How to Navigate in Realistic Space Travel

I just wanted to say that your videos have really helped me out with my full-time work modeling spacecraft and my own channel during 2023. Thank you for your videos.

The spacecraft 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 subsystem uses deviations to generate corrective commands to drive the spacecraft 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 that it was, is now the position that it isn't.
In the event that the position that it is in is not the position that it wasn't, the system has acquired a variation, the variation being the difference between where the spacecraft 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 spacecraft must also know where it was.
The spacecraft guidance computer scenario works as follows. Because a variation has modified some of the information the spacecraft 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, and by differentiating this from the algebraic sum of where it shouldn't be, and where it was, it is able to obtain the deviation and its variation, which is called error.

This topic suprisingly made me a lot more interested.

drugged up navigators

My own StarWars headcanon: Astromech droids are startrackers, using the stars to determine their EXACT location. Instead of a simple catalog, they use a map of the ENTIRE galaxy!... or as much of the galaxy as has been reliably mapped, anyway.

I love how many footage of shows you use , great ones to see in the future

Can you do a video on galactic mapping with sci fi cultures that have FTL. The first issue I see is that because the ships move much faster than light in these settings, which means maps need to account position and distance to determine where a Star should be via FTL, rather than the light that would be showing the stars past position.

It'll be interesting when GPS goes from Global Positioning System to Galactic Positioning System...

IIRC, Harry Turtledove's short story "The Road Not Taken" offers a unique scenario, where alien species with bronze-age-to-medieval technology also have FTL and gravity manipulation. Humanity is exceptional in having completely overlooked the very simple physical effect by which aliens traverse the stars. It's tangential to the story, but the fact that these otherwise primitive aliens navigate across light years by dead reckoning and memory of major stars—no math or computers involved, I don't even recall if they had drawn charts—was a fascinating detail in that unique story universe.

Even submarine launched ICBMs use star navigation (amongst other systems, of course)

Thanks for the content.

Navigation through the stars would be quite difficult. Light takes time to travel, so the stars aren’t even actually where they appear to be. The view we get of them is from where they were in the past. Meaning you have to predict where they’re headed, and used that prediction in relation to their distance to get a rough idea of where the star is now. While we can predict the movement of these objects, much like the predictions on hurricane movement, that becomes less certain over larger distances. Interference from other objects could make that course deviate in ways you couldn’t predict.

For example, let’s say there’s a blue shifted star, and through all the observations you’ve seen, it appears to be moving toward you. You set a course, but when you get there, oops. There was a black hole no one detected, and the star was orbiting that. While it was headed for you at one time, thanks to that orbit, it has now deviated away from your original intercept point. It’s apparent motion may not look very big, but it is now somewhere completely different. Plus, all the stars around you have not changed their positions as well. You are now lost.

Unrelated question: how do you spell the name of the person narrating this video? It’s such a cool sounding name, but I have no idea how it is spelled. The subtitles on the video are no help 😂

Another example of building a star map, albeit less realistic, is seen in E.E. "Doc" Smith's Skylark of Valeron, in which the heroes have been displaced so far from home they literally don't know where they are in the universe. Their saving grace is the incredibly detailed star map that was produced by the genocidal race they'd recently just finished exterminating. In order to get home, they have to build a ship/observatory with graduated circles a thousand kilometres in diameter with which to map the entire universe to the required precision.

It takes a while before the map they've built matches up to the map they've got.

I just blind jump/warp and rely on plot armor to not smack into planets at warp 7. It's worked so far.

X-Ray Pulsar Navigation is already accurate enough to within a few kilometers in a minute or two (based on the SEXTENT experiments aboard the ISS), hypothetically anywhere in the galaxy. For 99% of all space travel (real and imagined), that's good enough.

There is an often overlooked aspect of traveling at relativistic speed. The ginormous future cone.

The falcon has a spirit of rebellion that calculates all the nav math

No mention of the most bloodthirsty method of the astromonicon from warhammer 40k with the sacrifice of 1000 psychics a day?

Space navigation sounds like a pretty cool occupation

My ways of space travel are called "fuck it we ball" and "I fucking guessed"

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.

In my setting there are extra galactic beacons that are used for astro navigation.

"Pilgrims were the first space explorers and sailors. For five centuries they defied the odds. They embraced space, and for that, they were rewarded with a flawless sense of direction. They could feel magnetic fields created by quasars and black holes, negotiate singularities, navigate not just the stars, but space-time itself. "

Will you be doing ship reviews any time soon?
Been a while now.

Space navigation is a awkward concept, but the technology they use is no different that what we actually use. The "Inertial Navigation System" operates by use motion and rotation gyroscopes and sensors thus it can determines position, orientation, and speed of the vehicle without using the stars, Sun, Moon, planets or some outside visual reference. This was used by Apollo program to create a computer controlled navigation system.

Another method is use of X-ray/Gamma pulsars which permeate across the galaxy, the hyper bright burst of quasars. These objects remain fairly static and their pulse frequency is an ideal method to compare various distances.

If you can use Star tracking for moving about one Solar System, could one use Galaxy Tracking for Moving across a Galaxy?

Internal errors are not the reason you can't rely only on inertial sensors. The problem with inertial sensors is that they can be fooled by gravity. By that I mean they will fail to detect gravity when installed on a spacecraft that is being pulled by the same gravitational field. In order to have accurate dead reckoning it is necessary to account for any perturbations. The inertial sensors can only detect thrust and non-gravitational perturbations, like solar pressure.

I design underwater systems and its like this apart from there's no visibility, no RF signals and you get pushed around more 😂 Space would be massively easier!

Or you could just ask the Emperor of Mankind to sit on a golden chair and turn him into a big ass lighthouse

Ooch aye Shite in ma mooth

The spaceship knows where it is because it knows where it isn't.

What about Artificial Intelligence Navigation?

Loving the Space Engineers background music

Thank you for mentioning 4D! As a physicist, I love your videos, thank you!

In the Expeditionary Force series Book 1 "Columbus Day", Human Soldiers were taken to train on Alien Weapons on another planet and they brought astronomers with them to figure out where they were in the galaxy by looking for stars they knew their characteristics.

.

Inspired, yes.

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

In the sci-fi I'm writing, a lot of terms are absolutely arbitrary. Like the "north" of a solar system is determined by the poles of the primary, and the plane of the ecliptic when (most) planets are orbiting counter-clockwise, and headings are based on an angle between the bow and the primary, with the primary always being 0.

I remember the Star Trek TOS Technical Manual had a page that summed up how they handled course tracking, with the computer integrating a SINS platform, several elements of what would be needed for dead reckoning(engine output, records, helm response, etc), as well as external systems including the various scanners, a telescope, and a "civil spaceways beam rider" which I'm guessing would be a type of space-GPS system from before we had a term for that.

I think you might only need to positively identify any 4 stars to get time and location in the galaxy.

In the 1980s my boat had some of the most advanced navigation systems in the world.

The primary system was the ESGN: The Electrically-Suspended Gyro Navigator, which utilized two IMUs (Independent Monitoring Units) each consisting of a beryllium ball being spun a a rate of many thousands of revolutions per minute, while suspended in an electromagnetic field.

Accelerometers fixed to the containment structure monitored any changes to the rotating spheres due to external inputs and extrapolated that into useful data for navigation.

Of course, like all inertial navigators, you have to be absolutely sure of your location when the system is initialized. In that regard, we used the exact coordinates of the pier we were alongside or, at sea, a "SatNav" fix from one or more of the Navy's fleet of satellites in low-Earth orbit.

Back then, we could also rely on LORAN, a radio-directional based system that was actually, surprisingly good at what it did.

Lastly, we used "Dead-Reconning", which took our last-known good position, then used the ship's underwater log (speed), gyrocompass heading, and known sea-currents to extrapolate a position. If we could go to periscope depth, we would take a star- shot to refine our position, or, obviously, during the day, a sun-observation.

Always find it hilarious GPS essentially started with some tech guy trying to test if general relativity works.

Or you could just grab your copy of 'The Hitchhiker's Guide to the Galaxy' and ask the next Xenomorph who picks you up....:D

Speaking of navigating. I’m kinda wonder how many ship’s helmsman in sci fi able to pull off an extreme maneuver with just a touch screen? I mean, think about those USS Enterprise E conn and the Expanse iPad like thingy that the pilot uses, it looks rather hard to use that to control a massive aircraft given how cumbersome they would be.

U hope add why need bigger ship and effects lofe onbore or my politics and policy's

Even in the Military we say Lost = Dead.
That statement is never truer than out in space.

Navigators are going to be the difference between knowing where you are going to being lost in the void of space.