China's Space Program News Thread

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delft

Brigadier
Re: The heater in Yutu

Yutu uses a Pu 238 radioisotope heater. See
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. This source gives a half-life for Pu 238 of 87.7 years. After calculating the heat necessary for Yutu to survive a night on the Moon it is easy to calculate how much Pu will have to remain at the end of the working life, and calculating back to the loading of the Pu not too long before lift off, but also counting with delays in lift off presumably and some slight safety factor for an increase in heat loss during lunar might you find the amount to be loaded. It appears that due to mechanical trouble that heat loss will be much greater. Do not forget that during the day the heat production of the Pu heater as well as all other heat absorbed by or generated within Yutu has to be radiated away, which necessitates a considerable radiator. A good reason to keep the Pu heater as small as possible.
 
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luhai

Banned Idiot
Jeff Head said:
The only source is the plutonium source. The sole source of heat and electricity for the Mars Viking 1 and Viking 2, and the Curiosity are their RTGs and the Plutonium in them. Without them, their would be no electricity and no heat. None.

As to the Yutu, my understanding is that the absolute major source of power are the solar panels and that the supplemental Plutonium power source is very small and is only meant to keep the powered down components from falling below negative 40 degrees C during the lunar night so they can be revived once the lunar night is over.

You may want to check me on that...but that is my understanding.
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Yutu uses Pu-238 electrical heaters, however, Pu-238 electric batteries is an
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Here is a overview of Yutu's thermal design, a extremely risky one, but also very light. (10Kg Capillary Pumped Loop used vs 100Kg conventional Loop Heat Pipe) Whatever happens to Yutu, it will offer important lesson for future Chinese designs. Since it's a totally new deisgn, encountering totally new failure modes.
[video=youtube;a2dEB4BEqJw]http://www.youtube.com/watch?v=a2dEB4BEqJw[/video]
 
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Equation

Equation

Lieutenant General
Here's an interesting article to read, while we wait for more news on YUTU. It has some good points but some alarmist views to it. Anyway, tell me what ya think.

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The Jade Rabbit is the cute face of China's space program; from its initial "soft" landing on the moon to engineering complications that mean it may never "reawaken" from its "first lunar slumber," the unmanned rover has received the kind of adoring coverage typically reserved for panda cams. But all of China's ambitions in space are not so friendly: Over the past decade, the country has been quietly militarizing the cosmos and it's gunning for the United States.

Since the end of the Cold War, America has been space's sole superpower, and it's not ceding that status without a fight. But in this hushed race for control of the orbit around Earth, China doesn't need to control everything to win; it just needs to take away the U.S.' strategic advantage. And it's doing so by turning the U.S.' own strength against it.

During a period of remarkable technological advancement, the U.S. pioneered, among other things, ground breaking GPS technology, integrating it to great effect in every aspect of its economic and military operations. From guiding smart bombs to smartphones, from early warning systems to surveillance, the superiority of U.S. military and civilian capabilities are heavily dependent upon satellites — making them a high priority target in a conflict.

To make matters worse for the U.S., American satellites are largely defenseless and difficult to replace; it wouldn't take much, in other words, to deal a crushing blow to the superpower's military might. Armed with that knowledge, China has been aggressively working on Anti-Satellite (ASAT) weapon systems.

In 2007, China shocked the world when it successfully destroyed an orbiting weather satellite with a specially designed missile. China has continued to perfect its anti-satellite missiles since then, but it has also pursued alternative methods to knock out satellites after it learned the hard way that blowing things up in space creates massive debris clouds that can accidentally damage or destroy its own satellites (see: Gravity).

To that end, China's military has invested heavily in jamming technology and cyber attacks along with more experimental weapons like high-energy lasers, and last year China successfully tested a satellite with a mechanical arm that could be used to attack or alter the orbit of other satellites.

Not to be outdone, in 2008, the U.S. sent a strong signal of its own by also shooting down a satellite with a newly developed anti-satellite missile. Meanwhile, last year, the Pentagon officially announced its program to develop anti-satellite weapons and defensive systems.

The space race is on, but in a potential conflict, the U.S. is automatically at a disadvantage given its reliance on satellites; China is not nearly as dependent on space for its military capabilities on earth as its still modernizing military largely relies on conventional weapons.

In a Congressional hearing on China's military space capabilities on Jan. 28, Ashley Tellis, a senior associate at the Carnegie Endowment for International Peace explained that US capabilities are too concentrated in too few satellites which are "remarkably vulnerable."

More troubling, the U.S. lacks the ability to quickly replace damaged satellites despite their importance in military operations.

"It's going to take a long time to get replacements up there," said Michael Krepon, a senior associate at the Stimson Center. "We're having trouble building satellites on time and on budget."

In contrast, China currently leads the world in annual space launches. With an arsenal of over 100 satellites in space, it is just a few shy of eclipsing Russia as the second largest satellite owner in the world. The U.S. has more than both combined, but again, it is that dominance that makes the U.S. vulnerable. While China may be rapidly closing the gap, it still remains far less reliant on space.

But, in many ways, the U.S. has been its own worst enemy in the military space race.

For instance, in 2010, the U.S. Air Force nearly lost a critical $2 billion communications satellite barely a day after it was launched because a contractor left a rag inside a fuel line. In an interview with The Diplomat, an anonymous space industry insider explained that egregious errors like forgotten rags are due to dramatic fluctuations in funding for space programs, which have resulted in missing generations of space engineers.

It is common for U.S. Air Force programs to be filled with "80-year-old PhDs and 20-year-old college grads," the insider said. With so few mid-level engineers to properly train new hires and pass on valuable skills, "the zero-practice grads make simple mistakes." Additionally, this skills gap has resulted in the loss of critical technical expertise like the ability to conduct complex orbital maneuvers.

For the foreseeable future, the U.S. space program is likely to continue to be in a precarious position given looming budget cuts and Congressional wrangling over funding priorities. For the current fiscal year the unclassified space budget is $8 billion, a 22 percent cut from the previous year, and next year's budget would cut more than half a billion dollars from key satellite programs.

Without a significant commitment to defending what is arguably its most important and vulnerable military assets, the U.S. will be at a considerable disadvantage in a full-scale conflict. But while the U.S. may be losing the space race to China for the time being, the path to victory is clear.

Robert Butterworth, the president of Aries Analytics, succinctly states that the key to the space race is research and development, but to keep the technological edge and invest in new capabilities "we're going to have to take it from design up" and it's "going to take a helluva lot of money."

In an age of austerity, will Washington pony up?
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Jeff Head

Jeff Head

General
Registered Member
Equation said:
Here's an interesting article to read, while we wait for more news on YUTU. It has some good points but some alarmist views to it. Anyway, tell me what ya think.

Please, Log in or Register to view URLs content!
Click to expand...
Commercial GPS satellites have always been vulnerable, and they always will be. But the US military does not just depend on the commercial GPS satellites.

Miitary "grade" satellites are not nearly as vulnerable and have some recourse besides just sitting there and waiting for a collision course to be progrmmed.

If a satellite can adjust its orbit, it can play havoc on hit to kill solutions that are the most common kill vehicles fo ASATs.

In addition, if a large military grade satellite has some electronics built into it and can deploy ECM and decoys, it can also mitigate the threat significantly.

So, the public, and to some degree the military, will suffer if commercial systems are brought down...but those are not the only systems up there.

These same potential attributes may well hold for any nation's military satellites, amking them a harder nut to crack in terms of bringing them down if they do have even those two capabilities I spoke of.
 
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chuck731

Banned Idiot
I believe sinius iridium reached the lunar sunrise today. It should become clear whether Yutu has survived lunar night in the next day or two.
 
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