
Stellar Navigation Using Network Analysis - GFK_of_xmaspast
http://allthingsgraphed.com/2014/12/05/stellar-navigation-using-network-analysis/
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throwaway_yy2Di

        "He pointed me at a Gliese astronomical dataset with 2223 of
        the closest stars. It's an older dataset, but it was perfect
        for what I needed."
    

Are you the author? You may be interested in ESA's Hipparcos catalog, which
reports parallax distances to 118,000 nearby stars. This is the most complete
distance catalog to date (its successor, Gaia, is currently measuring another
~1 billion).

ftp://cdsarc.u-strasbg.fr/pub/cats/I/311/

[https://en.wikipedia.org/wiki/Hipparcos](https://en.wikipedia.org/wiki/Hipparcos)

[https://en.wikipedia.org/wiki/Gaia_%28spacecraft%29](https://en.wikipedia.org/wiki/Gaia_%28spacecraft%29)

~~~
GFK_of_xmaspast
Not the author, I found it thru Patrick Durusau's blog:
[http://tm.durusau.net/](http://tm.durusau.net/)

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throwaway_yy2Di
Note it's probably not useful to "stop and refuel" on any trajectory in space,
since there's nothing slowing you down in a vacuum. Space flights are free
ballistic trajectories: you don't consume any fuel on the way, you just coast.

A more interesting network would look at gravitational slingshot [0]
opportunities between stars -- from their relative motion in the galaxy, or
from binary stars (orbiting each other), or exoplanets. Freeman Dyson noticed
[1] that if you found a white dwarf binary in its late stage of inspiraling,
you could get an absolutely ridiculous slingshot (~2,000 km/s = 0.01c),
entirely for free! Unfortunately these are extremely rare, since these orbits
quickly decay until the stars collide (possibly causing a Type Ia supernova
[2]... so, maybe not so unfortunate).

It's interesting to look at how interplanetary probes fly. According to the
Cassini engineers for instance [3], the shortest path from the earth to Saturn
is go fly around Venus, then come back to Venus a year later, than return to
earth... then go to Jupiter first.

You could benefit from powered flybys [4] too. There are nearby gravitational
wells much deeper than the sun's. Sirius B [5] (the white dwarf) should have
an surface escape velocity around 7,000 km/s -- although it'd be rather crazy
to engineer a white dwarf flyby (up to 100's of g's of acceleration, 10^10
W/m^2 thermal load).

[0]
[https://en.wikipedia.org/wiki/Gravity_assist](https://en.wikipedia.org/wiki/Gravity_assist)

[1]
[http://www.ifa.hawaii.edu/~barnes/ast242/Dyson_Machines.pdf](http://www.ifa.hawaii.edu/~barnes/ast242/Dyson_Machines.pdf)

[2]
[https://en.wikipedia.org/wiki/Supernova#Thermal_runaway](https://en.wikipedia.org/wiki/Supernova#Thermal_runaway)

[3]
[https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens_timeli...](https://en.wikipedia.org/wiki/Cassini%E2%80%93Huygens_timeline)

[4]
[https://en.wikipedia.org/wiki/Oberth_effect](https://en.wikipedia.org/wiki/Oberth_effect)

[5]
[https://en.wikipedia.org/wiki/Sirius](https://en.wikipedia.org/wiki/Sirius)

~~~
AllThingsGraph
Thanks for the information (fascinating!). A gravitational fly-by of Sirius B
would be crazy.

Straight-shot trajectory (and/or gravitational assist) would be the simplest
way to get the ship there, but other constraints might force one to "stop and
refuel":

* Energy needed to maintain life for duration of journey (e.g. hibernation) may exceed what you can store in one "charge" for your ship.

* Instead of 3D trajectory travel, perhaps the energy needed to "warp" or establish a worm-hole is proportional to the distance being travelled.

* Or, perhaps, the reliability and precision of calculated trajectories breaks down after certain distances; forcing a series of "hops" vs. a single trajectory in order to make the journey safe/reliable.

* Time may factor in. You may have enough energy, but perhaps components of the ship can't be expected to operate without error/failure for such long times. In that case, "stopping to refuel" might include expected repairs as well.

All hand-wavy a bit, but interesting to think about.

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mikeytown2
Reminds me of starting a new game of Stars! [1]. You have to plot what systems
you wish to visit and manage fuel use to how many light years away that system
is. There is a lot of strategy in picking flight plans [2].

[1]
[http://en.wikipedia.org/wiki/Stars!](http://en.wikipedia.org/wiki/Stars!)?

[2]
[http://web.archive.org/web/20040102151647/http://crisium.com...](http://web.archive.org/web/20040102151647/http://crisium.com/stars/stars/ssg/ssg04frm.htm)

