How to Navigate in Realistic Space Travel

Spacedock delves into the fascinating subject of space navigation.

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Spacedock does not hold ownership of the copyrighted materiel (Footage, Stills etc) taken from the various works of fiction covered in this series, and uses them within the boundaries of Fair Use for the purpose of Analysis, Discussion and Review.

[mitwhitgaming]

I like the idea of your average star-hopping, rag-tag smuggler in a sci-fi setting actually being really good at calculus, because you would have to be in order to make a living in space.

[antguy]

Han Solo being a disguised super-nerd is quite the funny thought.

[rfletch]

"... a tall ship, and a star to sail her by".

[TheSaneHatter]

"Wheel, telescope, astrolabe, compass: a ship's a ship"
- Doctor Who, 'Curse of the Black Spot'

[kiwiwarlord]

I love that you are making a few videos on a bit more of the practical matters of spaceflight. In my studies as a civilian mariner we where taught that gps simply works by caculating our distance to any gps satelite. If you have the exact distance to a minimum of three satelites, you know exactly where you are. The distance is calculated by measuring the time it took the signal to reach the vessel ( usually down to a fraction of a mili-second), As Distance= Speed* time traveled, and we know speed and time, this isn't that hard for a computer.

[countfizix]

You can go a level above and use quasars for extra-galactic (maybe out to order 0.1-1B LY) navigation in a similar manner to pulsars as the ~200 brightest have well defined absolute brightness and distance. These quasars are also incidentally, the reference points the GPS satellites use to estabilish their own location as they are far more fixed in space from our perspective than the sun is relative to stuff like pulsars or bright local stars.

[CantankerousDave]

In one of the later Foundation books, the main character insists on making the hyperspace jump calculations himself (which can take hours or even days) because he doesn't trust the ship's newfangled "com-pyoo-ter" to do it properly.

[deep.space.]

One more thing about FTL-capable civilizations is that, when you warp/hop to another point in space, you are seeing starlight, their redshift, and positions, at vastly different points in time. Say, our map of Proxima Centauri's position today, in Earth's inertial frame, is its position 4.2 years ago. And that's the second closest star to us.

[benst]

In Star Wars lore, astronavigation information was regularly updated via the holonet. It seems the Empire could have effectively controlled who could travel where by cutting off updates.

[marwcelin]

The missile knows where it is at all times. It knows this because it knows where it isn't, by subtracting where it is, from where it isn't, or where it isn't, from where it is, whichever is greater, it obtains a difference, or deviation. The guidance sub-system uses deviations to generate corrective commands to drive the missile from a position where it is, to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position where it was, is now the position that it isn't. In the event of the position that it is in is not the position that it wasn't, the system has required a variation. The variation being the difference between where the missile is, and where it wasn't. If variation is considered to be a significant factor, it too, may be corrected by the GEA. However, the missile must also know where it was. The missile guidance computance scenario works as follows: Because a variation has modified some of the information the missile has obtained, it is not sure just where it is, however it is sure where it isn't, within reason, and it knows where it was. It now subtracts where it should be, from where it wasn't, or vice versa. By differentiating this from the algebraic sum of where it shouldn't be, and where it was. It is able to obtain a deviation, and a variation, which is called "error"

[BFVgnr]

I'm currently reading the Frontlines series by Marko Kloos. "Orders of Battle" has the main character's ship sucked into an Alcubierre bubble, where FTL is capable. In human vessels, the farther the system from the entry node, the longer the transit. When drafted along by the alien vessel, they go farther than ever before, and with the shortest transit time they'd seen.
For example, the 150 light year transit requires a full 24 hours in Alcubierre. But the alien bubble takes them 900 light years, over a mere 33 minutes.
When they determine their position, they use what is referred to as Galactic Positioning, which uses known pulsars as points of reference. The fine points are not addressed, but they determine themselves to be 900LY from Earth space.

[KorianHUN]

I worked on a sci-fi world where the main form of FTL navigation was based on measuring pulsars. The navigational computer held a large darabase of pulsars and large stars with information to calculate changes based on age. Naturally FTL would mean the signals from the same pulsar were not the same 1000 and 8000 lightyears from it.
Navigational accurace was based on how accurate your pulsar database was.
However a small angular difference and any gravitational interference would change your trajectory. To nerf FTL but allow for it as a story element travel required a lot of shorter jumps. Constant readings confirmed the accuracy of the navigational system and the computer automatically adjusted jump direction based on it. This was the way to allow FTL travel even for damaged ships.
And traveling to other galaxies required getting the appropriate pulsar and system maps.

[sophietaylor]

A realistic star tracking system on a galactic scale would need significant computational power, I think, in order to calculate the movement of individual stars from the positions listed in the ephemeris.

Another factor is navigating while travelling at relativistic velocities; you have to deal with non-simultaneous, non-causally-linked events being ordered arbitrarily. You also would have to deal with the fact that new stars are born and old stars die; stars which are in the catalogue might not be around any more, and stars which meet all the criteria for being in the catalogue might not be in them, because they were born after the last update of the catalogue.

[deanlawson]

For solar system nav, I can see us setting up solar system GPS satellites/beacons in lagrange points of each of the planets, just doing the same type of GPS calculations we do now with satellites around our planet, just on a much bigger scale, and it can be just as accurate, and will move with the planets as they move.
For interstellar nav, the only real feasible method has got to be Pulsar nav. Those things are very regular and "reliable", and can get you reliably to another star system, or space based installation close enough to use transmitted beacons from the remote system or installation you are approaching, kind of like a layered series of systems.
Serious fast nav computing with multiple redundant backup nav computers checking and cross-checking each other would be essential for doing all of this.
This is really interesting for a video topic - Thanks for this!

[captainmatthew]

fun fact i had a lecture from the person who discovered pulsars today. i wish i saw this video first so i could of asked about if she thought of or heard of the navigation use. her name is Dame Jocelyn Bell Burnell if anyone is wondering.

[originaluddite]

The phrase "Borg know-how" conjures the image of a gruff yet reliable cyborb tradesperson in overalls.

[RorikH]

Hey, I just thought of the reference-star navigation idea myself, mostly because in Starfield Cora Coe keeps saying, "on Earth people used the stars to navigate, but that doesn't work in space" even though in Space there's... pretty much nothing else to use to navigate.

[Woodclaw]

I think a great foundation for this subject is Dava Sobel's "Longitude", an essay about how difficult it was to calculate your position at sea during the age of sail.

[Phrancis]

GPS is indeed a very clever and accurate form of military navigation that Reagan released to the public after the Korean Air 007 was shot down by the USSR in the early 80's after it strayed into Soviet air space. I was a young child at the time, but flew on that same Boeing 747 KAL-007 on the same route a year prior.

[mahatmarandy]

If I recall correctly, given how far away, the stars are from here, pretty much any solar system within about 13 ly of earth is going to have essentially the same constellations. Some individual stars may be a little brighter or a little bit dimmer, but their sky is basically the same same as our sky. And again, if I recall correctly, you can ghetto out about as far as 35 ly and still recognize the same constellations we see from here. They will be somewhat deformed compared to what they look like in the night sky, butmstill fairly recognizable