How hot does a typical NASA Radioisotope Thermoelectric Generator get? I've searched around, and I've gotten conflicting answers from "barely warm enough to melt snow" to "1000C".
Matt Damon used it to keep him warm while he was filming his movie on Mars, so what's the deal? Is it only a little bit warm but very inefficient so that most of the heat escapes and is comfy, or is it so hot it'd vaporize your entire skeleton but 97% efficient so that it just barely feels comfy?
How hot does a typical NASA Radioisotope Thermoelectric Generator get? I've searched around...
Jaxon Garcia
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Jordan White
>barely warm enough to melt snow
Very ambigious.
This pellets is red hot from the radiation. So there's that.
Jordan Clark
>Matt Damon used it to keep him warm while he was filming his movie on Mars
Wut? Who has been feeding you info?
Henry Gutierrez
>hot from the radiation
That's a pellet of plutonium, but at what point does plutonium begin to glow red from heat? It has a melting point of ~639C, so somewhere between that and room temperature, I suppose. Not very specific, but it seems there's not as much information about plutonium knocking around as there is about iron for some annoying reason.
Colton Bell
en.wikipedia.org
You can find the thermal output of various RTGs here, but not the temperature because that is going to vary depending on the environment (full sunlight vs total darkness in vacuum for example will vary wildly).
>What is the material that the plutonium dioxide fuel is "clad" in?
>Multiple layers of protective material protect and contain the fuel and reduce the chance of a release of the plutonium dioxide. The plutonium dioxide pellets are first clad in iridium, a strong, ductile, corrosion-resistant metal with melting point greater than 4820 degrees Fahrenheit (2660 degrees Celsius).
>How hot is the fuel clad (iridium) inside an RPS?
>Depending on the RPS design and operating conditions, the temperature of a fuel clad could range from 1382 to 2012 °F (750 to 1100 °C).
Grayson Baker
>750 to 1100 °C
Thanks, user. Snow confirmed blown the fuck out by plutonium.
I found that one kg of plutonium-238 heats at a rate of 570 watts, which is like 18C per second in the middle of a neutral room filled with air, and the voyager space cruiser's rtg has ~4.5kg of pu-238 inside it, which means it would heat up at a rate of 81C per second in normal conditions.
Even with layers upon layers of dampening material, how has the voyager not melted into a hot ball of slag considering the only method of cooling in vacuum is radiation, and the voyager has fuckall for surface area compared to the heat it's generating?
Josiah Hernandez
>at what point does plutonium begin to glow red from heat?
The same temperature as everything else. The color of incandescence is determined by temperature.
Dominic Thompson
Is that right?
It actually even makes sense, god damn. I learned some basic shit today that I really should have learned a long time ago.
Lincoln Bennett
It's powered by radioactive decay, which isn't affected by temperature, so the equilibrium temperature depends on the cooling rate. If you insulated it well enough, it would eventually heat itself into a cloud of plasma.
I think they're pretty much always passively cooled, so the internal temperature depends on the environmental temperature, and things like air density. I'm sure they design them to keep well away from potentially damaging temperatures even under the worst foreseeable conditions.
He's talking about a scene in The Martian, a movie about Matt Damon filming a movie on Mars. (the movie is about running out of ketchup on Mars)
Landon Barnes
So wait. Supernovas emit massive blasts of gamma rays because the photons they're ejaculating are simply so hot that they're vibrating in the gamma frequency? That's it? That's so simple that I think I just assumed it couldn't possibly be the case, because science is usually complicated as fuck. Occam's razor, you know? "the simplest explanation is only the correct one if you're ridiculously intelligent, otherwise it's just typical human brain dribblings."
The scale ends at gamma, though, so does that mean that there's nothing in the universe that can (as far as we've observed) heat up photons any hotter than 300 ExaHertz? Or does that mean that even if we could magically heat a photon to an infinite energy level, it would still just be a gamma particle? And women complain about a glass ceiling; they should meet a photon.
>If you insulated it well enough, it would eventually heat itself into a cloud of plasma.
That's what I thought, but what kind of insulation + passive cooling is that effective in vacuum when housed in such a tiny, compact frame? Voyager doesn't have seven miles of radiator tendrils dragging behind it, does it?
>the movie is about running out of ketchup on Mars
The greatest tragedy to ever befall a man, fictional or otherwise.
Brandon Powell
Depends entirely on the elemental composition and design.
Carnot cycle shows hotter is better.
Dylan Brooks
Think of a photon as a packet of energy. The more energy you pack into the shorter its wavelength.
Also photons decay into longer wavelengths over time (or distance), but don't tell physics students or they will REEEEEEEEE
Charles Gray
>Voyager
en.wikipedia.org
>The spacecraft was built with 3 Multihundred-Watt radioisotope thermoelectric generators
en.wikipedia.org
>Each RTG generated about 2400 Watts of thermal power.
>157 watts of electrical power initially
>total weight of 37.7 kg including about 4.5 kg of Pu-238
>312 silicon-germanium (SiGe) thermoelectric couples
>The initial thermoelectric couple hot junction temperature was 1273 K (1832 °F) with a cold junction temperature of 573 K (572 °F).
Apparently passive radiation in space is enough for a compact object with small cooling fins to reject a couple of kilowatts at the temperature a self-cleaning oven reaches. The interior temperature is hot enough to melt aluminum, but not quite hot enough to melt copper.
Here's more examples:
en.wikipedia.org
Jordan Lopez
radiator efficiency is proportional to T^4.
The hotter the radiators, the more heat they can reject.
Logan Torres
>falling for an obvious bait thread
Noah Davis
>The spacecraft was built with 3 Multihundred-Watt radioisotope thermoelectric generators
Well fuck I was way off there, but in an unexpected direction.
>interior temperature is hot enough to melt aluminum, but not quite hot enough to melt copper
>The hotter the radiators, the more heat they can reject.
That's so god damn cool. In my mind, I really want to believe that those radiators glow like motherfuckers out there in space. I'm guessing they don't, though, at least not very brightly, because I read up on incandescence from earlier in the thread, and it looks like things don't visibly glow until they're at least 800C. A typical candle apparently burns at 1656C, which is about 800% hotter than I thought those things were. I mean shit, candles are 30% the heat of the surface of the fucking sun! Mind blown as fuck right now.
I was genuinely curious, actually, but thanks.
Ryder Gonzalez
>candles are 30% the heat of the surface of the fucking sun!
Your rectum is 30% of the melting point of aluminum.
Christopher White
...
Isaac Roberts
Your blood is at about 82% of its boiling point.
Justin Carter
Bullshit, no you werent, not with a line like the "while Matt Damon was filming"
Joseph Parker
Your blood is closer to 84% of its boiling point.
Jeremiah Fisher
Oh, here we go. One of you "the Mars filming was a hoax" conspiracy nuts. I bet now you'll try to tell me that Armageddon was a hoax as well.
Ian Carter
To do this right, you need at least a conspiracy theory infographic if not a ranting youtube video.
Lucas Ward
That could be a fun little hobby, actually.
Matthew Long
>> how has voyager not melted
the radiators are big enough
External temperature was measured to be 572 K, which is hot, but not that hot
en.m.wikipedia.org