China's Jade Rabbit lunar rover dies on moon | Hacker News Reader

China's Jade Rabbit lunar rover dies on moon

cbc.ca

102 pointsmileswu74 comments

I found it quite appropriate that the referenced CBC article referred to it as a moon "buggy."

More seriously, I'm excited to see more countries, and more people in general, involved in space exploration.

I also think that instead of pointing to the rover's failure, we shout point to its success: Launching a rover to the moon and getting it to work in any way, shape, or form, is a pretty amazing triumph. Sure, the US did it several decades ago, but not all NASA missions were successful, and it's to be expected that you need a few iterations to get the bugs out.

To be fair that's also what the US called the Lunar Rover:

http://en.wikipedia.org/wiki/Lunar_Roving_Vehicle

Let's not bury Yutu alive in our haste to eulogize it. The rover is awake and transmitting. Lot of news sites have been reporting on news from many many hours ago. My guess is the mechanical error interfered with the solar intake and delayed the power-on process.

http://news.xinhuanet.com/english/sci/2014-02/13/c_133111283...

This is a shame, but most people -- even in space programs -- don't appreciate how cold the Moon's shaded areas become. It's now estimated that these areas get to 26 Kelvins -- that's 26 degrees above absolute zero. To get a sense of how cold this is, Pluto's average surface temperature is seven degrees warmer.

Also consider that, because of the specifics of the Moon's orbit, a given area stays shaded for just over 14 days each month. That's a long time at a very low temperature. Unless a spacecraft has a way to heat itself during the long lunar night, its electronics will self-destruct.

Does China have the capabilities and reserves of radioactive material to make probes with RTGs?

It has a radioisotope heating unit https://en.wikipedia.org/wiki/Yutu_%28rover%29#Specification...

Online accounts say there's a radiation source for heating during the lunar night, but it seems one of the solar panels used for normal operations didn't fold up properly (by folding up these panels are closer to the heat source) before the sun went down, and that exposed component froze and was ruined, which sealed the spacecraft's fate.

Source: http://www.dvice.com/2014-2-12/chinas-jade-rabbit-lunar-rove...

Looks like it: http://en.wikipedia.org/wiki/Timeline_of_the_Republic_of_Chi...

They had capability to produce required material decades ago.

They also have sufficient nuclear arsenal to warrant maintaining stockpiles of the stuff: http://en.wikipedia.org/wiki/China_and_weapons_of_mass_destr...

You are confusing the Republic of China, commonly called Taiwan (which is the subject of your first link) with the People's Republic of China, which sent this robot to the moon.

Both of them have nuclear power though (but only PRC has nuclear weapons) and radioactive material in sufficient quantities.

> Pluto's average surface temperature is seven degrees warmer.

What about the temperature in Pluto's shaded regions (if there are any)?

Maybe Pluto's atmosphere keeps the temperature warmer? I assume it's too far from the sun to have any unshaded versus shaded regions.

The average "temperature" of empty space is 3K, due to heating by background radiation. That's a big enough difference to have a warmer sun-facing side and a cold, shaded side.

>To get a sense of how cold this is, Pluto's average surface temperature is seven degrees warmer.

That doesn't give me a good sense because I have no idea how Pluto's average surface temperature compares to typical on-Earth temperatures that I have experienced. This gives me a better sense:

26 K = -247.2 C

Is that with the windchill?

No atmosphere, therefore no wind, thus no windchill.

You must be fun at parties.

Or -413 F for us silly Americans.

Oh, so something like Canadian winter. ;)

IMHO you're better off thinking in Kelvins. Room temperature is 295 Kelvins, the cosmic background radiation (the leftover glow of the Big Bang) is 2.7 Kelvins, and between the stars, far from any particular star, an object naturally cools to the universe's background temperature of 2.7 Kelvins.

Fun bit of trivia: If a moon rover could maintain speed of about 11 miles per hour (17 Kilometers per hour) forever, it could circle the moon in 28 days, and would be moving fast enough to stay on the light side of the moon. That doesn't seem very fast, but with the moons low gravity and all.... You'd have to be doing science while catching big air.

That said, temperature works differently in hard vacuum - with no air to conduct/convect the heat away, isolated objects don't actually get "cold" the way they would in a pool of liquid nitrogen or something. Notice you don't hear about the ISS freezing at night.

The ISS is only in shade for 45 minutes at a time, which is orders of magnitude less than a lunar night.

But speaking of that: how long is too long to spend at 26K in a vacuum? Are there any good articles/videos that talk about what happens to various materials at such extreme temperatures in a vacuum?

I think the point of the parent comment was that simply being in a cold vacuum doesn't make you instantly cold. That still requires a process of heat transfer, which occurs in a fluid via conduction, convection, and radiation.

When immersed in a vacuum the conduction and convection heat transfer paths are sharply reduced, so the question then becomes how fast do you cool off via radiation alone?

I'm not a physicist so I don't know, but it's certainly nowhere near as fast as conduction/convection (in fact I believe heat dissipation was actually problematic for many spacecraft designs).

As it turns out, even on earth's surface, radiation is a more efficient heat transfer method than conduction and convection through the air. Objects under a clear sky quickly drop below air temperature in many circumstances.

Thank you! I did an hour jog tonight, and most of that time was spent trying to figure out why there was frost on the ground with an air temperature above freezing and a warm breeze.

I wonder if heat might also be conducting downwards to the frozen ground below.

What he's trying to say is that if you toss a rock into liquid helium or a 4 Kelvin zero g vacuum it's going to get colder faster via direct contact with the helium than via radiation in the vacuum.

Wow, that seems amazing but now that you mention it I think I've heard of that happening even in deserts.

No, actually, a vacuum is an ideal environment for radiating heat away -- better than an atmosphere, certainly. Surfaces in lunar shadow really do drop to an extremely low temperature over a period of days.

You changed the entire context by sticking the word 'radiating' in there. Yes vacuum is fine for radiation, but radiation is much slower than physical contact with standard pressure air.

> Yes vacuum is fine for radiation, but radiation is much slower than physical contact with standard pressure air.

Actually, it's the other way around. Under a clear sky at the surface of the earth, radiation is much more efficient than convection and conduction to air. This is why objects at the surface readily cool below air temperature at night.

Source: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/coobod.htm...

The linked example is a person losing heat energy under normal circumstances (23 C ambient, body temperature of 34 C). The example shows that a body loses 17 watts to perspiration, 11 watts to conduction (to the air and environment), and 133 watts to radiation.

Contrary to what many people think, a planet without an atmosphere loses heat to space very efficiently, solely by radiation -- indeed, that mechanism is more efficient in the absence of an atmosphere. But even with an atmosphere, radiation is the major heat loss mechanism, most more efficient than convection.

A great deal of effort has gone into keeping the ISS at civilized temperatures:

http://science.nasa.gov/science-news/science-at-nasa/2001/as...

It's got 100,000 watts of solar power, so that combined with good insulation means it won't freeze as long as the panels keep working...

Suppose China were to send another Rover up in the next 5 years, and it found this one. In theory, could this one be repaired? Or will the "electronics self-destruct" be thorough by then?

Some assumptions I have to make are:

• The RTG in Yutu (the rover already up) will last that long

• Yutu does not move, get struck by a meteor, or other normal events in space that will damage it further

• The team who understands Yutu is still around in 5 years

Then China could, in theory:

• Assemble a rover with the repair parts on board

• Launch it to the moon

• Land on the moon intact

• Locate Yutu

• Do a remotely-operated repair

There's a lot of risk in each of those steps. It might be an interesting mission to push the boundaries of tele-operated robotics etc. Realistically it seems less expensive to launch a second rover that has been improved based on the lessons learned from Yutu. Hopefully China can think of lots of things to improve the second time.

Interesting thought experiment, though.

You try, you fail, you learn. It's fantastic more countries are venturing into space exploration. Their next effort will build upon what they've learned.

Do countries typically share what they learn about these failures?

I know NASA has been publishing reports on all of their missions for a number of years. Here's a small collection: http://www.hq.nasa.gov/alsj/alsj-mrs.html

I believe that after Challenger, NASA has even published technical reports regarding all aspects of the cause of failure and the steps to prevent it.

My biggest shock was "Why haven't I heard about this lunar rover before!?"

I'm not news hound, but I do spend too much time on tech sites (HN/Reddit) that would report this. I remember years ago mention of China (and India) moon missions. But, really first man mad object to land in 37 years should have been blasted over most news sources.

After shock... "Kick ass, we're (finally) getting back on the moon!"

It was definitely on the front page of all techie sites, including HN and Reddit.

Many comments thereof lamented the lack of coverage by the mainstream media.

It even made the Daily Show with Patrick Stewart hilariously dressed up as the rover, slowly dying.

http://www.thedailyshow.com/watch/tue-february-4-2014/who-fr...

Not surprised. He has been bashing China for a while, which is the trending topic in the mainstream media anyway. Though I do wish some of the media agencies strike out of the group-thinking, and examine what NASA has been up to for the past decade, and what needs to be improved in terms of space exploration.

I haven't seen any trend of bashing China, unless of course reporting honestly is bashing.

NASA, despite its huge budget cuts, in the last decade has operated three rovers on Mars, landed one new one (via spectacular jet crane awesomeness). They've built new types of rockets, taken pictures of the universe, continued to do valuable research in science and space. Continued to be a major contributor to the ISS. And much much more.

I think the real question here is, where have you been for the last decade?

I haven't seen any trend of bashing China, unless of course reporting honestly is bashing.

Well, this is a bit subjective, in my book selective reporting that focuses on negativity is bashing.

I am all for more budgets for NASA. Quite frankly, I don't follow NASA's missions very often. For the past decade I did hear from time to time that NASA sent rovers to some planets. Meanwhile, I kept hearing the flip-flop stories about the water on Mars. It gave me impression that NASA either went hugely under-budget on their Mars' missions or they spread themselves too thin. That was my point (admittedly I may need to soften my tone in my comment). Not sure if NASA had a vision problem, in my opinion, it may have made more impact and (hopefully) got more funding if they narrowed down their scope of missions and obtained more decisive results.

The flip-flop comes from mainstream media interpretation of the science, usually not from the people that are part of the missions. Even the "science journalists" that are attached to bigger missions frequently dramatize findings in order to "make it a compelling story" (source: one of my exes was such a journalist.)

> either went hugely under-budget on their Mars' missions or they spread themselves too thin

I think that is a misread of the situation; the lack of a consistent narrative and publicity across NASA and its missions has more to do with the organizational structure of the PR and public education/outreach within NASA than the science or the mission management itself.

the US, english-speaking media tends to only point out extremely good, and extreme bad things about china.

this paints a really extreme (go figure) picture of china. some people think it's the most amazing place on earth and some people think it's some kind of post apocalyptic hellscape.

as always, the truth can be found by actually going there, something most people with very strong opinions about china have never done and probably never will do, in all likelihood

He is a comedian, whose "bit" is being critical. He takes jabs at just about everything he covers.

this episode was really stupid

A moon rover is a bit substantial for what constitutes "tech" these days. OTOH, you've probably read multiple stories on Flappy Bird.

it was a top story on NPR for 4 days straight. by top story I mean it was what was on when I drove into work

There were some discussion earlier, on HN:

https://news.ycombinator.com/item?id=6904717

https://news.ycombinator.com/item?id=7128978

Yes, ISRO (India's space agency) sent an orbiter and impactor to Moon called Chandrayaan-1, back in 2008. NASA and ISRO's instruments on-board Chandrayaan-1 had detected water on Moon.

It's good to see rekindled interest in science missions to satellites and planets. I'm eagerly waiting for ISRO's next Moon mission, Chandrayaan-2, which will have a soft lander and a rover. Probably in 2016 :)

Well that sucks.

Is anyone here a big follower of the Chinese space programme? I follow "western" space efforts pretty closely, but with heavy military involvement, a preoccupation with face-saving, and the language barrier, I find the Chinese programme nigh on impossible to track. Do they have the same sort of spending split that NASA has with respect to the manned v. unmanned programmes? Or does their unmanned programme get substantially more than a pittance? As things stand, I'm not even able to tell if they are actually serious about space outside of military use, or if it's all just a prestige play. Anyone care to fill in some detail?

We, Chinese, do not know too much details either. It is hard for us to know details about the spending.

I tried to google it with key words like "Chang'e budget", but found nothing useful. However, I did found an article about the history[0]. Here is some fact: Back to 90s, there were Chinese scientists suggesting for lunar exploration. But the projects requires a budget around 1.5B, which was declined by the prime minister LI Peng (Family name first.)

0. http://www.baike.com/wiki/%E4%B8%AD%E5%9B%BD%E6%8E%A2%E6%9C%...

I wish the Chinese space program the best. Every success pushes mankind (all nationalities) forward in our understanding of the universe.

That. Hopefully we can get another space race this time against China. Sending people to Mars or establishing moon colony for example.

I suspect Elon Musk will win that one and as a result America :)

SpaceX is doing quite well thusfar.

I spent 2 minutes with google and it seems the closest I could get is this: http://news.qq.com/a/20120625/000134.htm Basically it says the total spending on manned space missions is less than RMB 40B from 1992 to 2013. That translates to about 6.7B in current ratio.

2 NEST to send man to space. Not too bad IMO.

Hard to say what happened from the sketchy reports, but there's been some mention of "mechanical problems" due to lunar dust, and hibernation problems. I guess they have some mechanical movement involved in hibernation mode. Pre-positioning solar arrays, maybe? Storing instruments?

Lunar dust is notoriously abrasive, having formed in a non-erosive setting. It's a well known problem for lunar exploration, and NASA's done a lot of work on it. Not a lot of recent practical experience, of course.

The Chang'e designers must have known about the problem. Apparently they underestimated it, or just missed. Hopefully there's some good lessons learned for future missions. Getting there and working for a lunar day is a pretty good job in itself.

The team is still working on it. There is hope still.

http://gbtimes.com/opinion/jade-rabbit-still-fighting-despit...

Chinese space program had come a long way. Interesting test would be how they handle this failure. Will they go assigning blame and scapegoats. Or will they learn from this mistake and improve quality control/redundancy for future missions.

Its entirely possible to do both...

I expect the latter, they aren't known to give up big dreams so easily. Consider for instance that India and Russia have had numerous failed launches for various rockets and / or space probes and both countries continue to try again and eventually succeed. Why would China not try again? I pray they do. Chinese or American or Russian or Indian, I want to see a minimal human habitat on the moon in my lifetime. Our species deserves that much, for all the work done so far.

There is no such thing as deserve, especially in cases like this. There is no ice cream for failure.

Well I mean you can go out and buy ice cream if you're at mission control and not dead. And I guess you can eat some astronaut ice cream as your air runs out or you freeze to death if you are in space.

But this isn't some deserve type thing.

Shame as well space exploration is still so primitive and infant that I root for any nation venturing out there. Too bad its clouted by military achievements.

Seems like there is hope: http://www.planetary.org/blogs/emily-lakdawalla/2014/possibl...

Actually, it's working - not perfectly, but it's 'awake,' sending and receiving signals:

http://news.xinhuanet.com/english/sci/2014-02/13/c_133111283...

Xinhua is adding new info on Twitter:

https://twitter.com/XHNews

Does anyone know if there are images from this rover available on-line ? I'd love to see some hi rez shots of the Earth with the Moon's horizon in the shot.

Here are some images of a mock-up of the rover, being shown off at a science conference in Beijing. It's an impressive technical achievement.

http://www.stuff.co.nz/science/9448077/China-sending-jade-ra...

http://www.businessweek.com/articles/2013-11-26/chinas-jade-...

http://imarstore.blogspot.com/2013/11/technology-china-going...

The question is, why is Europe being nuked in the background? Note how the images are from at least 3 different angles, so it's not like some reporter got a Photoshopped picture ...

http://www.reddit.com/r/WTF/comments/1t37gn/wtf_is_a_mushroo...

http://rt.com/news/europe-nuclear-explosion-china-440/

FYI, according to recent news[0], The lunar rover is recovered now. Sorry that I did not find a source in English.

0. http://www.bbc.co.uk/zhongwen/simp/china/2014/02/140213_yutu...

I like the name "Jade Rabbit" :)

It sounds like a dildo name to me.

Culture difference.

Jade Rabbit is a figure in Chinese legend, companion of a fairy named Chang'e.

>companion of a fairy named Chang

Now it even sounds more like a dildo name.

It is a dildo name, if you believe the Jon Stewart show clip in the other comment on this page ...

News: it wakes up now.

Good luck getting the warranty honoured ;)

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