34
votes
How did theorists determine that the atmosphere attenuates enough to support unpowered orbits?
If 200 miles up counts as a low earth orbit height, then the appreciation is as old as Newton's Principia, that there was no atmosphere left there, and nothing like atmospheric drag to oppose motion.
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20
votes
How did theorists determine that the atmosphere attenuates enough to support unpowered orbits?
The scale height is a useful way to describe how the atmospheric pressure decreases with altitude. From Wikipedia,
For planetary atmospheres, scale height is the increase in altitude for which the ...
- 2,367
10
votes
Accepted
How close do gravitational 2-body hierarchy levels get?
The zone of influence of a larger body over a smaller body is known as the hill sphere. Within this sphere the gravitational attraction of the larger body will dominate its satellite and satellites ...
- 7,786
8
votes
Is it possible to create an analytical ephemeris from raw position and velocity of a Body?
It's possible, because that's partly how VSOP was made, but the amount of effort involved is immense. What you are describing is at the very least a doctoral thesis, if not several of them.
Why not ...
- 6,753
7
votes
What are "transcritical, pitchfork, period-doubling, torus, and subharmonic bifurcations" in the context of three-body orbits? (e.g. butterflies)
I can attempt an answer by summarizing some of my favorite dissertations. Forgive some of the word vomit below, this is certainly not the most elegant or succinct explanation. I'll give a bit of a ...
- 716
6
votes
How did theorists determine that the atmosphere attenuates enough to support unpowered orbits?
No answer has yet mentioned the concept of hydrodynamic equilibrium, which dates back to Newton. The Earth's atmosphere has been more or less stable for billions of years. It is not expanding or ...
- 71.3k
4
votes
Mars transfer window frequency
It turns out you have a lot more flexibility in terms of transit times and surface stays than you'd think. I really like this plot by Casey Handmer.
Above the X-axis, it shows the transfer windows ...
- 41
4
votes
How did theorists determine that the atmosphere attenuates enough to support unpowered orbits?
Sea level air pressure is 101.3 kPa (14.7 psi). This means there are 1.03 kg of air in 1 cm² column of air stretching from sea level to space (this is 14.7 pounds of air in a 1” square column). One ...
- 13.8k
2
votes
Is it possible to create an analytical ephemeris from raw position and velocity of a Body?
Not "analytical" but you can compute your own cubic splines to an arbitrary accuracy.
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- 319
2
votes
How did theorists determine that the atmosphere attenuates enough to support unpowered orbits?
Depends how far back you want to go.
People would've climbed mountains a very long time ago and would've noticed less air. It would be reasonable to conclude that if you went even higher up there ...
- 131
2
votes
Could the Lunar Lagrange Points work for space telescopes?
Pros and cons of space telescope in an Earth-Moon L2-associated libration orbit
Pros:
Some orbits will allow the possibility of spending some time behind the Moon which can completely eclipse Earth. ...
- 149k
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