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Japan: Moon lander Slim comes back to life and resumes mission

296 points| neversaydie | 2 years ago |bbc.co.uk

140 comments

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[+] t43562|2 years ago|reply
Scott Manly did a great explanation. The lander lost a rocket nozzle when it was in the final part of its descent - hovering and taking pictures of the landing site. Nozzles make the rocket's thrust much more effective so basically it lost thrust on one side.

It had very good software which adjusted to this and brought it down softly enough to land but it couldn't stop the pitch over.

The spacecraft landed within 50m of it's target which is exceptionally good accuracy and that part of it's mission was a complete success.

The rocket nozzle problem may have been due to a stuck valve or some other problem and obviously they have work to do on that but apparently something similar has happened on a similar design before.

[+] stcredzero|2 years ago|reply
Scott Manly did a great explanation.

Someone remarked below, "It is just like Kerbal."

In KSP, I've landed a nuclear rocket on the Mun, and had it tip over. Then I put 2 and 2 together, and put landing gear on that side of the craft! This allowed me to use the craft as a lunar rover. To get back, I'd pick a hill to use as a ramp, and do a "Dukes of Hazard" launch.

Once, I even demonstrated this in person to Scott Manley!

[+] NotSammyHagar|2 years ago|reply
Thanks for that. I hadn't heard this detail in the mass media sites I read about it. HackerNews as usual has a succinct summary, why can't normal media be this clear? I think it's because most journalists are missing an engineering background. Just adding those few sentences tells us so much more.
[+] beAbU|2 years ago|reply
Should have collaborated with some of the BattleBots/Robot Wars teams to include one of those flippers that up turn an upside-down bot right-side-up again.
[+] drtgh|2 years ago|reply
They designed the LEVs like that[1][2] for to deploy them some meters before landing. My guess is they expected it may happen with the main probe and something made them not include it in the design (Perhaps to concentrate all on the testing and analysis of the navigation and therefore it would be extra payload as other user comment, or something else, I do not know).

[1] LEV-2, https://www.youtube.com/watch?v=S_8TwJgKfYQ

[2] LEV-1, https://www.youtube.com/watch?v=Ej4ZMp4a2xw&t=4782s

[+] infinet|2 years ago|reply
This must be a common problem in space travel. The tiny spaceship in Men in black 2 also landed upside-down, but it has movable legs to correct position.
[+] jpgvm|2 years ago|reply
Self righting combat bots are awesome!
[+] RetroTechie|2 years ago|reply
"The spacecraft ran on battery power for several hours before authorities decided to turn it off to allow for a possible recovery of electricity when the angle of sunlight changed. (..)

The lander will analyse the composition of rocks in its search for clues about the origin of the moon, Jaxa said."

Not so quick.. does this involve correcting its orientation? Or should this be read as "remains toppled over, but some camera work possible" ?

Available solar power must be a big constraint in remainder of this mission, probably?

[+] sp332|2 years ago|reply
The solar panels were pointing away from the sun at the time. But the moon is rotating, and the solar panels are now pointing the right way to get power.
[+] makeitdouble|2 years ago|reply
There's two smaller robots launched from SLIM (lev1 and soraq) continuing the mission on the surface, taking photos etc.

In particular at least one of them can directly talk to earth.

[+] szundi|2 years ago|reply
Not getting up but wait for the sun to get just above the horizon sometime and then turn on
[+] jvm___|2 years ago|reply
I'm just laughing at the Japanese scientist who downloads the image data, converts it to a regular file format and then goes into photo viewer and clicks the "Rotate" button twice to flip the image so that it's the right way up.
[+] stcredzero|2 years ago|reply
Available solar power must be a big constraint in remainder of this mission, probably?

I guess Slim isn't all in the shady!

[+] kuschkufan|2 years ago|reply
The armchairism in this thread is something else. Happy the mission is not lost and kudos to JAXA.
[+] smashed|2 years ago|reply
To be honest I had read the entire article and did not get the very important fact that it landed upside down.

Perhaps people are reacting to the very bad reporting by the BBC, not at the slim mission team itself.

[+] stcredzero|2 years ago|reply
The armchairism in this thread is something else.

Right. Now we need more comments starting with, "What about...?"

[+] soco|2 years ago|reply
Landing upside down is what they call "the glitch"? How could that be fixed, did it have some way to restore its position? Or only the solar cells were turned upside up? What happened there in the end?
[+] adrian_b|2 years ago|reply
Actually it has landed on one lateral side, not upside down.

The engine nozzles that are now directed upwards were intended to remain on one lateral side. The lander was supposed to rotate one quarter turn after landing, to bring the engine nozzles from downside to a lateral side. Instead of that, it has rotated a half of turn, bringing the nozzles upside, due to an excessive horizontal speed at contact.

The solar panels are now on one lateral side instead of on the upper side.

Initially that lateral side was opposite to the Sun. After the Moon has rotated, the Sun has begun to illuminate the panels, though it is likely that the generated power has remained much lower than intended.

If they can no longer move it, they will have to save power, because they will be able to recharge the battery only during a small part of the Lunar day.

[+] echoangle|2 years ago|reply
Its the second sentence in the Article. It is still in the original position but the angle of sunlight has shifted so light is now hitting the solar panels of the lander.
[+] firtoz|2 years ago|reply
You just send the commands upside down and it works
[+] resolutebat|2 years ago|reply
The lander has no way to correct its orientation, and in any case was never designed to survive in the lunar night, which starts in a few days on February 1st.
[+] nanna|2 years ago|reply
> Statistically, it has proven very hard to land on the Moon. Only about half of all attempts have succeeded.

Why is this still the case given that NASA were able to land humans on the moon 55 years ago, not to mention do so in a way that could also bring them home?

[+] enlyth|2 years ago|reply
I'm guessing having humans on board makes it easier, since they can tend to the landing instead of having to do it semi-autonomously all the way from Earth
[+] nolok|2 years ago|reply
Because most of the time it's something small and "dumb" that cause the issue, but with no human there it's not possible to fix it instantly.

The difficulty is in planning for every contingency possible in advance, which you can't, and then hope that whichever one your mission encounters is in the list you planned for, essentially.

[+] yencabulator|2 years ago|reply
SLIM is a technology demonstrator for landing on slopes, with "pinpoint landing" accuracy (say, 10 meters).

Previous landings had to be made on limited large flat areas, deemed relatively safe for several kilometers around, and often the landing happened just in the rough vicinity of the target area, kilometers off the mark.

[+] jansan|2 years ago|reply
This is really interesting. They had a team of incredibly smart people and it seems that humans on board can handle difficult situations better than a computer. Apollo 11 would probably have crashed without a highly trained human on board.
[+] jacquesm|2 years ago|reply
That never happened. 54 years. I should know, I watched it happen and I'm 58.
[+] kitd|2 years ago|reply
>80 years ago

Either this is wrong or I'm doing great for 84

[+] hcrean|2 years ago|reply
Budget is likely a large contributing factor.
[+] pvaldes|2 years ago|reply
Easily solvable in the design. Is a robot, it does not need a head and a tail, or to carry people that needs to have their heads up.

Just remove the up and down constrains and make any part able to be the upper part, or design it as a tumbler doll.

[+] HarHarVeryFunny|2 years ago|reply
Sounds like Monty Python and the Holy Grail.

"I'm not dead yet!"

"It's just a flesh wound!"

[+] szundi|2 years ago|reply
It is just like Kerbal
[+] bookofjoe|2 years ago|reply
"First Man" (2018)

https://youtu.be/PSoRx87OO6k?si=OPCRv2nLyhdvh9Lo

https://youtu.be/w4GtJB5WAlQ?si=ASRrv1K0akxJwj-I

Armstrong's coolness under pressure as the Eagle lander's fuel dwindled to within 30 seconds of "Empty" is depicted with gripping intensity in this film.

[+] Gravityloss|2 years ago|reply
He survived a lot of close calls. He ejected in Korea, Gemini 8 spinning, the LLRV crash. And then the moon mission. He was exceptional under pressure. David Scott was flying with him on Gemini and gave kudos in his autobiography.
[+] kerbs|2 years ago|reply
If you’ve played Kerbal, you feel for this.
[+] WilTimSon|2 years ago|reply
I'm curious about this bit: "In a post on X, formerly Twitter, Jaxa shared a photograph taken by Slim of a nearby rock that it nicknamed a "toy poodle"."

What does nicknaming mean here? Is it the lander doing some sort of pattern recognition or how exactly does a machine generate a nickname?

[+] pvaldes|2 years ago|reply
It's been a really, really, long journey, a quick nap and like new again.
[+] aa6ll|2 years ago|reply
Does someone has an idea for how the communication/fixing was done?

Was it radio waves of flipping bits? Or how does that work?

[+] nothis|2 years ago|reply
>Its solar cells are working again after a shift in lighting conditions allowed it to catch sunlight, the agency said.

>It could not generate power when it landed on 20 January as the solar cells pointed away from the Sun.

Sounds like they were just lucky with the angle of sunlight.

[+] m3kw9|2 years ago|reply
I thought it landed upside down. If so they will just try to do stuff like that?