How will navigation be accomplished on space ships?

[danimarie37]

I am a writer. I am writing about a ship that can travel across the Milky Way but not further. I want some opinions about how navigation will work if human beings avoid extinction long enough to develop such a craft. I love Star Trek, but the whole alpha quadrant, delta quadrant thing isn't precise enough. Any ideas?

 

[RS_Russell]

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[michaelmozina]

I vote that you use pulsars in the Milky Way and distant galaxies. They have very specific and highly regular rotation cycles that would make them "unique" and they could provide directional pointers.

http://outreach.atnf.csiro.au/education ... e/pulsars/

 

[xXTheOneRavenXx]

I personally would us software for 3D renderings of constellation maps. Software can be programed to predict what pattern the stars of each constellation would appear in from various angles. From this point the software could take a live photographic overlay as seen by the navigator to determine current position. This data could be fed into another software to plot these points on a 3D graphic map of the galaxy. With this data triangulation would be made easier. Perhaps by this you could orient your craft.

 

[ZenGalacticore]

I am a writer. I am writing about a ship that can travel across the Milky Way but not further. I want some opinions about how navigation will work if human beings avoid extinction long enough to develop such a craft. I love Star Trek, but the whole alpha quadrant, delta quadrant thing isn't precise enough. Any ideas?

It seems to me that like the sailors of yore, they would navigate by the stars. :lol:

Seriously. They would obviously have computers advanced enough to tell them the relative positions of these and those known stars, as well as their bearings in-transit with such 'spacemarks' as the center of the galaxy, the Large and Small Magellenic clouds, cephied variables, supergiants like Beetlegeuse and Arcturas, the constellations, the Orion Nebula, etc.
Try creative license with a mixture of the best science you can blend with your creativity. That usually seems to work. After all, IMHO, sci-fi that tries to be TOO scientifically accurate usually comes out a tad boring because it lacks some of the pow and pizzazz of the good ole imagination in the realm of 'what if in the future we do it this way..."
In the meantime, find out how we navigate our robotic craft like Voyager One and Two and many others so precisely through the vastness of our own Solar System. And I mean "precisely", because that's what we do, for the most part, already.
It's something to do with the navigational x, y, and r on the 3-d graph thingy. hehe.

 

[dragon04]

Whether the ocean be of salt water or hard vacuum, the stars guide all sailors. That's fitting.

 

[vogon13]

{my remarks are specific to an advanced Dyson type nuclear pulse interstellar vehicle}


Good question. BTW, I don't recall any mention of navigation concerns for an interstellar capable Orion vehicle (<.1C) in the Dyson book.


I will postulate the omission is due to there being some serious constraints on such a flight making the navi issue moot.

Such a vehicle (possibly the product of 4 centuries of earth GDP) would only be launched towards a well researched target star. That stars distance, proper motion, space velocity, direction, etc. would all be known to reasonable precision prior to launch, and would be crucial make or break criteria in the selection process. Any star with a 'bizarre' trajectory (steeply inclined orbit to galactic plane, speed in excess of galactic escape velocity, etc.) would be deselected as a target prior to launch.

Further, a .1C capable vehicle (30,000km/sec) with a reasonable surplus of propulsion modules upon arrival at the target star would be capable of correcting for a 'trivial' 300 km/sec 'surprise' in the expected motion of the target system.

Also, the craft is large enough (it is a multi-million ton craft after all) to carry sufficient astronomical equipment to monitor the target throughout the flight. Approach velocity can be determined via monitoring Doppler shift of stars spectral lines. Also, orientation of the ecliptic of the target star can be determined by differential Doppler of opposite limbs of the star during approach. Heck, you can mount some mirrors on the pusher plate and make an interferometer to study the target for decades on the way there if you want. Correcting approach vector to put craft in stars equatorial plane at the end of the braking maneuver is trivial.

The proper motion (drift perpendicular to approach vector) can be allowed for in the braking phase, assuming the acceleration phase error is large (unlikely).


Essentially, any star selected is going to be traveling <200 km/sec relative to our sun, and this differential is tiny compared to the speed capability of the craft. Essentially, you are trying to nail a kid on a bicycle (who is constrained to move at a constant speed in an unchanging direction) with a high performance race car, the kid does not have the capability to evade you.

 

[vogon13]

{additional}

Interstellar navigation for an Orion type vehicle should be rather simple conceptually. The location of our sun and the vehicle will be known to high precision all the way to the target star. Further, the target star will have been selected, among other criteria, for ease of orbit insertion upon arrival. As the vehicle approaches the target, the on board instruments will continuously refine the accuracy of the target star's motion and position and orientation. The Orion vehicle will be launched with these values having rather large error bars, but as the trip progresses, the precision will improve. The vehicle will be launched with the capability of rendezvous with the target with the large error bars for all the measurements. As the position/velocity/orientation is refined, the calculated fuel (performance) margin will actually improve (statistical likelihood) and the vehicle will perhaps have sufficient margin for a more prolonged exploration of the target system prior to debarkation.

There are very few 'surprise' scenarios that could complicate the arrival:

* Target star turns out to be in a distant orbit about a large cold dead massive object, this becomes apparent during braking as the star moves through apastron and appears to 'reverse' it's proper motion. This actually is not a big deal, velocity change for the target star is low and within maneuvering capability of craft regardless of when the exact displacement is realized.

* dim red dwarf discovered enroute along flight path requiring deflection of craft to avoid debris disk. Again, unlikely, anything big enough to cause problem would be discovered prior to launch.

* bad combination of refinement of errors of target star motion/velocity/direction results in vehicle having insufficient delta v for rendezvous. Well, for every 100 Orions launched, if this happens once, I guess the program still would be considered a success. {too bad for the crew on that particular craft, though.}

 

[vogon13]

Note the decel phase into the target star system will take 20 to 50 years, and will extend over 1 light year. Breaks in the deceleration phase can be scheduled for observation of the target and refinement of the braking vectors.

Imagine watching the target from the craft, and it is drifting (from your viewpoint) right to left. You can orient the vehicle slightly to the right during braking to cancel your approach velocity while this will simultaneously noodge the craft left along the rendezvous vector. The trick is to cancel the approach velocity (relative to the star, noting in some cases it might actually have a velocity component towards our sun) and at the point the craft velocity is zeroed out in that direction, to have the craft achieve a transverse velocity matching the target system, with whatever appropriate speed /direction you want to tour the target system with.

Other than avoiding debris disks and 'alien' Kuiper Belts, there seems little reason to have much information on other stars/objects in our galaxy for a successful flight.

 

[MeteorWayne]

See silylenes' post here. I think he just answered the question, if it works....

Intragalactic GPS accurate to 1 meter !

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