In a PLOT TWIST, the JAXA lunar lander, SLIM, has survived the lunar night (which is bloody cold and was expected to irrevocably freeze all circuits).
SLIM is a technology demonstration, designed to test tech for touching down with pinpoint (<100m) accurate at a target site. The mission achieved this in spades, with estimated accuracy of ~3-4m, although tipped due to the loss of one of the main engines.
SLIM carries 1 science instrument, which it's used but... I guess will now use some more!
SLIM'S ALIVE!! The team reestablished communication with the spacecraft after the Sun inched round in the sky and hit the solar panels. Wild science'ing instantly began!
I don't think #SLIM has a long lunar surface program. It is primarily a technology demonstration to test the image matching navigation (100% success) and 2-step landing (busted due to the loss of one of the two main engines). So I think the multi-band camera will snap hundreds of images while the Sun is up, and then be done.
JAXA's Smart Lander for Investigating Moon (SLIM) is getting ready for landing on the lunar surface tomorrow Friday Jan 19 at 15:20 UTC.
The spacecraft, nicknamed the “Moon Sniper,” will demonstrate precision landing in a target area less than 100m in diameter, using real-time image recognition technology.
The spacecraft will land on a sloping surface near the crater Shioli.
SLIM carries a number of science instruments and will also deploy 2 rovers.
This slide from the briefing, translated using Google lens and posted on twitter, indicates that one of SLIM engine nozzles fell off during landing.
Yikes 😱
It shows an image of the falling nozzle captured by one of the cameras around 00:19:20 JST, just when it lost telemetry.
With one nozzle missing, the lander would have started rotating, while the software tried to compensate using the other thrusters.
Here is another translated slide from the JAXA SLIM briefing.
It states that the main engine was operated at higher load during 8 orbit changes and during the power descent phase, but there were no signs of abnormality in the main engine until the event occurred.
The the -X side (failed) engine had rather mild combustion conditions compared to the +X side engine.
The team believes that some external factor other than the main engine affected the the -X side main engine.
This slide shows that around 00:19:18 JST, when the JAXA SLIM lander was hovering around 50 m, one of the two main engines (the one on the -X side) experienced a failure, as shown by the green line in the graph; the total thrust fell by about 50%, the -X side engine temperature did not rise as expected.
Translated slide 17 states that the JAXA SLIM lander is believed to be oriented upside down, the main engine facing upwards and the solar panels facing west.
Which means that the solar panels should start receiving sunlight and hopefully charging the batteries starting today, as shown in the graphs below (graphs created by me).
The image of the lander with the lunar background is computer generated, not an actual photo.
SLIM did not land upside down. In spite of one failed engine, SLIM touched down upright and with nominal speed. It was the lateral leftward speed that caused it to rotate post touchdown.
The final resting place is 55m east of the target landing site.
At the 50 m hover mark, the positional accuracy was within 10m!
SLIM sent back data and images until it was shut down after 2.5 hours.
Here is some info on the orientation of the JAXA SLIM lander's solar panels.
The solar panels are facing southwest. NW would have been better, since SLIM is at 13.3°S. In the image taken by LEV-2, the solar panels are not visible.
So, there is some hope of a revival as the Sun moves farther west.
This is based on matching an image from a similar location (but from a much higher angle) using the lunar map at LROC. The shadows imply it too.
NASA's Lunar Reconnaissance Orbiter (LRO) today published this image and location of the JAXA SLIM lander on the lunar surface. The image was taken on Jan 24, five days after landing.
The 1st image below shows the new LRO image. SLIM is a tiny dot in this image. The 3 other images below it zoom out of the area to provide more context. I extracted them from the LROC map site and a NASA site.
A note about that iconic image of the upside down JAXA SLIM lander taken by the LEV-2 rover.
The lander appears to be in quite good shape. It is not visibly damaged, shattered or crushed, which a hard landing or a soft landing on its head would cause. As stated by JAXA, the spacecraft must have landed upright, its legs absorbing the vertical speed of 1.4 m/s and then gently rolled over due to its lateral speed.
Instruments and comms were up for 2.5 hours until shut down.
👏👏
Confirmation from JAXA that the team has succeeded in establishing communications with the SLIM lunar lander and has resumed operations!
They have successfully obtained an image using SLIM's Multi-band Camera.
As expected, the batteries are getting charged by the afternoon Sun. They only have a few days left for science operations before the Sun sets and the lunar night begins.
Check out the rest of this thread to learn more about the SLIM lunar mission.
The reference to the "toy poodle" in the tweet by JAXA most likely refers to the rock named "Toy Poodle" in the image below taken by SLIM's Multi-Band Camera on Jan 25.
JAXA assigned nicknames to several rocks in the image as shown below.
An acknowledgement and a thank you note from the JAXA SLIM team to NASA's Lunar Reconnaissance Orbiter (LRO) and ISRO's Chandrayaan-2 missions.
The two missions have provided valuable data to make SLIM's pinpoint lunar landing objective a reality.
Note that even though the Chandrayaan-2 lander crashed during landing on 6 Sept. 2019, the Chandrayaan-2 orbiter has stayed operational and continues to provide hi-res science data.
There is but a slim chance that SLIM can survive the lunar night, which starts tomorrow. It does not have radioisotope thermoelectric generators (RTG) to provide heat and power to its electronics. Nighttime temperatures can fall to a chilly -130° C, 140 K.
Also, due to the solar panel's SW orientation, batteries won't get recharged until late afternoon on the next lunar day, i.e., around Feb 26.
It is a bitter-sweet Good Night for the JAXA SLIM lander as its transmission was turned off by ground station at 00:29:40 UTC. There is hope that it may wake up about 3 weeks from now as the Sun lights up its solar panels again. There is also the realization that this was probably the last transmission from SLIM.
The Sun sets at the SLIM site tomorrow morning around 09:00 UTC.
Come to think of it, SLIM managed to meet most its objectives, in spite of the failed engine.
👏 🙏 #SLIM#Space
52/n
Here is a parting gift by the JAXA SLIM lander as night fell around it earlier today.
It is an image taken by the CAM-PX camera just before the sun set. The sun is at such a low elevation that only the tops of the small rocks and the hills in the background are lit up. This is the same scene whose image was taken on Jan 19 in the morning sun, as shown in the 2nd image below.
Wishing you and your two rover buddies - sweet dreams.
While the fate of Odysseus remains TBD we get a sensation from Japan: https://twitter.com/SLIM_JAXA/status/1761973417820238275 - their lunar lander #SLIM has survived the lunar night and is talking to Earth! And it is even too warm right now for continuous operations ...
JAXA compact robots pull off world’s first feats on Moon mission: https://www.asahi.com/ajw/articles/15169167 - the two small robots were released onto the Moon when #SLIM was nearing a point 5 meters above the surface.