. By comparing the results, investigators will be able to assess effectiveness and requirements regarding infrared sensor capability, sensitivity, and spectral resolution. The Multispectral Scanner ML 71-5203, is designed to measure characteristic radiation simultaneously in thirteen spectral bands covering visible through thermal infrared for evaluation of the usefulness of multispectral observations in crop identification, vegetation mapping, land use determinations, soil moisture measurements, surface temperature mapping, and identification of contaminated areas in large bodies of water. The scanner uses a 24-inch primary mirror and a new image plane scanning technique, providing an instantaneous ground resolution of 260 feet square. The results will be used to evaluate the feasibility of automatic data processing techniques for identification of earth resources features and to compare imagery from several spectral bands with the photography obtained with the multispectral camera. The wider spectral coverage of the Skylab scanner will be used to obtain data for correlative studies with repetitive, four band Earth Resources Technology Satellite multispectral data. The Microwave Radiometer/Scatterometer and Altimeter ML 70-7110, and the L-Band Radiometer, ML 71-5202, are new systems not previously flown in space. Theoretical studies and aircraft flight experience indicate that these sensors should be of particular value to oceanography and hydrology. However, their requirements for large antennas and high power are beyond the capacity of the current generation of automated satellites. The Skylab sensors will permit evaluation of the usefulness of microwave measurements from orbit. The experiment is designed to support studies of varying ocean surfaces, wave conditions, sea and lake ice, ocean clouds, snow cover, seasonal vegetational changes, flooding, rainfall, soil types and textures, soil moisture averages, heat output of metropolitan areas, and the design of future microwave measurement systems. The common antenna is a 44-inch parabolic reflector capable of scanning over a wide range of angles, either along the flight path or from side to side. From orbit the equipment will observe an eight by eight nautical mile area. The L-Band radiometer will provide data on the brightness temperature of the Earth's surface to a high degree of accuracy. Since this temperature varies significantly with soil moisture, the radiometer will provide useful information on soil moisture content and rainfall measurements in remote areas. The Skylab Earth Resources Experiment Package, along with the other elements of the Earth Resources Survey Program will be operated as a research facility whose data will be made available to a wide range of U. S. and international investigators. |