Athena Moon lander officially FOADs – falls over and dies – in crater The Athena lander, which touched down on the Moon on Thursday and promptly fell over, has been declared dead by its operators. The spacecraft missed its intended landing point by more than 1,300 feet (400 metres), coming down in far more rugged terrain than intended – in a crater, no less – and toppled over. According to its …
I thought of a commercial for children's toys that stand back up when they fall down. Also a practice dummy for martial arts training.- they have heavy rounded bottoms. Something to consider, keep weight as low as possible, and inherently stable. Landing legs that stick out at 60 degree angles might do it.
some time ago I solved a problem with passive coin sorting to exclude 50 cent coins with a cheap plastic cover over a coin counter. Part of the design made sure (as much as possible) that correctly sized coins were too unstable to lay flat and would naturally fall through the holes. It works pretty well [very few coins don't "just fall through"] but some of the 'not fall through' coins of correct size do so because of the limits of manufacturing with plastic film, so the peaks that make coins fall had necessarily rounded tops instead of pointy.
Take a look at the Alpaca lander which has a different set of compromises. It starts long and thin to fit in a fairing for launch. When it separates from the launch veheicle it moves sideways so it is short and wide. Just before landing on the Moon it drops the outer pair of tanks. After landing it extends solar panels vertically to catch some sun light at the south pole.
Alpaca beats Athena for stability at the cost of needing moving parts to get power. This is less of a risk for Alpaca because if the solar panels get stuck someone can get out and push.
Starship HLS uses the weeble strategy. Tons of take-off propellant settle to the bottom of the tanks shortly before the landing burn.
The intuitive design changes for Athena V2 are to replace the payloads with take-off propellant, land near an inhabited Moon base and move the sun underneath the south pole.
"Starship HLS uses the weeble strategy. Tons of take-off propellant settle to the bottom of the tanks shortly before the landing burn."
The only way to settle the propellants is to burn the engine. Shortly before they can be floating all over the place. Starship HLS is risking stability with needing to wind down people on a crane that's outside the footprint of the vehicle. The pictures are very happy representations of vertical ship on the surface of the moon. The reality is the moon isn't particularly flat and the cable crane needs the ship to be highly vertical to work or it might pull the ship over or scrap along the side in use.
"Making it tall and narrow doesn't seem very... intuitive?"
Balance a pencil on your finger tip and then try to do the same thing with something flat. The taller thing is easier to control. There are limits and ratios, but balancing a rocket on flaming exhaust is a tough business. Look up Masten's Xombie vs. Armadillo's Pixel.
The three rovers have managed to crawl from the wreckage. But alone, silent, without the Nokia base station, unable to talk to each other, let alone ask for directions from Earth - which remains unaware of their survival. They are left to drive (and jump) into the wilderness. The two wheeled rovers stay in sight of each other, for the company, until the NASA rover, in an insane fit of jealousy that the MIT machine has its colony of AstroAnts as its pets and friends, rams it and both tumble into a rill. Unable to climb out, the larger machines succumb. Leaving only the AstroAnts behind, to cannibalise the rovers' remains for spare parts and settle down into a small civilisation that worships the dream of, one Lunar Day, returning too the Holy Landing Site with its fabled Golden Foil Wrapped riches, the 4G El Doradio.
Of the rocket propelled drone's fate, no-one is certain, although the AstroAnts tell each other scary stories of a shape that appears for a moment above the lip of the rill as it travels restlessly, leaping, leaping, leaping.
"Could someone with more engineering chops than me explain whether something like rapidly expanding telescoping legs could work? Such that they extend asymmetrically."
Such a design could very well be implemented, albeit at the cost of considerably greater expense, weight and volume, thus reducing mission options. The main limitation is, though, that it is a solution for the wrong problem.
Unmanned probes landing on the moon suffer from both limitations in altitude measurement and terrain scanning on the one hand, and a limited ability of flight software on the other to make intelligent decisions on how to deal with a final descent onto an unsuitable landing spot. Boulder fields are notorious for throwing off altitude measurements (both RADAR and LIDAR based), and recognizing one upon final descent, hovering, and then flying sideways aiming for a more suitable spot is simply beyond the current robotic capabilities. For the Apollo pilots this was routine (they were pilots after all) but automated probes continue to struggle with it.
What we need is better flight software that can make more accurate assessments of altitude regardless of terrain quality, that can recognize unsuitable landing spots, and can navigate autonomously to a better landing location using whatever fuel remains (and, if necessary, choosing the best possible option among multiple less-than-ideal spots). That's not easy.
That said, probes falling over is nothing new. Luna 23 was the last one to do so, if I am not mistaken, in 1974. And while the Surveyor probes were low and squat and by design very hard to tip over, the Surveyor program's good success rate (5 out of 7) was mainly due to the fact that these probes landed in smooth terrain.
So the design of the landing struts is not the main problem here, nor is center of gravity. The problem is that a good landing in less than perfect lunar terrain needs piloting skills, including recognition, assessment, decision and dexterity which current robotic systems still cannot meet.
> Such a design could very well be implemented, albeit at the cost of considerably greater expense, weight and volume, thus reducing mission options.
While reducing mission options is a definite down side, having no mission at all would seem to me to be a worse outcome.
Surely a more conservative approach that gets a spacecraft successfully to the surface with a possibly more limited payload but the casters all pointed in the desired direction is better than a more ambitious one that fails to do so.
JPL has done things incrementally with the Mars landers and rovers to great success.
The "move fast and break things" approach might work with software (at least for a time) but the "think things through and make careful steps" approach gets more science done in the long run.
It all depends on where you land.
The Surveyor probes landed in relatively flat, dust-filed basins. As did the Blue Ghost. None of these had exotic adjustable landing struts and none of them fell over. Landing in a crater on the lunar South Pole, on the other hand, is an entirely different matter, because this is entirely different terrain.
Incidentally, the Viking probes that landed on Mars had regular struts too, but they were lucky enough not to be upset by boulders. Had they come down a few meters from where they happened to land things could have ended badly. Sometimes it's just a matter of luck, given the limitations of robotic probes to deal with unfavourable landing locations.
Perversely made think of the the sequence of the last Soviet leaders.
Some definitely looked like that they had previously received the attention of a taxidermist augmented by soviet mechatronics.
Presumably when the batteries wouldn't charge or the hydraulics sprung a leak another carcass was heaved out of the Party warehouse.
Of course for its sins the US is now getting an indecent dose of perestroika and glasnost à la put[a]in.
There’s a great scene, in the totally stupid film ‘Whoops Apocalypse’, where the Soviet Premiere dies. So they wheel his deputy in on his own hospital bed, attach jump leads between their nipples, and restart the leader.
The film also involves Rick Mayall as an SAS troop leader, and the terrorists sending their demands to the US president by singing telegram. Did I mention it was really silly?
So much depends on the terrain they are landing on and the landing profile. These are small landers with little spare fuel for landing manoeuvres, small less accurate sensors and other limitations. Being 400m out on a open plain is fine, in a crater filled plain, not so much and.guess what the South Pole mostly consists off ?
FYI, Blue Ghost landed in a flat basin in the northwest of the moon, not where Artimes is planning on going to.
"FYI, Blue Ghost landed in a flat basin in the northwest of the moon, not where Artimes is planning on going to."
The south pole is very interesting, but I see it as too aggressive of a landing spot for a lunar return mission right out of the gate. I have loads of videos on the MER rover mission(s) to Mars and in planning, the landing site selection was crucial to be as benign as they could find. The rovers were going to find loads of interesting things to look at no matter what so taking big risks to get to what might be an "even more interesting" location was silly. I see the same with the moon. The fixation on reuseablity seems silly to me as well. Eventually, sure, it's not a bad goal, but it's another complication to stick up front. First missions could be sent to prepare sites that make it much easier to have reusable craft touching down and taking off. Those craft could be expendable being designed in a way that provides materials to use in other constructions like Mechano (Erector) sets.
Soon the moon will be littered with space trash and dead landers. Several of the moon missions (IF we ever get back there) would be clean up missions, collect all this stuff and send it back to burn up on reentry. Humanity needs to expand to other planets to survive but will leave piles of junk as they planet hop. Seems better just to stay on Earth and minimize the damage.
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Never throw out stuff that you might be able to use. Where would Mark Watney be if someone had "cleaned up" the Mars Pathfinder before his mission?
Its going to have to involve some level of self determination as there isn't enough bandwidth and too much latency to deal with these problem from here in realtime and that is assuming you are aiming to land on the near side of the moon where you can get a signal.
Of course its not like you can throw a GB200 on there or something, you have issue of power consumption, heat, etc to deal with, and the big issue seems to be sensors at the moment. And how do you build a training model, Athena probably gathered a ton of landing data but there isn't any easy way to retrieve it to build your model with.
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