Re: Chang'e Project 嫦娥工程

[Jacek Radzikowski]

There is a satellite orbiting around L2 point (second Lagrangian point -
point outside of Moon's orbit, where gravitational and circular motion
forces allow an object placed there to be locked to the Moon's motion),
which acts as a relay between Earth and the lander:
https://en.wikipedia.org/wiki/Chang%27e_4#Queqiao_relay_satellite
The mission was very closely monitored by a group of radio operators and
astronomers, who were calculating the space probe's orbital parameters
using observations of Doppler frequency shifts in transmissions from the
satellite:
https://skyriddles.wordpress.com/2019/01/07/change-4-lunar-orbit-a-postmortem/
Similar technique was used last year to identify IMAGE satellite, which
NASA declared dead after system failure in 2005:
https://skyriddles.wordpress.com/2018/01/21/nasas-long-dead-image-satellite-is-alive/

Jacek
kw4ep



On Fri, Jan 11, 2019 at 1:03 AM Alex Fraser <beatnic at comcast.net> wrote:

> There is some discussion in this Wikipedia article of the communications
> system used with the Chinese moon lander.   I was wondering if the had a
> world wide tracking system.
> I would assume they have a relay satellite orbiting the moon as it landed
> on the back side.
>
> It's an interesting read
> https://en.wikipedia.org/wiki/Chinese_Lunar_Exploration_Program
>
> --
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