Talk:Polar orbit

Remaining problems with the article

• Not 90 degrees relative to the viewpoint of someone standing on the planet's equator!

 -- should probably read "to the plane of the Equator" NinjaWolfHybrid (talk) 21:43, 24 February 2010 (UTC)

• Not a different longitude everytime necessarily. A satellite with the same orbital period as the rotational period of the planet will pass over the same spot every time. And an integer multiple of the period...

 Done (Sdsds - Talk) 03:03, 10 May 2007 (UTC)

• AND the longitude of the satellite precesses (sp) during every orbit. So the longitude is not the same suring one orbit nevermind two successive.

Paul Beardsell 22:34, 11 Sep 2004 (UTC)

• The article mentions the special case of a geosynchronous polar orbit without going into any detail:

"Except in the special case of a polar geosynchronous orbit, a satellite in a polar orbit will pass over the equator at a different longitude on each of its orbits."

The quote could be implying that "geosynchronous polar orbit" is a special term for polar orbits that pass over the SAME longitude on each pass. If this is the case, it should be spelled out, because I would interpret "geosynchronous polar orbit" to mean an object that remains in a fixed position above one of the Earth's poles. If this is what's meant, then it's not an "orbit," an orbit is the gravitationally curved path of one object around a point or another body. Normally geosynchronous satellites do "orbit" because at the same time the Earth spins, the satellite goes around too. In the "special case of a geosynchronous polar orbit" there would be no curved path around the Earth. The object would in fact be orbiting the Sun next to the Earth, but not orbiting the Earth, and would therefore not technically be in "geosynchronous orbit." So, without the ability to Orbit the Earth, a satellite hovering above the pole would gradually fall to Earth unless it was able to counteract this force. So a satellite could only remain in geosynchronous polar "orbit" (maybe proximity is a better word) by using propulsion or some kind of advanced technology like anti-gravity or solar sails. NinjaWolfHybrid (talk) 21:55, 24 February 2010 (UTC)

Cost, launch site?

I assume it costs more to get something in a polar orbit since you don't have the earth's rotation helping you out. Also, shouldn't the ideal launch site be on one of the poles? If so, where do polar orbits get launched from? —Ben FrantzDale 05:15, 15 March 2007 (UTC)

A satellite can be launched to a polar orbit from anywhere. In the simplest case, the rocket simply accelerates mostly northward or mostly southward, with some westward component (dependent upon latitude) to null the eastward component owed to Earth's spin. But of course, due to the problem of where the lower booster stages fall, there are only certain sites which get used for polar orbits. Preferably booster stages will fall into the ocean. From Vandenberg in California, payloads can be launched due southward and stages fall into the Pacific to the West of Mexico. From within Asia, particularly the Baikonur Cosmodrome in Kazakhstan, the first stages fall out in desolate steppes. Second stages fall much further afield and do occasionally slam into people's farms. I'm not sure if anyone's ever been killed outright by a Russian 2nd-stage; but the farmers out there are very resourceful and, if they can cart away a rocket before the licensed scrap dealers get there, they often cut up the metal skins and use them for building materials.

The Earth's rotation doesn't "help out" satellites, they stay up by orbiting at an altitude/speed that properly counteracts the Earth's gravity, not by maintaining airspeed. You could launch a polar orbiting satellite from anywhere, you just have to launch it towards one of the poles. NinjaWolfHybrid (talk) 21:31, 24 February 2010 (UTC)

Earth's spin does help. Even as I type I am moving eastward. I have a certain fraction of orbital velocity already. That fraction ranges from zero-mph at either of Earth's poles to about 1,000-mph on the Equator. Considering that orbital speed on a low orbit is about 17,500-mph, a free 1,000-mph can up payload capacity significantly.

Sure, the Earth rotation helps the launcher (rocket!) when the target is an orbit with a relative low inclination. That can be seen as one of the reasons why Geostationary spacecraft by preference are launched from sites close to the equator, for example Guiana Space Centre.

Spacecraft that should be put in polar orbit are launched from the existing launch facilities where-ever they are, for example Plesetsk Cosmodrome or Baikonur Cosmodrome and also from Guiana Space Centre (European Remote-Sensing Satellite, Envisat). The geographical position itself is of little importance!

Stamcose (talk) 22:12, 16 March 2011 (UTC)

There is no disadvatage if multiple satellites (constellation) are used in a polar obit configuration

Satellite phone providers such as Iridium, are able to provide phone access globally anywhere on land, or at sea using their constellation of 66 satellites in a polar orbit configuration, at an altitude of 780 kilometers (485 miles). —Preceding unsigned comment added by Tjmartinez (talk • contribs) 18:29, 19 September 2007 (UTC)

My interpolations

Most polar orbiters you see - the ones that go over in somewhat more than an hour - don't go over the pole, for a very good reason, which I've explained and referenced. I believe that this is the most common case. What I have no reference to is *why* 100 mins is a common period (I think it is, though I'm not certain of that). I think its probably because its fast enough, and anything faster gets too much atmos drag, though I'm not at all certain of that. Any satellite experts are welcome to comment William M. Connolley (talk) 21:29, 15 November 2008 (UTC)

Strange sentence - Possible improvement of the entire text

The sentence: "To keep the same local time on a given pass, it is desirable for the orbit to be as short as possible, which is to say as low as possible." is strange!

As long as the inclination is the right one matching the altitude the local times of the nodes will stay constant, see formula in Sun-synchronous orbit. No special advantage for "as short as possible, which is to say as low as possible" in this respect!

As well as having a reference to Sun-synchronous orbit there should be a reference to Frozen orbit.

I plan to propose some re-write!

Stamcose (talk) 11:03, 25 June 2011 (UTC)

Polar geosynchronous orbit

The first paragraph mentions polar geosynchronous orbit, is there such a thing? I can't see how it would work.Carlwev (talk) 16:34, 9 August 2011 (UTC)

Agreed. Deleting because there is no source. hac (talk) 09:51, 25 November 2013 (UTC)

Sun Orbit?

The explanation of "Sun Orbit" is not very explanatory. Needs better treatment. --23.119.204.117 (talk) 04:01, 3 December 2017 (UTC)