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0

Yes, based upon what was done for the last time Halley's comet came by. https://en.wikipedia.org/wiki/Suisei_(spacecraft) Fifteen burns of Suisei's 3 N motors during the period of April 5–10, 1987, yielded a 65 m/s velocity increase for a 60,000 km Earth gravity assist swingby on August 20, 1992, helped it establish a Heliocentric orbit around the sun. ...


3

As everyone else has mentioned, there doesn't seem to be a mission for a true parabolic escape, especially since an exact parabolic trajectory is a target of zero size and therefore there is a zero chance of hitting it exactly. Also, a true parabolic orbit only makes sense in a two-body model. Once you consider the gravity of anything else, the orbit ...


0

Satellites put into geostationary orbit tend to use zero excess velocity trajectories to conserve more fuel for later positioning/adjustment


4

I can't think of one. For mission planning there is nothing special about parabolic velocity. There is something special from the perspective of teaching orbital mechanics as it is the boundary between closed and open orbits, but from a practical mission point of view it looks just like a very long ellipse or a barely open hyperbola for many, many years. ...


5

Parabolic escape trajectory is only theoretical, it only "works" in a two body system, and in a two body system "escape" is a meaningless practice anyways. In a multi body system the forces from other bodies, especially around the edge of the gravity well, make parabolic escape impossible: before you'd have zero velocity the other body would've already ...


12

Why would one want to choose zero excess velocity upon escape? If you aren't in a great hurry, and you have a small delta-V budget, and you want to visit the Trojan points L4 or L5, you can do so by getting just outside of Earth's sphere of influence, then lowering or raising your solar orbit very slightly to get ahead of or fall behind Earth. You wouldn't ...


19

Why zero excess velocity? Well, with almost zero excess velocity you can stay near Earth, but not too near. For example, the Spitzer space telescope did this to communicate with Earth while avoiding radiant heat from Earth. It's been drifting away, but slowly enough that other factors first reduced its effectiveness.


2

I think your problem is just a matter of terminology. Almost all of the orbits you hear about are elliptical. Some are almost exactly circular, but that counts as a special case of elliptical. Orbits like that keep going round and round, and stay within a certain distance of the primary. You might have the impression that's part of the meaning of "orbit". ...


4

This relates to the concept of escape velocity, which is the speed needed to escape an object's gravity well. Even though gravity has an infinite reach, the fact that its force reduces quadratically with distance means that it only takes a finite amount of energy to climb out of a planet's gravity well. For some fixed energy cost, you can get arbitrarily far ...


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