For those wondering if the Japan's SLIM lander (Smart Lander for Investigating Moon) landed on the moon, it successfully made a soft landing but the situation is bad - if it's not completely over with. I watched an English translation of coverage during touchdown, and it appeared to be going successfully but once it touched down, they shut up. That's not a good sign.
This screen capture of the channel I was watching is from a few minutes after it showed having landed in the graphic at the upper right. Not the uppermost right, but the two panels that show altitude on their vertical axis and have two pictures of the SLIM in the middle of the bottom with white areas indicating the lunar surface environment. The image's time tag is 10:23 AM EST or 1523 UTC, and the Space.com source article says landing was about 10:20 - which seems about right. The channel went silent and I switched to an official JAXA channel that I hadn't seen at first. They eventually gave a press conference about two hours later.
The image of the SLIM ship in that upper right graphic shows the lander in the wrong orientation. Slim had a unique approach to its landing (less than 2 minute video here) in which it was to contact the surface on two protruding legs and roll over onto another two legs as well. If that picture in the screen capture is based on position telemetry, something kept it from flopping over onto the third and fourth legs. Perhaps that's the root cause of their problem.
The issue was explained as the solar panel system not charging the lander's batteries. One of the people explaining things in the press conference explained that the spacecraft appeared to have landed within the planned 300 meters of its target in the Shioli Crater in the Mare Nectaris (Sea of Nectar) but that it might have landed in an orientation that wasn't allowing the solar panels to get sunlight. The angle of the sun to the surface changes over time, both in a lunar day (four Earth weeks) and in a lunar year (12 lunar days), which he interpreted to mean that the probe may suddenly start responding at some time. That said, like India's Chandrayaan 3, SLIM was intended to work for two weeks and didn't include heaters to ensure it could make it through the two weeks of lunar night.
SLIM also carried two tiny rovers — a little hopper called LEV-1 and a ball-shaped craft known as LEV-2. ("LEV" is short for "Lunar Excursion Vehicle.") These little robots were designed to deploy from the SLIM mothership, gather some data of their own and snap photos.
The data indicate that both LEV-1 and LEV-2 deployed as planned, JAXA officials said today. And LEV-1 is known to be working, adding to the mission's achievements.
It's a mixed situation. The batteries only have so much charge and we have no idea if they can get the solar charging system working in time. In the positive column, Japan becomes the fifth nation to land on the moon (this is a JAXA mission, their equivalent of NASA, so not a private company's mission like Peregrine). The micro-rovers are operational and can probably complete at least some parts of their missions. All we can do is watch.
You know, we've had radioisotope thermoelectric generators for a very long time, and have used them on all sorts of space-based applications for a very long time. When will people stop using stupid solar only?
ReplyDeleteSeriously, less battery and panel and more RTG, please!
The watermelons disagree. With MASSIVE enthusiasm.
Delete25 years ago I was saying I wanted an RTG for my bicycle headlight so I'm a bit of an advocate, too, but which is heavier? In a mission like this which was considered low cost I'd imagine the one that costs the least to send to the moon would get the advantage.
DeleteI can see a tradeoff where the RTG is heavier but allows much more power.
Come to think of it, I haven't heard anything about KRUSTY lately. Big for a mission like this, but maybe they could be made smaller.
But there's a trade-off. Weight of solar cells and battery and charge equipment and battery management equipment (like warming coils and cooling coils) versus the weight of an RTG setup of one type or another.
DeleteWith RTGs, you can accidentally land upside down or on your side or in a dark friggin hole of doom or covered in dust and still have power.
Once again, the power of heavy lift and heavy built like SpaceX is doing will succeed over the 'make it lightest and barely strong enough and...' design philosophy of legacy aerospace.
Agree RTGs (including KRUSTY) are the better choice. In this instance, I do not think it would have made a difference if the lander is upside down.
ReplyDeleteA couple years ago I read they were running low on the isotope the RTG uses; IIRC it was a by product of plutonium production and hasn't been made in 30 years.
DeleteHave you seen any articles on this?
Jonathan
I haven't - but that doesn't mean a whole lot. I read a half dozen sites daily and their emphasis is current news. If nobody is talking about it, it won't show up. I'm more likely to find a story about a startup getting funding than something like this.
DeleteAnyone who knows something is invited to comment.
Thanks, Jeff. Makes sense - especially with something difficult and expensive to produce and store. No demand, so why produce it?
Delete