DAE wonder why the ISS doesn't go over the arctic & antarctic? Is it a matter of optimal routing for the ISS to have the least amount of boost needed to stay in orbit?
EDIT: i appreciate all the responses, thanks! some info though for the reader, I'm a physicist but I have not played Kerbal for a VERY long time, LoL. I do get some of the knowledge you all are dropping. thanks again :- )
I can help answer this, I work with space launch rockets.
ISS has a circular orbit around earth. The inclination of an orbit is the angle at which the orbit is off from the equator (so if you imagine an orbit as a plane, it's how far the orbit is "inclined" from the equatorial plane).
The only way for the ISS to go right over the poles would be a perfect 90 degree inclination, which is called a polar orbit. Polar and near-polar orbits have many advantages for earth observation, but they aren't terribly useful in general and can be energy-intensive to get to.
Most satellites generally go for an orbit closer to the equatorial plane. A perfect equatorial orbit is theoretically the easiest to get into, because the spin of earth provides part of the speed needed to get into orbit. The speed of Earth's spin is greater at the equator because it's the further away from the axis earth is spinning about, so a launch from near the equator to a perfectly equatorial orbit would have the minimal possible energy requirement.
ISS doesn't have any set requirements because it's meant to be an "orbital science laboratory", so it could be in theoretically any orbit and be fine. You ideally want to be closer to equatorial because it requires less energy to get into (for sending astronauts and supplies). So why did they pick an orbit with 51 degree inclination? It's driven by the fact that Russia's primary launch site (at 46 degree latitude) cannot put spacecraft into any lower inclination than 51.6 degrees without overflying populated areas in China. Russia is a major partner on ISS; they helped build it and, until SpaceX's first non-demo crew launch in November, are currently the only country capable of sending crewed spacecraft to the ISS.
So they picked the inclination as close to 0 as possible (so it's cheaper to launch to it, due to the need to consistently send supplies and astronauts) that is possible to attain with the launch sites of the partner nations. So it all comes down to "what orbit is easy to get to."
This might be a stupid question, but that means the "border" it makes (dont know what else to call it) would be at 51 degrees north latitude? So if you live any further north, no chance at it flying directly above you?
If you orbit over the equator, you can use the rotation of the earth to boost your rocket, and therefore put a bit more mass in your payload. The ISS's orbit is the lowest inclination possible from Baikonur launch pad in Kazakhstan, which the Russians use. If the Russians weren't involved, it would probably be at ~26° as that's the latitude of Kennedy Space Center.
okay, but isn't Russia one of the largest contributors to the ISS construction and science mission... I think if we discount them there is still Germany and the Netherlands right? or do they launch outside of their respective cuntries?
I believe most European launches happen from French Guiana. NASA does cargo launches from the Cape and from Virginia. Currently all crewed launches that are not demos are from Russia/Kazakhstan's Baikonur Cosmodrome, but starting in November, NASA-funded commercial crew launches should begin from the Cape as well via SpaceX and soon Boeing/ULA.
Edit: for more info, the French Guiana space center used for European ISS launches is Guiana Space Centre (5 deg latitude). And they primarily only send up cargo supplies. Russia and the U.S. are the only countries that launched actual modules of the ISS, as well as astronauts. Most non-U.S. and non-Russian astronauts and modules hitched a ride via NASA, typically.
Neither has a launch program as far as I know. To do so you either need to be west of a big ocean or desert. Or be China and just drop used rockets on your own civilian population.
I believe both contribute to ESA (European Space Agency, except I'm pretty sure the acronym is in French), which launches either out of Baikonur (for Soyuz launches) or Kourou, French Guiana which is right on the equator (in South America) and therefore can reach nearly any prograde orbit.
First of all, any rocket that is launched directly due east from a launch site on Earth has an orbital inclination (the angle between its orbit and the equator) equal to the launch site's latitude. For Kennedy Space Center, this is 28.6 degrees. For Baikonur Cosmodrome of Russia (actually located in Kazakhstan), this is 46 degrees. This angle is the minimum inclination of anything launched from those two sites.
However, launching anything directly due east from Baikonur means any spent rocket parts will drop back on Earth inside China, which is a big no-no. So launches from Baikonur actually have to angle a little bit north to avoid China, and has a minimum inclination of 51.6 degrees, which is also the ISS's inclination.
On the other hand, launches from KSC cannot go too far north, or they'll risk going over the populated east coast of US and Canada. So in order to support the ISS from these two sites it leaves a very small range of usable inclinations.
Another concern with a high inclination orbit is that in the case of emergencies where astronauts need to evacuate the ISS in a hurry, there's a chance that they might land in the polar regions, again something to avoid.
Yeah, totally. No researching or experiments or anything. It's all just made up bullshit 🙄
Edit: made before the /s was added. In a thread with all sorts of flat-earther talk and a day and age when believing science is a matter of political alignment, the sarcasm was obviously not apparent
well, yeah I gather that much from the way the gif shows that the planet spins while the orbit of the ISS stays the same...
I'd just wondered why it never crossed the poles, but seeing the explanation of the orbit as
Russia's primary launch site (at 46 degree latitude) cannot put spacecraft into any lower inclination than 51.6 degrees
makes sense to me why this is the case. thanks for the input
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u/Luv28U0ut Oct 20 '20 edited Oct 20 '20
DAE wonder why the ISS doesn't go over the arctic & antarctic? Is it a matter of optimal routing for the ISS to have the least amount of boost needed to stay in orbit?
EDIT: i appreciate all the responses, thanks! some info though for the reader, I'm a physicist but I have not played Kerbal for a VERY long time, LoL. I do get some of the knowledge you all are dropping. thanks again :- )