tailieunhanh - Satellite Communications Part 18

Tham khảo tài liệu 'satellite communications part 18', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Satellite Motion 501 Solar Radiation Pressure The Pressure of Light In the first time when the first satellites were launched in the Earth s orbit solar radiation the pressure of light was neglected. The motions examinations of the satellite Vangard 1 indicated that there are some discrepancies. These perturbations were possible to explain by the pressure of light. The pressure of light on the Earth s surface is very tiny and really practically zero but in the orbit this effect can change position of satellite especially if the mass of satellite is small and its effective cross section is very big. So this effect could be studied better at the satellite EHO 1 which really was a weightless balloon with small mass and big cross section. The module of acceleration aa of a satellite under influence of the solar radiation pressure can be determined by the equation A . . aa Pr . 67 m where Pr - the force of light pressure on the unit of area A - the area of satellite cross section and m - the mass of satellite. It should be noted here that the satellites enter into shadow of the Earth and so the problems with the pressure of light are more complex although small. The solar radiation pressure which is reflected back from the Earth s surface causes an effect called albedo. The pressure of reflected light also affects on the satellites but this effect can be for the most number of cases practically neglected. From the perturbations of Earth s satellite motion it was determined in the paper Sehnal 1978 which parts of the Earth s surface give bigger or smaller albedo. The solar radiation pressure which is reflected to the Earth s satellite from the Moon also affects on the Earth s satellite but this effect is smaller than this of Earth s albedo. The other influences The low satellites have very big velocities something more of 7 km s but this velocities are relatively small comparing to the velocity of light 300 000 km s . Meanwhile this relativistic effect needs .

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