Satellite Pass for Earth Stn – Prediction of Ground Trace Coordinates & more.
by R C Chakraborty, July 17, 2015, Pages 268 – 390.
(This is Sec. 7, pp 268 – 390, of Orbital Mechanics – Model & Simulation Software (OM-MSS), Sec. 1 to 10, pp 1 – 402.)
Satellites, look like slow-moving Stars, are most visible when they are in Sunlight while the viewer is in darkness.
A typical Satellite in low Earth orbit (LEO) circles the Earth about 16 times each day.
The Orbital Velocity of a LEO satellite is about 7500 meters/sec.
The Orbital Velocity of a Geo-stationary satellite is about 3007 meters/sec.
The Moon, the only natural satellite of earth has orbital velocity about 1003 meters/sec.
Satellite Pass for Earth Stn, is Computed for following six satellites : LANDSAT 8, SPOT 6, CARTOSAT-2B, ISS (ZARYA), GSAT-14, and MOON.
The ‘Satellites Pass’ goes through a Time_Step of 2 minutes (120 sec). For Moon the Time_Step is of 1 hr (3600 sec).
The input is respective Satellite’s NASA/NORAD ‘Two-Line Elements’ (TLE).
The Output is Predictions of instantaneous Ground trace Coordinates, look angles & more at each Time_Step on computer screen in a Table form where
respective columns indicate :
Col 1 – Orbit no, Col 2 – Node Ascending or Descending, Col 3 to 6 – Input time GMT D H M S,
Col 7 – True Anomaly, Col 8 – Sat Height from earth surface, Col 9 – Sat at Perigee, Equator, or Apogee,
Col 10 – Sat Velocity, Col 11 , 12 – Latitude & Longitude at sub-satellite point on earth surface,
Col 13 – Sat Slant Range from earth stn, Col 14 – Distance of sub-satellite point from earth stn,
Col 15 , 16 – Sat Pitch & Roll angles, Col 17 , 18 – Sat Elevation & Azimuth angles at earth stn,
Col 19 – Access to Sat through On Board Computer or Direct Line Of Sight based on elevation angle at ES,
Col 20 , 21 – Sun Elevation & Azimuth angles at sub-Satellite point on earth surface,
Col 22 – Data Acquisition using Visible Band Camera or Night Vision Devices as per illumination over observed surface,
Col 23 to 26 – Local Mean Time at earth stn, Col 27, 28 – Sun Elevation & Azimuth angles at earth stn,
Col 29 – Distance of Sub-Sun point on earth surface from earth stn,
Col 30 – Line number .
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