Specific orbital energy

In the gravitational two-body problem, the specific orbital energy ϵ {displaystyle epsilon ,!} (or vis-viva energy) of two orbiting bodies is the constant sum of their mutual potential energy ( ϵ p {displaystyle epsilon _{p},!} ) and their total kinetic energy ( ϵ k {displaystyle epsilon _{k},!} ), divided by the reduced mass. According to the orbital energy conservation equation (also referred to as vis-viva equation), it does not vary with time: In the gravitational two-body problem, the specific orbital energy ϵ {displaystyle epsilon ,!} (or vis-viva energy) of two orbiting bodies is the constant sum of their mutual potential energy ( ϵ p {displaystyle epsilon _{p},!} ) and their total kinetic energy ( ϵ k {displaystyle epsilon _{k},!} ), divided by the reduced mass. According to the orbital energy conservation equation (also referred to as vis-viva equation), it does not vary with time: