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Unmanned Spaceflight.com > Earth & Moon > Lunar Exploration > Chang'e program
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Xerxes
My Chinese is just ok, but I would translate them like so:

逐梦 = Dream Chaser
光明 = Bright (literally, but also as in a bright future)
玉兔二号 = Jade Rabbit #2
探索 = Explorer
征途 = Trek (like a long voyage, but not the same word as in Star Trek, oddly)
精灵 = Genius
无畏 = Fearless
望舒 = To Spread Across the Moon / To Spread Our Hopes (this one is sort of a subtle pun that's hard to translate)
行者 = Walker (as in the sense of walking the Earth like an ancient monk)
金兔 = Gold Rabbit
Phil Stooke
Thanks!

And now Andrew Jones has these meanings:

逐梦 - Zhu Meng (chasing the dream, dream catching)
光明 - Brightness
玉兔二号 - Yutu II (Jade Rabbit 2)
探索 - Exploration
征途 - Expedition
精灵 - Genius (Fairy or elf)
无畏 - Fearless
望舒 - Wang Shu (a god that drives for the Moon in Chinese mythology; also can be used to refer to the Moon)
行者 - Stroller or Hiker
金兔 - Golden Rabbit

https://gbtimes.com/change-4-shortlist-of-1...s-space-program


EDIT: I would interpret 'genius' like the latin 'genius loci', or spirit of a place, associated with a place, rather than the modern English meaning of Genius.

Phil
Phil Stooke
http://lilacsat.hit.edu.cn/dashboard/pages_en/pics-b.html

This website posts pictures from the little student camera (from the Harbin Institute of Technology) on Longjiang 2 (also know as DSLWP-cool.gif, which can be commanded by radio amateurs on Earth. One of the most recent is this one:

Click to view attachment


- showing the farside and Earth. The green channel is severely underexposed so this is processed to remove a purplish tint and to brighten the image.

Phil

mcmcmc
QUOTE (Phil Stooke @ Nov 9 2018, 11:30 PM) *
http://lilacsat.hit.edu.cn/dashboard/pages_en/pics-b.html

This website posts pictures from the little student camera

Really cool.
It's a pity they don't release any timestamp, which would allow an amazing animation!
Phil Stooke
Here's another with a few missing lines.

The time data may be available. I will look for it.

Phil

Click to view attachment

EDIT: more data here:

https://charon.camras.nl/public/dslwp-b/

See also this very useful blog:

https://destevez.net/
mcmcmc
I wonder what this sat will see while Chang'e4 is incoming.
Phil Stooke
Check out this excellent blog by Daniel Estevez:

https://destevez.net/2018/11/november-dslwp...moon-and-earth/

- and if you go right to the end you will find an animation exactly like that mentioned above by mcmcmc.

Phil
Phil Stooke
And a mosaic of two recent images (Mare Humboldtianum* in the top right corner)

Phil

Click to view attachment

EDIT: * corrected 'Moscoviense' to 'Humboldtianum' above - how could I have made that silly mistake?
Phil Stooke
Chang'e 4 launch set for tomorrow. We still don't have the rover name yet.

Phil
nogal
It seems that the name was to be decided by an on-line vote, similarly to Chang'e-3 rover, and the most popular was 光明 - guangming ("Brightness"). However a committee was supposed to have made a final choice by late October.

See https://gbtimes.com/online-vote-decides-top...ide-of-the-moon

The article has other interesting info on the mission and links to many relevant pages. In here it says that live coverage of the launch seems unlikely.
Fernando
Edit: Liftoff was successful and Andrew Jones has tweeted an unofficial video stream
Thorsten Denk
It seems that the Cháng'é-4 launch has been successful! wheel.gif wheel.gif wheel.gif
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.
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
QUOTE (Steve G @ Dec 13 2018, 12:23 PM) *
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
QUOTE (Phil Stooke @ Dec 13 2018, 03:25 PM) *
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

QUOTE
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.)
Thorsten Denk
Hi all!

Cháng'é-4 is now in the final 15x100km orbit!
https://gbtimes.com/change-4-lowers-orbit-r...ide-of-the-moon
Very nice video there!

I herewith dare to predict the landing time: cool.gif
02 January, 00:00 UTC (midnight) at 178.1° East.

How do I get there?
Quite simple calculations with the publicly available data:

First looking at the orbital plane:
Lunar orbit insertion (LOI) was on 12Dec at 08:39 (all times UTC)
in (- assumption! -) a plane exactly perpendicular to the earth vector, this means "face-on" and over the poles.
Furthermore: Landing site: Between 176.4° and 178.7° East. (This is from here.)
The orbital plane therefore has to rotate between LOI and landing between 271.3° and 273.6°.
Or, more precisely, the Moon under it. smile.gif
Since a sidereal lunar rotation lasts 27.3217 days,
this corresponds to a time from LOI to landing of 20.590 and 20.764 days.
That falls between 01Jan 22:48 and 02Jan 02:59 (as said, UTC).
That's a period of just over 4 hours, enough for two passes.

And now, when exactly?
The insertion into the final orbit of 15x100km was early today (30Dec) at 0:55 UTC.
This injection occurs in the aposelene, this means half an orbit from periselene!
And the periselene is logically (almost) over the landing site.
The orbital period can be calculated (113.68min), so you just have to look
when a multiple-plus-zero-point-five of the orbit period falls into the the time frame calculated above.
This is the case (UTC) on 01 Jan at 23:58 (37.5rev) and on 02 Jan at 01:51 (38.5rev).

With uncertainty in the minute range and a bit of time for the final (slow) approach,
it will be midnight UTC on January 2nd.
And the backup opportunity at 177.0° East just before 2h UTC.

To all this also fits that on that day, the Moon in Beijing rises at 03:45 (Beijing time).
The landing would be at 07:58, the backup landing at 09:51, and the moonset at 14:23.
Perfect timing for the ground stations.

Some (dis-)agreement here? rolleyes.gif

Best
Thorsten
Bernard
No disagreement.
This looks brilliant to me.
nprev
Very impressive orbital mechanical detective work, Thorsten! smile.gif It will be fascinating to see how this plays out.
charborob
1- Is there an official Chang'e 4 website?
2- Do we know if the landing will be transmitted live?
nogal
1- Is there an official Chang'e 4 website? I've been combing the web and couldn't find any
2- Do we know if the landing will be transmitted live? All mentions I've seen say it will not

Andrew Jones of the gbtimes has been providing coverage of the mission. On that page is this interesting link
The Sun is reporting a Jan 3 landing at about 1:00 UTC, which matches with a tweet I've seen (but lost the reference to).
EDIT: techradar has a story about "how to watch live online" by visiting the CGTN site. But this site is unavailable to several European countries, including mine.
Thorsten Denk
QUOTE (nprev @ Dec 31 2018, 10:14 AM) *
Very impressive orbital mechanical detective work, Thorsten! smile.gif It will be fascinating to see how this plays out.

Thanks nprev.
But apparently something is wrong: huh.gif
(1) The LOI plane was not perpendicular to Earth
(2) The orbital plane did not remain constant
(3) They will land somewhere else (not Von-Kármán)
(4) They already have landed but didn't tell
(5) I did a mistake somewhere
Will be interesting to see what was the reason...
Thorsten
Phil Stooke
What are we about to see?

Almost everywhere i look in Von Karman southeast of the central peak the surface is characterized not only by the expected craters but also by a multitude of small troughs or valleys. This scene is about 4 km wide:

Click to view attachment

Hazard avoidance should allow CE4 to land in a level spot, but traverse planning may be interesting. I will not speculate as to the origin or depth of these features at the moment.

Phil

EDIT - 7 January - These grooves are further west than the actual landing site. Our area is free of them.
Explorer1
Unconfirmed social media reports of a successful landing at 2:26 UTC!
Presumably downloading the landing footage before any official announcement on state media (what I would do to maximize public outreach).
Hungry4info
Official Chinese media are reporting successful landing.
charborob
Landing announced on Xinhuanet link
Hungry4info
ohmy.gif
nprev
Remarkable. Congratulations to China! smile.gif
Explorer1
First surface image from the far side. A historic achievement!

Nearby crater and distant hills, should make finding the location easy enough; LRO should pass over the area on January 4th from what I've read.

Another image of the landing legs on social media; I can't find the original so I won't link it yet.

Video here (skip to 1:11 for apparent real time descent imagery, should make it easy for our resident cartographer to pinpoint the area wink.gif )

https://krcom.cn/2656274875/episodes/104219...324354331200641
Sym05
Smartphone screenshot of CCTV 13 news cannel. 14:00 Beijing time edition. Screen in the control room shows the expected landing zone and expected landing point (only one decimal) 177.6 E, 45.5S

Click to view attachment
Phil Stooke
Okey-dokey, here we go.

These are the views from that landing video:

Click to view attachment

This is an overlay of the landing site image posted just above this, overlain on a Quickmap image of the area:

Click to view attachment

Zooming in, the area looks like this:

Click to view attachment

And here two frames from the video are located.

Click to view attachment

That points to the approximate site. No doubt more tomorrow.

Phil

Phil Stooke
One other comment - the hills on the horizon in the one surface view we have are south of the lander. They are part of the rim of Von Karman, not the central peak. The direction of lighting in the image clearly shows that this must be looking south.

Phil

Click to view attachment
Webscientist
Congratulation to CNSA and the engineers! smile.gif
Surprised! I don't see a lot of stones in the first view and the surface seems to be particularly soft with a lot of dust.
It looks like dry clay (in a windy day), the kind of clay you find in Roland Garros for instance! biggrin.gif
Baywa
QUOTE (Thorsten Denk @ Jan 2 2019, 07:22 PM) *
(3) They will land somewhere else (not Von-Kármán)


What makes you think so? In this videoclip (link provided by Explorer1)at 0:21, from looking at the features that's von Kármán crater (I compared with the Virtual Moon atlas).

Thomas
Thorsten Denk
QUOTE (Baywa @ Jan 3 2019, 10:16 AM) *
What makes you think so? In this videoclip (link provided by Explorer1)at 0:21, from looking at the features that's von Kármán crater (I compared with the Virtual Moon atlas).

Thomas

It's just one out of five points from a list of possible reasons why the calculations in post #76 are not correct.
It was written before the actual landing.
Now (after the landing) we know that this point is not the reason.

In any case, congratulations to the Chinese for the successful landing! wheel.gif wheel.gif wheel.gif

Thorsten
Baywa
OK - so I mixed up the OR and the AND operator. rolleyes.gif But I would really, really want to figure out what actually happened starting at orbital insertion and ending with the landing approach. For example, maybe they changed the inclination of the orbit?

Thomas
charborob
Photo of the landing pad on the Moon (link)
Sym05
From twitter:
https://twitter.com/Cosmic_Penguin/status/1...6621587456?s=09

"Based on the few descent photos available right now someone in Chinese social media has provided finding charts for #ChangE4. (https://t.co/UiIjI3ngKY) Maybe someone here can get rough landing coordinates of it from the photos below?"

Original post on Weibo (Chinese language)
https://m.weibo.cn/status/HagktpCG8
wildespace
QUOTE (Phil Stooke @ Jan 3 2019, 08:22 AM) *
One other comment - the hills on the horizon in the one surface view we have are south of the lander. They are part of the rim of Von Karman, not the central peak. The direction of lighting in the image clearly shows that this must be looking south.

Phil

Click to view attachment

I think the view is towards the largest crater in the immediate vicinity, to the east/south-east of the lander: http://bit.ly/2F5NB9U

P.S. QuickMap is strugging to serve so many requests today!
Hungry4info
Yutu 2 deployment.
tolis
QUOTE (Hungry4info @ Jan 3 2019, 04:42 PM) *
Yutu 2 deployment.


My..that was quick!

A somewhat pedantic comment on Phil's earlier remark about viewing directions (Phil, please correct me if I messed up somewhere).
It is true that the direction of lighting implies that the mountain ridge on the horizon must be south of the lander and therefore part
of the rim of Von Karman, rather than its central peak, but this inference takes also into account the addiitonal
knowledge of time of (lunar) day. If the landing were to have taken place near local sunset, witnessing the same shadow direction
right after landing would imply a northwards view.

Further on the issue of mountains, I recall from looking at pictures of the Von Karman floor posted earlier with the likely
location of Ch4 in it that there is a "positive relief feature" just north of the landing site which >should< be closer
than either the central peak or the crater rim of VK. It would be interesting to see what that looks like from ground level.

Looking forward to those 360 deg panoramas!
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