China lands Jade Rabbit robot rover on Moon

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scotsdavy1
reply to post by alfa1

 

Most photos of the moon in the early days were all in black and white even though they could have used colour instead. Colour ones show up more detail than b&w ones

While it is true that some color images are good for some details, photographers (and even planetary imagery specialists) would tell you that black and white is an excellent imaging tool due to the contrasts and tonality of it. Some type of detail is better seen using black and white.

Color sometimes confuses the issue when trying to discern tonal differences between objects and materials. One of the reasons the Mars Exploration rovers (Opportunity and Spirit) sent back the raw imagery as gray scales, instead of having those gray scale images processed into color before the rovers sent the images back, is because the raw gray scale images could provide greater detail for some of the science they wanted to do.

The color processing for Spirit and Opportunity was done here on Earth, so they did have the advantage of color when they wanted it, but they also had the advantages that black and white offers (especially considering those black-and-white picture used to make the color picture were imaged through filters of various wavelengths).

In the case of Apollo, we are talking about film images, not the digital images from the Mars Exploration rovers, but the point about black and white being sometimes very useful still stands.

Well said.

A good example is that I operate a meteor camera. It is small Watec WAT-902H2 Ultimate CCD video camera which has sensitivity adjustment. It is basically a very sensitive security camera which can see stars and other dim objects in the sky like satellites and meteors.

A color version of the same camera would not be this sensitive.

GaryN
reply to post by wildespace

 

From the page you link to:

Zhang He, deputy designer of the probe, said though the temperature disparity is greater than scientists had anticipated, all the equipment on the moon is in "perfect" condition,

Any idea what they mean by "disparity"?

They mean the temperature they expected at the landing site or onboard the probe is greatly different than the one they expected.

JadeStar

GaryN
reply to post by wildespace

 

From the page you link to:

Zhang He, deputy designer of the probe, said though the temperature disparity is greater than scientists had anticipated, all the equipment on the moon is in "perfect" condition,

Any idea what they mean by "disparity"?

They mean the temperature they expected at the landing site or onboard the probe is greatly different than the one they expected.

If they are talking about the temperature disparity between the Sun striking the temperature sensing-instrument and the temperature-sensing instrument in the shade, then the unexpected disparity could have something to do with the material from which the temperature-sensing equipment is made.

"Hot" or "cold" on the Moon (or in any vacuum, and the moon is for all intents and purposes virtually a vacuum) the same as the hot or cold here on earth. On Earth, when we say it is hot or cold, that is a measurement of the temperature of the AIR. There is no air on the moon, and the vacuum of space does not either get hot or cold.

The measurement of heat due to sunlight on the moon (or in space) would be the measurement of the sunlight heating something up. No air = nothing to heat up. However, the sunlight hitting the temperature sensing device could heat up that device...BUT the amount that device would heat up is a function of the material it is made from. Something reflective would reflect sunlight and heat up less than something black and light-absorbent.

Therefore, that's why I said the unexpected disparity could have something to do with the material from which the temperature-sensing equipment is made.

reply to post by Komodo


Er, thanks Komodo, but I do know what the word means ( I have Google too!), but was wondering if anyone knew what it applied to in this case.

@ JadeStar

They mean the temperature they expected at the landing site or onboard the probe is greatly different than the one they expected.

Yes, but no figures for what they expected and what they got?

Hey SGIP, yeah, measuring temps in a vacuum is kind of weird I guess. If the sensor is in direct Sun, then I'd think it would get very hot, no air molecules to carry any heat away, just re-radiating to space, so reflective value and thermal conductivity, and maybe mass need to be known? In the shade, it would get the light reflected from the surrounding area I imagine, and in total dark it would read a value the same as the outside sensor at night?
I've been wondering though if there are differences in temperature between Lunar early morning and noon, and late afternoon. With no atmosphere for the Sun to be absorbed in at low sun angles, should the temperature be the same for as long as the Sun is 'up'? Questions, questions, always questions...

Panorama view of Chang'e 3 landing site
www.youtube.com...

Link to a slightly better version (unencoded by Youtube): v.qq.com...

Using Google Translate:

News from the National Defense Science and Technology Industrial Development Bureau, and after successful completion of the lunar soft landing, Chang E III has entered the stage of scientific exploration, the use of cameras on the lander returned topography image, the researchers produced a panorama debut landing zone photos.

On this chart, we see the Chang-e III sangrakwol place overall, relatively flat, but around the landing site, the distribution of a large number of rocks and craters, especially in places lander ten meters away, there is a relatively large impact craters. In the course of Lloret de Mar, the Chang-e III completed the world's first unmanned lunar spacecraft hovering autonomous obstacle avoidance, avoiding the craters.

It is understood that the moon is going through midday hours, the rover spent the actual temperature being the highest temperatures of over 100 degrees Celsius environment through hibernation mode.

I take it "sangrakwol" is the lander, but no idea what Lloret de Mar has to do with anything. Any Chinese experts here wanna give a better translation?

Here's the panorama reconstructed by Phil Stooke:


In other Chang'e 3 news, Xinhua reports that the rover roused today from its noontime "siesta," a few days earlier than originally planned. The rover hibernates over the high temperatures of lunar noon and cold temperatures of lunar night.

google translated messed up the 2nd section, it should be like this:
" From this picture, we can see the Chang'e III landing site is relatively flat, but there're rocks and craters nearby, especially the crater just 10 meters from the landing site, during the landing the Chang'e III autopilot landing system successfully guided the lander moved away from this crater."

Using Google Translate:

News from the National Defense Science and Technology Industrial Development Bureau, and after successful completion of the lunar soft landing, Chang E III has entered the stage of scientific exploration, the use of cameras on the lander returned topography image, the researchers produced a panorama debut landing zone photos.

On this chart, we see the Chang-e III sangrakwol place overall, relatively flat, but around the landing site, the distribution of a large number of rocks and craters, especially in places lander ten meters away, there is a relatively large impact craters. In the course of Lloret de Mar, the Chang-e III completed the world's first unmanned lunar spacecraft hovering autonomous obstacle avoidance, avoiding the craters.

It is understood that the moon is going through midday hours, the rover spent the actual temperature being the highest temperatures of over 100 degrees Celsius environment through hibernation mode.

I take it "sangrakwol" is the lander, but no idea what Lloret de Mar has to do with anything.

Any Chinese experts here wanna give a better translation?

Here's the panorama reconstructed by Phil Stooke:

In other Chang'e 3 news, Xinhua reports that the rover roused today from its noontime "siesta," a few days earlier than originally planned. The rover hibernates over the high temperatures of lunar noon and cold temperatures of lunar night.

edit on 21-12-2013 by wildespace because: (no reason given)

Yutu has had to deal with direct solar radiation raising the temperature to over 100 degrees centigrade on his sunny side, while his shaded side simultaneously fell below zero.

So the Chinese don't know how to build a parasol to shade it from the Sun? Wouldn't need to weigh much or be very strong as there is no wind on the Moon to bend or break it. Or maybe design it so the solar panels would move to provide shade?

IamSirDrinksalot

surfinguru

Daedalus

another thing...everyone is talking about mining the bejesus out of the moon....unless they're planning to replace the mass they remove, with something else, i foresee problems with this plan..

That's always my first thought when I hear people discussing mining the resources of the moon. The moon has such a significant daily impact on our world, how can anyone in their right mind think that changing the current equilibrium is ok?

In my small walnut brain, I would think less moon mass equals the moon moving out of earths orbit sooner than it would naturally do so. Now maybe if that mass is transferred to Earth, the Earth creates additional gravitational pull to offset the loss of moon mass???

I don't know, to me it just seems like a really, really bad idea to wholesale remove lunar mass.

Really, do you know what the mass of the moon might be? 81 billion quoted on the interweb.

Possibly the most we can mine on Earth is 80 thousand tonnes per day (based on Googles most efficient mines), mining at that rate, it would take over 2500 years to erode the moon to nothing.

But if you think how much could anyone really remove from the moon...

The Americans brough back 0.4 tonnes of moon rock over 3 years, if my shaky maths are right, that would take 200,000 days to mine or 550 years to mine 80,000 tonnes.

So lets say the Chinese, who cant do it on earth, can send a robot mining set up to the Moon (are you keeping up?).

And then lets say that the robot mining set up can run without human mechanical help for a while..and then, it mines and finds some resources which it can refine and put into transport boxes to be loaded into vehicles that can return to Earth from the Moon....

Perhaps now, you will stop worrying about altering the moons gravitational fields and creating tsunamis on earth.

Jeesus help me....

you ARE aware that it's possible to explain something, and convey a point WITHOUT being rude, and talking down to people.....right?

if your assessment is right, then that's wonderful. thank you for your thoughtful and lengthy explanation...perhaps next time, you can be a tad more polite.

Some decent images from the lander, inclusing stereo pairs, if anyone's interested: chn.chinamil.com.cn...

Cool landing photo:

Can anyone tell me how far away those rocks on the horizon would be in the main photo? It's interesting because its so flat... and you can see the curvature of the moon, unless that's a function of the camera itself.

I've been comparing photos of this with some NASA ones, and you *can* see stars in these pictures; I don't think it's an artifact of my computer screen. Pull this up, click on it to enlarge and then look closely at the sky. There's one 'star' that is probably a planet and easy to find; tilt your screen a bit and you can make out hundreds of stars, unless my laptop screen has pixel issues. There's a lot of variance of brightness in them, and you can almost make out constellations, but there's really too many to do that. It's really a shame and a wonder why NASA didn't see fit to take some photos of Saturn in all those missions from the moon. Didn't they have a telescope on the lander or the orbiter? At least binoculars?

NASA

signalfire
Can anyone tell me how far away those rocks on the horizon would be in the main photo? It's interesting because its so flat... and you can see the curvature of the moon, unless that's a function of the camera itself.

The lander was still quite high up (about 15 km), so what you see in the image is stretching for hundreds of kilometers. The "rocks" on the horizon is the mountain range called Montes Recti, stretching about 90 km from end to end. The large crater in front of them is Laplace F, 5.27 km in diameter. I can't tell for certain above which spot the lander was when it took this image, but going approximately, it was about 150 km from the mountain range, and about 70 km from the crater:

signalfire
I've been comparing photos of this with some NASA ones, and you *can* see stars in these pictures; I don't think it's an artifact of my computer screen. Pull this up, click on it to enlarge and then look closely at the sky. There's one 'star' that is probably a planet and easy to find; tilt your screen a bit and you can make out hundreds of stars, unless my laptop screen has pixel issues. There's a lot of variance of brightness in them, and you can almost make out constellations, but there's really too many to do that. It's really a shame and a wonder why NASA didn't see fit to take some photos of Saturn in all those missions from the moon. Didn't they have a telescope on the lander or the orbiter? At least binoculars?

NASA

I can see the bright object in that photo (Venus or Jupiter), and perhaps two or three stars, but definitely not hundreds of them. Some digital noise or dust specs on the film might come off looking like stars, but the simple fact is that you see bright sunlit surface of the Moon, and the camera's exposure was set for that. Taking a proper photo of stars would require a long exposure (at least a minute), and a camera set on a tripod or tracking mount. Apollo astronauts didn't have those, neither did they have telescopes or binoculars on the ground. They did photograph stars from the orbiter, using UV photographic film.

Yutu and the lander are preparing to hibernate for the lunar night. After they "wake up", the rover has the following targets for exploration, according to this article in Chinese: news.xinhuanet.com...

A large pyramid-like stone about 42 meters southwest from the lander, which scientists have never seen before; the high ground to the west [presumably the rim of the large crater nearby], overlooking the surrounding environment; and the crater more than 10 meters to the north [that small crater rimmed with white boulders seen in the first images].

The rest of the article talks about creating 3D topographic maps of the area using the stereo cameras, to ensure safe operation of the rover and to plan for future objectives.

reply to post by wildespace


The Moon phase could also explain some of the light fall off noticed in some of the pictures. I know it was explained that many of the pictures now being shown are screen grabs from the over head display. But, as the terminator moves toward the landing area, the shadows will grow much longer and the sun will not reflect off the surface in the same manner.

Current Moon Phase

interesting reading

GaryN
Hey SGIP, yeah, measuring temps in a vacuum is kind of weird I guess.

See this post for a primer.

If the sensor is in direct Sun, then I'd think it would get very hot, no air molecules to carry any heat away...

Air does its best cooling when it is moving across the hot surface and carrying the heat away, thus the fan on your car's radiator and the little fan on your computer's CPU heat-sink (Trivia: Modern Pentium/Athlon-type CPUs cannot be used in unmanned satellites & probes because no air means no air cooling, and liquid-cooling is just one more thing to go wrong on a years-long mission. The electronics on manned spacecraft & space stations can use liquid cooling because there are guys there to fix it when it breaks).

Without a wind, air can still carry away heat through convection, but it's not very effective. All other things being equal, if you have two sunlit items of the same material, one in vacuum and one in calm air, the vacuum sample may get ~10% hotter.

...just re-radiating to space, so reflective value and thermal conductivity, and maybe mass need to be known?

Correct! Knowing the absorbance, emissivity and reflectivity of materials are crucial to designing equipment for work in space. I know a couple of engineers who work on satellite designs, and they can vouch for this.

One of the "gotchas" of working on the Moon is that the fine, dark lunar soil gets everywhere, and affects the thermal characteristics of equipment if it's not cleaned-off. The Apollo 12 crew had a lot of trouble keeping the first Apollo Lunar Surface Experiment Package (ALSEP) clean. On the rover missions (Apollo 15, 16 & 17) the TV camera had to be brushed-off at every stop to keep it from overheating, and on Apollo 17 the Surface Electrical Properties Experiment failed due to overheating as a result of dust contamination.

In the shade, it would get the light reflected from the surrounding area I imagine, and in total dark it would read a value the same as the outside sensor at night?

Essentially correct. This lead to another "gotcha" on Apollo: The LM's thermal design took into account the reflected light of the lunar surface. However, on the Apollo 15 mission, they forgot that the landing site was bordered on two sides with high mountains that reflected more sunlight on the landed LM. This caused higher than anticipated heating. They took this into account on Apollo 17, which landed in a mountain-ringed valley.

I've been wondering though if there are differences in temperature between Lunar early morning and noon, and late afternoon. With no atmosphere for the Sun to be absorbed in at low sun angles, should the temperature be the same for as long as the Sun is 'up'?

No. The operative term here is insolation, which is how much solar energy is received for a given area in a given time (note that this doesn't include reflectance & absorbance, just how much energy is falling on the area - R & A is what happens next). Thanks to the projection effect, sunlight hitting a surface at an angle is more spread-out and therefore weaker per unit area than sunlight hitting from straight overhead. This is main reason why the the poles of a planet are colder than the equatorial regions (Some people mistakenly believe this is because the atmosphere (for those worlds that have one) attenuates more light. Not only is insolation a much greater factor, air circulation actually moderates the temperature fluctuations). Thus the daily temperature profile on the Moon looks something like this.

Questions, questions, always questions...

But good questions. That's why I enjoy this topic so much. In learning the answers, we gain a deeper understanding of how the universe works (from a scientific standpoint) and how we can use it to make cool things (from an engineering perspective - Think about it: There are engineers in the US, Russia and China who built things with their own hands, and then got to see pictures of their very own handiwork sitting on the surface of the Moon!!! How incredibly cool would that be?).

People who think (I use the term loosely) that it was all faked are missing out. They don't care about learning, or creating. They don't understand the drive that carries achievers to great honor. I don't think they want to understand, because then they might have to come to grips with their own lack of motivation. Perhaps they have a political/ideological axe to grind. Maybe it's just easier to accept their own lack of achievement if they pretend nobody else has accomplished anything either.
It's sad, really...

signalfire
I've been comparing photos of this with some NASA ones, and you *can* see stars in these pictures; I don't think it's an artifact of my computer screen. Pull this up, click on it to enlarge and then look closely at the sky. There's one 'star' that is probably a planet and easy to find; tilt your screen a bit and you can make out hundreds of stars, unless my laptop screen has pixel issues. There's a lot of variance of brightness in them, and you can almost make out constellations, but there's really too many to do that. It's really a shame and a wonder why NASA didn't see fit to take some photos of Saturn in all those missions from the moon. Didn't they have a telescope on the lander or the orbiter? At least binoculars?

NASA

Given the brightness of the lunar surface it's much more likely that they are blemishes from the original photos and/or the scanning process. Some surface photographs from Apollo 14 and 16 did capture Venus, which is one of the brightest objects in the sky and thus stands out more against the surface glare.

They had a telescope on the lunar surface for Apollo 16 but this was designed to look at the far UV spectrum - I'm currently working on a web page examining these, but you might want to google the S201 experiment for Apollo 16, there are quite a few reports out there with pictures from them. This site has some of the images.

Several Apollo missions also took a camera lens specifically for low light stellar photography. The F1.2 lens went on a Nikon 35mm camera and was used in lunar orbit. Jupiter and Venus were captured on several photographs, and one sequence if images from Apollo 17 accurately tracks Jupiter's movement over 51 hours when compared with modern astronomical software - here's what I found:



Here's my favourite one - it shows Venus as the brightest object with Mars just below it. You can make out Saturn in the glare of the window frame:



To capture these they had to put up a special blind, turn out the lights and stop the passive thermal control - the roll of the command module designed to stop one side getting overheated in the sun. More on my website here.

LRO (Lunar Reconnaissance Orbiter) has spotted the lander and the rover. Huzza!
Link

LROC NAC view of the Chang'e 3 lander (large arrow) and rover (small arrow) just before sunset on their first day of lunar exploration. LROC NAC M1142582775R, image width 576 m, north is up [NASA/GSFC/Arizona State University].

Chang'e 3 landed on Mare Imbrium (Sea of Rains) just east of a 450 m diameter impact crater on 14 December 2013. Soon after landing, a small rover named Yutu (or Jade Rabbit in English) was deployed and took its first tentative drive onto the airless regolith. At the time of the landing LRO's orbit was far from the landing site so images of the landing were not possible. Ten days later on 24 December, LRO approached the landing site, and LROC was able to acquire a series of six LROC Narrow Angle Camera (NAC) image pairs during the next 36 hours (19 orbits). The highest resolution image was possible when LRO was nearly overhead on 25 December 03:52:49 UT (24 December 22:52:49 EST). At this time LRO was at an altitude of ~150 km above the site, and the pixel size was 150 cm.

Looking through LRO's past images of the Chang'e 3 landing site, I came across this oblique view (at approx 45 degrees angle) - wms.lroc.asu.edu...
The resolution is 1 meter per pixel. I think oblique views are nice, as they give a kind of bird's eye view, or a view from a plane / orbiting spacecraft.


The image has been flipped (hopefully) the right way up, deinterlaced, and a red star added to mark the landing site

signalfire
I've been comparing photos of this with some NASA ones, and you *can* see stars in these pictures; I don't think it's an artifact of my computer screen. Pull this up, click on it to enlarge and then look closely at the sky. There's one 'star' that is probably a planet and easy to find; tilt your screen a bit and you can make out hundreds of stars, unless my laptop screen has pixel issues. There's a lot of variance of brightness in them, and you can almost make out constellations, but there's really too many to do that. It's really a shame and a wonder why NASA didn't see fit to take some photos of Saturn in all those missions from the moon. Didn't they have a telescope on the lander or the orbiter? At least binoculars?

NASA

Sorry its very unlikely if you look at this picture.

[atsimg]http://files.abovetopsecret.com/images/member/0f3c5691ac08.jpg[/atsimg]

This was on the film backs for the Apollo Hasselblad cameras shutter speed 1/250 or 1/125th of a second apertures f5.6, 8 or 11 also the film wasn't high speed.

The surface conditions are like a sunny day on Earth it's NOTHING to do with surface glare they had to expose for bright sunlight because that was how the surface was lit!