Can two objects solar powered, equal in weight, traveling on the same orbital path in the opposite directions propel each other to intersect on the opposite side of the Earth in alignment to propel again gaining altitude in orbit?

Compared to most normal artificial satellites would propellant used adjust altitude or coarse from orbital perturbation could be negated by alternating magnetic fields OMA?

Does an orbit exist in which orbital perturbation effects both parts in favor alignment?

I understand that in a lower orbit, when you increase speed you gain altitude - and to maintain a higher orbit you must then decrease the speed less than what the lower orbit speed was.

Can the velocity be increased, then decreased on the first pass or by 2 rings one that pushes and the other pulls while inside the OMA would the passenger it would feel a quick-lifting jerk?

Alternative or in conjunction: After the acceleration on the 1st pass the object and OMA then meet on the opposite side of the Earth on the 2nd pass to decelerate to reestablish orbit at a higher altitude?

Could they at the least maintain orbit?

Would there be any practical use of this device like kicking other nonfunctional satellites out of orbit?

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Starting low around the Earth, the device orbits in one direction and the ship in the opposite direction. As they are equal in weight, they would propel each other and then slow on the opposite side of the Earth off each other to gain altitude and maintain orbit.

Once it has the maximum speed that a ship can stay in orbit the ship would break orbit and possibly pass through another much heavier device orbiting the moon to laterally propel the ship. Then Mars and its moons can be used to come back and forth for a less propellant way of travel?

Magnetic decelerator

This is not a particle or magnetic accelerator but a gif (picture) of a Earth magnet passing through a copper tube that shows that you could also have a magnetic decelerator be in orbit of a planet and use it to slow incoming ships before re entry.


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    $\begingroup$ SE bans are usually temporary cooling off periods so you most likely already have access back. If your account is somehow broken then you should contact the community support team and ask them to look into it. $\endgroup$ – Tim B Feb 15 '18 at 17:30
  • $\begingroup$ The problem with your scheme is that you are not getting symmetry. They are already in orbit, and have a velocity around the Earth, let's call that v. If they are pushing away from each other at say 100 meters per second, the ship now has an orbital speed of v + 100, while the mass has a speed of v - 100. This makes their orbits different, not symmetric. $\endgroup$ – MichaelK Feb 23 '18 at 6:37
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    $\begingroup$ Wait, now I see what you mean... they orbit in opposite directions. Ok, that makes more sense. Well good luck to you... you now have a 16 000 meters per second rendezvous to try to aim perfectly right. Do not screw up... or things go bad to quick you will not even have time to say "Oh s...". youtu.be/ywZQqIl7pg8?t=45s $\endgroup$ – MichaelK Feb 23 '18 at 7:40

Every time you add velocity to an object its orbit will grow more elliptical, So the accelerator would have to constantly be adjusting its orbit to intercept the vessel it is accelerating. This maneuvering would require more delta-V than it would take to just accelerate the craft traditionally (if such maneuvers were even possible at all.) You would need a series of accelerators each placed very very carefully on intercepting courses for a series of increasingly elliptical orbits until the vessel hit escape velocity at around 7.1 kilometers per second. Even making this possible, its till incredibly wasteful and inefficient compared to simpler methods

Escape velocity is achieved much more easily with far less resources and delta-V expenditure using a gravity assist to slingshot around the moon or some other planetary body. A link describing gravity assists:


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  • $\begingroup$ Since the accelerator is said to have equal mass to the projectile and in a matching retrograde orbit, after accelerating they could still be in matching orbits. They will also not necessarily be in more elliptical orbits. That is true if the acceleration happens at perigee, but they will be more circular if it happens at apogee. $\endgroup$ – Lex Feb 14 '18 at 6:42
  • $\begingroup$ @TCAT117 it could be just used to increase and decrease altitude. Mars was a little over the top. Just around the Earth ? $\endgroup$ – Muze Feb 15 '18 at 21:11
  • $\begingroup$ Its physically possible but fiscally detrimental. Adding some extra fuel to your space ship is an order of magnitude less expensive than placing an electromagnetic accelerator that big into orbit. Also, a magnetic accelerator that large is going to wreak havoc on electrical systems. Your basically discharging an EMP directly into the vessel each time. I can think of one scenario in which it makes sense though. A large volume of traffic consisting of simplistic unmanned cargo pods thats you accelerate at unsurvivable rates for manned missions to fire them off into the solar system. $\endgroup$ – TCAT117 Feb 15 '18 at 21:49
  • $\begingroup$ Who said it had to be big to start with. Maybe it can be used just to maintain orbit and used along with gravity assist. Maybe all it can do is go from low L1 orbit to high L2 orbit. $\endgroup$ – Muze Feb 20 '18 at 17:52
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    $\begingroup$ To make it economically feasible youd need a high volume of traffic. Maybe if cargo and personel were being shipped off somewhere in droves it could justify the expense. If you were bumping a few hundred objects a month into higher orbits for years at a time it would only save a tiny bit of fuel per launch but over a long enough lifespan it could pay for itself. $\endgroup$ – TCAT117 Feb 21 '18 at 5:22

It can be done with a couple of important provisions:

1) A simple mass driver will not suffice as your payload will increasingly be pushed to the outside as it's boosted. You need to add what amounts to a maglev train to it to keep your spacecraft in orbit until you're ready to release it. Note that this means the whole system must be solid and that causes stability problems. (A solid ring will not remain in orbit without correction.)

2) When you fire this you're going to mess with the orbit of the ring. That's a bad thing. The solution to this is to equip your ring with two mass drivers, not one. You put your spacecraft in the ring and also three dummy payloads of the same mass. One starts beside your spacecraft in the other ring, pointed the other way. The other two are positioned likewise but 180 degrees away. All are boosted at the same rate and released at the same instant. The ring will be subject to 4 pushes at the same time which will almost perfectly cancel each other. Unless you can somehow build the two rings inside each other (how do you eject the stuff from the inner ring???) you get a slight twist imparted to the ring but otherwise it doesn't go anywhere. That can be countered the next time you fire by switching which ring goes forward and which goes backwards.

Note that all the engineering headaches mean this is probably not something you would ever want to build as there's a simpler approach:

Build your ring on the moon. You need two maglev support systems but you avoid all the other engineering headaches I mentioned above. If you will accept 5g during boost (unpleasant but tolerable) this gives you an ejection velocity that will take you anywhere from somewhat inside Mercury's orbit to a bit over solar escape velocity.

Putting the ring around Earth increases the maximum velocity but of how much use is that? Unless there's a catcher ring around the destination world you have no way to safely arrive.

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  • $\begingroup$ @Muze We have maglev trains now. There's no contact, why should speed matter? $\endgroup$ – Loren Pechtel Feb 13 '18 at 5:00
  • $\begingroup$ You arrive by aerobraking at your destination - assuming it has an atmosphere, of course. As with Mars orbiters/landers. $\endgroup$ – jamesqf Feb 13 '18 at 18:42
  • $\begingroup$ @jamesqf No. If you're coming in faster than you can get from 5G going around the moon the aerobrake will be fatal on any world in our system. $\endgroup$ – Loren Pechtel Feb 13 '18 at 21:47
  • $\begingroup$ @Loren Pechtel: Why fatal? Obviously, if your arrival speed is too high, there won't be sufficient braking to slow you enough to achieve orbit, but as long as your vehicle has adequate heat shielding, aerobraking should not present any problems that I can see. $\endgroup$ – jamesqf Feb 14 '18 at 20:12
  • $\begingroup$ @jamesqf I'm not saying you would fry--that's a matter of how good your heat shield is. I'm saying you would be squashed. You simply don't have enough distance to shed your speed. $\endgroup$ – Loren Pechtel Feb 15 '18 at 2:49

Probably Not.

The other answers have focused on the geometrical issues with this scheme, as well as its efficiency when compared to using traditional propellants.

What everyone seems to assume is that the magnetic field of the mass driver would remain constant with each passing. It would not. The magnetic field would lose more energy than the kinectic energy gained by the vessel-driver system - otherwise you would be in violation of the 2nd law of thermodynamics.

In order to make up for that energy loss, you would either have to resort to chemical or nuclear reactions, with which you would be hard pressed to find something more efficient than using rockets anyway, and would only take you so far depending on how much fuel you have, or you would need to use solar energy. The ISS has 2,500 square meters of solar panels and is able to generate up to... 120 kilowatts. That is about 160 HP. That is a huge killjoy when you compare to the Soyuz launcher, which gives you an output of around 26,000,000 HP. To match the power of a Soyuz launcher with solar, you would need 406,250,000 square meters of panels. That is almost the area of San Jose, California's third largest city. You can get more energy per area from solar if you get closer to the sun, but if you go to orbits higher than that of Earth's you will require even more panel surface.

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  • $\begingroup$ It could be artificially triggered like a rail gun. That is 120 kilowatts per hour. That can be stored energy and released in less then a second on each pass. On acceleration they would pass each other 2 times or more per orbit around the Earth. Low orbit is 92 minutes so about 90 kw stored per pass. Highest orbit it would produce. High orbit 23 hours times 120 kilowatts equals 2,760 kw can be released in one hour and compress that in a second it should be around 10,000,000 kw per second. As non practical it may be will it work? Plus 1 for the information. $\endgroup$ – Muze Feb 15 '18 at 21:00
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    $\begingroup$ @Muze I suppose you are calculating that power with the solar panels of the ISS. Indeed, you can store energy for each pass. A back of the napkin calculation provides us with 9,936,000 kWH for 23 hours of collection. If you release all of that in one second, you get a power equivalent to approximately 36,800,000,000 kW, for one second. That is 49,066,666,666.666 HP, or almost 2 billion soyuzes. I don't think any material would resist that without disintegrating. This is not necessarily bad... It means you could reduce the amount of power you store and release. $\endgroup$ – Renan Feb 15 '18 at 22:06
  • $\begingroup$ I would start small scale for sure. $\endgroup$ – Muze Feb 15 '18 at 22:09
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    $\begingroup$ The difference between the ISS power and the Soyuz launcher is that the ISS can supply that 160 hp continuously (barring periods when it's in the Earth's shadow). The Soyuz may have a lot of power for a short time, but it runs out of fuel very quickly. For instance, the Dawn spacecraft had less than 40 m^2 of solar panels (and spent most of its time further from the Sun than Earth), which kept its ion engines operating for years. $\endgroup$ – jamesqf Feb 16 '18 at 4:15


Rather than use a hoop, you can use a second train. Every time they pass each other in orbit, they push off each other, creating a more elongated orbit.

You wouldn't go straight from Earth to another system, though.

You'd build up velocity around the earth to travel to the sun, then you would repeat the process using the sun's vastly superior gravity, as well as a convenient fusion reactor - allowing you to build up a much, much higher velocity.

You aim both ships towards your target system, and they set out together.

When they get to the target system, they use its sun to slow down again; orbiting around it and using each other to break. Then make the final trip to the destination planet when they are going slowly enough to be captured in orbit.

And that's how you get across space without any propellant. Plz send my nobel prize in the mail.

The length of the trains wouldn't matter - your maximum speed is governed by the escape velocities of the 4 orbiting bodies - Earth, Sol, target sun & target planet, although a longer one would need fewer orbits to accelerate without pasting the monkeys.

There would also be a lot of planets that would be mathematically impossible to get to.

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  • $\begingroup$ I don't think this would work. The setup requires symmetrically mirrored orbits. When moving from Earth's gravitational influence to the sun's, you get a base of 30km/s from Earth's orbital velocity. To get symmetric orbits around the sun, your trains need to exit the Earth system at 30km/s in the retrograde direction to cancel this unsymmetric velocity out. Exiting with that much speed seems unlikely since only the last meeting of the trains can push it above Earth escape velocity. If you can add 30km/s in this meeting, you should just use that ability for a mass driver. $\endgroup$ – Lex Feb 14 '18 at 6:56
  • $\begingroup$ @Lex, only if the two trains have exactly the same mass. If one is heavier than the other, you can get the required asymmetrical orbits. although the Math would be pretty tricky, with no room for error. $\endgroup$ – user47242 Feb 14 '18 at 13:27
  • $\begingroup$ I love the train approach. $\endgroup$ – Muze Feb 14 '18 at 19:27
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    $\begingroup$ send me a pm when I can read about it in a story ;] $\endgroup$ – user47242 Feb 14 '18 at 19:29

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