Space Force

[Broken_Erika]

Even by your own admission, you don't even know what geosynchronous orbit is...

I do! It's when you run in circles around a Geo Metro while synching your phone and MP3 player!

 

[hobbsyoyo]

That's absurd. The ambient temperature of outer space is 7 degrees kelvin (common myth about space being absolute zero. Certain quantum mechanics take over down there; the molecules don't just stop themselves). TYPICAL earth orbital temperatures range between -175 and 400 degrees kelvin. And you're launching $10 billion space junk in the air and parking it there. You don't get to takeoff/land/service/repeat, like your aircraft do. You can't do typical--you have to do worst-case. Materials have to work between 7 and 1000 kelvin. Come on, 75C doesn't even boil water, for crying out loud. How much do you want to bet the CPU on your computer at home was tested at 125C? And you mean to tell me your "superior", "military grade" spaceships weren't?

The ambient temperature of space swings wildly but in the regimes the vast majority of spacecraft operate in, it never gets to 7 or 1000 kelvin. That's insane.

Plus, it's not like we build satellites inside out. Everything is in boxes under nice thermal blankets, heaters and radiators as required. The space environment of LEO is fairly benign compared to deep space with a tendency toward higher-end temperature excursions during high-albedo alignments. But if the satellite ever got below -50C or over 75C on the inside, it would die.

There are certain components of a satellite which may operate at much higher or lower temperatures - say a crycooler on an infrared camera sensor - but not the whole satellite. We isolate those bits to keep the rest nice and cozy.

Meaningless to YOU, because evidently YOU do not even understand how basic ham radio works. Even by your own admission, you don't even know what geosynchronous orbit is...and then claim you "know" it doesn't take PhD's to make it happen.

The 'sychronous' in geosynchronous means that the satellite is more or less stationary from the point of the ground. This means it isn't whipping around the planet every 90 minutes and swinging between night and day every 45 minutes. In fact, they are in constant sunlight for about 50 weeks out of the year (with a year long 'eclipse' season in spring and fall with nights that last an hour) and are therefore extremely stable temperature-wise. Also, they don't manuever very much and the ground stations are always able to talk to them.

For these reasons, they are somewhat easy orbits to fly. I will admit, however, that geosynchronous orbits are one of the few I haven't been able to personally fly a bird in yet.

As the sharks on the Shark Tank say, "For that reason, I'm out." i hope you aren't on the program.

Please don't leave, this is a great platform for me to space cadet and is genuinely fun. I will not be a douchenozzle

 

[Timsup2nothin]

Please don't leave, this is a great platform for me to space cadet and is genuinely fun.

I have supreme confidence that you can space cadet just fine without him.

 

[hobbsyoyo]

But it's rude when I hijack random threads to talk about random space crap. This way I can have my cake and eat it too.

 

[Takhisis]

Nah, we've already eaten your cake while you weren't looking.

 

[Estebonrober]

Wait what is the "temperature" of a LEO satellite on average then? I was always under the impression that temperature being a measure of particle movement means it can be "hot" in space but since the particles are so far apart a human would still freeze. How does that work ? Nerds with an old basic physics class under their belt want to know.

It "heats" up pretty fast and gets "cold" pretty fast depending on sunlight right?

 

[Timsup2nothin]

Not really appropriate for "Space Force." We should start a thread where @hobbsyoyo can space geek out and teach us all the basics of physics in space.

 

[hobbsyoyo]

Wait what is the "temperature" of a LEO satellite on average then? I was always under the impression that temperature being a measure of particle movement means it can be "hot" in space but since the particles are so far apart a human would still freeze. How does that work ? Nerds with an old basic physics class under their belt want to know.

It "heats" up pretty fast and gets "cold" pretty fast depending on sunlight right?

The design goal is roughly room temperature. That also tends to be close to the temperature that satellites will naturally reach equilibrium at without active thermal control. This is an unwritten rule that plays a huge role in the success of CubeSats - smaller satellites have pretty uniform temperatures and their electronics (with bare bones heater systems) can keep them alive without a ton of in depth thermal analysis. Their shiny metal or solar cell exteriors also reflect most of the excess heat away while in sunlight as well.

If CubeSats were as finicky to design from a thermal standpoint as the larger birds, it would have stunted the industry as thermal engineers are uncommon and expensive.

Larger satellites require much more thermal design but it is not the case that you are ever designing internal components to live with 7k to 1000k swings - you design the whole satellite such that it settles around room temperature. There are day and night swings but in LEO they are less extreme than in deep space as both the Earth and Moon (to a muuuuch smaller extent) are radiating heat to the satellite and because in orbit, nights are shorter than days since you are above the Earth limb. Some orbits are even in permanent sunlight.

Deep space is a whole other challenge and those birds require a lot of active heating. Most deep space satellites will even include radioisotope heaters that provide no electrical power but continuously heat the satellite bus. Even for those satellites, the design goal is still usually near room temperature so the electronics are not designed for 1000 degree temperature swings.

Not really appropriate for "Space Force." We should start a thread where @hobbsyoyo can space geek out and teach us all the basics of physics in space.

I'll move future questions along these lines to the space cadet thread.

 

[Timsup2nothin]

I'll move future questions along these lines to the space cadet thread.

I was trying to get you another thread where you could geek out. It's cute.

 

[Takhisis]

When do I get my own thread where I can get hobbs to lose quality family time by waxing lyrical about my attempts at alternate worldbuilding?

 

[hobbsyoyo]

Do it I dare you

 

[Takhisis]

Fine.

Once I get rid of this job thing.

 

[Sommerswerd]

I don't know if this has been covered already and I'm too lazy to check... but first things first... Before there can be any discussion whatsoever about a "Space Force" we need to get at least 1 of the following 3 things invented first.

1. Ray-guns that make the "pew-pew-pew" or "eeeeeeeeeeey" sound when they fire (without the sound it doesn't count).
2. Space Marine suits with the giant metal hands and retractable visors (See, Buzz Lightyear, Raynor/Findley, The Adeptus Astares)
3. Lazer Swords (spelled exactly like this or it doesn't count)

 

[uppi]

Wait what is the "temperature" of a LEO satellite on average then? I was always under the impression that temperature being a measure of particle movement means it can be "hot" in space but since the particles are so far apart a human would still freeze. How does that work ? Nerds with an old basic physics class under their belt want to know.

It "heats" up pretty fast and gets "cold" pretty fast depending on sunlight right?

@hobbsyoyo has covered the engineering side and I would like to contribute a few things on the physics side.

Temperature is related to particle movement (more accurately: a particle velocity distribution), but it's primary use is to describe an equilibrium. If you have a closed system it will eventually reach a state where everything has the same temperature. If you have different kinds of particles, they may have different velocities and different energies, but you can use one temperature value to describe the whole system. This corresponds to our intuitive understanding of temperature. If you put some object outside in the shade, it will sooner or later be at the same temperature as the environment.

The situation in space is quite different: To reach equilibrium, the particles have to interact (usually with collisions). But in space there are so few particles that it takes forever for the temperature to equalize. So you can have very cold particles next to very hot particles as long a they barely interact. There are still some ways to define a "temperature" but like for any other out-of-equilibrium system, these should always come with big qualifiers - these temperatures are not a regular temperature. So if you put a satellite in space, the temperature of space actually doesn't matter that much - it won't equalize anyway. What you have to look at instead is how much energy does it gain (sunlight, heaters) and how much does it lose (mostly black-body radiation).

 

[Hygro]

Every time I read the thread title I hear the "G-Force" theme song and I imagine some chanters yelling "Space Force!"

You can hear where the Space Force goes, it's the opening two notes, and then happens later at the end of each phrase.

In the researching of this post I discovered no one actually sings "G-Force" but I thought they did.

 

[hobbsyoyo]

There was real news on the Space Force this week -

The administration gave up on plans for an independent Space Force. They have asked the DoD to produce and dissemenate to Congress a report showing how a space corp-esque branch of the Air Force might be set up within the Air Force. Trump has told the DoD that their plans must be extensible toward a more formal separation and creation of a new Department of the Space Force down the line. Along those lines, Trump is moving forward with creating a new Space Development Agency within the Air Force (to be added to the new Space Force immediately upon approval) to give the nascent organization freedom to try new approaches to space domination.

Even if Congress shoots down the Space Force - and it very likely will in my opinion - the new Space Development Agency should live on and hopefully contribute to new cutting-edge programs to the Air Force.

 

[hobbsyoyo]

I am very torn about how I feel about the Space Force. I feel the idea has merit and ultimately it means more jobs in my industry. But it's also in some respects condoning the weaponization of space. I don't think this will directly lead to a ton of "real" weapons platforms but it will mean more military hardware in space in absolute terms, even if the majority of it is just increasingly sophisticated cameras and radars.

On the other hand, more military hardware in space is directly correlated to more commercial and civil projects and I don't think our society will tolerate many more space jobs programs on top of the SLS and ISS unless they have a military bent. Government spending more than just about anything can lower barriers to entry into new markets by paying full cost and then some to the private sector. Not that I'm saying this method of industrial development is the most efficient or effective or even moral, but it does work and it's one of the few routes this country seems to tolerate when it comes to direct investment into industry.

Of course, the motivations behind this effort don't have a whole lot to do with my desire for a stronger aerospace sector. Instead it's largely about paranoia related to developments and pronouncements by Russia and especially China. The paranoia isn't entirely unfounded and I do think we can do better about managing our military space programs than the current Air Force.

But with Trump's administration proving to be the most inept and corrupt in decades, I fear this whole effort will turn into a massive cash grab with no benefits to anyone except shareholders in Lockheed, Boeing, SpaceX and the like.

 

[Estebonrober]

@hobbsyoyo has covered the engineering side and I would like to contribute a few things on the physics side.

Temperature is related to particle movement (more accurately: a particle velocity distribution), but it's primary use is to describe an equilibrium. If you have a closed system it will eventually reach a state where everything has the same temperature. If you have different kinds of particles, they may have different velocities and different energies, but you can use one temperature value to describe the whole system. This corresponds to our intuitive understanding of temperature. If you put some object outside in the shade, it will sooner or later be at the same temperature as the environment.

The situation in space is quite different: To reach equilibrium, the particles have to interact (usually with collisions). But in space there are so few particles that it takes forever for the temperature to equalize. So you can have very cold particles next to very hot particles as long a they barely interact. There are still some ways to define a "temperature" but like for any other out-of-equilibrium system, these should always come with big qualifiers - these temperatures are not a regular temperature. So if you put a satellite in space, the temperature of space actually doesn't matter that much - it won't equalize anyway. What you have to look at instead is how much energy does it gain (sunlight, heaters) and how much does it lose (mostly black-body radiation).

So does this mean every satellite is pressurized for its internal components sake? If it loses pressure due to say foreign object does that make it basically die due to temperature death?

 

[Estebonrober]

I am very torn about how I feel about the Space Force. I feel the idea has merit and ultimately it means more jobs in my industry. But it's also in some respects condoning the weaponization of space. I don't think this will directly lead to a ton of "real" weapons platforms but it will mean more military hardware in space in absolute terms, even if the majority of it is just increasingly sophisticated cameras and radars.

On the other hand, more military hardware in space is directly correlated to more commercial and civil projects and I don't think our society will tolerate many more space jobs programs on top of the SLS and ISS unless they have a military bent. Government spending more than just about anything can lower barriers to entry into new markets by paying full cost and then some to the private sector. Not that I'm saying this method of industrial development is the most efficient or effective or even moral, but it does work and it's one of the few routes this country seems to tolerate when it comes to direct investment into industry.

Of course, the motivations behind this effort don't have a whole lot to do with my desire for a stronger aerospace sector. Instead it's largely about paranoia related to developments and pronouncements by Russia and especially China. The paranoia isn't entirely unfounded and I do think we can do better about managing our military space programs than the current Air Force.

But with Trump's administration proving to be the most inept and corrupt in decades, I fear this whole effort will turn into a massive cash grab with no benefits to anyone except shareholders in Lockheed, Boeing, SpaceX and the like.

I agree with this, my only personal reservation is the treaties we've signed in the past. There are rumors about China and Russia both messing around with satellite to satellite intercepts and such.

 

[hobbsyoyo]

So does this mean every satellite is pressurized for its internal components sake? If it loses pressure due to say foreign object does that make it basically die due to temperature death?

Most components on most satellites are not pressurized. Many of the earliest satellites were however, as they did not have sophisticated thermal modeling tools for radiative heat transfer prediction. They understood it quite fine, but it is not easy to calculate those types of problems without advance computers and software. So they made the satellites pressurized because then the heat transfer problem reduces to a more 'normal' form which they could readily design against.


Almost none are built like that anymore - everything is vented to space. There are some very specialized components (usually scientific instruments) that require pressurization but most don't.

I agree with this, my only personal reservation is the treaties we've signed in the past. There are rumors about China and Russia both messing around with satellite to satellite intercepts and such.

They aren't really rumors at this point. Russia has been caught on more than one occasion in the act of flying uncomfortably close to foreign satellites. China practices against their own satellites and both have publicly put forward very aggressive space militarization plans. China and the US have recently blown up their own satellites while China and Russia each have a Space Force equivalent as well.