Type Alias: PeriApoRadiiType

type PeriApoRadiiType = {
  ra: number | null;
  rp: number;
};

Peri/apoapsis radii pair.

Definitions

r_{p} = a (1 - e), r_{a} = a (1 + e)

Conic validity

Elliptic / circular (( $a > 0, 0 \leq e < 1$ )): both ( $r_{p} > 0$ ) and ( $r_{a} > 0$ ).
Hyperbolic (( $a < 0, e > 1$ )): ( $r_{p} = | a | (e - 1) > 0$ ) and no apoapsis (unbounded), so set ra = null.
Parabolic (( $e = 1$ )) with finite ( $a$ ) is not represented; use parabolic relations or state vectors.

Units

Examples

// Elliptic example
const radii: PeriApoRadiiType = { rp: 6930e3, ra: 7070e3 };

// Hyperbolic example - no apoapsis
const flyby: PeriApoRadiiType = { rp: 10_000e3, ra: null };

ra: number | null;

Apoapsis radius ( $r_{a}$ ) (m) for closed orbits; null for hyperbolic trajectories.

rp: number;

Periapsis radius ( $r_{p}$ ) (m).