Energy, Non-coplanar solar system orbits for space ships

In summary, the conversation discusses two possible trajectories for a spaceship traveling from one planet to another in the solar system. Trajectory 1 remains in the xy plane, while trajectory 2 leaves the solar plane and returns to it later. The question at hand is whether there is any difference in energy required for the two trajectories. According to Newton's Law of Potential Energy for Gravity, the only factor that matters is the radius, not the angle of the trajectory. However, the angular momentum of the main body providing the gravity may play a role. The conversation also mentions the use of gravity assists and the Oberth Effect in space travel.
  • #1
Albertgauss
Gold Member
290
37
Hi all,

As many of you have seen, I am thinking about spaceship trajectories. This next question falls under the same subject, but it is an entirely different question from the previous questions I have asked.

Spaceships of the near future will fly in the plane of the solar system. Suppose if all the planets orbit the sun, they do it in the xy plane. The sun spins about its axis such that the sun's spin angular momentum vector points along the positive z-axis. Let's assume planet A is on one side of the sun, and planet B is on the other. I want to send a spaceship from planet A to planet B. I could do this two ways:

1) I could send the ship so that it remains co-planar with the solar system. Trajectory 1 remains in the xy plane also. If Trajectory 1 were to trace out a circle, the normal vector of this area would point along +/- z_axis. This is how ships of today would go.

2) Trajectory 2, the ship flies in an orbit where it still goes around the sun, but leaves the solar plane alltogether. Its orbit/trajectory is in the xz plane. At some point in this orbit, when the ship looks down many AU, it will see the sun's north pole. It will return to the solar plane when planet B is at the right place. If this trajectory were to be a circle, the normal vector to this circle would be +/- y_axis.

Ignoring, for the moment, the obvious advantages of Earth's tangential pick-up velocity, gravity assists, and Oberth Effects as obvious advantages to choosing the ship's co-planer trajectory #1, does trajectory 2 cost anymore energy than trajectory 1? Is there any difference in any energy for a spaceship that remains co-planar with the solar system, and for a spaceship that exits the solar plane and returns to it later?

Most basic, according to Newton's Law of Potential Energy for Gravity, only the radius matters, (-Gm1m2/r) but not the θ or ∅. HOwever, I know that if the sun spins in the xy plane, all orbits of planets and spaceships most naturally will settle in the xy plane after some time. This is also the same reason that accretion disks around stars and black holes are found in the xy plane of these objects, but not ever in the z-direction. That means, the minimum energy for such a system is to have everything travel in the xy plane. Thus, for anything to travel to in the xz plane, more energy would be required than to travel in the xy plane, but I can't see how, from Newton's Law of Potential Energy for gravity.

I guess the basic question is this:

Is there any difference in any energy for a spaceship that remains co-planar with the solar system, and for a spaceship that exits the solar plane and returns to it later?

Gravity says "NO", but I think angular momentum of the main body providing the gravity says "Yes", but I don't know how.
 
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  • #2
The two orbits would have similar ΔE, but vastly different Δv. Even future spaceships cannot neglect momentum.
 
  • #3
You can go from an orbit around earth, to an orbit around Venus with less than 7 km/s delta-v

http://www.projectrho.com/public_html/rocket/appmissiontable.php#id--Erik_Max_Francis%27_Mission_Tables--Delta_V_Required_for_Travel_Using_Hohmann_Orbits--Solar_System

If you wanted to go in an orbit across northpole of the sun, you'd have to cancel the 30 km/s orbital speed of the Earth and build up about 20 km/s orbital speed in a perpendicular direction, so you need about 36 km/s near the earth, and even more the match velocities with Venus, whose orbital speed is even higher.

The best way to get in such an orbit would be a gravity assist from Jupiter, as done by the Ulysses spacecraft which went to Jupiter to get in a polar orbit around the sun.
 

1. What is a non-coplanar solar system orbit?

A non-coplanar solar system orbit refers to a trajectory in which the orbiting object does not lie within the same plane as the majority of the other objects in the solar system. This type of orbit allows for greater flexibility and maneuverability for space ships, as they are not confined to a specific plane and can travel to different parts of the solar system more easily.

2. What is the advantage of using a non-coplanar orbit for space ships?

The advantage of using a non-coplanar orbit for space ships is that it allows for more efficient use of energy. By taking advantage of gravitational assists from other planets, space ships can conserve fuel and travel longer distances without needing to refuel. This can also reduce the overall cost of space missions.

3. How do space ships achieve a non-coplanar orbit?

Space ships can achieve a non-coplanar orbit through a process called a gravity assist. This involves using the gravitational pull of a planet to alter the spacecraft's trajectory and change its orbital plane. By carefully planning and executing multiple gravity assists, space ships can ultimately achieve a non-coplanar orbit.

4. Are there any risks associated with using non-coplanar orbits for space ships?

While there are some risks associated with using non-coplanar orbits, they are generally considered to be minimal. One potential risk is the possibility of collisions with other objects in space, as the orbiting object is not confined to a specific plane. However, with careful planning and monitoring, these risks can be minimized.

5. Can all types of space ships utilize non-coplanar orbits?

Not all types of space ships are capable of utilizing non-coplanar orbits. It requires a certain level of technology and precision in order to successfully execute a gravity assist and achieve a non-coplanar orbit. However, as technology continues to advance, it is becoming more feasible for a wider range of space ships to utilize these orbits.

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