Author Topic: LIVE: Chang'e-3 lunar probe and rover Lunar Landing December 14, 2013  (Read 470818 times)

Offline Dalhousie

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What's always difficult with Moon landing videos (i.e. also the same with Apollo vids) is how hard it is to get a sense of altitude above the ground. Seeing the horizon helps somewhat, but I think its curvature is exaggerated by the camera lens.

From my subjective perspective it looked about right.  I assume the camera experts among us can clarify this,

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As the lander gets closer and closer to the lunar surface, more and more craters appear that look just like the bigger craters seen from higher up, so it's like a never-ending fractal image.

It certainly looks like that!  But it's not strictly correct, as the Mare surface is not saturated with craters of this size, unlike the lunar highlands.  So there are lots of flat areas between the craters.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Dalhousie

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The Apollo TV images might have been brownish due to the TV quality but the Hasselblad images all show a very grey landscape

http://www.apolloarchive.com/apollo_gallery.html

Keith

The lunar surface actually shows a range of subtle colours depending on phase angle and composition.  Different parental rocks have different tones of grey, and lunar volcanic and impact glasses can be grown, green, or orange.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Star One

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Thanks for the link & no doubt we'll see Chang'6 as well as its backup. Makes you wonder what Chang'e 7 will be.
In addition to previous announcements discussed up in the thread, multiple sources just put out this story too

http://uk.reuters.com/article/2013/12/16/us-china-space-idUKBRE9BF03N20131216

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(Reuters) - China aims to launch its next unmanned lunar probe in 2017, with the key aim of collecting and bringing back lunar samples, an official said on Monday, after the country's first probe landed successfully on the moon over the weekend.
The development of the Chang'e 5 probe, tasked with the moon sampling mission, is well underway and it is expected to be launched around 2017, a spokesman for the State Administration of Science, Technology and Industry for National Defense said.

Note that a couple days ago there were some possibly misreported stories about Chang'e 5 being put on hold or delayed.

Another note, in the morning CCTV live coverage there was a segment with Indian space jouranlists, who mentioned that Chandrayaan-2 could fly in a "year or two", although written reports all refer to "about three years from now"


The Chang'e 3 design is adaptable to sample return is it not?


Offline jumpjack

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The Chang'e 3 design is adaptable to sample return is it not?


Looking at how big is the lander, probably it's just a matter of replacing the rover by the "samples collector", which would be heavier and bigger.
I think we should look for Chang'e 4 and 5 designs to figure out the sampler design, if they are already available.
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Offline JT355

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The Chang'e 3 design is adaptable to sample return is it not?


Looking at how big is the lander, probably it's just a matter of replacing the rover by the "samples collector", which would be heavier and bigger.
I think we should look for Chang'e 4 and 5 designs to figure out the sampler design, if they are already available.
I think I saw somewhere that for Chang'e 5 they are going to do an automatic docking in lunar orbit of the sample return vehicle and a booster module which will then take the sample back to the Earth, similar to how Apollo returned the astrounauts from the lunar surface. This is different to the Soviet sample return missions in that the launcher from the lunar surface went directly back to the Earth. I think this is a stepping stone to a manned mission after Chang'e 6 when they have mastered automatic lunar orbit docking technologies.

Offline saturnapollo

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The lunar surface actually shows a range of subtle colours depending on phase angle and composition.  Different parental rocks have different tones of grey, and lunar volcanic and impact glasses can be grown, green, or orange.

Only when you are relatively close up. The general view of the surface from any distance is grey. Not a chocolate brown as in these photos. Did you look at any of the surface photos on the link I posted?

During Apollo the only photos generally available to the public were in mainsteam magazines (Time, Life, Newsweek, Paris Match) and due to print quality in these days, the lunar surface ranged from green through brown. You now have access to these same photos in sites like Kipp Teague's and can see the true colour quality in the properly processed images from the original films.

These photos we are seeing now remind me very much of the magazine photos in the 60's. I don't know what type or quality of cameras are aboard and it may be that these are just RAW images which need further processing. However the Chinese are not noted for releasing high res images.

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The difference between Earth and the Moon is that the light curves are significantly shifted by the filtering of the atmosphere. What is "white" on Earth under natural light would not be white under direct unfiltered sunlight.

Exactly. Comparing photos of the LM under different lighting is a good example. On earth the black foil of the Descent Stage is just that - black. However on the surface of the Moon it looks a light to mid grey (and there are a lot of extreme closeups taken on the J-series of missions) and it doesn't just look like washed out black - these are properly exposed images.

Keith

Offline akula2

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My hearty congratulations to all Chinese who're involved in this wonderful mission. ESA too. I loved the content of both threads (quality time!), so many thanks for the invaluable contribution.

Please keep all those videos and photos coming  8)

Last but not least: Chang'e baby stay healthy and safe! Good luck to your historical mission  :)



Offline lucspace

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I wonder when (if?) we are going to see the further four photos of the lander that Yutu was supposed to take over the past 20 hours...

Offline savuporo

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Xinhua reports that scientific equipment has been turned on now without much details.

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Yutu's radar started working Sunday night to test the structure of lunar soil, according to Zou.

"Chang'e-3 will study the Moon's landforms, geological structure, substance, and potentially exploitable resources," he said, adding, "the lander will observe the Earth's plasmasphere through telescopes."
I like how often they keep bringing up exploiting resources. They talked about it at length yesterday in the CCTV live cast too. Hopefully the concept will become a globally understood idea.

Another observation, "Moon" and Chang'e have stayed as the 3-5th top story in the global news throughout the weekend.
« Last Edit: 12/16/2013 04:16 PM by savuporo »
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Offline elakdawalla

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Regarding the reason for the rover's HGA being on the mast: I'm pretty sure that the mast folds back down onto the body and one of the solar panels folds back over the mast during noon and night for thermal protection. (I've seen this in animations but can't recall seeing it described thus in print, so I'd welcome corroboration or denial.) This is only speculation, but: having HGA on the mast means you only have one thing you need to fold down into the body for thermal protection to work, a simpler design than having several foldable/deployable things.

Offline Robotbeat

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Congratulations, China, and well deserved! Now go for a manned mission to the Moon; it's the only way NASA's getting a budget increase! :)
« Last Edit: 12/16/2013 10:07 PM by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline Dalhousie

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The lunar surface actually shows a range of subtle colours depending on phase angle and composition.  Different parental rocks have different tones of grey, and lunar volcanic and impact glasses can be grown, green, or orange.

Only when you are relatively close up. The general view of the surface from any distance is grey. Not a chocolate brown as in these photos. Did you look at any of the surface photos on the link I posted?

Yes, and thousands of others.

Certainly the Moon is overall greyish, but there are subtle (and occasionally not so subtle) colour differences due to composition, texture  and phase angle.  Even a very modest stretch will bring these out, even in photos of the Moon through a small telescope.  Astronauts also referred to seeing these.

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During Apollo the only photos generally available to the public were in mainsteam magazines (Time, Life, Newsweek, Paris Match) and due to print quality in these days, the lunar surface ranged from green through brown. You now have access to these same photos in sites like Kipp Teague's and can see the true colour quality in the properly processed images from the original films.

These photos we are seeing now remind me very much of the magazine photos in the 60's. I don't know what type or quality of cameras are aboard and it may be that these are just RAW images which need further processing.

I was reminded much the same

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However the Chinese are not noted for releasing high res imagery

It's a bit early to be making such criticisms.  I am sure we will see plenty of good images in the months to come. 
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline savuporo

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However the Chinese are not noted for releasing high res imagery

It's a bit early to be making such criticisms.  I am sure we will see plenty of good images in the months to come. 

It's also a false accusation. Chang'e-1 and Chang'e-2 full resolution imagery and scientific instrument data can be obtained from here
http://159.226.88.59:7779/CE1OutENGWeb/

This is the initial data release announcement
http://meetingorganizer.copernicus.org/EPSC-DPS2011/EPSC-DPS2011-995-1.pdf

For example see this paper using this data:
http://www.lsgi.polyu.edu.hk/staff/Bo.Wu/publications/Wu_2013_EPSL_Co-registration_of_lunar_topographic_models_derived_from_ChangE-1_SELENE_LRO.pdf
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The Chang’E-1 data are currently publically available in Planetary Data System (PDS) format through the Lunar Exploration Data Release System (http://159.226.88.59:7779/CE1OutENGWeb/step.jsp).

http://paviavio.wordpress.com/2010/11/22/maybe-change-1-images-are-indeed-online/
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According to the status report of data publishing, three international organizations among 50 institutes have provided data to this website. They are:
      International Lunar Observatory (ILO) 2009.3.6
      European Space Agency (ESA) 2009.5
      Sternberg Astronomical Institute of Moscow State University 2010.3.31

And, officials have stated repeatedly that Chang'e-3 data will also be shared, presumably through similar means
http://news.xinhuanet.com/english/china/2013-12/14/c_132968313.htm
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Space exploration is the cause of mankind, not just "the patent" of a certain country. China will share the achievements of its lunar exploration with the whole world and use them to benefit humanity.

It is learned that all data obtained by Chang'e-3 will be open to the whole world. China's lunar exploration provides an opportunity for countries dedicated to peaceful use of outer space to advance space technology together.
« Last Edit: 12/17/2013 04:33 AM by savuporo »
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Online Steven Pietrobon

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Here are some snapshots taken during the descent about 30 or 15 seconds apart. The first shot shows the major features seen, Montes Recti (stop sniggling at the back there), craters Lapace F and Laplace FA, and the dark and light mare areas. Chang'e 3 landed in the dark mare. I've shown this as a red + in each image. During the turn in the latter images, the landing area disappears from view, so I've used other coloured +'s so as to track what you are seeing. In image 15, the + is over a white area, which is dust being stirred up by the engine. The next image shows the white area gone, due to the engine being turned off. I presume the dust seen just before final touchdown is due to the engine being briefly turned on to soften the impact of landing.
« Last Edit: 12/17/2013 06:38 AM by Steven Pietrobon »
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Offline akula2

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Congratulations, China, and well deserved! Now go for a manned mission to the Moon; it's the only way NASA's getting a budget increase! :)
NASA budget $35 Billion for 2013-14 is more than entire BRIC + Japan!

Unlike the ISS (without too much $-burden on one nation), I'm confident that few nations genuinely participate in the future Planetary and Deep space missions...
« Last Edit: 12/17/2013 07:00 AM by akula2 »

Offline AJA

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One thing I don't see is a color reference plaque to aid in color correction and white balance of the images, like we see on the Mars landers.  One red flag doesn't help much. ???


When we say colour calibration... what exactly are we going for? To mimic how something will look to the human eye? How is that objective? Also, apart from sensor drift, and different electronic noise etc. - what optical difference exists between the Earth and the moon environment that requires re-calibration once on the moon? A moonwalker would also face these different optical conditions (outside of his helmet i.e.) too .... so are we really calibrating, or distorting?

The difference between Earth and the Moon is that the light curves are significantly shifted by the filtering of the atmosphere. What is "white" on Earth under natural light would not be white under direct unfiltered sunlight.

Yeah... that's all fine.. but what I'm asking is: on what basis do we claim that the image carries more scientific information if it's colour corrected to "look like it would on Earth"

Think of it like this: All you need for the science is intensity information vs wavelength - ideally a continuous spectrum, but we'll take the usual 3 discrete channels. The science doesn't care whether that information is represented in one composite image (of all three channels) or whether it's three separate grayscale images in each of the RGB channels.

So, really - you're only combining the channels for the aesthetic qualities. Which now begs the question - why would you manipulate the image to look as if it will look on Earth? A human being on the lunar surface, would also notice that the colours are different on the moon. I would've thought you'd WANT that. If you want the image to convey that it was taken on the moon - then you'd leave it as it is...

The "weirdness" of the images, IMO, is the reason for the "surprisingly large amount" of attention this landing, and the pictures are getting. There's a stark contrast between a black sky and the brightly lit foreground ... and it screams "SPACE!"


The pictures from Mars - with the atmosphere, and softer contrast - look like Peter Jackson found a sepia lens, and another virgin part of New Zealand.


EDIT: Also, thinking about it now..the atmospheric distortion of the intensity spectrum can be estimated fairly easily by taking an image of the same target from different distances (differing amounts of scattering in the images) - provided that the FOV is the same, and the incident light has the same characteristics (so two images in rapid succession, or two images at the same time of day). Apply different models of scattering to determine which one replicates the data - and you now also have information about the atmosphere...
« Last Edit: 12/17/2013 07:23 AM by AJA »

Offline jumpjack

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I found an image showing how sample returner will probably be designed: just a "payload change" and a robotic arm added (maybe the lander already is equipped with a "slot" where to mount it):
http://bbs.9ifly.cn/data/attachment/forum/month_1101/1101031102466ce5de6bac2abd.jpg

http://bbs.9ifly.cn/forum.php?mod=redirect&goto=findpost&ptid=4587&pid=103735&fromuid=27122
« Last Edit: 12/17/2013 12:07 PM by Chris Bergin »
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Offline Phillip Clark

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Actually, the common descent stage was obvious from what the first concepts of the Chang'e 3 lander and Chang'e 5 sample-return mission were published.   What is missing from the above is the Earth return stage which remains in selenocentric orbit.
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Offline jumpjack

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Here are some snapshots taken during the descent about 30 or 15 seconds apart.
Nice work.
Are you able to put into just one image a scale showing size of a crater or distance between two craters?
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Offline jumpjack

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Here are some snapshots taken during the descent about 30 or 15 seconds apart.
Nice work.
Are you able to put into just one image a scale showing size of a crater or distance between two craters?
Returning just a rock or sand to Earth souldn't be that difficult: place it inside a small box with kevlar walls 5 cm thick, placed in the ascent module, use the ascent module itself to go back to Earth in all the time you need (1 week, 1 month, 1 year...), make it just fall down into the atmosphere , approximately calculating where it will finally impact on ground (Chinese desert ? Low depth area of Ocean?).
The kevlar box will arrive to ground with just 1 cm kevlar thickness remaining, it will dig up a 10 meters crater, but you will be still able to recover samples...

I suppose Chang'e3 lander is already designed for manned missions, so it should also be able to carry a descent module powerful (and then heavy) enough to also be used as a re-entry module.

Too simple?   ::)
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