Author Topic: LIVE: Chang'e-3 lunar probe and rover Lunar Landing December 14, 2013  (Read 321944 times)

Offline OzWill

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Nice!

One Q springs to mind - is the rover able to operate independently, out of visual range from the lander?

Thanks to Emily Lakdawalla and her translation of a press briefing, seems like the rover can operate by itself.

Quote
Wu Weiren also talked about the rover having autonomous navigation capability. The Soviet Lunokhods required television monitors and continuous round-the-clock shifts of drivers to manually tele-operate them. Wu said that Yutu can be operated in this mode, but that there is also a "completely independent operation mode" in which it can be navigated to waypoints. It can avoid obstacles using both long- and near-distance stereo vision through navigational cameras on the mast and hazard avoidance cameras on the body, just like NASA's Mars rovers. "If a stone is too big, the rover will automatically turn, then go around it." [15:41]

Offline Lars_J

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Nice!

One Q springs to mind - is the rover able to operate independently, out of visual range from the lander?

Thanks to Emily Lakdawalla and her translation of a press briefing, seems like the rover can operate by itself.

Quote
Wu Weiren also talked about the rover having autonomous navigation capability. The Soviet Lunokhods required television monitors and continuous round-the-clock shifts of drivers to manually tele-operate them. Wu said that Yutu can be operated in this mode, but that there is also a "completely independent operation mode" in which it can be navigated to waypoints. It can avoid obstacles using both long- and near-distance stereo vision through navigational cameras on the mast and hazard avoidance cameras on the body, just like NASA's Mars rovers. "If a stone is too big, the rover will automatically turn, then go around it." [15:41]

My question was not really related to navigation - it is more about communication ability. Can the rover operate independently of the lander on a long trek?

Online hop

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My question was not really related to navigation - it is more about communication ability. Can the rover operate independently of the lander on a long trek?
The big HGA on the rover mast says yes ;)

Offline plutogno

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plus, IIRC there is a beyond-the-horizon radio link with the lander
I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.
James Van Allen

Offline OzWill

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My question was not really related to navigation - it is more about communication ability. Can the rover operate independently of the lander on a long trek?

Did some digging, according to this report (sorry, in Chinese), the lander can relay data from Yutu, but both the rover and lander can communicate directly with Earth.

Offline AJA

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plus, IIRC there is a beyond-the-horizon radio link with the lander

The moon has a beyond-the-horizon radio-comm facilitating ionosphere?

Offline MadCow

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Don't know if these have been posted:


Offline plutogno

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to the Chinese speakers: any new info?
I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.
James Van Allen

Offline MadCow

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Not much new, apart from confirming the distance of each spot they took photos of each other. A - approx. 9 metres from the lander, B/C/D- approx. 10m, E - approx 18m. The big bold text reads: 5 spots, 5 angles.

Read a post from 9ifly, Mr Weiren Wu (chief desinger of Chang'e project) said on CCTV the instruments (or maybe he meant the vehicles) fared better than they expected in term of adapting the extremely high and low temperature. So he expected they should have a longer life span than original expected.

Online savuporo

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plus, IIRC there is a beyond-the-horizon radio link with the lander

The moon has a beyond-the-horizon radio-comm facilitating ionosphere?

Apparently, the answer is not as obvious as you would think.
http://ntrs.nasa.gov/search.jsp?R=20080046911
Quote
   Long-range, over-the-horizon (transhorizon) radio wave propagation is considered for the case of the Moon. In the event that relay satellites are not available or otherwise unwarranted for use, transhorizon communication provides for a contingency or backup option for non line-of-sight lunar surface exploration scenarios. Two potential low-frequency propagation mechanisms characteristic of the lunar landscape are the lunar regolith and the photoelectron induced plasma exosphere enveloping the Moon



Google for "Path Loss Prediction Model of Radio Propagation over Lunar Surface"

http://link.springer.com/chapter/10.1007/978-3-642-25002-6_77#page-1
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070025224_2007025210.pdf

Anyone want to bet that Chang'e/Yutu have 1Mhz tansceivers ?

EDIT: actually more likely, i would think they will have variable frequency transceivers and they'll run some surface radio propagation experiments across the likely frequency ranges.
« Last Edit: 12/22/2013 08:03 PM by savuporo »
Orion - the first and only manned not-too-deep-space craft

Offline Blackstar

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Not whining, cobber. No huhu.  Just saying that China is slow to share original data compared to NASA and ESA.

I think this is quite understandable. They are still building up experience, they are not a democracy, they have to learn how to manage public outreach.

SNIP

Actually I'm amazed by seeing this coverage for this mission. Respect to the past it looks to me quite an improvement. Derivative matters, not absolute value.

It is worth comparing what we are seeing from China on their space efforts with what we saw from the Soviet Union during the Cold War. They almost never announced a launch, even a scientific launch, before it happened. And does anybody know of a Soviet-era launch that was shown live on television? In addition, the Soviets did not provide details about spacecraft or mission goals prior to launch, and often only released bits of information after the fact.

In contrast, China has been quite open about their human and science space programs (and very secretive about their military space programs). They regularly discuss at scientific conferences their upcoming plans. And of course the CE-3 launch and landing were both carried live on television. If they had failed, it would have been a public embarrassment to China.

But I think you pointed out two important facts:

A-they are not a democracy
B-they are still leaning about how to do this

NASA had long experience operating in the open and therefore it is now easier for them to be open than to conceal things. China doesn't have that experience, and they have an authoritarian government that doesn't reward openness and often punishes it (after all, they have people who censor the internet and international television).

But I have a question: they have said that they are going to put the CE-3 information into the Planetary Data System. Does that include imagery? If so, it may be possible to get high quality imagery out of the PDS even if the Chinese don't directly release it to the press.

Online savuporo

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But I have a question: they have said that they are going to put the CE-3 information into the Planetary Data System. Does that include imagery? If so, it may be possible to get high quality imagery out of the PDS even if the Chinese don't directly release it to the press.
You are slightly misstating them. Existing CE-1 and CE-2 have been published in the same format as PDS uses, but they are not in NASA PDS, they have their own publishing system - Ground Research & Application System (GRAS)
And as stated above, yes they have high resolution imagery in their data releases.

See here http://meetingorganizer.copernicus.org/EPSC-DPS2011/EPSC-DPS2011-995-1.pdf

Quote
The format and naming convention of the CE-1/CE-2 data products follow the PDS ( The Planetary Data System ) standards issued by NASA. These ensure that, without knowing specific information about the payloads, the persons who have acquired data are able to use them directly and easily.

They have a tracker on their english site too showing numerous researchers across the world having obtained the data.
« Last Edit: 12/23/2013 12:31 AM by savuporo »
Orion - the first and only manned not-too-deep-space craft

Offline Steven Pietrobon

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A-they are not a democracy
B-they are still leaning about how to do this

Two very good points. I thought the coverage has been quite good, but one aspect they could improve on is providing a Press Kit. For western media I think it would be a big help in covering their future missions.
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Blackstar

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A-they are not a democracy
B-they are still leaning about how to do this

Two very good points. I thought the coverage has been quite good, but one aspect they could improve on is providing a Press Kit. For western media I think it would be a big help in covering their future missions.

I think that's a good point. There was in fact a substantial amount of information on this mission prior to launch, but it was not clearly collected in a single place. A good thing for them to do would be to have a press kit in both Chinese (Mandarin? I admit my knowledge of the languages they use is skimpy) and English.

There is another aspect to this issue and that is what is government policy vs. their culture. They may not do things the way Westerners expect simply because that's a cultural issue, not part of their official policy or rules. A colleague who works with the Japanese space program a lot has told me that it is common in their culture to never provide a definitive "no." They will often hedge and be vague, and you either have to understand how to read what they are really saying, or go out for drinks with them afterwards and coax a real answer out of them. He said that there was a clear contrast during meetings between the Americans, who wanted to get clear yes/no answers and emerge with a clear agreement, and his Japanese counterparts, who were concerned with many other things, such as saving face or not offending their partners.

So, for instance, somebody suggested much earlier in this thread that China doesn't provide launch dates until very soon before the actual launch. Is that a government policy? Or is it a cultural thing, where they want to be absolutely positively sure of a launch date--and don't want to commit themselves--before they announce it?
« Last Edit: 12/23/2013 02:35 PM by Blackstar »

Offline plutogno

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Yutu robot arm successfully deployed
link (in Chinese): http://www.chinanews.com/gn/2013/12-23/5653502.shtml
I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.
James Van Allen

Offline A8-3

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And does anybody know of a Soviet-era launch that was shown live on television?


I believe I recall the launch of the Soyuz for the Apollo-Soyuz mission being televised live, but that was certainly an exception. Does anyone else remember that?

Offline Hog

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Excellent coverage NSF, as always top notch info.

Question:  Does anyone know if Dec 25/13 is stilll the 1st opportunity for LRO to picture the Chang'e-3's landing site"?

TIA
Paul

Offline Blackstar

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I think this is the best quality image I've seen of the rover.

https://twitter.com/XHNews/status/414757536735047680/photo/1


Offline plutogno

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I believe I recall the launch of the Soyuz for the Apollo-Soyuz mission being televised live, but that was certainly an exception. Does anyone else remember that?

that was was surely shown on TV. one or both of the Vega launches were shown on TV.

edit: allow me to cite from my book "Robotic Exploration of the Solar System - Part 2":

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In fact, this was also the first time that the main launch vehicle of the Soviet planetary and lunar programs, introduced into service in the late 1960s, was actually shown on Soviet television. Nevertheless, even although the Proton no longer had a military role, the coverage was not allowed to disclose the actual ascent trajectory or the times of staging.
« Last Edit: 12/23/2013 02:52 PM by plutogno »
I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.
James Van Allen

Offline ugordan

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I think this is the best quality image I've seen of the rover.

The horizontal pixel size of 1024 suggests that it may, for once, be (a crop?) of an actual source image. Here's a quick white balance and an attempt to compensate for the apparent hue shift seen toward the left edge:

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