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GATE 2026 AE – Question 55

Flight Mechanics & Space Dynamics · Space dynamics: central force motion, Keplerian orbits, Kepler's laws and escape velocity · 2 marks · Numerical answer

An earth satellite moves in an elliptical orbit with a perigee altitude of 300 km and an apogee altitude of 3000 km. Assume that the radius of the earth is 6378 km. The eccentricity of the orbit is __________ (rounded off to three decimal places).

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Correct answer: 0.158 to 0.178

Explanation

The radii are $r_p = 6378 + 300 = 6678$ km and $r_a = 6378 + 3000 = 9378$ km. The eccentricity is $e = \frac{r_a - r_p}{r_a + r_p} = \frac{2700}{16056} = 0.168$.