'SLIM', which successfully landed on the moon, achieved the main purpose of the mission and received a 'perfect score', but the landing attitude became a hot topic
On January 20, 2024, Japan's lunar landing demonstration vehicle 'SLIM'
Japan's precision moon lander has hit its target, but it appears to be upside-down
https://phys.org/news/2024-01-japan-craft-successful-pin-moon.html
Japan's precision moon lander has hit its target, but appears to be upside-down | Hacker News
https://news.ycombinator.com/item?id=39128977
SLIM was launched on September 7, 2023 and successfully landed on the moon on January 20, 2024. With this, Japan became the fifth country to land on the moon, following the former Soviet Union, the United States, China, and India.
Japan's lunar landing demonstration vehicle 'SLIM' becomes the fifth country in the world to successfully land on the moon - GIGAZINE
One of the objectives of SLIM is to 'demonstrate high-precision landing technology on the moon.' Until now, the landing site for planetary probes has been chosen to be a place that is easy to land on. However, if it becomes possible to ``get off where you want to get off'', the possibilities for planetary exploration will expand, and this will be a major change in the future.
In fact, SLIM succeeded in making a 'pinpoint landing' with an error of less than 100 meters from the landing target point.
The success criteria established by JAXA in advance are as follows.
Minimum success: Landing on the moon using a small and lightweight spacecraft, ``Verifying optical verification navigation, which is essential for high-precision landing, by conducting an actual lunar landing descent,'' ``Developing a lightweight spacecraft system, and Achieve the following two items.
Full success: High precision landing within 100m accuracy is achieved. Specifically, the high-precision landing navigation system will operate normally, feed back appropriately to the guidance law, and analysis of post-landing data will confirm that the spacecraft operates normally and achieves landing accuracy.
Extra Sax: Even after transmitting technical data regarding high-precision landing, activities on the lunar surface will continue for a certain period of time until sunset, and a mission will be carried out on the lunar surface with an eye toward full-scale lunar and planetary surface exploration in the future.
In other words, this mission can be said to have achieved 'full success.'
In addition, just before landing, the lunar surface exploration rover 'LEV-1' and the transformable lunar surface robot 'LEV-2' were successfully released, and SLIM images taken by LEV-2 were transmitted from the lunar surface. It's getting worse. LEV-2 was stored in a spherical shape, but it transformed and deployed on the lunar surface. It took pictures of its surroundings under autonomous control, and from among these images, the SLIM used an algorithm to select images that fell within the field of view and transmitted them. It is said that he has done so.
Overall, it can be said that this mission went well, but it is known that after landing, SLIM was not supplied with power from the solar cells, and was unable to land in the expected attitude. Images sent by LEV-2 also indicate that SLIM is not in its original landing position with its thrusters pointing upwards.
Regarding SLIM's moon landing, the Associated Press reported, ``Japan's precision lunar lander reached its goal, but appears to have turned upside down.''
Japan's precision moon lander has hit its target, but it appears to be upside-down | AP News
However, this expression 'it looks like it's upside down' is inaccurate, as SLIM uses a two-stage landing method to be able to land on slopes, so the thrusters end up facing sideways rather than downwards. It was going to be an attitude.
During this landing, the thrust of one of the two main engines was lost about 50m before landing, and the plane descended using only the other engine. The ground contact conditions, such as lateral speed and attitude, exceeded the specifications, resulting in the aircraft landing in a different attitude than planned.
On the social news site Hacker News, regarding the explanation given by Shinichiro Sakai, project manager of JAXA, at a press conference to discuss the results and achievements of the moon landing, ``Full marks for pinpoint landing'', smeej said, `` Full marks for that? Really? ?Couldn't it have gone better? '' he questioned.
In response to this question , makeitdouble said, ``The fact that we were able to land with such precision is a groundbreaking event, and Mr. Sakai says that it will change the way we think about ``where to land'' in the future. , I think the rating of perfect score is justified .''
Zem said, ``The important point seems to have been whether they could land accurately within a small area, and they accomplished that admirably. However, SLIM was aimed at targets just 100 meters away. Improved accuracy will allow the spacecraft to land closer to obstacles, allowing scientists to explore more locations on the moon. `` You will be able to access it .''
In addition, numpad0 mentioned that it was mentioned in the press conference that this is the third time a problem has occurred with the thruster of a JAXA/ISAS spacecraft, saying, ``It's more difficult than expected to operate the apogee motor accurately. It seems like that .'' he commented.
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in Science, Posted by logc_nt