Chang'e-4 lunar operations

[Bob Shaw]

A couple of Weibo shots I've not seen here - part of the 'creaky movie' landing video.

[Bob Shaw]

Here's the shot we've seen before, but with some work on the blown out highlights and a fair bit of sharpening. The major point (apart from seeing that the rover is safely unloaded) is the unusual soil texture. Those tracks are very crisp indeed (even when you discount sharpening).

[whitelancer64]

The rigoleth appears more "dirt"-ier than what we've seen from the near side. I would sure love to know the composition of that "soil". BTW, how is Chang'e 4 communicating with earth? Do the Chinese have a relay communications satellite in a halo orbit around EML-2?

My sincerest congratulations to the Chinese for this accomplishment. It was well done!

The first pictures from Chang'e 3 were brownish like that, too. Similar regolith colors can be seen on some Apollo photographs, as well. It may have something to do with the camera's color calibration, or the lunar "morning" sun angle. More "noon" lunar time the surface may appear more gray because more light is bounced away into space.

[clongton]

The regolith appears more "dirt"-ier than what we've seen from the near side. I would sure love to know the composition of that "soil". BTW, how is Chang'e 4 communicating with earth? Do the Chinese have a relay communications satellite in a halo orbit around EML-2?

My sincerest congratulations to the Chinese for this accomplishment. It was well done!

The first pictures from Chang'e 3 were brownish like that, too. Similar regolith colors can be seen on some Apollo photographs, as well. It may have something to do with the camera's color calibration, or the lunar "morning" sun angle. More "noon" lunar time the surface may appear more gray because more light is bounced away into space.

I'm not talking about the color. I'm looking at the texture. Look at the ridges of those tracks. Very well defined. Just does not look like the dusty regolith we saw on the near side.

[Lars-J]

The regolith appears more "dirt"-ier than what we've seen from the near side. I would sure love to know the composition of that "soil". BTW, how is Chang'e 4 communicating with earth? Do the Chinese have a relay communications satellite in a halo orbit around EML-2?

My sincerest congratulations to the Chinese for this accomplishment. It was well done!

The first pictures from Chang'e 3 were brownish like that, too. Similar regolith colors can be seen on some Apollo photographs, as well. It may have something to do with the camera's color calibration, or the lunar "morning" sun angle. More "noon" lunar time the surface may appear more gray because more light is bounced away into space.

I'm not talking about the color. I'm looking at the texture. Look at the ridges of those tracks. Very well defined. Just does not look like the dusty regolith we saw on the near side.

I think you forget how well defined prints were on the moon. (see bottom of attached image)

Any different appearance is more likely due to the tires being a different construction/thread.

[Galactic Penguin SST]

Apparently the LOI profile of Chang'e 4 was limited enough that had it launched a day late it would not have been able to land at the prime landing zone. It would have to land 13 degrees of longitude away (to the west), at Chrétien crater.

The prime landing zone wss chosen such that the back up landing zone would also be suitable for operations.

Source

[SciNews]

Images from testing, differences from the Chang'e-3 Yutu, little footage from separation

[wahaha]

[FutureSpaceTourist]

Larger version:

https://twitter.com/cgtnofficial/status/1081151126626398208

[Satori]

China Focus: China's upgraded lunar rover drives on moon's far side.

Chinese media, netizens hail historic landing on moon's far side.

Astronomers worldwide hail China's successful landing of Chang'e-4 lunar probe.

Interview: Landing of Chang'e-4 on moon a great achievement, says Spanish expert.

China Focus: Scientists expect breakthrough findings on moon's far side.

[wahaha]

[Blackstar]

China Focus: China's upgraded lunar rover drives on moon's far side.

This article has some good details on Yutu-2:

"LIGHTER

The 135-kg new rover is 2 kg lighter than its predecessor and is the lightest rover ever sent to the moon, said Jia Yang, deputy chief designer of the Chang'e-4 probe, from the China Academy of Space Technology (CAST).

The main reason for the weight reduction is the removal of a robotic arm and its replacement with an instrument developed by Swedish scientists to analyze the radiation environment on the lunar surface, said Jia.

Like Yutu, which landed on the moon at the end of 2013, the new rover carries subsurface penetrating radar to detect the near-surface structure of the moon and an infrared spectrometer to analyze the chemical composition of lunar substances.

Two panoramic cameras, like two eyes, can take high-resolution, color images.

The rover, with a design life of three months, can cross rocks as high as 20 cm, at a maximum speed of 200 meters per hour.

SMARTER

At nighttime on the moon, temperatures can drop to about negative 180 degrees Celsius. During the Chang'e-3 mission, the ground control center instructed that the rover would remain dormant each night, said Zhang He, executive director of the Chang'e-4 probe project, from CAST.

Once the sun would rise, Yutu would wake automatically, but it needed ground control to instruct it to start the work mode, Zhang said.

However, Yutu-2 will automatically enter the dormant state according to the level of sunlight, and it can also enter the work state on its own.

"We made this adjustment because communication between ground control and the Chang'e-4 probe on the far side of the moon is not as convenient as communication with Chang'e-3 on the near side," said Zhang.

STRONGER

China's first lunar rover Yutu suffered a mechanical fault after driving about 114 meters five years ago.

"How to solve that problem so that it won't happen again was the main challenge in developing the new rover," said Zhang Yuhua, another deputy chief designer of the probe.

"We have improved the layout of the wires on the new rover and taken measures to prevent short circuits. We also made a fault isolation design so that if a problem occurs, it will not affect the whole system," said Sun Zezhou, chief designer of the Chang'e-4 probe.

"Compared with Yutu, our second rover is stronger," said Shen Zhenrong, a designer of the rover, from CAST.

"We are confident our new rover can run farther on the moon and obtain more scientific results," Sun said."

[gdelottle]

A bit off-topic but I hope someone can answer a question.

The Queqiao relay satellite is in Halo orbit. I understand that in a frame of reference rotating with the Earth-Moon axis the orbital "plane" remains the same, except for some small variation due to the nature of Halo orbit. This is the trick allowing the satellite to be in contact with Yutu-2 all time, as there is no obscuration during the 28 orbit of the Moon around the Earth.

Is this correct? And if this is the case, how can this happen without consuming some relevant energy like for any change in the orbital plane? Who is "paying" for that in terms of potential or kinetic energy?

[eeergo]

https://twitter.com/AJ_FI/status/1081230532900503559

Noon hibernation coming up in 5 days.

[eeergo]

A bit off-topic but I hope someone can answer a question.

The Queqiao relay satellite is in Halo orbit. I understand that in a frame of reference rotating with the Earth-Moon axis the orbital "plane" remains the same, except for some small variation due to the nature of Halo orbit. This is the trick allowing the satellite to be in contact with Yutu-2 all time, as there is no obscuration during the 28 orbit of the Moon around the Earth.

Is this correct? And if this is the case, how can this happen without consuming some relevant energy like for any change in the orbital plane? Who is "paying" for that in terms of potential or kinetic energy?

The perturbation caused by Earth, allowing this special kind of "Moon" orbit to be achieved, is carrying the brunt of paying for the plane precession halo orbits imply. The orbital plane remains perpendicular to the Earth-Moon line throughout the moon's orbit. See this paper for example: http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?1979CeMec..20..389B&defaultprint=YES&filetype=.pdf

[JulesVerneATV]

View from halo orbit at a Lagrange

https://twitter.com/AJ_FI/status/1081095992865423360/photo/1

[Phil Stooke]

http://m.bldaily.com/china/news/p-373798.html

A picture near the bottom of this report shows tentative plans for the early operations.  It exactly mirrors what was done by the previous rover.

[Blackstar]

http://m.bldaily.com/china/news/p-373798.html

A picture near the bottom of this report shows tentative plans for the early operations.  It exactly mirrors what was done by the previous rover.

[chetan_chpd]

Why is there is so less images released this time during chang’e 4? Chang’e 3 gave us landing video and hi-res images of lander by rover almost within a day or two. Hope everything is alright there.

[chetan_chpd]

I think this the reason, there could be more images after 10 jan.

https://spacenews.com/chinas-lunar-rover-enters-standby-mode-for-noon-nap-as-change-4-tests-continue/