Chang'e-4 farside landing mission Options

[Thorsten Denk]

It seems that the Cháng'é-4 launch has been successful!
https://mp.weixin.qq.com/s/tUuiI9Ng6CJeQBqkFATguA

Thorsten

[kenny]

This is fullest info I found , albeit no updates since launch.
Landing accuracy has to be more precise than Chang'e 3.

Xinhua news agency on Chang'e 4

[Phil Stooke]

https://www.projectpluto.com/pluto/mpecs/18103b.htm

Interesting item on the CE4 upper stage, detected in an asteroid survey, with a comment on its post-lunar flyby orbit.

Phil

[kenny]

Video showing the preparation of Chang'e-4 and rover, and some explanation of the descent profile compared with Chang'e-3.

Chang'e-5 video

[Hungry4info]

Chang'e 4 is now in lunar orbit.
http://www.china.org.cn/china/2018-12/12/c...nt_74268339.htm

[nprev]

Good article from The Planetary Society on this milestone and anticipated future events.

[Steve G]

I'm amazed by the size of their mission control for the spacecraft. I don't think Apollo 11 had half as many.

Attached thumbnail(s)

 

[Phil Stooke]

A bit of concern here - let's hope all is well.

Phil

https://skyriddles.wordpress.com/2018/12/13...-from-the-moon/

[MahFL]

I'm amazed by the size of their mission control for the spacecraft. I don't think Apollo 11 had half as many.

Looks like the back two rows are hangers on....

[Hungry4info]

A bit of concern here - let's hope all is well.

Apparently the spacecraft is okay? Just not in the orbit we all assumed it would be in.
https://skyriddles.wordpress.com/2018/12/14...arks-the-orbit/

[kenny]

According to this news story from Dec 17, the Chang'e-3 lander (which is still active) is being inhibited from "waking up" on Dec 18 so as not to interfere with the upcoming landing of Chang'e-4. So despite the general absence of news, it appears Chang'e-4 is still on track.

Chang'e-3 preps for Chang'e-4 landing

[Explorer1]

From the amateur radio listener's post, it appears CE-4 remains in constant view of Earth; would need a heavy delta-vee change or longer wait for precession of the orbit to take it over the far side landing sight.
Given CE-3's surprise last minute change of landing location, I'm actually wondering if they've made another announced change on this mission as well...

[Phil Stooke]

The moon rotates under that orbit plane, the landing site passes through the orbit plane twice a month, and no change in the orbit is needed for the landing site to be in the right place at the appropriate time.

China is not saying much, but assuming the spacecraft is healthy I can't see any cause for concern.

Phil

* Also there was no sudden change in the CE3 landing site. The landing area was called 'the Sinus Iridum landing area' but it extended well outside of Sinus Iridum. CE3 landed at its eastern end, which makes sense because if you target that and a technical problem causes a delay of a few orbits, you just land further west in the landing area (as the Moon rotates under the orbit plane). If you target the landing in central Sinus Iridum and have to delay, you risk the landing site slipping into mountainous terrain.

[JTN]

gbtimes reports "Chang'e-4 has had several "phone calls" with Queqiao while around the Moon, with a 'good' signal".

https://gbtimes.com/change-4-lander-makes-c...rom-lunar-orbit

Chang'e-4 is expected to make its landing attempt in the South Pole-Aitken Basin in early January, with the targeted site understood to be the southern floor of the 186-km-diameter Von Kármán crater.

[Explorer1]

Thanks for the explanation Phil...I should have thought a bit more about the geometry!
I wonder if they will attempt another video of the landing, if the bandwidth is good enough. The Chang'E 3 footage was amazing!

Incidentally, I checked, and there is a slightly longer signal delay through the relay satellite (about 0.4 seconds) than there would be for a near side landing (since signal needs to travel to the Lagrange point past the Moon, the far side surface, and then back again.)