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

#1

Post by docbrown » Thu, Jan 03, 2019, 4:41 AM UTC

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

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

#2

Post by soheil » Thu, Jan 03, 2019, 5:37 AM UTC

Nice

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

#3

Post by jackconnor » Thu, Jan 03, 2019, 5:40 AM UTC

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.

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

#4

Post by A2017U1 » Thu, Jan 03, 2019, 5:49 AM UTC

Copying earlier comment:

Wikipedia seems to say the rover mission duration is 3 months, yet the previous rover traveled for a year and transmitted a bit longer. The Chinese seemed quite coy about it failing last time (as with many things) so perhaps underpromising in this case?

This all preparation for China's planned permanent radio telescope on the far side which would be a huge boon for astronomers by escaping Earth's EM interference.

Also out left field is the 3kg "self sustaining" biosphere of silkworms and plants with a camera inside. Interested to see how long it survives.

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

#5

Post by arduanika » Thu, Jan 03, 2019, 5:49 AM UTC

"...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.

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

#6

Post by taneq » Thu, Jan 03, 2019, 5:54 AM UTC

A2017U1 wrote: post #4

Copying earlier comment: Wikipedia seems to say the rover mission duration is 3 months, yet the previous rover traveled for a year and transmitted a bit longer. The Chinese seemed quite coy about it failing last time (as with many things) so perhaps underpromising in this case? This all preparation for China's planned permanent radio telescope on the far side which would be a huge boon for astronomers by escaping Ear…

> Also out left field is the 3kg "self sustaining" biosphere of silkworms and plants with a camera inside. Interested to see how long it survives.

Aw man, that's how you get giant mutant moonworms.

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

#7

Post by stcredzero » Thu, Jan 03, 2019, 5:55 AM UTC

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 Lagrange points has been known about for a long time. If you want to cite something more recent and innovative pertaining to Lagrange points, astronomers, rocket scientists, and engineers have been working on fuel saving chaotic trajectories through the Lagrange points.

Arguably, the fact that they are the first to implement the L2 halo does win the Chinese space agency some innovation points.

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

#8

Post by datumy » Thu, Jan 03, 2019, 5:57 AM UTC

amazing communication system.

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

#9

Post by 789body » Thu, Jan 03, 2019, 5:58 AM UTC

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 wrote a *different* book, *also* called *Principia Mathematica*, which isn't *really* about mathematics at all; it's about what we would todaycall physics."
    "Then why did he call it Principia Mathematica?"
    "Because the distinction between mathematics and physics wasn't especially clear in Newton's day--"
    "Or maybe even in zis day," Rudy said.

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

#10

Post by stcredzero » Thu, Jan 03, 2019, 6:02 AM UTC

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…

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.

Yeah. It's not the most apt choice of words.