Editing Orbital mechanics (section)

===Parabolic orbits===
If the eccentricity equals 1, then the orbit equation becomes:
:<math>r={{h^2}\over{\mu}}{{1}\over{1+\cos\theta}}</math>
where:
*<math>r\,</math> is the radial distance of the orbiting body from the mass center of the [[central body]],
*<math>h\,</math> is [[specific angular momentum]] of the [[orbiting body]],
*<math>\theta\,</math> is the [[true anomaly]] of the orbiting body,
*<math>\mu\,</math> is the [[standard gravitational parameter]].

As the true anomaly θ approaches 180°, the denominator approaches zero, so that ''r'' tends towards infinity. Hence, the energy of the trajectory for which ''e''=1 is zero, and is given by:
:<math>\epsilon={v^2\over2}-{\mu\over{r}}=0</math>
where:
*<math>v\,</math> is the speed of the orbiting body.

In other words, the speed anywhere on a parabolic path is:
:<math>v=\sqrt{2\mu\over{r}}</math>