Earth satellites are objects which revolve around the earth. Their orbits will be circular or elliptical. The total energy of a circularly orbiting satellite is negative, with the P.E being negative but twice the magnitude of the positive energy. When the orbit of a satellite becomes elliptic both PE and KE vary point to point. The total energy remains constant and is negative. If the total energy is positive or zero , the objects escape to infinity. Satellites are always at finite distance from the earth and hence their energies cannot be positive or zero. Satellites in circular orbits around the earth in the equatorial plane with time period 24hrs are called geostationary satellites. Satellites which go round the poles of the earth in a north south direction are called polar satellites.
1. What is the total energy of elliptical orbiting satellites?
2. What happens if the energy of a satellite is positive ?
3. What are polar satellites ?
Answers
1) Like the case of circular motion, the total amount of mechanical energy of a satellite in elliptical motion also remains constant. Since the only force doing work upon the satellite is an internal (conservative) force, the Wext term is zero and mechanical energy is conserved.
2) The total energy of an circularly orbiting satellite is thus negative, with the potential energy being negative but twice is magnitude of the positive kinetic energy. ... Satellites are always at finite distance from the earth and hence their energies cannot bepositive or zero.
3) The Global Geospace Science Polar satellite was a NASA science spacecraft designed to study the polar magnetosphere and aurorae. It was launched into orbit in February 1996, and continued operations until the program was terminated in April 2008. The spacecraft remains in orbit, though it is now inactive.
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