Chang'e-4 lunar operations

[FutureSpaceTourist]

https://twitter.com/cnsawatcher/status/1836657383428198749

Yutu-2 rover has been working on the far side of the moon for nearly 5 years and 9 months, covering a total distance of 1,613 meters. It has exceeded its 3-month design lifespan and currently holds the record for the longest working time on moon. Source:m.weibo.cn/status/Oxqfggc…

[Phil Stooke]

I just noticed that, despite the source, this is not a picture of Chandrayaan 4, it is actually Chandrayaan 3.  Duh... I mean of course Chang'e 4 and Chang'e 3. Apologies.

[Dalhousie]

I just noticed that, despite the source, this is not a picture of Chandrayaan 4, it is actually Chandrayaan 3.

Don't you mean Chang'e, rather than Chandrayaan?

[Phil Stooke]

Ouch!  Yes I do - just looking at Chandrayaan. I will change the original but leave this to record my shame.

[Phil Stooke]

Chang'e 4 and Yutu 2 have been operating on the Moon since this day in 2019, 6 years. As far as I can tell there has been no movement since March. LRO images Yutu 2 almost every month and shows it had not moved from March to June. Some recent images tweeted by Seger Yu (https://x.com/SegerYU/status/1863788924969312386) show it was in the same place in September.

[Phil Stooke]

Following up on that post - Andrew Jones had an article about this apparent immobility of Yutu 2 here:

https://spacenews.com/yutu-2-rover-likely-immobile-on-the-moon-after-historic-lunar-far-side-mission/

which quoted me saying the rover had not moved since March last year. That was based on LRO images up to June and pictures from 8 September tweeted by Seger Yu.  The 8 September images are from the afternoon of the 71st lunar day.

A new LROC NAC image has just been released, taken on 26 September, just after dawn on lunar day 72. It's noisy but it shows something which is probably Yutu 2 after a move in the afternoon of day 71, so the rover is apparently still operating.

The picture added here consists of 2 sections of LROC NAC image M1481962702R, 26 September 2024, very early on day 72. Bottom: the long shadow cast by the Chang'e 4 lander. Top: an apparent shadow cast by a barely resolved object. Probably the Yutu 2 rover! - and if it is it has moved about 15 m in the afternoon of day 71.

The period of immobility is apparently over. I would hope for a less noisy image in coming months to confirm this.

[Phil Stooke]

Here is the latest LRO NAC image of Yutu 2, recently released. The rover is visible, with its tracks. I have marked two earlier positions seen in LRO images. An updated map will follow when I can get to it.

[Phil Stooke]

Another month, another image. Here is Yutu 2 on 27 January 2025.  A careful overlay onto the last image shows it has moved another 4 or 5 m west in the month between images.

[Phil Stooke]

Continuing to monitor Yutu 2 in LRO images. This shows the rover on 23 February this year. It has moved a very small amount (c. 1 or 2 m) since the last image.

[Phil Stooke]

This is my current map of the recent part of Yutu 2's journey.  We are just getting 1 or 2 drives per lunar day, probably one in the morning and one in the afternoon, for a total of about 5 or 6 m per lunar day.  Recent points with dates are from LRO images, end-of-drive points are from those images plus surface images of the tracks.

[Phil Stooke]

Two extremely informative tweets by Seger Yu: 

https://twitter.com/SegerYU/status/1963488056868323653       

https://twitter.com/SegerYU/status/1963456333451317384    

The rover is not doing well. Very small moves as I have been saying.  No images for a few lunar days, but VNIS (an IR spectrometer) was working recently and the neutral atom instrument is still being used. In Chinese but translations are becoming more accessible.

[Phil Stooke]

Seger Yu has outdone himself with this post, linking to a .csv file of rover positions throughout the mission. I have it but have not yet had a chance to do anything with it. 

https://twitter.com/SegerYU/status/1964740866502980033

[Phil Stooke]

Here are two more LRO images of Yutu 2 with dates on the images (lunar days 78 and 80). These are the most recent except for one image taken at night. I don't know why. The position is different from the last one I illustrated, but there is no change between these two. The tracks show up well, especially in the first one.