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

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

#41

Post by tanilama »

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, with only one rabbit being her companion.

Sounds familiar? Yep I believe if you are a Naruto fan, you can make a lot of connections.

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

#42

Post by FigmentEngine »

stcredzero wrote: post #7
jackconnor wrote: post #3

The way they used the L2 point to lasso a relay satellite so they could transmit information from the rover on the far side is stunning too. This was really brilliant, China's space program has really become something.

The way they used the L2 point to lasso a relay satellite So confusing to put it that way. No one has caught anything with a rope or a cable, as far as I know. Basically, they are orbiting a relay satellite around the L2 Lagrange point so that the relay has line of sight with both the landing point and Earth. Obviously, if it just sat at L2, the moon would be in between the relay and the Earth. Orbiting around Lagran…

actually things can and have been caught. Space tethers have been succesful https://en.m.wikipedia.org/wiki/Space_tether_missions#TSS-1R...

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

#44

Post by dang »

phendrenad2 wrote: post #28
jackconnor wrote: post #3

The way they used the L2 point to lasso a relay satellite so they could transmit information from the rover on the far side is stunning too. This was really brilliant, China's space program has really become something.

I know you don't mean to be patronizing, but this reads as patronizing.

"Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith."

https://news.ycombinator.com/newsguidelines.html

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

#45

Post by ageofwant »

ericye16 wrote: post #29
taneq wrote: post #22

Earlier quoted context omitted.

It wasn't in TFA, but here's a source: https://www.bbc.com/news/science-environment-46724727 > The lander carries a 3kg (6.6lb) container with potato and arabidopsis plant seeds - as well as silkworm eggs - to perform biological studies. The "lunar mini biosphere" experiment was designed by 28 Chinese universities. (Source for the silkworms, at least. I must confess that giant mutant moonworms are only conjecture...…

Hm, doesn't this violate the prime directive (or planetary protection guidelines)?

It absolutely does. You should file a complaint with the PDIPTF (Prime Directive Interplanetary Police Task Force) currently HQ in Ark 9, "My hole is bigger than yours", Holm 42, Level 686 on Makemake. In person. Be sure to ask for a complaints receipt.

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

#46

Post by ageofwant »

joejerryronnie wrote: post #21
XorNot wrote: post #19

Earlier quoted context omitted.

I'm pretty happy if China wants to throw shade at the US over space program accomplishments. I'd prefer a measuring contest over space accomplishments then building more earth-bound weapons systems.

And how long before the space program accomplishments start looking just a little like space-based weapons systems. I’m sure Chinese military leadership can extrapolate as well as the Pentagon can.

As soon as possible. Man being man, we only seem to be able to accomplish things under threat of violence.

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

#47

Post by turbinerneiter »

stcredzero wrote: post #7
jackconnor wrote: post #3

The way they used the L2 point to lasso a relay satellite so they could transmit information from the rover on the far side is stunning too. This was really brilliant, China's space program has really become something.

The way they used the L2 point to lasso a relay satellite So confusing to put it that way. No one has caught anything with a rope or a cable, as far as I know. Basically, they are orbiting a relay satellite around the L2 Lagrange point so that the relay has line of sight with both the landing point and Earth. Obviously, if it just sat at L2, the moon would be in between the relay and the Earth. Orbiting around Lagran…

Isn't there a solar telescope around sun-earth L1?

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

#48

Post by vidarh »

FigmentEngine wrote: post #42
stcredzero wrote: post #7

Earlier quoted context omitted.

The way they used the L2 point to lasso a relay satellite So confusing to put it that way. No one has caught anything with a rope or a cable, as far as I know. Basically, they are orbiting a relay satellite around the L2 Lagrange point so that the relay has line of sight with both the landing point and Earth. Obviously, if it just sat at L2, the moon would be in between the relay and the Earth. Orbiting around Lagran…

actually things can and have been caught. Space tethers have been succesful https://en.m.wikipedia.org/wiki/Space_tether_missions#TSS-1R...

Yes, but not in this instance.

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

#49

Post by tome »

789body wrote: post #9
jackconnor wrote: post #3

The way they used the L2 point to lasso a relay satellite so they could transmit information from the rover on the far side is stunning too. This was really brilliant, China's space program has really become something.

This comment threw me for a loop - "L2" and "lasso" triggered the pattern recognition in my head for "regression regularization" and it took a moment to realize the topic was still orbital dynamics. Come to think of it, saying "Lagrangian" wouldn't have prevented my confusion - not that there's anything wrong with the terminology in OP. I'm reminded of a passage in Cryptonomicon , which I've been rereading: "Newton w…

Off topic: That quotation is a bit strange because the full title is "Philosophiæ Naturalis Principia Mathematica", or "Mathematical Principles of Natural Philosophy", which describes exactly what it is ("Natural Philosphy" basically being "science").

https://en.wikipedia.org/wiki/Philosophi%C3%A6_Naturalis_Pri...

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

#50

Post by dingaling »

trothamel wrote: post #23
sowbug wrote: post #13

Earlier quoted context omitted.

I'd interpret the stated duration as a criterion for whatever budget they came up with. Building something that'll last 90 days in a harsh environment is a lot less expensive than one that needs to last at least a year. And assuming the folks monitoring the rover aren't working for free, the budget needs to include their cost of employment for a fixed amount of time.

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 have flown years ago and we'd be on JWST Gen 3 by now, doing actual science.

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