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Comment by janmo | Hacker News Reader

There is also the interesting idea of building a radio telescope on the moon. https://en.wikipedia.org/wiki/Lunar_Crater_Radio_Telescope

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I think this might have been posted on HN recently. To me this is a far more appealing project. It could require very little payload weight, and it achieves something that is only really possible on the moon.

I would like this to be the project that really drives future human presence on the lunar surface.

According other headlines, they are going to need to create a radio free zone on the moon as they are talking about installing a 4G network.

They build on the far side to address this.

But why put it on the moon? Why not out in space? For the same launch costs we could fly a much larger structure in zero gravity.

Could we? I assumed the whole point was to use a crater as a ready-made, almost-parabolic dish, meaning that only the receiver and suspension wires would have to be sent over -- vastly reducing the required payload vs constructing an entire 1km diameter dish in space.

A crater isn't a dish, you need to line with with antennae. The extra material to support those antenna in free fall is minor.

But the cost difference in landing anything on the moon is massive. Every kilogram of payload sent to low earth orbit takes roughly 15 Kg of fuel. To land a Kg of payload on the moon requires roughly 80 kg of fuel.

It makes a sphericalcap reflector and shields from radio from the Earth and Sun. You may get something similar by putting a satellite in earth syncro orbit on the dark side of the moon.

https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_...

I'm not sure but the moon would probably create a radio shadow shielding it from radio waves originating from earth as well.

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