Start Date
4-1971 8:00 AM
Description
The NASA Earth Resources Technology Satellite (ERTS) program is considering the possible use of laser communications to transmit data between a satellite and earth. Such a transmission requires a relatively clear line-of-sight between the satellite and a receiving station on earth. This study considers the effect of clouds on laser transmissions from space.
To get an indication of the receiving capabilities for a selection of ground receiving stations, the authors made a preliminary evaluation of the monthly mean percentage-of-possible-sunshine statistics. With a network of six stations optimally placed, a satellite passing over the contiguous United States would generally be within range of three or more of the stations. With this choice of receiving stations the preliminary evaluation indicated a high probability of data receipt via laser communications.
To test the capability of such a network of ground stations more rigorously and to consider only the planned (morning) hours of ERTS passage, a simulated operation used 5 years of January and July data. A relationship was established between the reported opaque sky cover and the minutes of sunshine recorded in the hour in which the cloud observation was made. The simulations involved a series of hypothetical satellite crossings over the United States. For each crossing, probabilities of clear line-of-sight were calculated from the opaque sky cover observations and the relationship established between opaque sky cover and sunshine.
Probability of a Clear Line-of-Sight Through the Atmosphere for a Satellite Based Laser Communications System: A Feasibility Study
The NASA Earth Resources Technology Satellite (ERTS) program is considering the possible use of laser communications to transmit data between a satellite and earth. Such a transmission requires a relatively clear line-of-sight between the satellite and a receiving station on earth. This study considers the effect of clouds on laser transmissions from space.
To get an indication of the receiving capabilities for a selection of ground receiving stations, the authors made a preliminary evaluation of the monthly mean percentage-of-possible-sunshine statistics. With a network of six stations optimally placed, a satellite passing over the contiguous United States would generally be within range of three or more of the stations. With this choice of receiving stations the preliminary evaluation indicated a high probability of data receipt via laser communications.
To test the capability of such a network of ground stations more rigorously and to consider only the planned (morning) hours of ERTS passage, a simulated operation used 5 years of January and July data. A relationship was established between the reported opaque sky cover and the minutes of sunshine recorded in the hour in which the cloud observation was made. The simulations involved a series of hypothetical satellite crossings over the United States. For each crossing, probabilities of clear line-of-sight were calculated from the opaque sky cover observations and the relationship established between opaque sky cover and sunshine.
Comments
No other information or file available for this session.