# Is it possible to speed up the moon's orbit with today's, or near-future technology?

And I mean only making the moon orbit the Earth faster: no change in distance from Earth required. Is such a thing possible?

• Actually, changing the orbital speed does require changing the orbital distance, unless you're physically tethering the moon to the earth somehow. – Nuclear Wang Mar 27 '18 at 17:52
• There is obviously no (logistics) technology to get a significant amount of stuff to the moon within reasonable economic limitations (which is kind of already included in "technology") nor is anyone really working on creating that possibility (why would you?), so no. – Raditz_35 Mar 27 '18 at 17:53
• Read up on orbital dynamics. If the moon speeds up, it will get farther. – Aify Mar 27 '18 at 18:09
• @Nuclear Wang: There actually is a way you could speed up the moon's orbit without changing the distance: increase the mass of the Earth. There are obvious practical difficulties there, though :-) – jamesqf Mar 27 '18 at 18:34
• @jamesqf You've got me there! I suppose we could also decrease the mass of the moon, which could be done concurrently with your earth embiggening. – Nuclear Wang Mar 27 '18 at 18:53

# Not with anything like modern or near future technology

And DEFINITELY not while maintaining the same orbital distance

The problem here is that orbital speed (considering a much larger primary mass) is a factor ONLY of the mass of the primary body and the distance they are apart as determined by the following equation.

$$v=\sqrt{\frac{GM}{r}}$$

Where v is orbital speed, G is the gravitational constant, M is the mass of the primary body (in this case, Earth), and r is the distance from the center of the primary mass to the center of the orbiting mass.

In order to increase the velocity of the moon, you're dealing with this equation.

This gives us the following options to accelerate the moon.

### Move the moon closer to Earth.

This will naturally cause it to speed up. This may have Consequencestm on Earth, particularly those related to tidal forces. This would require us to apply sufficient force to relocate a 73.4 yottagram (7.34*1022kg) object.

We can't do this. It's too big. Even considering asteroids that are 12 orders of magnitude less massive or more, we are struggling to figure out how we could gradually nudge them aside if we thought they were going to hit Earth.

### Make Earth Bigger

The other component to that equation that we can mess with is the Mass of the primary body--Earth. If you increase the mass of Earth, the moon will speed up. The problem is, Earth is huge. And the Law of Conservation of Mass is a pesky bugger that says we can't just get mass from nowhere. So, we're basically going to have to go cannibalize another planet for parts and them drop them (carefully, I hope) down to Earth's surface.

Again, we can't do this. The scale is far too massive.

### Brute Force

Here we get to the pinnacle of impossibilities.

Take the moon, strap gigantic rockets to it pointing in several different directions, and use them to accelerate the moon, but also force it to maintain its present orbital distance. Do this forever. This process is not used in real life even on something as tiny as a satellite, because it takes vastly too much energy. If you are going to burn energy, either use it to scoot yourself somewhere else in orbital distance...or go all out and try to hit escape velocity.

Naturally, you're dealing with the aforementioned 73.4 yottagram object. Only now you have to apply absurd Forces to it from multiple directions at once!

Again, not possible.

First, you can't keep the same orbit and change the speed. Try playing Kerbal Space Program if you want to learn about orbital mechanics (or do the math, but KSP is more fun).

As far as changing the orbit of the moon..

With more or less current technology, you could set up self sustaining factories on the moon, These would mine moon rocks, refine some iron from them, and launch them into space using magnetic launchers. You'd need colonies that were producing their own food and other materials, at both Lunar poles. Again, not impossible with current technology - there is ice at the lunar poles to work with.

So..

The moon orbits at 1km/sec. If we mine and fire 1% of the mass of the moon at 100 km/sec (in the opposite direction to travel), that should double the orbital velocity. That means 7x10^20kg of material, so assuming you have 1000 launchers, each launching 100kg every 10 seconds - so 10,000kg/sec - that would take 7x10^15 seconds, or about 2x10^8 years. So, just leave your operation running for 200 million years, and you are there.