Author Topic: LIVE: Chang'e-3 lunar probe and rover, CZ-3B - Xichang - December 1, 2013  (Read 316241 times)

Offline Blackstar

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Thanks for that photo.  I think that it provides an important clue about what China may be planning for future uses of its lander stage.  The Yutu rover seems too small for its lander stage, necessitating the moving ramp arrangement.  Yutu seems to me like a precursor test article - like (a) Pathfinder.  A pathfinder for bigger things.

I don't think so. I think that the lander is big so it can support a future sample return mission. There's a lot of logic to proving that out now, with a small rover as the payload.

Offline Blackstar

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While other nations have a systematic progression in abilities, the U.S. seems to have giant surges and then pulls back resting on its laurels...

I disagree with that. You can probably find where I have posted explanations of the decadal survey before. I think that it provides a great guide for missions that serve a larger purpose. The United States is a mature space power and has a good system for deciding upon science missions.

Now human spaceflight is different. It's less logical and methodical. But the U.S. planetary exploration program over the past several decades, particularly since the mid-1990s, has been a rational and well-planned program. Underfunded, of course...

Offline Rocket Science

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While other nations have a systematic progression in abilities, the U.S. seems to have giant surges and then pulls back resting on its laurels...

I disagree with that. You can probably find where I have posted explanations of the decadal survey before. I think that it provides a great guide for missions that serve a larger purpose. The United States is a mature space power and has a good system for deciding upon science missions.

Now human spaceflight is different. It's less logical and methodical. But the U.S. planetary exploration program over the past several decades, particularly since the mid-1990s, has been a rational and well-planned program. Underfunded, of course...
My bad, I should have been more specific in my comment was meant for HSF.  I agree with you with respect  to our probes and landers. They have returned outstanding results and surprising longevity which is a tribute to their designers and constructors...
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Offline edkyle99

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Thanks for that photo.  I think that it provides an important clue about what China may be planning for future uses of its lander stage.  The Yutu rover seems too small for its lander stage, necessitating the moving ramp arrangement.  Yutu seems to me like a precursor test article - like (a) Pathfinder.  A pathfinder for bigger things.

I don't think so. I think that the lander is big so it can support a future sample return mission. There's a lot of logic to proving that out now, with a small rover as the payload.
I agree, but also believe that additional payloads are likely.  Luna did big rovers and sample returns.  Why not Chang'e?

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Offline NovaSilisko

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I agree, but also believe that additional payloads are likely.  Luna did big rovers and sample returns.  Why not Chang'e?

 - Ed Kyle

That's been my impression from as soon as I saw how big the lander is. It can serve as a general purpose payload delivery vehicle, from a small rover as it's doing now to a sample return rocket. Nice to see design modularity and commonality in these sorts of things!

Offline savuporo

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Luna did big rovers and sample returns.  Why not Chang'e?
They have already stated that the same ( or slightly scaled up ) platform will be used for Chang'e-5 and 6, which are sample return missions. However, it will need a bigger carrier rocket, i.e. CZ-5
« Last Edit: 12/03/2013 01:47 AM by savuporo »
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Offline Prober

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The few articles I've read suggested that the entire sequence is fully automated..
It would have to be fully automated, as you cant rely on radio signal working at the critical moment, however having a fully automated sequence never prevents human overrides - for high level decisions that are not made within milliseconds.
wonder how much time to send/received signals?
 
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Offline Blackstar

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I agree, but also believe that additional payloads are likely.  Luna did big rovers and sample returns.  Why not Chang'e?

But here's the question: what would be next? Assume CE-4 is a rover, and CE-5 and 6 are sample return missions. What is there left to do? You pose a big rover. But why? What can a big rover accomplish what the current rover cannot?

A few possible answers: greater mobility, including truly independent operation from the lander. A better instrument suite.

But that brings us back to some very fundamental questions, such as what is driving the Chinese lunar program. Is it primarily science? Or is it primarily developing engineering capability? Or is it a near equal mix of both? I would not simply assume that they want to go bigger and bigger, not until we have an idea of why they are doing any of this.

One possibility is that after CE-6 they lose interest in the robotic exploration of the Moon. At that point they could shift to a human lunar program. Or they could turn to robotic exploration of the solar system, such as Mars.

Offline savuporo

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But here's the question: what would be next? Assume CE-4 is a rover, and CE-5 and 6 are sample return missions. What is there left to do?
This thread is diverging very far from Chang'e-3 related things isnt it ?
( What's left : land at polar latitudes, confirm presence of ice, test in-situ resource utilization concepts, find lava tubes, land a telescope on the far side .. the list is long and really subject of a different thread, and many things can fit on a reasonably sized lander platform, especially if you think modular design )
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Offline Blackstar

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While other nations have a systematic progression in abilities, the U.S. seems to have giant surges and then pulls back resting on its laurels...

I disagree with that. You can probably find where I have posted explanations of the decadal survey before. I think that it provides a great guide for missions that serve a larger purpose. The United States is a mature space power and has a good system for deciding upon science missions.

Now human spaceflight is different. It's less logical and methodical. But the U.S. planetary exploration program over the past several decades, particularly since the mid-1990s, has been a rational and well-planned program. Underfunded, of course...
My bad, I should have been more specific in my comment was meant for HSF.  I agree with you with respect  to our probes and landers. They have returned outstanding results and surprising longevity which is a tribute to their designers and constructors...

But with regards to American planetary science spacecraft, I would not point simply to individual results or longevity. The genius of the program is how methodical and logical it is. It has checked off numerous big questions about the solar system, making substantial progress at developing a better understanding of how it formed and what it is like right now.

For instance, look at NASA's Mars exploration.

Pathfinder/Sojourner-->Mars Global Surveyor-->Mars Climate Orbiter (failed), Mars Polar Lander (failed)-->Mars Odyssey-->Spirit and Opportunity-->Mars Reconnaissance Orbiter-->Phoenix-->Curiosity.

Look at all the missions since Mars Observer conked out in the early 1990s. What you see is an incredible turnaround. NASA altered its plans. Instead of one or two really big missions every couple of decades, they went to a systematic approach, launch window after launch window, building on the results of the last missions, developing new technology along the way, and learning lessons. It's pretty damned amazing when you take it all in.

You can do the same with the rest of the solar system. In the past ten years NASA has put the first spacecraft in orbit around Mars, first in orbit around Mercury, first to orbit an asteroid, plus multiple asteroid and comet missions. A very systematic exploration of the solar system.

It's a pretty amazing success story. There are a few holes. Venus has been largely neglected. The ice giants have not yet been explored. And arguably the Jovian system deserves more attention (not just Europa), which it will get when Juno arrives and then when ESA finally flies their Ganymede mission. But it's a great example of government working, doing things right.

Offline Blackstar

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And here's where I'll quibble with the real intent of your statement:

While other nations have a systematic progression in abilities, the U.S. seems to have giant surges and then pulls back resting on its laurels...

My bad, I should have been more specific in my comment was meant for HSF.

I'm not sure I'd agree with that characterization either. Note that we operated shuttle for THIRTY YEARS. That was neither a giant surge nor resting on laurels. Similarly, ISS took ten years to construct, and now it is being operated.

Now we can argue specific mistakes, and I think there were many. I don't particularly think that the U.S. approach to the space station--building a giant structure over a decade--was a good idea. But I am disagreeing with your characterization of NASA's human spaceflight program as one of surges and respites. I think it has been much more methodical than that.

Offline Blackstar

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This thread is diverging very far from Chang'e-3 related things isnt it ?

As long as we're having fun, what's the problem?

( What's left : land at polar latitudes, confirm presence of ice, test in-situ resource utilization concepts, find lava tubes, land a telescope on the far side .. the list is long and really subject of a different thread, and many things can fit on a reasonably sized lander platform, especially if you think modular design )

And I'm going to state my point again:

But that brings us back to some very fundamental questions, such as what is driving the Chinese lunar program. Is it primarily science? Or is it primarily developing engineering capability? Or is it a near equal mix of both? I would not simply assume that they want to go bigger and bigger, not until we have an idea of why they are doing any of this.


If this is all build up for an eventual human program (which the Chinese have not decided upon yet), then that will lead them in a different direction than if this is all part of a long-term lunar science program.

So that then gets to the question about who is setting the goals and priorities for China's lunar robotic program, of which Chang'e-3 is but one part?

Offline QuantumG

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As long as we're having fun, what's the problem?

Sounds good to me.

Quote from: Blackstar
And I'm going to state my point again:

But that brings us back to some very fundamental questions, such as what is driving the Chinese lunar program. Is it primarily science? Or is it primarily developing engineering capability? Or is it a near equal mix of both? I would not simply assume that they want to go bigger and bigger, not until we have an idea of why they are doing any of this.

Some other other possibilities:

* maybe it's just a nice way to employ the kind of people they want employed
* feel good reasons like: all the really good countries are doing it
* whatever the Chinese equivalent of funding in districts is..

Quote from: Blackstar
If this is all build up for an eventual human program (which the Chinese have not decided upon yet), then that will lead them in a different direction than if this is all part of a long-term lunar science program.

So that then gets to the question about who is setting the goals and priorities for China's lunar robotic program, of which Chang'e-3 is but one part?

.. and is it more than just one voice?
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Offline savuporo

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But that brings us back to some very fundamental questions, such as what is driving the Chinese lunar program. Is it primarily science? Or is it primarily developing engineering capability? Or is it a near equal mix of both? I would not simply assume that they want to go bigger and bigger, not until we have an idea of why they are doing any of this.
IMO these are actually pretty useless questions to ask, and no answers given by the source will ever be believed anyway. What is driving the US space program ? What is driving telerobotic ocean exploration ? Why mess around in the Arctic ? In fact, why do anything costly, dangerous or anything of no immediate economic benefit ?

The honest answer in case of Chinese will be a mix of _everything_ is driving the program, because there are likely thousands of people involved in the program ! Scientists want to do science, policitcians approving the budgets are in it for the national prestige, engineers want to fly cool shit etc etc, same as everywhere, and there is no ultimate secret answer.

But, you can go back and read http://www.bbc.co.uk/news/25141597 , and i selectively quote:
Quote
Ouyang has himself been blunt about this in the past, as here in 2006: "Lunar exploration is a reflection of a country's comprehensive national power," he said in an interview with the official newspaper People's Daily. "It is significant for raising our international prestige and increasing our people's cohesion.
..
He explained that there were three motivations behind the drive to investigate the Moon.

"First, to develop our technology because lunar exploration requires many types of technology, including communications, computers, all kinds of IT skills and the use of different kinds of materials. This is the key reason," he told BBC News.

"Second, in terms of the science, besides Earth we also need to know our brothers and sisters like the Moon, its origin and evolution and then from that we can know about our Earth.

"Third, in terms of the talents, China needs its own intellectual team who can explore the whole lunar and solar system - that is also our main purpose."

But you, me or anyone else here is not going to take these statements at face value anyway, are we ?

I still suggest spin up a separate thread for the discussion thats not specific to Chang'e. There are lots of useful updates and references and nuggets of on topic updates and information in this thread, anyone coming back to find them is going to be annoy.ed
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The thread's fine (removing a moderator warning). We're in post launch and discussion usually follows.

What we'll do is set up a second update thread tomorrow for specific updates relating to the journey and for landing, allowing this thread to continue as-is, while having a second thread for updates only.

Offline sdsds

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Your autonomous software identifies the primary and backup positions and orientations for landing, and there is a short time window where signal from ground can override the primary selection.
I can totally see doing it that way. Particularly if the propellant budget allows for a bit of hovering during that window. Here's another radical idea: if the propellant budget allows, and the landing takes place at a location where an undetected boulder is problematic, one could imagine a lander hopping to an alternate site (or alternate orientation) before deploying its rover!

Quote
if i recall correctly Russians had many human in the loop triggers for their "automated" sequences back then.

I wish the details of those missions were more a part of our current mission design culture!
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Offline Blackstar

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But that brings us back to some very fundamental questions, such as what is driving the Chinese lunar program. Is it primarily science? Or is it primarily developing engineering capability? Or is it a near equal mix of both? I would not simply assume that they want to go bigger and bigger, not until we have an idea of why they are doing any of this.
IMO these are actually pretty useless questions to ask, and no answers given by the source will ever be believed anyway.

Poppycock. That position is just an excuse to not think about the why, just watch the pretty pictures and talk about rockets. It's like saying "Why? Reasons!"

Somebody sets the policy in the Chinese space program. And they clearly have a policy, both for human spaceflight, and for their lunar robotic program. This stuff just doesn't happen via immaculate conception. Look at the progression from CE-1 to 2 to 3. Increases in technology, capability, and science goals. What's the driver? Is there a roadmap that says "Do X first, followed by Y, followed by Z"? (They must have some kind of roadmap, otherwise they wouldn't be doing X, Y and then Z.) Do they have a science priorities committee that does this? How does the Chinese space program establish their priorities, and what are those priorities? And who is doing it? Who are the officials who are making the call? Just because we don't know the answers now doesn't mean that there are no answers.

For starters, the Chinese Academy of Sciences appears to be involved. That would be a good place to start.

And I'd note that the reason I'm asking these questions is that I'm pretty familiar with how it happens in the United States (being directly involved in it). Over here stuff doesn't "just happen," so my guess is that it doesn't just happen in China either.

Understanding that is a good step to figuring out what they might do after CE-6.




Offline jcm

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Object B (presumably CZ-3B 3rd stage) catalogued as
39459/ 2013-070B in 358 x 906 km x 22.82 (epoch Dec 1, 1930UTC)

That's answered a question I posed up thread about whether the third stage would be de-orbited or not.

Hmm - do we really think this is the third stage?  The apogee at separation was 389109 km. To lower the apogee
to only 906 km would involve a 3000 m/s retro burn. Given the fuss they made about having to enhance the CZ-3B
to support this mission, it seems unlikely they had that much spare capacity.

Perhaps it is a debris object that came off  during engine restart - the inclination is a bit surprising too (the ground
track does not go back through Xichang, so it must have had a plane change after MECO1?). It does seem to
be associated with the CE-3 mission, but I'm not sure what it is yet.

Will be interesting to see a radar cross section value.

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Offline savuporo

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Somebody sets the policy in the Chinese space program. And they clearly have a policy, both for human spaceflight, and for their lunar robotic program. This stuff just doesn't happen via immaculate conception.
Policy is never set by a single Somebody unless we are dealing with dictatorship - which China isnt. A good policy decision is a result from inputs of multiple sources ( academia, finance, political leaders, partners etc ) - and it would seem that this is working OK for a Chinese space program.  But i get where your questions are coming from now and yeah - it would be interesting to ask this from someone like Ouyang. Whats the process of defining the policy ?

Quote
Look at the progression from CE-1 to 2 to 3. Increases in technology, capability, and science goals. What's the driver? Is there a roadmap that says "Do X first, followed by Y, followed by Z"? (They must have some kind of roadmap, otherwise they wouldn't be doing X, Y and then Z.)
They have communicated the existing roadmap up to CE-6, and its very much incremental technological capability evolution. From the other side its complemented by whats planned with Tiangong and Shenzhou, and both of these seem to keep them busy for next several years.
Making very long term roadmaps in rapidly evolving technology world is not very useful excercise anyway - i would expect they make further decisions once CE-3 has proven itself.

Quote
Do they have a science priorities committee that does this?
I sincerely hope not.

Quote
How does the Chinese space program establish their priorities, and what are those priorities? And who is doing it? Who are the officials who are making the call? Just because we don't know the answers now doesn't mean that there are no answers.
...Understanding that is a good step to figuring out what they might do after CE-6.
Asking the question - how does your space roadmap and policy definition process really work ? is quite different from asking "why are you doing this ?" IMO. First question is interesting for me, too, second one not so much.
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Offline savuporo

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And now back to relevant updates, english language interview with Professor Yang Yuguang, from the China Aerospace Science and Industry Corporation
http://english.cntv.cn/program/general_news/20131202/102062.shtml

He again stresses scientific aspects and technology advancements aspects of this mission to the impatient anchor.
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