The upper portion shows the ground track for PANSAT (red line) for two consecutive orbits (thus, two lines). The two (yellow) lines which are nearly vertical, shown on the right side of the ground track portion, show the day/night threshold, including penumbra and umbra.
The lower figure shows a view of the satellite with the perspective fixed such that the viewer is in the line passing through the satellite and the sun. The moon is shown as a black disk which covers the sun. Shortly before the satellite passes behind the Earth, the solar flux increases resulting in a rise in the solar panel output.
It is interesting to note that as the sun sets over India, PANSAT (flying 345 miles above the Earth) is still in sunlight.
The final plot shown is the solar panel currents during this time. There is a noticeable dip in the currents prior to the satellite entering the Earth's shadow.
Download the orbit view animation in a Quicktime movie format (480 x 360, 10.3 megabytes).
Here's a plot of the solar panel currents (GIF image, 85 kbytes).
Here's a plot of the solar panel currents (JPG image, 375 kbytes).
This page last updated: 13 August 1999.