Basic Astrodynamics: Understanding Total Energy

  • Context: Undergrad 
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SUMMARY

The discussion centers on the total energy of a satellite in different orbits, specifically addressing the relationship between kinetic and potential energy. It is established that a satellite at a higher altitude has a lower total energy due to the negative nature of potential energy, despite the common misconception that higher orbits require more energy. The participants clarify the calculations for kinetic, potential, and total energy in circular orbits as functions of radius (r), leading to a better understanding of the energy dynamics involved.

PREREQUISITES
  • Understanding of classical mechanics, specifically energy concepts
  • Familiarity with gravitational potential energy equations
  • Knowledge of kinetic energy calculations in orbital mechanics
  • Basic grasp of circular motion and orbital dynamics
NEXT STEPS
  • Study the equations for kinetic and potential energy in circular orbits
  • Explore the concept of negative potential energy in gravitational fields
  • Learn about the conservation of energy in orbital mechanics
  • Investigate the implications of altitude on satellite energy and stability
USEFUL FOR

Aerospace engineers, physics students, and anyone interested in satellite dynamics and energy calculations in astrodynamics.

BaryS
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Using the well established classical equation to determine the sum of kinetic and potential energies of a satellite at two different altitudes, the result is a lower total energy at the higher altitude. Since the speed is less and the height is greater I think I understand this result. Yet I would have thought it would take more energy to place a satellite in a higher orbit. What am I missing in this understanding?
 
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I think you've made a mistake. The total energy is in fact higher in a higher orbit. Remember that the potential energy is negative. Can you write down the kinetic, potential, and total energy for a circular orbit as a function of r?
 
You are right, I searched and found a calculation error - thanks.
 

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