China lands Chang'e-4 on far side of Moon • Hacker News Board

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

#151

Post by njarboe » Thu, Jan 03, 2019, 4:55 PM UTC

metta2uall wrote: post #135

bluGill wrote: post #128

Earlier quoted context omitted.

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.

Competition between the USA and the USSR produced the first orbiting satellite in Oct, 1957 and a man on the moon, twelve years later, in July, 1969. The USSR gave up on Space tech and so did the USA so that we couldn't land a man on the moon if we wanted to 50 years later. If the USSR had continued on to try and go to Mars we would have been there decades ago. Only with Elon Musk's vision for a Mars colony and his company SpaceX, is space technology advancing again. He also has stated that he hopes for some competition as he knows it can really push people to excel.

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

#152

Post by nitrogen » Thu, Jan 03, 2019, 4:56 PM UTC

sthomas1618 wrote: post #149

dempseye wrote: post #52

Earlier quoted context omitted.

The trisolarian plot in Cixin Liu's The Three Body Problem also seems to have borrowed from this myth.

Having read (and enjoyed) that trilogy, I'm not making the connection. Which part?

There is a 3-star system that causes periodic droughts on a planet in the system based on which star(s) the planet's semi-stable orbit crosses.

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

#153

Post by bhhaskin » Thu, Jan 03, 2019, 4:58 PM UTC

xanipher wrote: post #110

rsynnott wrote: post #100

Earlier quoted context omitted.

Unless you're an ancient Greek, that isn't particularly surprising; it was not part of current traditions when used as the name of a spacecraft.

Learning about the gods of old greece and their stories is still part of the curriculum in a lot of European countries. I doubt most would think of the Moon Landing first.

Same here in the states.

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

#154

Post by tabtab » Thu, Jan 03, 2019, 5:06 PM UTC

ngcc_hk wrote: post #122

brainwipe wrote: post #54

Earlier quoted context omitted.

Regarding underpromising - there might be a little management of expectations but to paraphrase a friend in "the biz": facing away from the Earth means that the stuff you need to be reliable jumps up in complexity and with that complexity comes a foreshortening of life. She then babbled incoherently in a way I enjoyed but didn't understand. Love the idea of a dark side telescope!

Dark side is not really not dark side as the moon is shined by the sun all rounded and hence we have eclipse (by the moon). But I guess the other side would as someone posted no em wave from earth and that help.

So it's "radio dark", not "sun dark". (At least per human radios.)

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

#155

Post by stcredzero » Thu, Jan 03, 2019, 5:15 PM UTC

789body wrote: post #16

stcredzero wrote: post #10

Earlier quoted context omitted.

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.

It's a fine choice of words. It's just a coincidence.

No one is capturing anything with a rope or cable. It's a rotten choice of words.

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

#156

Post by stcredzero » Thu, Jan 03, 2019, 5:21 PM UTC

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...

actually things can and have been caught. Space tethers have been succesful

Indeed, so a choice of words that indicates this was going on in this instance is all the more confusing.

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

#157

Post by metabagel » Thu, Jan 03, 2019, 5:22 PM UTC

But did they find a Nazi moon base?

http://ironsky.net/

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

#158

Post by Rebelgecko » Thu, Jan 03, 2019, 5:33 PM UTC

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…

I wouldn't say it's overengineering. If you design something to have a 99.9% chance of lasting 90 days, the odds are really good that it's still going to be working at 180 days. I don't know what the bathtub curve for a Mars rover looks like, but I imagine a disproportionate amount of failures occur in the first week. If you can make it through that, you're going to make it until major systems fail or your solar panels die. You could get rid of hardware redundancies like 2 of the wheels, but that'll just increase the odds of you getting stuck on a rock while the rover is still functional.

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

#159

Post by nosequel » Thu, Jan 03, 2019, 5:35 PM UTC

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.

China doesn't exactly play nice with others. Even other tech companies have almost given up on working with China. When you deal with them, it is a one way street. What would the US get from any partnership with China besides China stealing any technology they could get their hands on?

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

#160

Post by Rebelgecko » Thu, Jan 03, 2019, 5:37 PM UTC

Retra wrote: post #118

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.

Do you know why NASA doesn't partner up with China? Because it sounds like you think those political differences are insignificant.

It's currently illegal for NASA to work with China. There's been a line in the NASA appropriations bills for the last 5 years or so saying none of the money they're receiving can be used bilaterally or in cooperation with China