Putting An Observatory On The Moon's 'Dark' Side

wytcld writes: "CNN reports astronomers are pushing for a radio telescope on the 'dark side of the moon' (do real astronomers call it the 'dark side,' when it gets plenty of light?). The proposal by Yuki David Takahashi is amazing mostly because a guy just starting work on his Master's is managing major press for it. Still, a nice dream."

Earth?

[Anonymous Coward]

I see an issue: talking to it - the moon is in the way.

but, maybe if earth's radio broadcasts interfere with radio telescopes in someway, this would avoid that

Communication to the dark side (of the moon)..

[Yakman]

How would the observatory communicate with the Earth though, since the "dark side" means it never actually faces the earth? They'd have to have a satellite orbiting the moon, recieving data while on the dark side and sending it back while on the "light" side.

Alternatively have 2 geostationary sats such that the observatory can transmit to one, and that one transmits to another one it can "see" which has line of sight to earth.

I'm sure there's a simpler solution, but i'm no space communications guru :)

The temperature is as low as 80K in polar regions (reduced thermal noise in detectors). - 40K inside permanently shadowed craters (coldest place in the Solar System!)

Heh, with temperatures like that they could REALLY overclock the PCs running these observatories!

Re:Earth?

[bitchslapboy]

If this thing could be contructed, then it means putting an antenna array in a precise location using robotic equipment. The ability to do this requires a telemtry infrastructure that could easily be used after the construction is over to transmit the data to Earth for analysis. There are any number of ways to do this. Most likely the plan calls for satellites orbiting the moon to transmit the data to Earth. They could also lay fiber optic cable across the surface of the moon to a relay station in view of Earth.

Re:Typical academic thinking

[Duncan3]

Why not? you just spent ~$60 (15B) to bailout the airlines, and you didn't even notice did you.

Re:International Space Station

[AnalogBoy]

Ammendment to above comment: The shuttle's highest launch to date was the HST launch to my opinion, which was in the 300-400 MI LEO.

Correction: I'm stupidtired.
Change:
22,500 FT
to
22,500 MI in reference to the clarke orbit.

Re:If you're a RADIO astronomer, yes...

[dragons_flight]

The Earth and moon are 384,000 km apart. Given the masses of each, the gravitational balance point is at 346,000 km from the center of the Earth. The moon has a radius of 1,700 km. Consequently there is a region from about 100-9,000 km above the surface of the moon that would give reasonably stable circular orbits (at least with respect to a satellite lifetime of say 20 years). It does however rule out any lunar-synchronous satellites since they would be well outside the quasi-stable region.

Since we want the base on the dark side of the moon, we do in fact need some way to talk to it. One possibility is of course putting up a satellite around the moon, and whenever it flys over the telescope picking up the data and sending it back during it's next pass near the earth. Or a series of lunar satellites could relay continual contact. Alternatively you could build relay station on the Earth facing side and establish some kind of connection to the other side (lots of fiber optic cable, laser relay towers, etc.)

Re:For you lazy people ;-)

[Rebel Patriot]

This is a highly difficult undertaking. Communication is the one and only reason to do such a thing. In effect, it would take at least a base station (as oppossed to a second satellite) on the moon's pole to make this work. This would be enough to filter out the radio transmission and only send/receive those that need to communicate with the bird.

First of all the bird would have to be placed a considerable distance from the moon to conteract not only its gravity, but also the Earth's. It is, in effect, in geosychronous orbit about the moon AND in orbit about the Earth as well.

The physics of this might not be as difficult as some think. It may involve something as simple as putting around Earth in the same orbit as the moon, only at a much greater distance to account for the moon's gravitational effects as well.

With this said, I highly doubt this will happen untill we can figure out a legitimate way of keeping low-maintenance satellites in orbit indefinately. I would much rather see any money going to this project be spent on researching some way to convert electricity (particularly solar energy) into direct thrust so no chemical fuel is needed to adjust satellite positions.

Re:There is a problem...

[Technician]

A geosync orbit on the earth gets the force averaged out as the moon orbits the earth.. The moon does not have that advantage.

A syncronus orbit on the moon would have a additive one direction pull on the satelite steadly pulling it out of position. Check the path of the orbit of anything placed in a stationary orbit over anyplace on the moon except directly between the moon and earth, or directly over the far side of the moon. A handy spot "beside" the moon where the earth and farside of the moon can communicate in a stationary orbit will not stay put for long.

The accelerating force is in one direction for a very long period of time. Earth satelites do not have this problem as the lunar gravity pulls for a relatively short period of time in one direction and shifts in the other direction for the same period of time as the moon orbits. The satelites wobble a little just like the ocean tides come and go. A moon satelite will get pulled and keep going... it won't wobble just a little. It will move until it reached the other side (East to West) and then it will come back (West to East). True it will take years to get a cycle complete, but the thing will not stay stationary.

Re:The name...

[freaq]

a more complete snippet:

"There is no dark side of the moon really...as a matter of fact, it's all dark from time to time."
--pink floyd, _dark_side_of_the_moon_

gotta love parametric equalizers - just don't let your kids choke back a marley before playing with them. the results are...irritating, i've been told, enough to put you off your favourite albums.

calling it floyd station would be hilarious on two counts. recall where the monolith was found in clarke's _2001_, and who got called out to see it...