Earth-Moon Fire Pole

Post by HopDavid » Thu, May 24, 2018, 6:18 PM UTC

ColinWright wrote: post #34

lmilcin wrote: post #28

Unfortunately it is inaccurate. Actually, the person sliding the pole would be like an object changing orbit. Remember, Moon orbits Earth. Even at L1 you can't just push yourself and coast along the pole. The movement along the pole is changing orbits and as we know this requires energy. In this case if you push yourself along the pole you would suddenly find yourself drifting away from it. That's of course if you co…

> Actually, the person sliding the pole would be like an object changing orbit. Remember, Moon orbits Earth. Even at L1 you can't just push yourself and coast along the pole. The movement along the pole is changing orbits and as we know this requires energy. In this case if you push yourself along the pole you would suddenly find yourself drifting away from it. Suppose you tether yourself to the pole with a ring, and…

A.K.A. Coriolis force. Something that needs to be looked at in space elevators and orbital tetehrs as ascending (or descending) payloads exert a sideways push (or pull) on the tether and thus induce oscillations.

Post by HopDavid » Thu, May 24, 2018, 6:28 PM UTC

lmilcin wrote: post #48

ColinWright wrote: post #45

Earlier quoted context omitted.

Quoting: > Note: While you're flinging yourself along, be careful not to drift out of reach of the pole. Hopefully you brought some kind of safety line so you can recover if that happens. Of course you have lateral forces on the pole, that's not in question. But if you're sliding down the pole then you're, you know, sliding down the pole. That means you are hanging on to it somehow, or tethered to it, or something. T…

Colin, you are right. Of course if you are sliding along it you have some option to grip it and thus provide additional force needed to keep you in the vicinity of it. Of course, if you decide to actually fall to Earth from L1 that starts becoming problem. I'm too lazy to calculate exact terminal velocity you would reach when falling L1 to Earth (it won't be the 11km/s you would reach if you were falling from Moon or…

Altitude of EML1 is about 320,000 kilometers. An ordinary 320,000 x 300 km earth orbit would be moving 10.81 km/s at perigee.

As an object falls towards earth it will surge ahead of the moon and the moon will be pulling it backwards. This makes effective apogee more in the range of 300,000 km.

A 300,000 x 300 km orbit has velocity of about 10.8 km/s at perigee.

In other words, dropping from the neighborhood of L1 will still give you speed very close to escape velocity by the time it reaches earth.

In the case of orbital tether, an elevator car would have gripping wheels in contact with the tether. If its's descending the wheels can power a generator to charge the elevator car's battery.

Re: Earth-Moon Fire Pole

Re: Earth-Moon Fire Pole