Author Topic: LIVE: Chang'e-3 lunar probe and rover Lunar Landing December 14, 2013  (Read 470676 times)

Offline Dalhousie

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Sir Patrick Stewart dresses up as China's dying lunar rover, bids farewell to humanity.

http://www.theverge.com/2014/2/5/5384412/sir-patrick-stewart-dresses-up-as-chinas-dying-lunar-rover-bids

Yeah, but I found Jon Stewart's gurning and try-hard manner too painful to watch. Even he can be funnier than that...

Agreed... I really hate this whole "lol china sucks they only did something we did 40 years ago" thing.

And of course the US has never had a robotic lunar rover.
"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 Blackstar

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And of course the US has never had a robotic lunar rover.

Yeah, only the four on Mars. Rather pathetic.

Offline JohnFornaro

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Sir Patrick Stewart dresses up as China's dying lunar rover, bids farewell to humanity.

http://www.theverge.com/2014/2/5/5384412/sir-patrick-stewart-dresses-up-as-chinas-dying-lunar-rover-bids

Yeah, but I found Jon Stewart's gurning and try-hard manner too painful to watch. Even he can be funnier than that...

Agreed... I really hate this whole "lol china sucks they only did something we did 40 years ago" thing.

Well, like they say, those who can't ... Blogg.
Sometimes I just flat out don't get it.

Offline JimO

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No follow-up news anywhere I can find about the China Space Facebook page claim of signal from the lander.

Offline JimO

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http://pjm.uhf-satcom.com/twtr/change3_lander2.jpg
http://pjm.uhf-satcom.com/twtr/change3_lander2_uplink1.jpg
Whoa!! The first chart is labeled "uplink reflected off the moon". In English this means the radio command from Earth just bounced off the surface and was detected as a pulse, NOT that any signal from a vehicle on the moon was received and decoded on Earth. This could just be a translation problem, OR a complete misunderstanding by the page's operators in Beijing. It's NOT evidence that either vehicle is functioning. The second chart DOES claim downlink, but I can't read it, and no official press announcement seems to have been made. Unpop the champagne corks, friends -- at least for a little while longer.

Offline plutogno

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the guy who tweeted these images - https://twitter.com/uhf_satcom describe the downlink image as:

Quote
A nice signal from the Chang'e'3 lander after its 'sleep'

I don't know how to interpret the spectrum, though.
note that he posted two reflected uplink spectra and commented on the second

Quote
uplink TX went off deactivating 8496MHz downlink from lander!

Offline Blackstar

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Yeah, but I found Jon Stewart's gurning and try-hard manner too painful to watch. Even he can be funnier than that...

I like Stewart a lot, but he has never been very pro space exploration. I've watched him for years and for many years he would occasionally do a segment that went something like "Mars rover found water on Mars. Who cares?" or "Cassini spacecraft found ice around Saturn. Who cares?" He has done less and less of those things over the years, but he's not the kind of host who regularly has astronauts or space scientists on his show, other than Neil deGrasse Tyson.

On the other hand, Stephen Colbert whose show follows Stewart's every night,is clearly a space enthusiast. There are lots of examples of this. He often has on scientists and astronauts and has stories about spaceflight. His humor about space might be silly, but it rarely comes from the opinion that it is a waste of money.

Offline Mader Levap

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Yeah, only the four on Mars. Rather pathetic.
Yep, it is pathetic saying "Nyah, China did something (Moon robotic rover) that USA did 40 year ago" when, in fact USA did NOT deployed any Moon robotic rover. This is called lie.
Be successful.  Then tell the haters to (BLEEP) off. - deruch
...and if you have failure, tell it anyway.

Offline TrevorMonty

Even if Rover is dead the mission is far from a failure. They proved their lander technology and how successfully place a Rover on moon. Not bad for a first attempt.

Offline edkyle99

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Agreed... I really hate this whole "lol china sucks they only did something we did 40 years ago" thing.
Landing on the Moon is a significant achievement.  The fact that it happened after a 37 year gap is important.  So is the size of that lander, and what it implies for the future.

Yes, the USSR scored all of the lunar robot "firsts" (flyby, far-side image, impact, orbit, landing, rover, sample-return, not to mention first orbit and landing on both Mars and Venus), and the U.S. landed 12 people, but the last lander, Luna 24, was in 1976.  Apollo ended more than four decades ago.  NASA is currently parceling off the remains of its dormant launch site.  Not only has the Luna program long been shut down, but the USSR itself no longer exists. 

The fact is that right now only China has an active lunar landing program.  Only China has something on the Moon that may still be active.  Everyone else is just watching. 

 - Ed Kyle
« Last Edit: 02/11/2014 05:43 PM by edkyle99 »

Offline veblen

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Yeah, only the four on Mars. Rather pathetic.
Yep, it is pathetic saying "Nyah, China did something (Moon robotic rover) that USA did 40 year ago" when, in fact USA did NOT deployed any Moon robotic rover. This is called lie.


A lot of those comments on other sites came from people not that into space exploration who were talking about rovers on the moon in 1972. The ones driven by astros of course. Stop making such a big deal about it.

Offline plutogno

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uhf_satcom reports:

Quote
No signals tonite on 8.4GHz from either the Chinese lunar lander or the rover. Will keep monitoring the situation for a bit...

Offline Steven Pietrobon

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http://pjm.uhf-satcom.com/twtr/change3_lander2.jpg
http://pjm.uhf-satcom.com/twtr/change3_lander2_uplink1.jpg
Whoa!! The first chart is labeled "uplink reflected off the moon". In English this means the radio command from Earth just bounced off the surface and was detected as a pulse, NOT that any signal from a vehicle on the moon was received and decoded on Earth. This could just be a translation problem, OR a complete misunderstanding by the page's operators in Beijing. It's NOT evidence that either vehicle is functioning. The second chart DOES claim downlink, but I can't read it, and no official press announcement seems to have been made. Unpop the champagne corks, friends -- at least for a little while longer.

OK, I'm an electronic engineer so I might be able to add some insight here. First of all the graphs are at 496 MHz downlink and 209 MHz uplink, while the text says 8496 MHz downlink and 7209 MHz uplink. This is confusing. Why doesn't the graph just show the frequencies being measured, i.e., 8496 and 7209 MHz? Maybe the system conveniently has two frequency multipliers at 7 and 8 GHz, so that the resultant intermediate frequency values are 496 MHz and 209 MHz, respectively.

For the 496 MHz downlink, the upper curve shows the frequency spectrum at a signal level of -75 dB (that's pretty low). There is no clear peak in the centre and the signal looks pretty random. The blue signal below shows signal amplitude as a function of colour. Red is a high signal level while blue is low. The horizontal axis is frequency and the vertical axis is time, indicated by the values at the left. In this case we see pretty clear the signal level gradually rise from about -75 dB at 495 and 497 MHz at the edges to -69 dB at 496 MHz at the middle. That's a pretty weak signal, as to be expected from the lander which won't have much transmit power. The bandwidth could be around 2 MHz.

For the 209 MHz downlink we see a much stronger signal at -56 dB at a very narrow bandwidth. The bandwidth looks to be only 20 to 30 Hz! With coding, the data rate might only be 5 bit/s. We can also see the frequency changing with time. In the 200 second interval shown, the frequency shifts about -60 Hz indicating the source is accelerating away from us. Using the formula dv = c*df/f0 we get dv = 3x10^8*60/7.209x10^9 = 2.5 m/s. The acceleration is dv/T = 2.5/200 = 0.012 m/s^2, a very low value, probably indicative of the Moon appearing to accelerate away from the observer.
« Last Edit: 02/12/2014 05:29 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline Dalhousie

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And of course the US has never had a robotic lunar rover.

Yeah, only the four on Mars. Rather pathetic.

True but irrelevant.  Chang'e 3 and Yutu are major achievements and should be celebrated as such, not the subject of infantile nationalistic sneers from the commentariat.
"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

Online Comga

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Yeah, but I found Jon Stewart's gurning and try-hard manner too painful to watch. Even he can be funnier than that...

I like Stewart a lot, but he has never been very pro space exploration. I've watched him for years and for many years he would occasionally do a segment that went something like "Mars rover found water on Mars. Who cares?" or "Cassini spacecraft found ice around Saturn. Who cares?" He has done less and less of those things over the years, but he's not the kind of host who regularly has astronauts or space scientists on his show, other than Neil deGrasse Tyson.

On the other hand, Stephen Colbert whose show follows Stewart's every night,is clearly a space enthusiast. There are lots of examples of this. He often has on scientists and astronauts and has stories about spaceflight. His humor about space might be silly, but it rarely comes from the opinion that it is a waste of money.

[OT]Do you remember the story about NASA renaming the exercise treadmill after Colbert, (Combined.... Resistance Trainer or some such)  instead of a node when his fans overwhelmed a naming contest?  They were said to offer another clever bactronym for STEWART for renaming the toilet (Sanitary....Waste....) which he was said to decline.  Good choices for all involved. [/OT]


It was a particularly childish segment.  Chang'e is a real accomplishment.
While the US can and has done this, we should again, but China did.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Online Svetoslav

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So this is it.

http://www.ecns.cn/2014/02-12/100479.shtml

Chinese rover has been lost forever.

Offline NovaSilisko

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So this is it.

http://www.ecns.cn/2014/02-12/100479.shtml

Chinese rover has been lost forever.

So Yutu is dead and Chang'e is blind... now I have this awful and sad image in my mind of Chang'e trying to find her rabbit but being unable to, not knowing it's died.  :(

Offline plutogno

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OK, I'm an electronic engineer so I might be able to add some insight here.

thanks Steven, that's much clearer now!

Online Galactic Penguin SST

So this is it.

http://www.ecns.cn/2014/02-12/100479.shtml

Chinese rover has been lost forever.

At this stage probably nothing but an official statement release would matter - there are too many claims and guesses out there at this moment to actually determine the rover's status... ;)
Chinese spaceflight is a cosmic riddle wrapped in a galactic mystery inside an orbital enigma... - (not) Winston Churchill

Offline KelvinZero

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So this is it.

http://www.ecns.cn/2014/02-12/100479.shtml

Chinese rover has been lost forever.

Lost is a pretty accurate term for much of space but I think we should find a different one for the moon.

We will always know exactly where it is, probably even see it occasionally, and it will be right there waiting for us when we finally go to visit.

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