China's Space Program News Thread

[chuck731]

Does it matter? Clearly not, since your scenario never happened. Otherwise, you would not have used "if" so often.

The simple reality is that none of the Apollo landers required extra fuel that you claimed they needed. They all landed successfully with fuel left, showing your idea of adding an other extra 30~60 fuel is completely pointless. This means your whole example of Apollo 11 doesn't even support your argument.

Your whole rationale behind extra fuel is that you think Chang'e 3 will need to wait for decision from Earth during landing. Yet, you have been told repeatedly that the lander will perform all maneuvers and decision-making autonomously. I don't see why you are still trying to argue.

No, at least one of the Apollo landers needed almost all of the extra fuel I claim they needed. If you think just because no mission actually ranout of fuel, then the probility of any mission running out of fuel is therefore zero or negligible, then you need to seriously study probability theory to better get a handle on how to estimate the probability of available fuel being exhausted prior to touch down on any particular mission, given fuel was nearly exhausted in one out of 6 actual missions.

The whole rationale behind the extre fuel is chang'e 3 might need it to find a spot to land. Whether the lander perform decision loop Onboard or off board via datalink is virtually irrelevant to the fuel reserve needs, because the appropriate amount of extra fuel would give hover time many times longer the the difference in time between an closed onboard decision loop, and an open off board decision loop.

 

[blacklist]

... The whole rationale behind the extre fuel is chang'e 3 might need it to find a spot to land. Whether the lander perform decision loop Onboard or off board via datalink is virtually irrelevant to the fuel reserve needs, because the appropriate amount of extra fuel would give hover time many times longer the the difference in time between an closed onboard decision loop, and an open off board decision loop.

it is irrelevant if the speed of onboard processing is the same as the the time needed by datalink comm to earth which is as you claim as much as 2 second...

if the onboard processing need less than 1 second then the hovering time would be halved.

 

[blacklist]

Bet it is part of the booster exhaust...

Luckily no one was hurt.

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DRAGON SPACE
China space launch debris wrecks villagers' homes: report
by Staff Writers
Beijing (AFP) Dec 03, 2013


Debris from the rocket carrying China's first moon rover plummeted to earth in a village more than a thousand kilometres from the launch site, crashing into two homes, a report said Tuesday.

The incident about nine minutes after the launch of the Chang'e-3 mission early Monday happened in Suining county in the central province of Hunan, which has been hit by space wreckage nearly 20 times, the Xiaoxiang Morning Post said.

"Three of the roof beams have crashed down on our house, and a big hole has been punched into our barn," one local resident told the paper.

"The huge sound scared the living daylights out of me," said another.

A picture showed a somewhat baffled-looking villager peering at the curved shape of what appeared to be a rocket nose-cone, below a gaping hole in his roof.

Authorities gave the residents 10,800 yuan ($1,800) and 5,200 yuan in compensation, the paper said. No one was injured.

A Long March-3B carrier rocket, China's most powerful such vehicle, blasted off at around 1:30 am Monday from the Xichang Satellite Launch Centre in southwestern China.

The lunar rover mission is part of China's ambitious space programme, which has the goal of establishing a permanent space station by 2020 and eventually sending a human to the moon.

But debris from China's numerous space launches has frequently found its way to Suining county, which has been hit by rocket parts nearly 20 times since the early 1990s, the Xiaoxiang Morning Post reported.

Last May wreckage from a rocket sent up by the Xichang Launch Centre crashed into homes and hit a high-voltage wire in the area, according to the Shanghai Daily News.

In October 2011 a steel frame weighing more than 250 kilograms (550 pounds) landed in a field after another satellite launch, and other wreckage pierced a house roof.

 

[TerraN_EmpirE]

Does it matter? Clearly not, since your scenario never happened. Otherwise, you would not have used "if" so often.

The simple reality is that none of the Apollo landers required extra fuel that you claimed they needed. They all landed successfully with fuel left, showing your idea of adding an other extra 30~60 fuel is completely pointless. This means your whole example of Apollo 11 doesn't even support your argument.

Your whole rationale behind extra fuel is that you think Chang'e 3 will need to wait for decision from Earth during landing. Yet, you have been told repeatedly that the lander will perform all maneuvers and decision-making autonomously. I don't see why you are still trying to argue.

Neil Armstrong did go to manual and fly the Eagle using extra fuel to protect the craft from a unexpected formation of craters

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but that was in 1969 its 2013 now. the lander and Bunny are both unmanned and the critical point when extra fuel might be of use is taken up by the lag time between Chinese mission control and the moon.
One extra fuel would do little good by the time a course correction reached it its to late.
two 44 years of satellites mapping, and observation means the Landing spot is likely much safer then the first pick on Apollo 11

 

[Engineer]

No, at least one of the Apollo landers needed almost all of the extra fuel I claim they needed.

No, none of them did. Apollo 11 carried the fuel it was designed to carry, and the lander still landed with 25 seconds of fuel left over despite a manual interference. Other landers have even more fuel left over. They clearly did not need to carry another 30~60 seconds of extra fuel. Not only that, but another 30 seconds of fuel can be cut down which goes completely opposite to your claim.

If you think just because no mission actually ranout of fuel, then the probility of any mission running out of fuel is therefore zero or negligible, then you need to seriously study probability theory to better get a handle on how to estimate the probability of available fuel being exhausted prior to touch down on any particular mission, given fuel was nearly exhausted in one out of 6 actual missions.

Probability is not needed here. Has an Apollo lander crashed due to lack of fuel? No, and the fact is simple as that. This proves the fuel already carried by the Apollo spacecraft is sufficient. The spacecrafts did not need an extra 30~60 fuel contrary to your claim. In turn, this invalidates your use of Apollo spacecraft as an example for your argument. Your attempt to spin 0/6 into 1/6 is laughable.

The whole rationale behind the extre fuel is chang'e 3 might need it to find a spot to land. Whether the lander perform decision loop Onboard or off board via datalink is virtually irrelevant to the fuel reserve needs, because the appropriate amount of extra fuel would give hover time many times longer the the difference in time between an closed onboard decision loop, and an open off board decision loop.

You clearly have no idea what you are talking about. A loop that requires input from ground station requires at least 2.6 seconds, based on the distance between Earth and Moon. This does not include the time it takes for ground equipments to process the information, present said information to decision makers, have decision makers form a decision, and have decision processed by ground equipments to send back to the lander. On the other hand, the closed-loop control on the lander just takes fractions of a second. HUGE DIFFERENCE! This is why your original idea of having ground control to determine where to land the spacecraft during descend is not possible.

Furthermore, finding a spot to land means taking two pictures of the area during descend to generate a 3D map of the landing site, to which obstacle avoidance algorithms will be applied. Finding a spot to land does not mean the lander will be flying around like a helicopter.

 

[chuck731]

No, none of them did. Apollo 11 carried the fuel it was designed to carry, and the lander still landed with 25 seconds of fuel left over despite a manual interference. Other landers have even more fuel left over. They clearly did not need to carry another 30~60 seconds of extra fuel. Not only that, but another 30 seconds of fuel can be cut down which goes completely opposite to your claim.


Probability is not needed here. Has an Apollo lander crashed due to lack of fuel? No, and the fact is simple as that. This proves the fuel already carried by the Apollo spacecraft is sufficient. The spacecrafts did not need an extra 30~60 fuel contrary to your claim. In turn, this invalidates your use of Apollo spacecraft as an example for your argument. Your attempt to spin 0/6 into 1/6 is laughable.


You clearly have no idea what you are talking about. A loop that requires input from ground station requires at least 2.6 seconds, based on the distance between Earth and Moon. This does not include the time it takes for ground equipments to process the information, present said information to decision makers, have decision makers form a decision, and have decision processed by ground equipments to send back to the lander. On the other hand, the closed-loop control on the lander just takes fractions of a second. HUGE DIFFERENCE! This is why your original idea of having ground control to determine where to land the spacecraft during descend is not possible.

Furthermore, finding a spot to land means taking two pictures of the area during descend to generate a 3D map of the landing site, to which obstacle avoidance algorithms will be applied. Finding a spot to land does not mean the lander will be flying around like a helicopter.

You ostentatious refusal to demonstrate any grasp the implication of a 0/6 that really is quite close to 1/6 upon the overall probability of failure, on the other hand, shows something somewhere between a disagreeably overweening form of naiveté and, how shall we say this, a blustering deficit of intellectual honesty.

Good day.

 

[Engineer]

You inability to demonstrate any firmly grasp the implication of a 0/6 that really is quite close to 1/6 upon the overall probability of failure, on the other hand, shows something that is somewhere between overweening naiveté and, how shall we say this, deficit of intellectual honesty.

Good day.

If you seriously believe 0/6 is quite close to 1/6, then you need to go back to junior high to review your fractions and decimals. There is no implication between the two aside from what is in your imagination. No failure simply does not equal to one failure.

 

[TerraN_EmpirE]

Gents lets break this up its starting to cross that line.
Agree to disagree and move on please.

 

[escobar]

Chang'e-3 will not perform a planned third trimming of its trajectory along the earth-moon transfer orbit. The first two orbital trimmings were highly exact, which resulted in the probe being capable of meeting the demands of near-moon deceleration and follow-up orbital control. Noting good adaptability in the flying control plan for Chang'e-3 it has been decided that a third orbital trimming is not necessary.

 

[blacklist]

awesomme...

i guess we will see it land on the moon ahead of schedule ?

Chang'e-3 will not perform a planned third trimming of its trajectory along the earth-moon transfer orbit. The first two orbital trimmings were highly exact, which resulted in the probe being capable of meeting the demands of near-moon deceleration and follow-up orbital control. Noting good adaptability in the flying control plan for Chang'e-3 it has been decided that a third orbital trimming is not necessary.