Pseudo-orbit Classifications
- Horseshoe orbit: An orbit that appears to a ground observer to be orbiting a certain planet but is actually in co-orbit with the planet. See asteroids 3753 Cruithne and 2002 AA.
- Exo-orbit: A maneuver where a spacecraft achieves an orbit that is unstable due to atmospheric drag.
- Lunar transfer orbit (LTO)
- Prograde orbit: An orbit with an inclination of less than 90°. Or rather, an orbit that is in the same direction as the rotation of the primary.
- Retrograde orbit: An orbit with an inclination of more than 90°. Or rather, an orbit counter to the direction of rotation of the planet. Apart from those in Sun-synchronous orbit, few satellites are launched into retrograde orbit because the quantity of fuel required to launch them is much greater than for a prograde orbit. This is because when the rocket starts out on the ground, it already has an eastward component of velocity equal to the rotational velocity of the planet at its launch latitude. A gravity assist around the moon can reduce the fuel premium. Retrograde orbits might be used as part of anti-satellite warfare.
- Mars transfer orbit (MTO)
- Halo orbits and Lissajous orbits: These are orbits around a Lagrangian point. Lagrange points are shown in the diagram on the right, and orbits near these points allow a spacecraft to stay in constant relative position with very little use of fuel. Orbits around the L1 point are used by spacecraft that want a constant view of the Sun, such as the Solar and Heliospheric Observatory. Orbits around L2 are used by missions that always want both the Earth and Sun behind them. This enables a single shield to block radiation from both the Earth and Sun, allowing passive cooling of sensitive instruments. Examples include the Wilkinson Microwave Anisotropy Probe and the James Webb Space Telescope. L1, L2, and L3 are unstable orbits, meaning that small perturbations will cause the orbiting craft to drift out of the orbit without periodic corrections.
Read more about this topic: List Of Orbits