Well, Twitter only (or other Twitter reformatter), unless you wanted the source material.
Which is a Radiolab podcast.
Both the thread and the podcast appeared on the same day, and involved the same Latif Nasser. One isn’t the source of the other. (still, thanks for the link)
Fun. Much of the podcast parallels very closely with the first half of the Borges short story Tlön, Uqbar, Orbis Tertius.
Now that I heard the whole podcast, it ends rather like the Borges story as well – in both, efforts are underway to make reality conform with the fictional invention.
(No spoiler needed – since, at least for now, the podcast ends unresolved.)
It awakens !
They must have known this was likely to happen as soon as the sun’s position shifted into a more favourable angle for the craft’s solar panels to pick up.
I don’t suppose SLIM has any way to right itself?
But maybe it doesn’t have to. If it’s not handicapped by its unorthodox orientation and the mission plan can be adjusted to accommodate it, I guess there wouldn’t be any need to.
Eta: nvm
From what I’ve read, it was never expected to survive through the lunar night anyway?
So it was always going to be a short mission.
I do rather wonder about these missions that won’t survive the lunar night, though?
Presumably they are technology demonstrations, and patriotic “show the flag” exploits.
But how difficult would it be to construct something which can survive a lunar night?
Do you really need a radioisotope battery to do so?
I admit I am not enough of a materials scientist to address this…
I’d sooner bet the limiting factor is just the weight of the batteries necessary to last 2 weeks. Heavier batteries mean a heavier vehicle structure and a more powerful engine that needs more fuel and the heavier structure and more powerful engine themselves need more fuel and the fuel itself needs more fuel and …
Pretty soon you need an extra thousand kg to last 2 weeks. Which means you need a bigger rocket to launch it which means …
That x^4 term in the rocket equation really bites hard.
But your probe doesn’t have to be actively operating during the lunar night.
Could you not design the system so that it hibernates and wakes up the next lunar day when the solar cells start delivering power again?
So I guess the question resolves to: which components are irreversibly damaged by the lunar night temperatures?
Obviously this is not ‘rocket science’, and people at least as smart as us must have thought about it?
Surviving cold, even if inactive, without being able to power heaters might be one engineering challenge of a device with limited stored power.
Maybe at some point we can use rockets that bite, chew, and swallow.
That’s a common way to make a homemade rocket engine - use an acrylic body that consumes itself as fuel.
My question exactly. One might think that quite a bit of research should have already been done about this?
Create a battery of some sort which can reboot a system sufficiently for photovoltaic panels to bring everything back up when solar energy becomes available again?
Is there something about current silicon PV panels which causes them to become permanently broken at low temperatures? Or other components (semiconductors etc)? I can imagine that a lot of things will not work well at cryogenic temperatures, but since they are solid-state, I don’t see why a period of extreme cold would necessarily destroy them?
Doesn’t Virgin’s spaceplane do something like this. Burn some sort of rubber using nitrous oxide as an oxidiser?
Not, of course, as if that tourist gimmick has anything to do with any actual space program…
Yeah, it’s a hybrid motoer that uses nitrous and HTPB, a rubber compound. It’s a siolid fuel but it doesn’t consume the rocket casing.
The lunar surface is very thermally unfriendly. Temps range from -130°C (at night or in permanently shaded areas) to 120°C (in full sun). The Apollo missions were timed to take advantage of lunar twilight to avoid temperature issues, but if you intend to operate a lunar lander during daylight and preserve it at night, there are several extra hurdles to address:
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Battery charge retention. Battery efficiency diminishes at low temperatures. The lithium-ion cells used in SLIM, if they are typical cells, will lose more than 90% of their efficiency by the time the battery drops to -40°C. The colder the system gets, the less juice it will have to maintain its remaining heat, so for the batteries’ sake, you need to keep it at no less than -10°C in sleep mode.
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Circuit integrity. Extreme heat and cold cause thermal expansion and contraction, so if the temperature extremes aren’t regulated, any place where unlike materials are connected is vulnerable to cracking and separating–including connections in and to the batteries, internal connections in the circuitry, and even between layers in the solar cells.
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The cooling system. Without some way to ensure that part of the craft is in the shade, passive/radiant cooling isn’t likely to be enough for 2 weeks of more-than-boiling heat. The craft would likely need some kind of fluid-loop cooling system. The ISS uses anhydrous ammonia for its cooling loops because if its low freezing point…at -77°C. So you would actually need to heat your cooling system as well, or it would freeze up during the long night.
None of these are insurmountable technical challenges. We can solve all of them with current state of the art, but solving them requires adding equipment to the lander. As LSLGuy pointed out, that rapidly adds tremendous cost and difficulty to launching the craft. Unless you’re planning a long-term mission, it’s just not worth it.
This is cool - they found lichen growing on the outside of the ISS. It’s Earth Lichen obviously but it shows that this hardy life form can survive in conditions that NO other organism can. Perhaps it is something that will come in handy in the future.