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blogfast25
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Quote: Originally posted by SupFanat  | | Geostationary satellites would have the same speed as the atmosphere at such altitude. Ideally it would orbit the Earth as if it were bound to Earth
surface but in the practice the orbit isn't as precious. |
That's basically word salad.
Geostationary orbits are orbits too. AAHD's derivation holds perfectly for such orbits too.
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blogfast25
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| Quote: Originally posted by SupFanat | About re-entry... Adiabatic compression can produce high temperatures.
But what about adiabatic expansion which gives low temperatures? How low are the reachable temperatures? |
I don't know. The braking force due to air-drag is given by (IIRW) F<sub>drag</sub> = k v<sup>n</sup>, as explained high up.
The braking force performs mechanical work acc.:
dW = F<sub>drag</sub> dx
That work is converted to heat energy, at least in part, causing both the air (around the object) and the object itself to heat up. Very hard to
calculate, I think...
It's obvious that the heat shields of the Apollo capsules and space shuttles heated up very strongly upon re-entry. Shooting stars are meteorites
burning up in the higher atmosphere, due to entry heat.
[Edited on 28-5-2015 by blogfast25]
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SupFanat
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| Quote: Originally posted by blogfast25 | | Quote: Originally posted by SupFanat | | Geostationary satellites would have the same speed as the atmosphere at such altitude. Ideally it would orbit the Earth as if it were bound to Earth
surface but in the practice the orbit isn't as precious. |
That's basically word salad.
Geostationary orbits are orbits too. AAHD's derivation holds perfectly for such orbits too. |
If the atmosphere still exists on such altitude and rotates around the Earth with the same speed as the satellite then the satellite doesn't move
relative to atmosphere.
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blogfast25
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| Quote: Originally posted by SupFanat |
If the atmosphere still exists on such altitude and rotates around the Earth with the same speed as the satellite then the satellite doesn't move
relative to atmosphere. |
True but that doesn't change anything, fundamentally. Air drag is ZERO at 35,786 kilometres above earth.
http://en.wikipedia.org/wiki/Geostationary_orbit
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SupFanat
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The zero speed relative to atmosphere means the air drag would be zero even if the atmosphere were dense at such altitude?
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blogfast25
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| Quote: Originally posted by SupFanat | | The zero speed relative to atmosphere means the air drag would be zero even if the atmosphere were dense at such altitude? |
Yes but it's a nonsensical question: orbital period and orbital radius (and Earth's mass) are tied to each other by Kepler's Law. No low altitude
geostationary orbits, for instance.
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SupFanat
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I hope they make better geostationary weather satellites which show as many color channels as they want for some scientific purposes but they don't
forget about "true color" version as well.
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blogfast25
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| Quote: Originally posted by SupFanat | | I hope they make better geostationary weather satellites which show as many color channels as they want for some scientific purposes but they don't
forget about "true color" version as well. |
Colour is in your mind. Not important...
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SupFanat
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I hope it's thinkable. I want to view Earth from great altitude but I can't reach even low earth orbit, a fortiori such high orbit that the Earth
appears as disc. So the only chance is...virtual trip.
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turd
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Source: https://en.wikipedia.org/wiki/Pale_Blue_Dot
You're welcome.
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SupFanat
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Thank you but billions of kilometers/miles is too tall. I prefer thousands of kilometers/miles.
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