Temperature regulation in Earth orbit

In summary, the temperature on the sun-facing side of the orbiting Space Station would soar to 250 degrees F (121C), while thermometers on the dark side would plunge to minus 250 degrees F (-157C). The temperature could range from as cold as arbitrarily close to the CMB temperature to as hot as arbitrarily close to the sun's temperature. However, on the moon, it would be different depending on the location. It can get pretty cold on some parts of the polar regions of the moon that are sheltered from the sun and the earth.
  • #1
Treva31
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If I had an object in an orbit around the Earth that I kept continually shaded from the sun, how cold would it get?
Assuming the shade device was not physically connected to and was sufficiently far away from the object to not radiate any heat to it.

And if I actively adjusted how much shade the object was under could I regulate the temperature to anything I wanted?
Between -100 and +260 celcius I would guess?
Assuming an orbit in continuous sunlight.

Would it be any different on the Moon?
 
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  • #2
Treva31 said:
Between -100 and +260 celcius I would guess?
Assuming an orbit in continuous sunlight.
According to NASA (based on the ISS experience) it would be 121C to -157C:

Without thermal controls, the temperature of the orbiting Space Station's Sun-facing side would soar to 250 degrees F (121 C), while thermometers on the dark side would plunge to minus 250 degrees F (-157 C).

Would it be any different on the Moon?
It would be different on the moon depending on the location. It can get pretty cold on some parts of the polar regions of the moon that are sheltered from the sun and the earth. See this NASA temperature map of the moon.

AM
 
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I could understand 121C as it the Stefan Boltzman equivalent temperature for the Solar flux density of 1360W/m2. But, how are we getting -157C, that I did not understand.
 
  • #4
Andrew Mason said:
That's not actually an answer to the OP's question. That's the answer for a particular system, if unregulated. The OP is asking what you can get with purpose-designed passive regulation (a heat shield and insulation). In theory, the answers should be:

1. As cold as arbitrarily close to the CMB temperature
2. As hot as arbitrarily close to the sun's temperature.
[3. Anything in between.]

I'm not sure why anyone would test the upper limit, but googling gives me one example down to 60K (-213C):

https://www.google.com/amp/s/www.re...itude_orbit_control_in_micro- spacecraft /amp
 
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Anand Sivaram said:
I could understand 121C as it the Stefan Boltzman equivalent temperature for the Solar flux density of 1360W/m2. But, how are we getting -157C, that I did not understand.
When shaded from the sun and nearby planets, the only thing an object radiates against is the CMB.
 
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CMB has a temperature of 2.7K or -270C. But, Moon craters are one of the coldest places in the entire solar system at 26K. Any reason for this difference?
 
  • #7
Don't forget, that in (low) orbit around Earth a little under a half-sphere of thermal radiation input comes from Earth. Also, for overall considerations one can usually safely ignore CMB thermal input when there are other (significant) sources around.
 
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That could be a valid point, the Earth has an average albedo of 0.3, that would mean that we are reflecting 30 percent of solar energy back to space.
 
  • #9
Anand Sivaram said:
CMB has a temperature of 2.7K or -270C. But, Moon craters are one of the coldest places in the entire solar system at 26K. Any reason for this difference?
The moon is a big rock and it stores heat.
Anand Sivaram said:
That could be a valid point, the Earth has an average albedo of 0.3, that would mean that we are reflecting 30 percent of solar energy back to space.
When you're trying to get something reeeaaally cold, that's a lot. Also it's not really about Earth's albedo, but its radiation temperature. If an object in LEO has a side facing Earth, Earth fills up most of its field of view on one side. So the minimum temperature on that side is the night-time temperature of Earth.
 
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  • #10
Anand Sivaram said:
That could be a valid point, the Earth has an average albedo of 0.3, that would mean that we are reflecting 30 percent of solar energy back to space.

Its not just albedo radiation, there is also a thermal contribution from the atmosphere itself. For "first-order precise" work one can consider the Earth to be a spheric black body radiator at around -20 deg C. See [1] for a description relevant to a nano-sat and [2] for a similar question answered on stackexchange.

[1] http://webapp.tudelft.nl/proceedings/ect2012/pdf/chandras.pdf
[2] https://space.stackexchange.com/que...temperature-of-a-satellite-orbiting-the-earth
 
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1. How does temperature regulation work in Earth orbit?

Temperature regulation in Earth orbit is primarily controlled by the balance between incoming solar radiation and outgoing thermal radiation. The Earth's atmosphere also plays a role in regulating temperature by trapping some of the sun's heat and redistributing it around the planet. Additionally, human activity such as space missions and satellite launches can also impact temperature regulation in Earth orbit.

2. What are the main factors that influence temperature in Earth orbit?

The main factors that influence temperature in Earth orbit include the distance from the sun, the tilt of the Earth's axis, the Earth's atmosphere, and human activity. The distance from the sun determines the amount of solar radiation received, while the tilt of the Earth's axis affects the distribution of this radiation. The Earth's atmosphere traps some of the sun's heat and redistributes it, and human activity can also impact temperature through the release of gases and particles into the atmosphere.

3. How does temperature vary in different parts of Earth's orbit?

Temperature can vary significantly in different parts of Earth's orbit. When the Earth is closest to the sun (perihelion), temperatures are generally warmer due to the increased amount of solar radiation. On the other hand, when the Earth is farthest from the sun (aphelion), temperatures are generally cooler. The tilt of the Earth's axis also causes seasonal variations in temperature in different parts of the orbit.

4. How do astronauts regulate temperature in space?

Astronauts regulate temperature in space by using environmental control systems in their spacecraft or spacesuits. These systems can control the flow of heat, humidity, and air circulation to maintain a comfortable temperature for the astronauts. Additionally, spacesuits are designed to provide insulation and regulate body temperature through cooling or heating mechanisms.

5. How does temperature regulation in Earth orbit affect life on Earth?

Temperature regulation in Earth orbit plays a crucial role in maintaining a habitable environment for life on Earth. The Earth's atmosphere and its ability to trap heat help regulate the planet's overall temperature, which is essential for supporting diverse ecosystems and sustaining human life. Changes in temperature regulation due to human activity, such as the release of greenhouse gases, can have significant impacts on the Earth's climate and ultimately affect life on the planet.

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