In orbital mechanics, a Hohmann transfer describes the path taken to transit between two orbits of differing radii while traveling 180° around their common focus. Conventional analyses consider such a path to be the most efficient transfer method for traveling between circular orbits located on the same plane. Hohmann Transfer Orbit February 27, 2014 MAVEN was launched into a Hohmann Transfer Orbit with periapsis at Earth’s orbit and apoapsis at the distance of the orbit of Mars. The spacecraft will travel more than 180 degrees around the Sun in its transfer orbit, which requires 10 months to set the stage for Mars Orbit Insertion in September 2014. An average Hohmann transfer orbit to Mars requires 259 days and a delta-v of 3,9 km/s. An hyperbolic orbit depending on aerocapture for braking can reduce this to 90-150 days depending on the year of travel.
For the Hohmann transfer, we demand that: Rearranging, the required fractional change in velocity from the first impulse is So we can get the rocket to reach the height for an instant, but we need a second impulse to keep it there and circularise the orbit. Say this requires an additional change in velocity. Lecture capture from my Mars Explorations class, discussing how Kepler's laws of planetary motion can be used to determine the minimum energy.
In orbital mechanics, the Hohmann transfer orbit is an elliptical orbit used to transfer between two circular orbit of different altitudes, in the same plane.The orbitalmaneuver to perform the Hohmann transfer uses two engine impulses, one to move a space craft onto the transfer orbit and a second to move off it.This maneuver was named afterWalter Hohmann, the German scientist
Explanation:
The diagram shows a Hohmann transfer orbit to bring a spacecraft from a lower circular orbit into a higher one. It is one half of an elliptic orbit that touches both the lower circular orbit that one wishes to leave (labeled 1 on diagram) and the higher circular orbit that one wishes to reach (3 on diagram). The transfer (2 on diagram) is initiated by firing the spacecraft’s engine in order to accelerate it so that it will follow the elliptical orbit; this adds energy to the spacecraft’s orbit. When the spacecraft has reached its destination orbit, its orbital speed (and hence its orbital energy) must be increased again in order to change the elliptic orbit to the larger circular one.
Due to the reversibility orbits, Hohmann transfer orbits also work to bring a spacecraft from a higher orbit into a lower one; in this case, the spacecraft’s engine is fired in the opposite direction to its current path, slowing the spacecraft and causing it to drop into the lower-energy elliptical transfer orbit. The engine is then fired again at the lower distance to slow the spacecraft into the lower circular orbit.
The Hohmann transfer orbit is based on two instantaneous velocity changes. Extra fuel is required to compensate for the fact that the bursts take time; this is minimized by using high thrust engines to minimize the duration of the bursts. Low thrust engines can perform an approximation of a Hohmann transfer orbit, by creating a gradual enlargement of the initial circular orbit through carefully timed engine firings. This requires a change in velocity (delta-v) that is up to 141% greater than the two impulse transfer orbit (see also below), and takes longer to complete.
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Hohmann Transfer Problem
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