The Dark Side of the Moon

[johnturley]

The BBC have repeatedly referred to where the Chinese spacecraft, which has recently landed on the far (non-earth facing) side of the moon, as being the 'Dark Side of the Moon', however where it has actually landed is in fact on the currently sunlit side of the moon, otherwise it would not have able to transmit the pictures it did, via a lunar orbiter. 

It never ceases to amaze me how many of the general public erroneously seem to think that the earth facing side of the moon is in permanent daylight, and that the far (non-earth facing) side of the moon is in permanent darkness, maybe the Pink Floyd album didn't help.

John 

Edited June 4 by johnturley

[Elp]

I thought the whole point of an orbiter was that signal can be uploaded to it so once it's in line of sight of earth it can transmit as it's not near the surface like the landing craft is.

Edited June 4 by Elp

[johnturley]

9 minutes ago, Elp said:

I thought the whole point of an orbiter was that signal can be uploaded to it so once it's in line of sight of earth it can transmit as it's not near the surface like the landing craft is.

Yes, being on the non-earth facing side of the moon, the spacecraft cannot transmit directly to the earth, it has to be via a lunar orbiting satellite.

John

[Nik271]

I don't think many journalist give enough thought to distinguish between 'far side' and 'dark side' of the Moon. In fact the 'Dark side' has more mystery in it so goes in the title, just as Pink Floyd did 

[Gfamily]

3 hours ago, johnturley said:

Yes, being on the non-earth facing side of the moon, the spacecraft cannot transmit directly to the earth, it has to be via a lunar orbiting satellite.

John

Interesting that the Chinese have two relay satellites, Queqiao, and Queqiao-2.  The original Queqiao was in a Halo orbit around the Earth/Moon L2 point which keeps it permanently on the far side of the Moon.  However, that requires it to perform regular burns to keep stable in its orbit. 

So, for Chang'e 6, the Queqiao-2 relay satellite was sent into an extremely elliptical orbit (ultimately 200x16,000 km on each axis), that means it can spend about 2/3 of its orbit within range of the far-side surface at the South Pole. 

This orbit should be stable for at least a decade, without having running out of fuel  

https://en.wikipedia.org/wiki/Queqiao-2

[Mr Spock]

There is no dark side of the moon really. As a matter of fact it's all dark.