# Characteristic energy

Characteristic energy

In astrodynamics a characteristic energy ($C_3\,\!$), a form of specific energy, 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 magnitude of the specific orbital energy ($\epsilon$) of the escaping object.

## Parabolic trajectory

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

$C_3=0\,$

## 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.

## References

Wikimedia Foundation. 2010.

### Look at other dictionaries:

• Characteristic energy length scale — The characteristic energy length scale χ describes the size of the region from which energy flows to a rapidly moving crack. If material properties change within the characteristic energy length scale, local wave speeds can dominate crack… …   Wikipedia

• Energy-dispersive X-ray spectroscopy — (EDS, EDX or EDXRF) is an analytical technique used for the elemental analysis or chemical characterization of a sample. As a type of spectroscopy, it relies on the investigation of a sample through interactions between electromagnetic radiation… …   Wikipedia

• Energy filtered transmission electron microscopy — (EFTEM) is a technique used in Transmission electron microscopy, in which only electrons of particular kinetic energies are used to form the image or diffraction pattern. The technique can be used to aid chemical analysis of the sample in… …   Wikipedia

• Characteristic mode analysis — is a method used in electromagnetics to solve for currents and fields generated by a scattering object. The object can be any size or material. When an electromagnetic wave is scattered by an object, currents are induced on said object, which… …   Wikipedia

• Characteristic x-ray — A high energy electron interacts with a bound electron in an atom and ejects it. The incident electron is scattered and the target electron gets displaced from its shell. The incident electron energy must exceed the binding energy of the electron …   Wikipedia

• Characteristic state function — The characteristic state function in statistical mechanics refers to a particular relationship between the partition function of an ensemble. In particular, if the partition function P satisfies P = exp( − βQ) or P = exp( + βQ) in which Q is a… …   Wikipedia

• Energy (signal processing) — In signal processing, the energy E s of a continuous time signal x ( t ) is defined as:E {s} = langle x(t), x(t) angle = int { infty}^{infty}{|x(t)|^2}dtenergy in this context is not, strictly speaking, the same as the conventional notion of… …   Wikipedia

• Characteristic polynomial — This article is about the characteristic polynomial of a matrix. For the characteristic polynomial of a matroid, see Matroid. For that of a graded poset, see Graded poset. In linear algebra, one associates a polynomial to every square matrix: its …   Wikipedia

• energy — /en euhr jee/, n., pl. energies. 1. the capacity for vigorous activity; available power: I eat chocolate to get quick energy. 2. an adequate or abundant amount of such power: I seem to have no energy these days. 3. Often, energies. a feeling of… …   Universalium

• Energy Systems Language — The Energy Systems Language (right), also referred to as Energese , Energy Circuit Language and Generic Systems Symbols , was developed by the ecologist Howard T. Odum and colleagues in the 1950s during studies of Tropical Forests funded by the… …   Wikipedia