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NASA signs $1bn deal with Northrop Grumman to build studio apartment in lunar orbit with room for 3 vehicles

Cuddles Silver badge

There are a few advantages. Firstly, it's important to remember that the shape of an orbit depends on your frame of reference. A NRHO looks weird when you look at it in an inertial reference frame (ie. in this context, you'd take one in which the Sun is stationary and the Earth and Moon are moving), but it actually ends up effectively being a highly elliptical orbit around the Moon. Although it's not quite a real Moon orbit, since the Lagrange points effectively mark the point where you're outside any stable orbit of a body.

So you end up with an orbit that has a fairly close approach to the Moon for when you want it, but with much lower delta-v needed to get to the orbit, and with relatively small staion-keeping requirements. Since you're orbiting in the north-south plane rather than equitorial, you never have any loss of communication and only occasional, short eclipses for power to worry about. It's not the best choice in every respect, but overall it has a good combination of properties compared to the alternatives.

"Is this so the moon-bound ships can dock way out and "hitch a ride" down to low Moon orbit where the lander detaches for the final leg?"

Unfortunately that can't work. If you want to get close to he Moon, you need to change your momentum by a certain amount. Attaching yourself to something already in an orbit won't get you that change for free, it just means now you have a larger mass needing a smaller change in velocity, with overall exactly the same momentum change. This is why space elevators are a popular idea - you can't avoid the physics, but you can effectively bleed some of the momentum from the body you're attached to. As long as you're floating free, however, there's no way around needing some kind of rocket.

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