How would a secondary power source save it from being tipped over? That's a mission ending failure no matter how many redundant power sources you have.
this post was submitted on 09 Mar 2025
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Being tipped over doesn't inherently stop all of its equipment from working, I'm sure at least some of the sensors could otherwise still work, if they had power.
Even if only 10% of the sensors and equipment could still work, 10% would still be better than 0%.
True, but communication could still be a problem.
Generally this kind of probe will have a highly directional antenna that has pretty strict limits on it's aim. We would have to be very lucky for the antenna to not get damaged during the fall and end up in a position where it can still establish a connection. Even if all the science is fine, it's as good as useless if it can't communicate any results or accept commands.
Ah, but it did send data back before the battery ran down, at least enough data to confirm it fell over when it landed.
Weight == $$$
Wait, I thought Eggs == $$$
🤔
Yes, and eggs have weight.
So they couldn't use eggs as a power supply.
Therefore, the only alternative was to rely entirely on solar.
Meanwhile, they now have nuclear diamond batteries. Hell, the Voyagers have been running on aging plutonium for nearly 50 years.
You'd figure a modern expensive system like that might have a modern secondary power source, at least enough juice to run for two weeks FFS...
Who has nuclear diamond batteries? Those are a total myth drummed up to get investor money. They don't actually exist.
Sure the concept exists, in the form of betavoltaic batteries, those have been around for decades. They are tough and last dozens of years if not longer. The only problem is, they put out microwatts. You can use them in very niche applications, but those are few and far between. It's hard to convey how little power a microwatt is, it's basically nothing.
What you care about when going to space is energy density, and the proposed energy density of nuclear diamond batteries is very poor.
Rtgs are very useful for longterm missions, but are crazy expensive. They also aren't being made anymore, so getting a hold of one is hard. The weight is an issue as well, they are super heavy.
These commercial moon missions are primarily demonstrator missions. They aren't meant to last, they don't really have a goal and often don't do something useful. The idea is to show you can do it, so you can sell a product. Other people that do want to do useful stuff can then pay to get their stuff to the moon. So if the mission is over when the sun sets in two weeks time, that's perfectly fine.
'They aren't being made anymore'
Yep, I think we've identified at least part of the problem. Once humans figure out a technology that can last decades, we test it, verify it works, and then stop using it in favor of cheaper shit meant to fail as fast as a dozen eggs rot..
Meh that may be true in some ways, but not really in this case. RTGs were made using a surplus from production for nuclear bombs. As that production ramped down combined with better solar and batteries, the demand went down and it became more expensive to produce them. So not making them made sense.
An RTG is really only useful for missions that go far away from the Sun, making solar non-viable. RTGs are a pain in the neck all throughout the process, are heavy and expensive (even back in the day). The amount of electrical power an RTG delivers is also very low. This is because an RTG only gets warm, nothing more. So we put TEG (Seebeck) devices on the sides to generate electrical energy from the thermal gradient. But TEGs suck ass, they are super inefficient. For example the RTG the big Mars rovers use put out 2000W of thermal energy, but they manage to get only 110W of electrical energy out of that. So if you are near enough to the Sun, solar is the much better option.
Good explanation. People that design space missions have a lot of restrictions, and things that seem obvious on the surface can cause a lot of problems in practice.
Because for the amount of power needed they would have to halve its payload capacity if they used RTGs
Eclipses end, though. Being tipped over does not.
Quite true. Strangely, here on Earth they have smart robots that you can literally kick over sideways, and their sensors and hydraulics and stuff kick right in and set them back upright.
If you're gonna dump hundreds of millions of dollars into such a project, why not utilize all known, available, and proven technology?
Weight. That's the only actual answer.
It's extremely expensive to send weight to the moon, everything you list is more weight.
More weight but functioning vs multi-million-paperweight?
You're looking at it with hindsight. Sure it feels like spending another million $ designing, testing, and adding additional weight, along with removing weight from other parts looks like the right decision now.
Every design makes compromises, and every failure looks stupid when looking at the end result. The team had decisions to make and if they had the extra time and money, then making the existing design more robust with more testing and reliability would have been the better solution.
That's just private-sector efficiency taking control.
What other power source? There is only solar and nuclear in space. And not even NASA does nuclear unless absolutely required for the mission.
It's all about weight when going to space. It's one of the basic parts of rocket science. If you want to send 1 pound into space, you need to add gas to cover that weight, and the weight of the gas you add. Eventually you reach a point where the combined weight of the gas is more than the thrust it provides and you can't add more. Solar is light, a few hours of no power isn't a big deal over months or years of operation time, if you are confident things will come back on when there's light again.
Chief O'Brien would be so disappointed. he wouldn't like to be caught without a secondary backup in a crunch.