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Unmanned Spaceflight.com _ Chang'e program _ Chang'e-4 farside landing mission

Posted by: A.Nemo Jul 15 2015, 01:35 PM


Preliminary Suggestions for International Cooperation on Chang'E-4 Lunar Probe
Xu Y. (China)
http://www.unoosa.org/pdf/pres/copuos2015/copuos2015tech08E.pdf

An Introduction of Chang’E-4 Probe:
Probe(Lander,Rover)+ Relay Statellite
Soft-landing on lunar farside
Landing and roving exploration
Will be launched between 2018 and 2019

the probe:
Chang’E-4 probe,lander and rover have the same technical status with the Chang’E -3; but exploration will be redesigned; the payload will be reconfigered; The name of the probe might be changed.
Chang’E-4 probe is a backup spacecraft of Chang’E -3 probe. By now, all platform products of the probe have been manufactured, waiting for further AIT.
The probe will be launched by a long March 3B rocket from the Xichang Statellite Launch Center(XSLC) which is the same way with the Chang'E-3 between 2018 and 2019

The relay statellite:
will be first launched into a lunar transfer orbit about the end of 2018 in the whole mission, then starts its earth-to-moon jurnery alone, and will enter and run in a Halo orbit around the Earth-Moon L2 point; the design life is 3 years.
would provide relay service for the probe and the Earth, and carry out exploration.

Engineering objectives are as follow.
To realize the first soft landing on the lunar farside and perform exploration in human history.
To demonstrate technologies of lunar data relay, landing and roving on complicated terrains of the lunar farside, and lunar night power generation;
To perform further detailed survey on lunar environment in order to lay a foundation for subsequent lunar exploration mission.

Tentative Scientific objectives are as follow.
To study lunar surface dust features and its formation mechanism;
To perform in-situ measurement of lunar surface residual magnetism
and study its interaction with solar wind;
To study lunar surface temperature and particle radiation environment;
To perform lunar surface topology and material composition analysis,
shallow-layer structure survey and study;
To explore and study lunar interior structure of spheres;
To perform lunar based VLF astronomical observation and study

Posted by: A.Nemo Jul 15 2015, 01:43 PM

there is a puzzle news:
http://www.cnsa.gov.cn/n1081/n7529/n308608/725881.html
中欧深空探测研讨会在北京召开
发布日期:2015年07月14日 字体:【大】【中】【小】
  2015年7月9日至10日,中国国家航天局与欧洲空间局在京召开中欧月球探测研讨会,会议围绕嫦娥四号目标任务和有效载荷搭载进行了讨论。
  会上,欧洲空间局相关专家提出利用嫦娥四号搭载月震仪、快闪相机、激光反射器等载荷的建议。经商议,双方初步确定将月震仪和快闪相机等四个有效载荷纳入合作范围。欧洲空间局负责协商欧洲载荷以及其总成与接口,中方通过双边航天局长会晤推动建立载荷研制国技术团队,争取在2018年提交正样。
  来自法国巴黎索邦大学、瑞士苏黎世理工、澳门科技大学以及中国国家航天局探月与航天工程中心、中国科学院、北京大学、中国科学技术大学、中国地质大学等单位的专家学者参加了会议。

laser reflector, it means Chang'e 4 will be landed on nearside, What will happened?

Posted by: Juramike Jul 15 2015, 01:49 PM

(Edited!)

Posted by: Phil Stooke Jul 15 2015, 03:52 PM

The current Chinese plan is to land on the far side. The laser reflector is suggested as a high priority payload by an ESA group looking at cooperation. The two don't work together, so we don't know which way it will go. But it's not a contradictory plan, it's an external suggestion to change the plan. Probably won't happen, because the prestige (and science value) of the first far side landing is likely to trump that one payload suggestion.

Incidentally, there's really no reason why that laser reflector shouldn't be mounted on the landing stage of the Chang'E 5 sample return lander, which will be near side. That's a far more likely outcome than flying it on CE4.

Phil


Posted by: Yeh Sep 8 2015, 01:38 PM

Today there's an official confirmation from Xinhua (the state media) that CE4 will be land on the farside: http://news.xinhuanet.com/tech/2015-09/08/c_1116498505.htm (in Chinese).

Posted by: tolis Sep 9 2015, 01:46 PM

QUOTE (Yeh @ Sep 8 2015, 02:38 PM) *
Today there's an official confirmation from Xinhua (the state media) that CE4 will be land on the farside: http://news.xinhuanet.com/tech/2015-09/08/c_1116498505.htm (in Chinese).


In that case, they will need a relay satellite, either in lunar orbit or further afield eg Earth-Moon L2

Posted by: Phil Stooke Sep 9 2015, 01:54 PM

It's at L2. More details here:

http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=33402.0;attach=1064984

Phil


Posted by: bobik Jan 6 2016, 12:55 PM

QUOTE (A.Nemo @ Jul 15 2015, 02:43 PM) *
there is a puzzle news: ...

This refers probably to the micro-reflector array http://www.lnf.infn.it/esperimenti/etrusco/documentation/JAMP_2015013014523399.pdf (Instrument for landing-Roving laser Retroreflectors Investigations). INRRI has been sized to give the right signal for LOLA (Lunar Orbiter Laser Altimeter) on LRO. By the way, one INRRI was mounted on EDM Schiaparelli as long-time scientific asset.

Posted by: Thorsten Denk Jan 14 2016, 01:39 PM

It seems that Cháng'é 4 will go to the lunar farside end of 2018!

QUOTE
SinoDefence ‏@SinoDefence
Chang'e 4 mission given goahead.
Relay sat in Jun 18, followed by landing on Moon far side in late 2018.

https://twitter.com/SinoDefence/status/687618528933998592
http://www.chinadaily.com.cn/micro-reading/china/2016-01-14/content_14484287.html

Thorsten

Posted by: bobik Apr 14 2016, 06:01 PM

German http://www.uni-kiel.de/pressemeldungen/index.php?pmid=2016-106-mondmission&lang=en experiment is going to the lunar far side.

Posted by: A.Nemo Apr 15 2016, 08:19 AM

China Follow-on Luna Exploration Projects:
2018,Chang'e-4 to farside of Moon
2023,Chang'e-6(?) ,sample&return from farside of Moon
2025,Chang'e-?, south pole landing & large area cruise
2027,Chang'e-?, north pole landing & ISRU Experimental


 

Posted by: bobik May 17 2016, 06:45 AM

A http://els2016.arc.nasa.gov/downloads/ELS_2016_Abstract_Booklet.pdf installed on the relay satellite and the Swedish http://gbtimes.com/china/sweden-joins-chinas-historic-mission-land-far-side-moon instrument for the rover are two other European contributions to the Chang'e-4 expedition.

Posted by: Phil Stooke Jun 3 2016, 02:58 PM

http://www.chinaspaceflight.com/satellite/Deepspace/CE-4/CE-4.html

Chang E IV: June 2018 Long March rocket four C relay communications satellite in late 2018 Long March III B rocket lander and inspection devices.

This item includes an image of the general landing area in the Apollo basin. Long Xiao had suggested to me at LPSC that this would be the (or a) target

http://www.chinaspaceflight.com/usr/uploads/2016/06/03/1464941417135287.jpg

Phil

Posted by: Phil Stooke Jun 20 2016, 11:14 AM

A fascinating new paper is now online - Wang and Liu (2016), A Chang’e-4 mission concept and vision of future Chinese lunar exploration activities, Acta Astronautica (available online 11 JUne 2016). If you have access!

It suggests that Apollo basin is the most likely target but other farside basins are possible. Also looks ahead to future missions, including a suggestion that a robotic station could be built up, possibly as a precursor to human flights. From 3 to 5 landers near the south pole, carrying between them up to a dozen rovers, to build the station, which has obvious echoes of ESA's robotic lunar village.

Phil

Posted by: Explorer1 Oct 2 2016, 05:11 PM

http://spaceflightnow.com/2016/09/29/china-developing-mission-to-return-samples-from-far-side-of-the-moon/

Near side sample return might be launched next year, while the far side relay could be used by other space agencies for their own missions. It would certainly save good money!

Posted by: Phil Stooke Jun 6 2017, 04:15 PM

Chang'E 4 landing site:



https://www.chinaspaceflight.com/satellite/Deepspace/CE-4/CE-4.html


Landing area - 45.5 degrees south latitude, 178 degrees east longitude

This is on the flat floor of the large crater Von Karman, with a bit of ejecta from the relatively young crater Finsen. Until now most indications had been for a landing near the Apollo basin at about 42 south, 157 west (203 east).


Phil

Posted by: Phil Stooke Jun 11 2017, 08:24 PM

Here's a couple of maps showing the CE4 area.

Phil


Posted by: antipode Jun 12 2017, 04:37 AM

Phil

I take it Von Karman's walls are sufficiently lofty to be visible in any surface imagery taken from inside that box?

p

Posted by: Explorer1 Jun 12 2017, 05:35 AM

I wouldn't be so sure; the horizon is really close in the Chang'E 3 surface images. We shouldn't expect huge vistas anymore than we get them on Mars; cool terrain is by definition hazardous!
I would welcome being pleasant surprised to see anything more than a few km away, of course.

Posted by: Phil Stooke Jun 12 2017, 05:16 PM

Short answer - I think some relief will be visible. Von Karman is about 3500 m deep and some distant topography should show up.

I will post something on the Chang'E 3 thread about distant topography. There are distant hills to the north and west at distances of 10 to 15 km, protruding above closer topography. To the east the horizon is about 4 km from the lander.

Phil

EDIT: OK, I posted in the other thread. That was a very flat site, but local high spots can be seen about 10 km away. I would expect that either the central peak of Von Karman or the SE wall of the crater should be visible from the lander, and possibly both will be, as well as small crater rims closer to the landing site. Not high mountains like Taurus-Littrow, but distant features should be visible, appearing as low hills.

Posted by: Phil Stooke Jul 6 2017, 06:01 PM

More information on site selection for CE4. This image:

https://www.chinaspaceflight.com/usr/uploads/2017/07/06/1499353834140857.jpg

from this site:

https://www.chinaspaceflight.com/satellite/Deepspace/CE-4/CE-4.html

shows a number of sites at about 45 degrees north or south. I am preparing something on this topic, so I will post a map later. Some sites are in mare-type areas of the SPA basin or the large craters in that area, but the northern sites are all in or between large craters in the highlands (Mare Moscoviense is not one of these areas).

This is from a presentation at the German Aerospace Centre DLR, where China and Germany have just agreed to cooperate on the mission, Germany joining several other countries.

Phil

Posted by: Phil Stooke Jul 7 2017, 12:22 AM

Here is a map of those sites from the slide linked to above.

Phil


Posted by: JRehling Jul 7 2017, 01:32 AM

Probably everyone knows this, but on the Moon, the horizon is inherently closer than from a similar vantage point on Earth or Mars. Though the bowl of a crater may make the global curvature locally moot.

Posted by: Phil Stooke Jul 7 2017, 06:00 PM

That's true, of course, but the distance to the ideal horizon is not as important as the height and distance of significant relief features. Von Karman is about 160 km across and up to 4 km deep (wall height varies quite a bit). A good comparison might be with Flamsteed P, the flooded crater which Surveyor 1 landed in. It is 80 km across, but mostly filled with lava and with hills 1500 m high protruding above the plains. Hills 20 km away were visible in the Surveyor 1 panorama. Scaling up, I am confident there will be some relief on the CE4 horizon. Maybe if the landing is in exactly the worst place for viewing relief there would not be much, but from many areas some features will be visible.

Phil

Posted by: Phil Stooke Feb 27 2018, 07:49 PM

The Von Karman site may not be the final word on site selection... it was identified in a paper in 2017, but two papers by Jia et al. in 2018 (one in the Chinese Journal for Deep Space Exploration, the other in Planetary and Space Science, essentially the same content) prefer the site numbered S5 in the map a few posts above. It is south of the Apollo basin and closer to the centre of the SPA basin than any other of those mapped sites. I think all we have right now is competing suggestions, and the final target may still be uncertain.

Phil


Posted by: Phil Stooke Mar 18 2018, 06:09 PM

I'm at the Microsymposium just prior to LPSC. It just concluded, with presentations on the Chang'E program and others. Specifically for this thread, Von Karman seemed to be the likely site again - Apollo was promoted as a good site but probably for a future mission.

Phil

Posted by: Phil Stooke Apr 11 2018, 05:10 PM

Suggest a name for the CE4 relay satellite:

http://www.nssc.cas.cn/tzgg2015/tzgg_tzgg/201803/t20180329_4987980.html

(Google translation)

Concerning the notification of the recruitment of the No. 4 relay star name
Article Source: Release Time:2018-03-29
All relevant units:

  The fourth relay satellite will be launched in May 2018. Considering that the No. 4 mission will be the biggest bright spot in China's aerospace field in 2018, to further establish a good image of the lunar exploration project and expand the influence of the project, the Lunar Exploration and Space Engineering Center plans to use the project implementation unit as the main target for solicitation of No. 4 Relay star name.

  The No. 4 relay star name collection activity will take place from March 27 to April 15, 2018. The names so collected should reflect the theme of lunar exploration, have innovative and significant technological and cultural characteristics, be positive, and conform to the socialist core values.

  Specially invited your organization to participate in this solicitation. Please refer to the attachment for specific requirements.

  Attachment: Program for Selection of Relay No. 4 Relay Stars

  Moon Exploration and Aerospace Engineering Center

  March 27, 2018

Posted by: Phil Stooke Apr 22 2018, 06:20 PM

This link is to the current issue of China's Journal of Deep Space Exploration:

http://jdse.bit.edu.cn/sktcxben/ch/reader/issue_list.aspx

A very interesting set of papers about the CE4 landing site including several suggestions for landing sites and even rover traverse routes. Chinese language with English abstract, but Google document translation will help, and the illustrations carry a lot of information even without translation. Many of these papers will probably appear in English elsewhere at a later date. I can feel a map coming on...

Phil

Posted by: Phil Stooke Apr 23 2018, 11:48 PM

After a suitable gestation period, here is a map of the sites suggested for Chang'E 4 in Von Karman crater. The references are from the previous post except the mention of Snape et al. (2010) which is an LPSC abstract, easy to search for if you need it. THe bottom map includes possible traverses suggested by Mou et al. (2018)

Phil


Posted by: Phil Stooke Apr 24 2018, 02:38 AM

http://news.cnstock.com/news,bwkx-201804-4214240.htm

Google translate:

China Securities News reported on April 24 from the National Bureau of Science, Technology, and Technology that during the opening ceremony of the "China Aerospace Day" home event in 2018, Wu Yanhua said that the Chang'e 4 is one of the major tasks for China's space industry this year...

Wu Yanhua announced at the opening ceremony that the No. 4 relay star was named "Bianqiao" and the two small satellites were named "Longjiang No. 1" and "Longjiang No. 2".

Phil

Posted by: Phil Stooke Apr 24 2018, 09:39 PM

Interesting that Google translates that website to give the relay satellite name 'Bianqiao', but all other sources - AND using Google to translate just the characters for that name, give 'Queqiao'. The names mean Magpie Bridge (relay) and Dragon River (the two small satellites), and there are numerous tweets and stories out there today giving the background.

Late in the year we will presumably get a name for the new rover.

Phil

Posted by: Phil Stooke May 20 2018, 10:08 PM

The relay satellite was just launched successfully.

Phil

Posted by: nprev May 20 2018, 10:23 PM

Ah, thanks, Phil! Was wondering; didn't seem to be a live feed available anywhere.

Posted by: Explorer1 May 20 2018, 10:29 PM

Someone at the site pointed their phone at a screen, and streamed it out via a Chinese media platform; looks like the micro-satellites also separated successfully.

Posted by: John Moore May 21 2018, 09:30 AM

https://www.youtube.com/watch?v=TC1bsPDsKgQ of launch, or https://www.youtube.com/watch?v=jgiEr13zkJo (with different aspect view).

John Moore

Posted by: Phil Stooke May 25 2018, 10:40 PM

It seems all is well with our new mission - the relay satellite has passed the Moon and is on its way to its L2 halo orbit. The two little moon orbiters are in lunar orbit. Hoping for an image or two from the Saudi camera on one of them.

Phil

Posted by: Phil Stooke May 27 2018, 09:56 PM

Twitter: Jonathan McDowell @planet4589 2 hours ago

So it looks like Longjiang-2 (DSLWP-cool.gif is in a 350 x 13800 km x 21 deg lunar orbit. Longjiang-1 seems to have failed on May 21 and presumably remains in distant Earth orbit following its lunar flyby
------------------


I spoke prematurely in my last post - all seems well with the other two spacecraft but Longjiang 1 failed. The small camera is on Longjiang 2. I see some reports that radio enthusiasts will be able to download images from the camera, but I don't know the details yet.

Phil

Posted by: mcmcmc Jun 13 2018, 07:30 AM

"Are we there yet?" wink.gif

Posted by: Phil Stooke Jun 14 2018, 04:16 PM

We are!

http://spacenews.com/change-4-relay-satellite-enters-halo-orbit-around-earth-moon-l2-microsatellite-in-lunar-orbit/

Phil

Posted by: mcmcmc Jun 14 2018, 05:49 PM

QUOTE (Phil Stooke @ Jun 14 2018, 05:16 PM) *
We are!

http://spacenews.com/change-4-relay-satellite-enters-halo-orbit-around-earth-moon-l2-microsatellite-in-lunar-orbit/

Phil

Cool!

Posted by: mcmcmc Jun 14 2018, 06:53 PM

Hayabusa twitter aggregator
http://win98.altervista.org/hayabusa2/TwitterAggregator.html

Posted by: Thorsten Denk Jun 14 2018, 07:00 PM

Nice pic, but it's not new.
It's from Chang'e-5 T1, from october 2014.

This one is new, from the Longjiang-2 micro satellite.
The camera has captured its place of origin, Saudi Arabia. smile.gif

Thorsten



Posted by: John Moore Jun 14 2018, 07:13 PM

https://gbtimes.com/authors/658 are always useful for reference/updates.

John Moore

Posted by: mcmcmc Jun 15 2018, 06:51 AM

Better images from Saudi Arabia camera onboard Longjiang-2 satellite, the only survivor of the two small satellites launched together with Queqiao:




http://www.planetary.org/blogs/jason-davis/2018/20180614-longjiang-2-earth-pics.html

Posted by: Phil Stooke Aug 6 2018, 10:48 AM

Andrew Jones (https://twitter.com/AJ_FI) reports some new images from the Saudi camera. EDIT - Andrew has just pointed out to me that the image is not from the Saudi camera, but from a second camera which I was not aware of or had forgotten about. This was developed by students in China.

One, which I assume is a mosaic of many image strips, covers Mare Nubium. This shows the image coverage on a background from LRO Quickmap.

Phil


Posted by: djellison Aug 6 2018, 04:10 PM

I think those are just symptoms of SSTV ham radio downlink.

Posted by: Phil Stooke Aug 6 2018, 09:59 PM

Yes, looking at it now I'm inclined to agree.

Phil

Posted by: Phil Stooke Sep 19 2018, 06:47 PM

http://www.spaceflightfans.cn/39192.html#more-39192


Summarizing from the above link, using Google translation:


The Chang'e 4 rover will have a name soon. A competition was held starting on 15 August, and on 18 September a shortlist of the many submitted names was announced after a meeting in Beijing.


The shortlisted names are:

dream-by-dream
Guangming [= bright or brightness]
Yutu No.2
exploration
journey
elf
fearless
Wangshu (one of the former kingdoms of China 1000 years ago)
walker
golden rabbit


(the first one looks like a bad translation)

The final name will be picked in October.


Phil

Posted by: Explorer1 Sep 19 2018, 06:55 PM

Golden rabbit sounds really fun! It has my vote (for what it's worth...)

Posted by: Phil Stooke Sep 19 2018, 11:56 PM



Phil


Posted by: Xerxes Sep 20 2018, 02:34 PM

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

Posted by: Phil Stooke Sep 20 2018, 05:35 PM

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-10-names-revealed-for-chinas-lunar-far-side-rover?cat=chinas-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

Posted by: Phil Stooke Nov 9 2018, 10:30 PM

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:




- 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


Posted by: mcmcmc Nov 9 2018, 11:19 PM

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!

Posted by: Phil Stooke Nov 10 2018, 06:00 AM

Here's another with a few missing lines.

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

Phil



EDIT: more data here:

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

See also this very useful blog:

https://destevez.net/

Posted by: mcmcmc Nov 10 2018, 10:50 AM

I wonder what this sat will see while Chang'e4 is incoming.

Posted by: Phil Stooke Nov 18 2018, 08:34 PM

Check out this excellent blog by Daniel Estevez:

https://destevez.net/2018/11/november-dslwp-b-images-of-the-moon-and-earth/

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

Phil

Posted by: Phil Stooke Nov 18 2018, 08:45 PM

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

Phil



EDIT: * corrected 'Moscoviense' to 'Humboldtianum' above - how could I have made that silly mistake?

Posted by: Phil Stooke Dec 6 2018, 07:04 PM

Chang'e 4 launch set for tomorrow. We still don't have the rover name yet.

Phil

Posted by: nogal Dec 7 2018, 05:08 PM

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-three-names-for-change-4-lunar-far-side-rover?feature=chinas-change-4-mission-to-the-far-side-of-the-moon

The article has other interesting info on the mission and links to many relevant pages. In https://gbtimes.com/heres-what-you-need-to-know-about-the-change-4-mission-to-the-far-side-of-the-moonit says that live coverage of the launch seems unlikely.
Fernando
Edit: Liftoff was successful and Andrew Jones has tweeted an https://twitter.com/AJ_FI/status/1071111011380412416/video/1

Posted by: Thorsten Denk Dec 7 2018, 07:37 PM

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

Posted by: kenny Dec 8 2018, 11:50 AM

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

http://www.xinhuanet.com/english/2018-12/08/c_137659328.htm

Posted by: Phil Stooke Dec 10 2018, 06:10 PM

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

Posted by: kenny Dec 10 2018, 08:00 PM

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

http://www.parabolicarc.com/2018/12/09/video-closer-chinas-change4-lunar-mission/


Posted by: Hungry4info Dec 12 2018, 11:43 AM

Chang'e 4 is now in lunar orbit.
http://www.china.org.cn/china/2018-12/12/content_74268339.htm

Posted by: nprev Dec 12 2018, 06:20 PM

http://www.planetary.org/blogs/guest-blogs/2018/change-4-lunar-orbit.html?fbclid=IwAR0i1rWZKJPWEBf1tDoPAgUIfv6Lt0fktDvJ9XKt1JJ_3t0zWR3V7prl3b0on this milestone and anticipated future events.

Posted by: 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.

 

Posted by: Phil Stooke Dec 13 2018, 08:25 PM

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

Phil

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

Posted by: MahFL Dec 14 2018, 12:28 AM

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....

Posted by: Hungry4info Dec 14 2018, 03:41 AM

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/x-marks-the-orbit/

Posted by: kenny Dec 18 2018, 06:04 PM

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.

https://gbtimes.com/chinas-still-operational-change-3-moon-lander-to-hibernate-for-change-4-lunar-far-side-mission

Posted by: Explorer1 Dec 18 2018, 06:41 PM

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...

Posted by: Phil Stooke Dec 18 2018, 09:06 PM

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.

Posted by: JTN Dec 20 2018, 08:51 PM

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-contact-with-queqiao-relay-satellite-from-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.

Posted by: Explorer1 Dec 20 2018, 09:13 PM

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.)

Posted by: Thorsten Denk Dec 30 2018, 06:01 PM

Hi all!

Cháng'é-4 is now in the final 15x100km orbit!
https://gbtimes.com/change-4-lowers-orbit-ready-for-first-ever-landing-on-far-side-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 http://www.unmannedspaceflight.com/index.php?s=&showtopic=8057&view=findpost&p=236170.)
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

Posted by: Bernard Dec 31 2018, 08:10 AM

No disagreement.
This looks brilliant to me.

Posted by: nprev Dec 31 2018, 09:14 AM

Very impressive orbital mechanical detective work, Thorsten! smile.gif It will be fascinating to see how this plays out.

Posted by: charborob Jan 2 2019, 03:55 PM

1- Is there an official Chang'e 4 website?
2- Do we know if the landing will be transmitted live?

Posted by: nogal Jan 2 2019, 04:46 PM

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 https://gbtimes.com/how-the-change-4-spacecraft-will-land-on-the-far-side-of-the-moon?cat=chinas-space-programhas been providing coverage of the mission. On that page is this interesting https://twitter.com/coastal8049/status/1079566300135870464
https://www.thesun.co.uk/tech/8101134/china-probe-landing-dark-side-of-moon/ 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 "https://www.techradar.com/news/how-to-watch-live-online-as-china-attempts-to-land-on-the-moon" by visiting the https://www.cgtn.com/ site. But this site is unavailable to several European countries, including mine.

Posted by: Thorsten Denk Jan 2 2019, 06:22 PM

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

Posted by: Phil Stooke Jan 2 2019, 09:33 PM

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:



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.

Posted by: Explorer1 Jan 3 2019, 02:46 AM

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).

Posted by: Hungry4info Jan 3 2019, 04:24 AM

Official Chinese media are reporting successful landing.

Posted by: charborob Jan 3 2019, 04:25 AM

Landing announced on Xinhuanet http://www.xinhuanet.com/english/2019-01/03/c_137716800.htm

Posted by: Hungry4info Jan 3 2019, 04:59 AM

ohmy.gif


 

Posted by: nprev Jan 3 2019, 05:07 AM

Remarkable. Congratulations to China! smile.gif

Posted by: Explorer1 Jan 3 2019, 05:08 AM

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/1042194:4324354331200641

Posted by: Sym05 Jan 3 2019, 06:25 AM

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



Posted by: Phil Stooke Jan 3 2019, 08:06 AM

Okey-dokey, here we go.

These are the views from that landing video:



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



Zooming in, the area looks like this:



And here two frames from the video are located.



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

Phil


Posted by: 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



Posted by: Webscientist Jan 3 2019, 08:59 AM

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

Posted by: Baywa Jan 3 2019, 09:16 AM

QUOTE (Thorsten Denk @ Jan 2 2019, 07:22 PM) *
(3) They will land somewhere else (not Von-Kármán)


What makes you think so? In https://krcom.cn/2656274875/episodes/1042194:4324354331200641 (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

Posted by: Thorsten Denk Jan 3 2019, 09:33 AM

QUOTE (Baywa @ Jan 3 2019, 10:16 AM) *
What makes you think so? In https://krcom.cn/2656274875/episodes/1042194:4324354331200641 (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

Posted by: Baywa Jan 3 2019, 10:25 AM

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

Posted by: charborob Jan 3 2019, 11:03 AM

Photo of the landing pad on the Moon (http://en.people.cn/n3/2019/0103/c90000-9534393-7.html)

Posted by: Sym05 Jan 3 2019, 01:22 PM

From twitter:
https://twitter.com/Cosmic_Penguin/status/1080799826621587456?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

Posted by: wildespace Jan 3 2019, 03:59 PM

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



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!

Posted by: Hungry4info Jan 3 2019, 04:42 PM

Yutu 2 deployment.

 

Posted by: tolis Jan 3 2019, 05:13 PM

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!

Posted by: mmatessa Jan 3 2019, 05:18 PM

Rover/no-rover


Posted by: Steve G Jan 3 2019, 05:38 PM

The fact that you can see so far in the distance also indicates they have landed on a slight rise. Reminds me of the view from Stone Mountain on AS16.

Posted by: Phil Stooke Jan 3 2019, 08:11 PM

This is my interpretation of the view to the south and the crater rim - south up in the LROC wide angle mosaic. The rim is about 40 km away and the highest peak is 3 km above the plains. I wouldn't say it's 100% certain but I like it better than an interpretation where the relief is a nearby crater. I agree with Steve G that we are on a local rise. Sadly, not enough detail in the middle distance for an exact location yet.

Tolis, you are right about the time determining the direction if you base it on shadows, but we know the landing was mid-morning.

Phil


Posted by: John Moore Jan 3 2019, 08:37 PM

From mmatessa's animation, view of the shadows between each - Rover/No Rover - are shortening (note the change at the two small rocks nearby).

The sun is rising over the landed area, so, we must be viewing south as Phil suggests (if elsewise, looking northwards, the shadow changes would be reversed). The 'local sunset' mention may be due to that
of viewing the Moon from the Nearside, and anyways, why conduct a mission where the Sun is setting on the Farside, but more when it is rising - availing of its full potential to power-up (using the solar panels) the lander/rover overall.

John

Posted by: Decepticon Jan 4 2019, 01:59 AM

The pictures posted by China's media look like false color?


Are they using different color filters to bring details out?

The moon looks more like mars in the media released images.

Posted by: Phil Stooke Jan 4 2019, 03:23 AM

The surface images we have seen so far are just from a small monitoring camera - Chang'e 3 had several as well. The color is not accurate. We should soon see images from the much better cameras on the lander and rover, and they will have more realistic color.

Phil

Posted by: jccwrt Jan 4 2019, 10:20 AM

Edit: nevermind, wrong year. That will teach me not to post on no sleep...

Posted by: MahFL Jan 4 2019, 10:41 AM

QUOTE (jccwrt @ Jan 4 2019, 11:20 AM) *
Phil, here's a landing video you can probably use to pinpoint the landing site.

https://twitter.com/siyuan0zhao/status/1080671203315122177?s=19



That was the previous mission.

Posted by: charborob Jan 4 2019, 11:49 AM

Yutu 2 moved a few meters (http://www.cnsa.gov.cn/n6759533/c6805086/content.html):


Posted by: Station Jan 4 2019, 12:47 PM

short animation concerning recent lunar events wink.gif



Posted by: Station Jan 4 2019, 12:53 PM

I've just created the comparison of the Change 3 and 4 mission landing sites, well, first impression - very similar thanks to neighbouring small crater next to the lander's ramp wink.gif






Posted by: Steve G Jan 4 2019, 02:03 PM

I'm amazed by the lack of rocks. We'll have to wait for a full panorama to see what the rest of the landing site is like.

Posted by: neo56 Jan 4 2019, 02:59 PM

Animation showing the deployment of Yutu 2 rover wheel.gif The second picture is a low resolution caption of Chinese TV.
I desaturated the 4 pictures to obtain more realistic colors of Moon surface.


Posted by: Hungry4info Jan 4 2019, 04:48 PM

Anyone have any more information about https://twitter.com/LiuyiYiliu/status/1081163287159496706?

Edit: "After making the historic first tracks on the far side of the Moon, the Yutu-2 rover is going to enter "noon break" sleep mode til January 10, according to China's lunar program, as a precaution for high temperatures "

 

Posted by: Phil Stooke Jan 4 2019, 05:54 PM

The first Yutu did exactly the same thing. They may also need to wait for the lander's camera to provide a good panorama to help plan the traverse.

Phil

Posted by: charborob Jan 4 2019, 05:57 PM

QUOTE (Hungry4info @ Jan 4 2019, 11:48 AM) *
Anyone have any more information about https://twitter.com/LiuyiYiliu/status/1081163287159496706?

Edit: "After making the historic first tracks on the far side of the Moon, the Yutu-2 rover is going to enter "noon break" sleep mode til January 10, according to China's lunar program, as a precaution for high temperatures "


If you translate what is said in the link that I pointed to in my previous post (here it is again http://www.cnsa.gov.cn/n6759533/c6805086/content.html), that's what it says:
"After that, the No. 4 will usher in the high temperature test of the Lunar New Year. The patrol (= Yutu 2 rover) will enter the “noon break” mode and is expected to wake up on January 10." (Google translation)

Posted by: scalbers Jan 4 2019, 09:00 PM

Kind of neat to think of the rover taking a noon break when from the Earth's near-side perspective there's a new moon about that time.

Posted by: Hungry4info Jan 5 2019, 03:26 AM

https://mp.weixin.qq.com/s/7Eg-h_25VBO6_QjJiO_QIg

The three five-metre antennas for the radio spectrometer have been deployed, the German LND neutron dosimeter is working, and the lander's terrain camera is sending back images.

Posted by: Julius Jan 5 2019, 09:32 AM

Is the brown colour of lunar soil accurate? Is it dependent on lighting conditions on sun angle over horizon?

Posted by: MahFL Jan 5 2019, 10:04 AM

QUOTE (Julius @ Jan 5 2019, 10:32 AM) *
Is the brown colour of lunar soil accurate? Is it dependent on lighting conditions on sun angle over horizon?


No, it's a low res simpler contex camera, the Moon is not red.

Posted by: Webscientist Jan 5 2019, 01:49 PM

It is surreal to observe a surface devoid of any significant stones or rocks.
I imagine that the area is particular since we are in a large crater which appears quite flat from outer space. A large amount of volatile material resulting from the impact event must have filled the area. That's probably why, to a certain extent, the surface seems so cottony with a significant layer of dust (marking of the wheels).
I anticipate that we would have to dig to find the rocks.
I may be wrong but that's my impression at first sight.

Posted by: Steve G Jan 5 2019, 03:51 PM

There are examples during the Apollo missions with few rocks and boulders. This very excellent Apollo 14 picture illustrates that. (I took the liberty to remove the extremely annoying Reseau crosses.)


 

Posted by: wildespace Jan 5 2019, 04:59 PM

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



I'd like to share this image posted at the Above Top Secret forum (where genuine discussion about space missions does happen), I think this guy did some excellent detective work:



(orbital image is from Chang'e 2)
Source: http://www.abovetopsecret.com/forum/thread1225796/pg4#pid24085188

Posted by: Phil Stooke Jan 5 2019, 06:37 PM

That confirms the interpretation given in post #103 above in this thread. I am really looking forward to seeing the full horizon. I don't know if the central peak will be visible but it might be. A small hill 10 km north might be as well.

Phil


Posted by: Hungry4info Jan 5 2019, 07:34 PM

I took some of the frames Phil gave us from that control room footage and tried to stabilize the last couple of them, hoping to get an idea of where to look based off that. The imagery in the original video appears to move around in some areas and I'm not sure if this is just my own inability to follow the surface features or if the lander's autonomous hazard avoidance kicking in. Here's an animation of the last two frames, stabilized.



Based on this, and comparing it to imagery of the landing site, and knowing that there's a ~15-20ish metre crater just to the south of us, and assuming the lander continued all the way to the surface after the above animation without changing its course to avoid an obstacle, I think there's a good chance that the landing site is within a few metres of this location (marked with an X). Lat: -45.46738, Lon: 177.59876



It's not a perfect match, but I think it's a good candidate based on the above argument. I'm not very well satisfied with the difficulty in matching surface images seen in the rover deployment camera with what we see in this LROC image, but perhaps this can be explained with changes in illumination, and the difficulty in teasing out surface topology in a non-stereoscopic image at a more extreme viewing angle.

Posted by: Phil Stooke Jan 6 2019, 01:04 AM

I have been trying to make a match without success. This is as good as anything I had come up with. I was looking a bit further west.


http://m.bldaily.com/china/news/p-373798.html

A picture near the bottom of this report shows tentative plans for the early operations. It exactly mirrors what was done by the previous rover. Drive around the lander and image it from several positions.

Phil


Posted by: wildespace Jan 6 2019, 03:47 AM

After being deployed and travelling out for a short distance, Yutu-2 rover turned around 180 degrees for this photo:


(Source: http://www.abovetopsecret.com/forum/thread1228337/pg1 )

Hopefully, that means a photo of the lander coming up soon.

Posted by: John Moore Jan 6 2019, 05:22 PM

About the size of the crater - just a bit of supposition: let's say the rover travelled some 12 metres from the lander, and stopped some 7 metres before the edge of the crater, and then assume that the
wingspan of the rover is some 2 metres in all (not sure, the stats are probably available somewhere), then that would put the size of the crater at about ~ 22 metres (+/- a metre) in diameter.
If it is, in approximate, round that estimate, that's a pretty small crater to be looking for if just using the Quick-Map alone pushed at its max zoom. Therefore, one might have to go down the NAC route.

Posted by: scalbers Jan 6 2019, 06:06 PM

A somewhat similar view in Google Earth (switched to the moon).



Here is a video from Kaguya orbiting over Von Karman and Leibnitz, looking northward. Best view of the landing site is at about 0:27 into the video.

https://www.youtube.com/watch?v=D5oIoZkHYmY

Posted by: JRehling Jan 7 2019, 10:23 PM

QUOTE (Webscientist @ Jan 5 2019, 06:49 AM) *
It is surreal to observe a surface devoid of any significant stones or rocks.
I imagine that the area is particular since we are in a large crater which appears quite flat from outer space.


Material on a lunar plain is almost always either the reworked result of an impact locally or material flung long-distance from other impact(s). The material flying due to each impact will have its own function of distribution of size vs. distance (with, as we see looking at ray craters, some radial variation as well). To see a rockless site just tells us that somewhere in that function for some impacts is dust without rocks. But I wouldn't expect that to be, necessarily, a function of the immediate local history – it could be telling us about the impacts that occurred tens and hundreds of km away, and in what sequence.

Posted by: wildespace Jan 8 2019, 07:17 AM

QUOTE (JRehling @ Jan 7 2019, 10:23 PM) *
Material on a lunar plain is almost always either the reworked result of an impact locally or material flung long-distance from other impact(s). The material flying due to each impact will have its own function of distribution of size vs. distance (with, as we see looking at ray craters, some radial variation as well). To see a rockless site just tells us that somewhere in that function for some impacts is dust without rocks. But I wouldn't expect that to be, necessarily, a function of the immediate local history – it could be telling us about the impacts that occurred tens and hundreds of km away, and in what sequence.

Is the floor of Von Karman crater basically one big lava flood plain? That would explain the relative smoothness and the pits and groves observed in many place (collapsed lava channels?).

BTW, the nearby Leibnitz crater has some nice https://en.wikipedia.org/wiki/Lunar_swirls, caused by local magnetic fields deflecting solar wind. I wonder if Von Karman crater had some localised magnetic activity.

Posted by: threadworm Jan 8 2019, 03:46 PM

I'd forgotten I had an account here!

I made the image identifying the features in the background of the lander image smile.gif

I've also been busy downloading the Chang'e-2 data for the crater, and have made a 3D image of the hills in the distance, which you can get here:

https://www.dropbox.com/s/b0m5vb93rgozqkk/von%20karman2.zip?dl=0

Once extracted the open the index2.html file in either Microsoft Edge of Firefox (it won't work in Chrome). The base DEM layer is 20m resolution, and the photographic layer is the 7m resolution georectified (selenorectified?) on the 20m image. Here's a view from it:



I also did one from the Kaguya data:

https://www.dropbox.com/s/7je2v4ymzx1vhr5/von%20karman.zip?dl=0

same process for opening but this time the file is called index.html

Happy exploring smile.gif

Posted by: Phil Stooke Jan 9 2019, 04:45 AM

Very nice!

I have been going nuts, or as my kids might say, more nuts, trying to find the site in pre-landing LRO images. Not easy when we have so little to compare with the LRO image. There was supposed to be a new LRO image on about the 6th, but possibly it missed the site (???). This article:

https://www.businessinsider.com/china-far-side-moon-landing-change4-site-map-2019-1

says we have to wait until the end of the month.

For a while I thought I had a great clue. This tweet:



(Quanzhi was one of our students) shows somebody's idea of where the rover might go in the first week or so. Enlarging the middle of it we find this map:



For a while I thought the background might be a mission map made from descent images and I wasted many an hour looking for that pattern of craters. Then it dawned on me - it's the Chang'e 3 site flipped north-south! So still no idea.

Phil

Posted by: Phil Stooke Jan 9 2019, 07:33 PM

https://www.weibo.com/ttarticle/p/show?id=2309404326646026003185

This article was linked from the CLEP Weibo account. Link to it in Chrome to get a rough translation. It does not have much new in it but talks about the reason for taking a break in the middle of the day, to protect components from overheating. It confirms the lander is continuing to operate.

Chang'e 3 and Yutu did the same thing - a nap in the middle of the first day as a precaution against the noon heat. And it did it at the same place, after the second drive. If my memory is correct they did not plan to do this in the second day, but that is roughly when Yuyu stopped working. At the time I thought it might have been a heat-related problem, but we know now that it was an electrical fault instead. So it will be interesting to see if they do that again in lunar day 2.

The Lunokhods also took breaks around noon, but that was more to do with visibility for driving.

Phil

Posted by: Hungry4info Jan 11 2019, 02:07 AM

Panoramas!
http://www.xinhuanet.com/english/2019-01/11/c_137735844.htm
https://www.weibo.com/ttarticle/p/show?id=2309404327207332888406

 

Posted by: Phil Stooke Jan 11 2019, 02:56 AM

At last! They are great. Here's a circular version in my geometry. Much more on the horizon than I expected.

Phil


Posted by: Phil Stooke Jan 11 2019, 03:00 AM

And that takes us immediately to the landing site:



Phil

Posted by: charborob Jan 11 2019, 03:06 AM

High resolution panorama:
http://www.cnsa.gov.cn/n6758823/n6758842/c6805147/content.html

Posted by: Explorer1 Jan 11 2019, 03:14 AM

Wow! Right between those craters; my congratulations to the landing hazard avoidance team! Great rim views too.
Strange to think this is a landscape (unique in the solar system and probably the galaxy!) where Earth is never visible, yet its right next door....


Here's a rotated version of the vertical (Chinese-style?) panorama charbob posted:

 

Posted by: neo56 Jan 11 2019, 06:44 AM

I made a 360x180 version of the panorama and put it https://roundme.com/tour/350106/view/1179570.

Posted by: threadworm Jan 11 2019, 09:18 AM

Fantastic stuff - great detective work all round smile.gif

Just shows how deceptive distances are - I'd drawn some projection lines to the edge of the crater along the rover tracks and come up with a measurement of about 16m across for the crater immediately to the south but it looks to be more like 25m.

I've been looking at other sources for surface images and from what I can tell Japan's data is either too patchy or too dark to get a good look. India does have a swathe covering the crater but it is some way to the west of the landing zone, but if anyone wants to download it it's on orbit 3021 from the Chandrayaan site.

https://issdc.gov.in/CHBrowse/index.jsp

If you aren't registered you won't be able to browse to it, hence no direct link. It does at least show the craters to the north and south. There is another pass covering the far east of the crater, but frustratingly it's yet another one of those that is shown on their map but has no link and doesn't seem to be listed when you search for it.

Their own Chang'e-2 imagery barely catches the landing site.


Posted by: threadworm Jan 11 2019, 09:45 AM

The full resolution video has now been released:

http://www.cnsa.gov.cn/n6758823/n6758838/c6805157/content.html

Would have saved us a lot of time biggrin.gif

Here's a screenshot from the final stages.


Posted by: wildespace Jan 11 2019, 10:55 AM

Yass! Now we see the landing site properly.

Here's 360-degree panorama from the master Andrew Bodrov: http://www.360cities.net/image/first-lunar-far-side-panorama-change-4

Posted by: GoneToPlaid Jan 11 2019, 12:02 PM

Attached is an enhanced LRO image of the Chang'e-4 landing site.




 

Posted by: charborob Jan 11 2019, 12:40 PM

It looks like Yutu-2 made an almost 180-degree clockwise turn around the lander in order to photograph the side of it showing the Chinese flag:
http://www.cnsa.gov.cn/n6759533/c6805166/content.html

Posted by: elakdawalla Jan 11 2019, 06:12 PM

Here is the mp4 of the landing. As far as I can tell, it contains all the full-resolution frames in order with numbers and time stamps. The computer I'm working on today choked when I tried to export all the frames using Photoshop, or I would've posted the whole archive for you. If someone is able to do that, I'd be glad to host them on our S3 server.

https://planetary.s3.amazonaws.com/assets/images/3-moon/2019/ce4-descent-video-clep-cnsa.mp4
Credit: CNSA / CLEP

Posted by: stevesliva Jan 11 2019, 06:48 PM

Amazing how fractal the cratering is. Well, amazing when I realize I have no idea of vertical height when looking straight down. Otherwise I suppose it's about to be expected.

Posted by: neo56 Jan 11 2019, 08:42 PM

QUOTE (Phil Stooke @ Jan 11 2019, 04:00 AM) *
And that takes us immediately to the landing site:


Phil, where did you download this picture? I'm on the QuickMap LROC website but the resolution is not as good as your picture.

Posted by: charborob Jan 11 2019, 08:44 PM

I tried superposing Yutu-2's latest position on part of the panorama:


Posted by: Phil Stooke Jan 11 2019, 09:07 PM

"Phil, where did you download this picture? I'm on the QuickMap LROC website but the resolution is not as good as your picture."

This is the original image data, not the version used in Quickmap which is not nearly as nice.

In Quickmap you can use a selection tool to outline a polygon, and get a list of all LRO images crossing that area (the list is not really the full data set, some frames are not included depending on when it was last updated). Each item in the list is a link to a page which lets you zoom in on the image or download the raw data. I download the CDR 16 bit version.

You can also search for LRO camera images from their website:

http://wms.lroc.asu.edu/lroc

That is more likely to have everything currently available.

My next step is to use the landing video images to supplement the LRO coverage.

Phil

Posted by: HSchirmer Jan 11 2019, 10:05 PM

QUOTE (stevesliva @ Jan 11 2019, 06:48 PM) *
Amazing how fractal the cratering is. Well, amazing when I realize I have no idea of vertical height when looking straight down.

I've heard from family who flew over the Atlantic, Pacific and Gulf of Mexico that ocean waves are fractal.
You can't tell vertical height by looking down, waves at 10-feet up look just like waves at 100-feet up, which look just like waves at 1,000-feet up. That's why, when you're on a parachute, you don't look down; you look at the horizon to judge altitude, and you don't release the parachute harness until your feet hit the water.

- Interesting whether the fractal dimensions of cratering might constrain the atmospheric properties of moons and planets?

Curious- are there any papers on "fractal dimensions of lunar craters" addressing the range of sizes?

Posted by: neo56 Jan 11 2019, 10:07 PM

Thanks Phil. The resolution of images on the quickmap was enough to locate the landing site.
Here is a montage I did to help locate it.

https://www.flickr.com/photos/thomasappere/46653256822/sizes/o/

And my guess on the orientation of Chang'E 4 based on the shadows and position of craters:


Posted by: wildespace Jan 11 2019, 11:36 PM

QUOTE (neo56 @ Jan 11 2019, 08:42 PM) *
Phil, where did you download this picture? I'm on the QuickMap LROC website but the resolution is not as good as your picture.

For everybody's convenience, here's a high-quality NAC strip of the area:

http://wms.lroc.asu.edu/lroc/view_lroc/LRO-L-LROC-2-EDR-V1.0/M134022629LE

The landing site is slightly below the centre of the image strip.

200% scale crop:


Posted by: Phil Stooke Jan 12 2019, 06:25 PM

I know several of us were looking for the landing location in images like these before we saw the panorama. I looked at this place among many others, but I thought the hazard avoidance system would divert the lander away from a place like that which is surrounded by craters. There are nice smooth spots close by, to the west or northeast. But it's all about the scale of the hazard avoidance, I suppose. We did get a nice level area between the craters.

Phil

Posted by: Phil Stooke Jan 12 2019, 10:23 PM

While waiting for news of any activity on the 12th, here is a comparison of horizon features between the panorama and an LRO wide angle (heavily processed) image.

The central peak is visible, but Ba Jie crater is not. More than half of the horizon is the rim of Von Karman. The small hill about 10 km north of the lander, which might make a good target for the traverse, is probably visible as a low ridge labelled X here.

Phil



EDIT: My crater 'C' might be the one higher up on the rim of the main crater, with ridge D adjacent to it.

Posted by: wildespace Jan 13 2019, 08:19 AM

QUOTE (Phil Stooke @ Jan 12 2019, 06:25 PM) *
I know several of us were looking for the landing location in images like these before we saw the panorama. I looked at this place among many others, but I thought the hazard avoidance system would divert the lander away from a place like that which is surrounded by craters. There are nice smooth spots close by, to the west or northeast. But it's all about the scale of the hazard avoidance, I suppose. We did get a nice level area between the craters.

Phil

The landing footage shows the craft pausing briefly when over that location, seemingly detecting an even space between those craters, and "making the decision" to land there. Simple and effective, just like what Chinese would do.

https://www.youtube.com/watch?v=JJi_YEubKCY&t=1m54s

Posted by: wildespace Jan 13 2019, 08:46 AM

"The space probe is moving south across the Mün"

Excellent video processing and analysis here. https://www.youtube.com/watch?v=unEbg_dt3DM

Posted by: Huguet Jan 13 2019, 02:02 PM

Panoramas from chang'e-3 and chang'e-4. I expected the number and pattern of the impact craters to be more diferent beetween the two landing sites, it apears to have double of small craters (less than 1 meter) on the darkside.

 

Posted by: Thorsten Denk Jan 13 2019, 02:19 PM

I think we have to be careful with generalizing
"lunar farside" = "heavily cratered" = "this landing spot".

The first "=" is generally true,
but the specific Cháng'é-4 landing site
is a lava flooded crater and hence
should rather have properties of (near side) Mare areas.
Untypical for far side in general.

The difference in craters should be more indicative
to age than to "near" vs "far" side.

Thorsten

Posted by: Steve G Jan 13 2019, 08:03 PM

Chang'e 3 landed on lunar maria, Chang'e 4 on lunar highlands, which is a big difference especially in age, so I'd expect more craters in a highland area. Of course, that depends on the age of the basin in Von Karman.

Posted by: Phil Stooke Jan 14 2019, 05:51 AM

Von Karman is filled with basalt lava flows, probably not very different in age than typical mare basalts on the Earth-facing side of the Moon. Von Karman is in the highlands but its floor is not highland, in other words. But these things are deceptive. Because highland surfaces are older they have a thicker regolith, and it affects the survival of small craters during impact-generated siesmic shaking. Sometimes highland surfaces can look smoother and younger just because their craters are more softened by shaking. A slope helps that process, so the rolling topography of highland areas is ideal for erasing craters in this way.

Here is an example from Flamsteed, the almost completely buried crater in which Surveyor 1 landed in 1966. Mare basalt at the top, low relief highland surface at the bottom. The image is about 800 m wide, 1.9 south, 43.0 west. More craters in a given area on the mare, but the highlands are older. At this scale they just don't preserve craters. Larger craters are not erased this way so at broad scales the basic rule 'older = more craters' is true.

Phil


Posted by: kenny Jan 14 2019, 07:30 PM

Lovely little color video of Yutu-2 driving away from the Chang'e-4 lander and executing the 180 degree turn ...

https://www.youtube.com/watch?time_continue=56&v=1ZmYX5nVwLc

Posted by: Hungry4info Jan 15 2019, 06:42 AM

China's Chang'e-4 probe conducts first bio test on moon as first plant grows
https://news.cgtn.com/news/3d3d414f7949444d32457a6333566d54/share_p.html

Edit: From https://gbtimes.com/change-4-cotton-seeds-are-sprouting-on-the-far-side-of-the-moon Global Times article.

QUOTE
Chinese media state that the experiment contains six species: cotton, rapeseed, potato, arabidopsis, fruit fly and yeast, with Xinhua reporting that no signs of growth have been found among the species other than cotton.


 

Posted by: GoneToPlaid Jan 15 2019, 09:03 AM

[quote name='Phil Stooke' post='243419' date='Jan 13 2019, 09:51 PM']Von Karman is filled with basalt lava flows, probably not very different in age than typical mare basalts on the Earth-facing side of the Moon. Von Karman is in the highlands but its floor is not highland, in other words...

Phil

Very true. In fact, where Chang'e-4 landed is approximately -6km relative to the moon's mean radius. Definitely not highlands, and instead is lowlands within the huge Von Karman crater floor.

Posted by: Phil Stooke Jan 15 2019, 06:41 PM

I have been following the discussion here:

http://www.9ifly.cn/thread-5819-70-1.html

(in translation) which seems to be saying that a power failure has ended the biological experiment. Does anyone have any other information?

Phil

Posted by: Explorer1 Jan 15 2019, 08:03 PM

This (English) article says they were powered down for sunset (i.e. the experiment would not go past lunar night).
https://news.cgtn.com/news/3d3d414f7949444d32457a6333566d54/share_p.html

QUOTE
Now it is night on the Moon and the temperature has dropped to nearly 180-degree centigrade below freezing. All the equipment has powered down, and the remaining seeds and animals will be gradually decomposed down to organic fundamentals.

Posted by: Phil Stooke Jan 15 2019, 08:38 PM

OK, that's good. I had thought it was supposed to work through the lunar night with warmth and artificial light, though I know it piped in natural light during daylight. It does seem like a useful next step would be to allow longer operation on a future mission. Maybe that is more suited to polar missions, which we know are in the plan.

Phil

Posted by: wildespace Jan 16 2019, 11:30 AM

What the landing site will look in early morning. High incidence angle (86.68 degrees) view from http://wms.lroc.asu.edu/lroc/view_lroc/LRO-L-LROC-3-CDR-V1.0/M178833263LC


Posted by: Phil Stooke Jan 17 2019, 03:37 AM



I saw this picture tweeted on the 11th or 12th and then couldn't find it again to save it. Now I found it on this site (near the bottom):

http://py.qianlong.com/2019/0116/3064840.shtml


It is from the last position on the first lunar day, looking back on the tracks from that day's drive. Does anyone have a better version of it?

Phil

Posted by: kenny Jan 17 2019, 10:45 AM

According to the Google image-matching search function, that is the only version of that image on the internet at the moment.
Google's best guess for the subject of that image is a River Clyde steamer ! smile.gif

Posted by: Huguet Jan 17 2019, 01:23 PM

Yutu 2 will have a hard time avoiding all that craters, he will need to be making adjustments at almost every meter.

Posted by: John Moore Jan 17 2019, 08:31 PM

Looks like the top-left (squiggly) tracks are those where it stopped at the crater south (classic image, well-published at this stage), the rover did a 180 deg there (and more), and from the current image,
we're still looking back southwards as the Rover travelled north after two wheel-abouts (the Lander would be to the left - some several metres away).

Have a simulated image put together of the possible track, but it would have been poor to post.

The stopped-off position of the Rover is well within the lunar night-time -175 deg C temperatures now; waiting for further activation round the 28/29 Jan 2019. Fingers crossed.

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