Characteristic energy

From Wikipedia, the free encyclopedia

You have new messages (last change).

In astrodynamics a characteristic energy (C_3\,\!) is a measure of the energy required for an interplanetary mission that requires attaining an excess orbital velocity over an escape velocity required for additional orbital maneuvers. The unit of the characteristic energy is km2s-2.

Characteristic energy can be computed as:

C_3=v_{\infty}^2\,\!

where

v_{\infty} \, is the orbital velocity when the orbital distance tends to infinity. Note that, since the kinetic energy is one half mv2, C3 is in fact equal to twice the specific energy.

[edit] Parabolic trajectory

For a spacecraft that is leaving the central body (e.g. earth) on a parabolic trajectory:

C_3=0\,

[edit] Hyperbolic trajectory

For a spacecraft that is leaving the central body on a hyperbolic trajectory:

C_3={\mu\over{a}}\,

where:

\mu\, is standard gravitational parameter,
a\, is length of semi-major axis of orbit's hyperbola.

[edit] See also

Retrieved from "http://en.wikipedia.org../../../c/h/a/Characteristic_energy.html"