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China lands Chang'e-4 on far side of Moon

planetary.org

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Re: China lands Chang'e-4 on far side of Moon

#131

Post by bluGill »

Rooster61 wrote: post #123
vermontdevil wrote: post #104

Awesome. Too bad US freezes China out in working with NASA on space exploration. I think we all should partner up despite our political differences.

Please keep in mind that space exploration has always been rooted in and primarily (for better or worse) funded as a result of military applications. It's simply not possible to fully dispel that conflict of interest, at least not for the foreseeable future of world politics.

I have long said that the real reason for the international space station is to give Russia cover to keep their space engineers working. That is unemployed ex-soviet space engineers are are vulnerable to evil dictators offering them a job designing ICBMs (when you have no money/food moral considerations are less important)

Re: China lands Chang'e-4 on far side of Moon

#132

Post by Ankaios »

dingaling wrote: post #50
trothamel wrote: post #23

Earlier quoted context omitted.

I'll note that the mars exploration rovers Spirit and Opportunity were meant to last 90 sols (Martian days). Spirit lasted 2,210, and (assuming it doesn't reply) Opportunity lasted 5,111. When you have everyone working on the mission trying to make sure their part isn't the one that causes the mission to end before the 90 days are up, you get a long-lived rover.

The flip side to over-engineering is ever-ballooning budgets, fewer missions and more chance of random events curtailing the few missions that are flown. If the requirements state 90 days, design for 90 days - even if 180 days is achievable 'for free'. Otherwise there is no feedback loop to inform future requirements and 90 becomes an implicit 2000.b If JWST was designed for two years and a hard shutdown it would hav…

If JWST was designed for two years and a hard shutdown it would have flown years ago and we'd be on JWST Gen 3 by now, doing actual science.

JWST's design lifespan is not significantly driving its cost. Its cost derives from its complexity, and (crudely) its complexity follows from the aperture diameter and temperature it requires to achieve the scientific objectives chosen for it.

Re: China lands Chang'e-4 on far side of Moon

#133

Post by dbllxr »

tanilama wrote: post #41
arduanika wrote: post #5

"...and if the dam breaks open many years too soon..." Perhaps interesting to note the origin of this name for spacecraft. The legend "Chang'e flies to the moon" (嫦娥奔月) lies behind the Mid-Autumn Festival (featuring mooncakes, as it were). Point is, the names of Chinese space missions are every bit as carefully steeped in tradition as, say, Mercury/Gemini/Apollo.

The story behind Chang'e is also interesting. Essentially, she is the wife of a legendary hero, Hou Yi(后羿), who saved the mankind from dying of drought due to the presence of nine Suns, by shooting all but one of them down. Chang'e stole the Immortal Pill, and eat it alone without her husband knowing. After she ate it, her body became to float and she flied to the moon, to live there alone forever as her punishment,…

In one (more romantic) version of the lore, the Mystic Realm awarded Hou Yi (the husband) the Immortal Pill/Potion after he prevented the earth from being scorched. He and Chang'e were going to both take the potion so they can be together forever. A group of bandits heard about the potion, and broke into their home while Hou Yi was away, Chang'e had no choice but to swallow the potion entirely and that gave her divine powers in addition to immortality, she was able to escape and ascend into Heaven, and because she's no longer human, she and Hou Yi were forever separated...

Re: China lands Chang'e-4 on far side of Moon

#134

Post by pastor_elm »

xupybd wrote: post #87
arduanika wrote: post #5

"...and if the dam breaks open many years too soon..." Perhaps interesting to note the origin of this name for spacecraft. The legend "Chang'e flies to the moon" (嫦娥奔月) lies behind the Mid-Autumn Festival (featuring mooncakes, as it were). Point is, the names of Chinese space missions are every bit as carefully steeped in tradition as, say, Mercury/Gemini/Apollo.

They have to be careful then. Apollo now means more about the moon landings than the old traditions to me. I don’t know if that’s something the Chinese would like to have happen to their traditions.

better than what Nike is now

Re: China lands Chang'e-4 on far side of Moon

#135

Post by metta2uall »

bluGill wrote: post #128
vermontdevil wrote: post #104

Awesome. Too bad US freezes China out in working with NASA on space exploration. I think we all should partner up despite our political differences.

I'm not sure I agree. While there are obvious benefits to cooperation, competition has benefits too. I think the best cooperation is in terms of emergency rescue, backup communications, and sharing scientific results. Emergency rescues mean compatible docking systems to that if an opportunity arises technical problems don't stop the rescue. Of course actually catching something in space in time to pull off a rescue i…

The USSR and USA started cooperating in the 1970s and this has had very good results. For example being able to get to the ISS after the Space Shuttle accident, and arguably in easing political & military tensions. They continued to compete as well.

Re: China lands Chang'e-4 on far side of Moon

#136

Post by m3nu »

rsynnott wrote: post #102
m3nu wrote: post #82

Their logo has similarities to a certain sci-fi TV show.. https://www.space.com/22743-china-national-space-administrat...

I mean, https://en.wikipedia.org/wiki/Air_Force_Space_Command#/media...

I mean http://memory-alpha.wikia.com/wiki/Starfleet, "Seal of Starfleet in the alternate reality"

Re: China lands Chang'e-4 on far side of Moon

#138

Post by KineticLensman »

aflag wrote: post #98
GraemeL wrote: post #67

Earlier quoted context omitted.

The far side of the moon isn't dark. It has the same day/night cycle that causes the phases of the moon visible from Earth. On the other hand, it is shielded from radio emissions from Earth and might be a good place for a radio-telescope.

Surely it's darker than the earth facing side. I'm no rocket scientist, but I reckon at least some of the light the sun sends our way gets reflected. From experience, a moonless night sure feels darker than when the full moon is up.

The amount of reflected Earthlight would depend on your location on the Moon's nearside and the phase of the Earth.

The corollary of one side of the Moon always facing the Earth is that the Earth hangs in about the same place in the sky for any given point on the Moon's surface. Over a period of (earth) days the Earth's position would slightly but visibly oscillate due to libration [0]. This might slightly vary the incoming Earthlight (analogous to the Moon's illumination at the horizon vs. at the Zenith).

A much bigger effect, however, would be due to the phase of the Earth. As the Moon orbits it will sometimes be between the Earth and the Sun, sometimes further away. On the sun-side, the Earth would be more 'full' and thus there would be more light to reflect. This would significantly vary the incoming light.

[0] https://en.wikipedia.org/wiki/Libration

Re: China lands Chang'e-4 on far side of Moon

#139

Post by billfruit »

dandare wrote: post #77

How much lighter is the lander compared to Apollo moon lander? I mean, how far are the Chinese from sending people to the moon? The Russians landed a Lunokhod too but were very far from sending people to the moon.

Only recently did I come to learn, the Soviets had landed a Lunokhod, which actually returned sample of lunar soil back to earth.

Re: China lands Chang'e-4 on far side of Moon

#140

Post by metta2uall »

bluGill wrote: post #131
Rooster61 wrote: post #123

Earlier quoted context omitted.

Please keep in mind that space exploration has always been rooted in and primarily (for better or worse) funded as a result of military applications. It's simply not possible to fully dispel that conflict of interest, at least not for the foreseeable future of world politics.

I have long said that the real reason for the international space station is to give Russia cover to keep their space engineers working. That is unemployed ex-soviet space engineers are are vulnerable to evil dictators offering them a job designing ICBMs (when you have no money/food moral considerations are less important)

That was part of it though I think space engineers would never have been unemployed or out of food - just reassigned to much more boring projects. Russia also has ways of ahem "discouraging" unauthorised trade of military secrets.

With China's ICBMs, aren't they already advanced enough that collaborating on space exploration with NASA won't teach them much ICBM technology that they don't already know?

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