How do direction work in space because north,east,west and south are bonded to earth? How does a spacecraft guide itself in the unending space?
In: Physics
Just like on earth n,w,e,s are meaningless without a reference. The same will apply to space.
Since things move in space you will need to use coordinates relative to some set objects. Say certain stars. We havent really begun space exploration to really hammer out a good system but we do use angles and distance that are relative to earth.
Directions only work with a reference point (even on earth – the reference point could be the geographic or magnetic poles)
So in space, a traveller would need reference points – possibly using the center of the galaxy or distant galaxies as reference points. Of course it wouldn’t be called N, S, E, W because there are 6 “cardinal directions”.
For travel within the solar system, the sun would be a reasonable reference point perhaps along with a few distant stars.
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Ooh, I know this one. It’s called a [gimbal](https://en.m.wikipedia.org/wiki/Gimbal). The concept is used in [inertial navigation sysyems](https://en.m.wikipedia.org/wiki/Inertial_navigation_system). Basically, 3 gimbals provide your 3D reference (xyz) to orient yourself. The gimbals will always be spinning in the exact same orientation in space no matter how a spaceship flips and spins. There’s a scene in apollo 13 where they talk about [gimbal lock](https://en.m.wikipedia.org/wiki/Gimbal_lock), meaning they’re losing their ability to orient themselves because one of the gimbals is close to being “trapped” or “caught up” with another gimbal, losing orientation in that axis. [Here’s](https://youtu.be/OmCzZ-D8Wdk) a short video explaining it.
Edit: ~~Imagine two of the gimbals represent the xy-plane and its parallel with the Earth’s orbital plane around the sun. You can read the gimbals to tell you if you’re pointing “above” Earth’s plane of orbit or “below” Earth’s plane of orbit (assuming the North pole points “up” for us northern hemisphere dwellers).~~ I’m guessing, I shouldn’t do that.
More science related to gyroscopes and the relevant phenomenon with demonstrations you can see [here](https://youtu.be/XPUuF_dECVI?t=23m). See also 35:35 for another demo.
Edit: Silly me. Walter Lewin specifically talks about it in this video at 43:50. Watch that.
Edit: I’m an idiot. I’m talking about the gimbals like they’re spinning. They’re just the rings free to rotate and allow the central gyroscope to spin and maintain its initial position. Don’t trust everything anyone says.
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Currently we map objects in the sky using polar coordinates. Two angles and a distance.
Usually we use Earth as the centre point (in fact the viewers position on earth) and we work out the angle the object is from the centre line of the sky (that we define) and then the angle off the horizon.
This is declination and right ascension.
It doesn’t make much sense for an interstellar space ship to use earth as the centre point. So we might use the centre of the galaxy. Then define 0 degrees as the line through the sun.
So the solar system would be at 0°,0°,25kly
Changing direction would also likely use angles. Similar to how boats do it. Change angle a by x° and angle b by y°.
I don’t know how actual space craft do it but there it’s precedent in fiction with star trek. At the end of an episode the captain might command the helm to set a course 120 mark 43. That’s your two angles relative to something (the ship, the galactic plane or something)
When away from the earth, stars serve as a suitable reference point. The north star is still in the same direction, even in space, and other stars become easier to use because you are no longer on the surface of a rotating sphere. Essentially, in space every star can be the north star.
Spacecraft are able to determine their position and orientation through a combination of on board sensors (like star sensors) and off board trackers (like radar). Beyond that, it is typical to describe their position and velocity as an orbit. These orbits can be described using a few variables that indicate the size, orientation, and direction of the orbit. These are called “Keplerian Elements.”
So, for example if you wanted to convey information about a satellite above the Earth, you wouldn’t say “It’s 500Km above the ground, moving 7km/s in the Northwest direction” but you could say, “The satellite’s orbit has a semimajor axis of 6800km, with an eccentricity of .01, inclination of 23 degrees…”
Of course, there are other ways of keeping track of and describing these, but that’s one of the most basic ways.
Play [Kerbal Space Program](https://www.kerbalspaceprogram.com/). Here is a helpful xkcd to help understand why it will help.
[https://xkcd.com/1356/](https://xkcd.com/1356/)
Also why you won’t be ready for that NASA position.
[https://xkcd.com/1244/](https://xkcd.com/1244/)
As an add-on to D1Foley’s comment, check out Quill18’s “Kerbal Space Program for Complete Beginners” series on youtube. He covers this stuff and does a preeeeeetty good job of it.
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