Basic Astrodynamics: Understanding Total Energy

In summary, using the classical equation, the sum of kinetic and potential energies for a satellite at two different altitudes results in a lower total energy at the higher altitude due to the slower speed and greater height. However, this may seem contradictory as it would require more energy to place a satellite in a higher orbit. The clarification is that the total energy is actually higher in a higher orbit, with the potential energy being negative. By writing down the equations for a circular orbit, the error can be identified and corrected.
  • #1
BaryS
2
0
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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  • #2
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?
 
  • #3
You are right, I searched and found a calculation error - thanks.
 

Related to Basic Astrodynamics: Understanding Total Energy

1. What is total energy in astrodynamics?

Total energy in astrodynamics is the sum of the potential energy and kinetic energy of a celestial body. It is a measure of the total amount of energy that a body has in its current orbit.

2. How is total energy related to orbital mechanics?

Total energy plays a crucial role in orbital mechanics as it determines the shape and stability of an orbit. In a closed orbit, the total energy remains constant, while in an open orbit, it can change over time due to external forces.

3. What is the significance of understanding total energy in space missions?

Understanding total energy is essential in planning and executing space missions. It helps in determining the amount of energy required for different orbital maneuvers and predicting the trajectory of a spacecraft.

4. How is total energy calculated in astrodynamics?

The total energy of a celestial body can be calculated by adding the potential energy, which is determined by the gravitational pull of other bodies, to the kinetic energy, which is determined by the velocity of the body in its orbit.

5. Can total energy be changed in an orbit?

Yes, total energy can be changed in an orbit through various methods such as using propulsion systems or gravitational assists from other bodies. However, in a closed orbit, the total energy will remain constant unless there is an external force acting on the body.

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