# The Orbital Mass Accelerator Engine Theory

Can 2 satellites equal in weight traveling on the same orbital path in the opposite directions intersect and propel each other to gain altitude in orbit?

Can orbital perturbation be negated during intersection by alternating the magnetic fields to preset the 2 satellite's alignment to intersect the next pass?

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?

How presise could 2 satellites "thread the needle" in orbit?

How would propagation differ between a GEO and a Retrograde GEO?

• You may edit your question to go more directly to your main question. You spread several subquestion all along the context description, making the reading harder. – Manu H Apr 20 '18 at 5:46
• What a cool idea!! – Everyday Astronaut Apr 20 '18 at 9:38
• I must say I like this idea. Today it's exactly as insane as Tsiolkovski's idea of manned orbital flight on liquid hydrogen engines when he proposed it. – SF. May 12 '18 at 22:20
• In a strictly hypothetical sense, I wonder if an adaptation of this could be made for transporting a payload and the/a mass accelerator some interplanetary distance to be injected into an orbit around another planetary body, such that the payload may be returned to the original planet. – B.fox Dec 9 '18 at 14:54

In theory, yes, if the accelerator and the spacecraft are of the same mass, they'll gain the same amount of velocity when they pass, and so they'll meet at a higher altitude on the opposite side. If they aren't the same mass, then the lighter one gains more speed than the heavier, and they won't meet up again.

In practice, I don't think it's workable. The accelerator and the spacecraft will be affected by the usual sources of orbital perturbation (atmosphere, solar wind, Earth's irregular mass distribution, the gravity of other bodies) to slightly different degrees, so you need some active course correction to meet up properly on each pass. Your closing speed is over 15 km/s, so you will need to adjust trajectory on the approach extremely rapidly, and doing so will expend mass on the spacecraft.

• I agree, although this theoretically works, hitting the bullseye at this kind of relative speed is pretty insane and on collision would instantly destroy both craft. There would also be difficulties timing the magnetic field and you'd need to make sure that even if you hit bullseye, both craft need to be perfectly perpendicular otherwise your accelerations don't match up and you won't meet on the other side. – Dragongeek Feb 28 '18 at 21:33
• Suppose the accelerator was 5km long, and accelerated the spacecraft at 10g while it was inside it, it would add roughy 30 m/s to the spacecraft's velocity (and it's own) so you'd need (very roughly) 90 such passes to reach geostationary transfer orbit, taking about 75 hours. You also need a power source for the accelerator. Essentially, this is a way to lift your orbit using electrical power but no reaction mass. There are others, such as electrodynamic tethers that are probably easier, and less uncomfortable. Alternatively ion engines use very little reaction mass – Steve Linton Mar 1 '18 at 16:54
• The ISS’s orbit decays about 2km/month, or about 4m/orbit. A CubeSat in a similar orbit decays about 10x as fast, or about 40m/orbit. Precision capture at orbital speed would need a really big capture basket. – Bob Jacobsen Mar 1 '18 at 20:04
• One pass wouldn't be enough to reliably deorbit anything, the accelerator would need to be able to maneuver quite a bit to meet up with the stuff it was trying to deorbit, etc. – Russell Borogove Mar 5 '18 at 22:49
• @Muze If you are not in contact with the ship, you are not accelerated - you're either being left behind outside, or on your way to a collision with the aft bulkhead. – Saiboogu Apr 26 '18 at 17:16

Although I love the idea, this will not be practical for at least 2 reasons:

1. Cost: two spacecraft would need to be launched into opposite orbits. This can't possibly be efficient because earth's rotation would make at least one of these launches rather expensive. Also, I think to some degree, launch costs per kg payload decreases with increasing payload mass. If that's true, this concept would be more expensive than launching one single rocket with a payload twice as heavy. But, to be fair, part of that mass would have to be propellant.
2. On collision, the current orbit would be filled with debris of the bad kind. Particles of varying sizes and masses, heading in all directions. Failing once would increase chances of failure for subsequent tries, and increase risk for general spaceflight.