# Very Low Earth Orbit
**URL:** https://boards.straightdope.com/t/very-low-earth-orbit/673828
**Category:** Factual Questions
**Created:** [November 13, 2013, 4:37pm UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828 "2013-11-13T16:37:04Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@The\_Hamster\_King](https://boards.straightdope.com/u/The_Hamster_King)
#### Post date: [November 13, 2013, 4:37pm UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/1 "2013-11-13T16:37:04Z")
How fast would you need to be going in order to orbit the Earth at an altitude where you just skimmed the surface?
Assume a circular orbit around the equator. Assume air resistance isn’t a factor. Also assume that the Earth is homogenous enough that local variations in the gravitational field don’t introduce perturbations.
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### Author:  [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)
#### Post date: [November 13, 2013, 5:14pm UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/2 "2013-11-13T17:14:52Z")
Using an online calculator and a height above the surface of 1 meter, I got a velocity of 7.90973 km/s.
This is the calculator I used:
> **[Earth Orbit Calculator](https://www.calctool.org/astrophysics/earth-orbit)**
>
> This earth orbit calculator determines the speed and orbital period of a satellite at a given height above average Earth sea level.
ETA:
This site gives the same result and has a bit more explanation about the formulas involved.
[http://hyperphysics.phy-astr.gsu.edu/hbase/orbv3.html](http://hyperphysics.phy-astr.gsu.edu/hbase/orbv3.html)
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### Author:  [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)
#### Post date: [November 13, 2013, 7:33pm UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/3 "2013-11-13T19:33:30Z")
Interestingly enough, Arthur C. Clarke’s short story “Maelstrom II” concerns:
An astronaut is accidentally thrown into a highly eccentric orbit around the moon. It’s going to take some time to get a ship into an orbit capable of intersecting and rescuing him, but his orbit is _so_ eccentric that it actually intersects a mountaintop.
They blow the mountain up, letting him orbit through the place where the mountain was, giving him more time.
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### Author:  [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)
#### Post date: [November 13, 2013, 7:45pm UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/4 "2013-11-13T19:45:54Z")
You might think there’d be a big difference, but it’s quite minor.
The speed of an orbit is proportional to the [semi-major axis](http://en.wikipedia.org/wiki/Semimajor_axis). The earth’s radius is about 4000 miles, and the differences in length of axes is without rounding error. So if you look at a satellite at 4100 from the center, or 100 miles above the surface, the difference is minimal. The calculator gives 7.8116 km/sec. Pretty close.
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### Author:  [@MikeS](https://boards.straightdope.com/u/MikeS)
#### Post date: [November 14, 2013, 3:41am UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/5 "2013-11-14T03:41:31Z")
> [@robert\_columbia](#):
>
> Interestingly enough, Arthur C. Clarke’s short story “Maelstrom II” concerns:
And here I was expecting a link to [“The Holes Around Mars”](http://www.gutenberg.org/files/32360/32360-h/32360-h.htm).
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### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [November 14, 2013, 4:11am UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/6 "2013-11-14T04:11:34Z")
> [@MikeS](#):
>
> And here I was expecting a link to [“The Holes Around Mars”](http://www.gutenberg.org/files/32360/32360-h/32360-h.htm).
I remembered the story, and the name of the moon, but not the name of the story. 🙂 Thanks for the link.
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### Author:  [@Satellite\_Guy](https://boards.straightdope.com/u/Satellite_Guy)
#### Post date: [November 14, 2013, 6:19am UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/7 "2013-11-14T06:19:28Z")
I saw this thread, and did a double-take. I asked pretty much the same question, [seven years ago](http://boards.straightdope.com/sdmb/showthread.php?t=385861). Neat! 😃
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### Author:  [@j\_sum1](https://boards.straightdope.com/u/j_sum1)
#### Post date: [November 14, 2013, 7:47am UTC](https://boards.straightdope.com/t/very-low-earth-orbit/673828/8 "2013-11-14T07:47:03Z")
> [@Satellite\_Guy](#):
>
> I saw this thread, and did a double-take. I asked pretty much the same question, [seven years ago](http://boards.straightdope.com/sdmb/showthread.php?t=385861). Neat! 😃
Cool post username combo.