Documentation / @interstellar-tools/equations / characteristicEnergyC3

Function: characteristicEnergyC3()

function characteristicEnergyC3(vInfinity: number): number;

Defined in: orbits/characteristic-energy-c3.ts:31

Compute characteristic energy (C3) from hyperbolic excess speed.

Characteristic energy is defined as the square of the hyperbolic excess velocity:

$$C_3=v_{\mathrm{\infty }}^2$$

• If vInfinity is in km/s, C3 is in (km/s)².
• If vInfinity is in m/s, C3 is in (m/s)².

Common usage: preliminary interplanetary mission design and launch performance comparisons (e.g., "available C3" from a launch vehicle).

Parameters

Parameter	Type	Description
vInfinity	number	Hyperbolic excess speed $v_{\mathrm{\infty }}$ (must be a finite number).

Returns

number

Characteristic energy $C_3$ in squared speed units (e.g., (km/s)² or (m/s)²).

Throws

If vInfinity is not a finite number.

Example

// v∞ in km/s
const vInf = 3.2;
const c3 = characteristicEnergyC3(vInf);
// c3 === 10.24  // (km/s)²

See

https://en.wikipedia.org/wiki/Characteristic_energy