# 2 space stations each floating and remaining above earth at night and the other above

Discussion in 'Off-Topic' started by s0nny80y, Mar 15, 2016.

1. ### s0nny80yKing

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2 space stations, each floating and remaining above earth at night and the other above earth during day.

Is this ever possible?

Thanks,
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2. ### SenethroOverlord

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What? So, an equatorial orbit with a 24 hour period, but on opposite sides of the planet?

Uhhhh an orbit calculator I found suggests this would be possible at a height of 35875km assuming a circular orbit and I was able to put the numbers in correctly. ISS is at height of 330-410km so 36000km would be more than sufficiently high above the atmosphere.

Distance of moon is ~ 384,400 km so I wouldn't have thought it would interfere.

3. ### hobbsyoyoDeity

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You really have to define what you mean by 'day' and 'night' here.

Equatorial orbits with 24 hour periods are called 'geostationary orbits' and they are used by a ton of communications satellites. Even though they are above the same spot on the Earth, they do not experience the same day/night cycle as the ground below them. They only experience a pretty brief 'night' when the Earth or Moon eclipse them and are otherwise always in daylight.

Are you asking if a satellite can move in such a way that it is always above the light-side of the Earth? If so the answer is kind of sort-of using special 'sun synchronous' orbits (and really only a small subset of all the different types of sun synchronous orbits that ride the terminator). Like-wise, you could also position one to always be on the dark side of the planet with brief sunlit periods though good luck providing it with electrical power. However, it's important to note that unlike GEO sats, sun synchronous sats are not above the same point on the ground at all times. If you were watching one of these from the ground, you'd only get to view them for a minute or two every hour and a half (give or take depending on the orbital height) as they passed overhead. These types of orbits are used by spy satellites.

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5. ### hobbsyoyoDeity

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This is why I said he had to define what he meant by night and day. In everyday use, it's perfectly clear but space is weird man. Everyone's guess here is as good as any.