General Slower Than Light Interstellar Transit Times

[Sifu Blackirish]

I am currently working on a SF trilogy. Of course Terrans get to the stars, with their G-space drives. There is another group elsewherewhen, who also make an interstellar expansion. Unfortunately, the analogue of the person who made FTL in one universe does not do it there.

I have been looking for a long time for an easier method to calculate STL transit times for home and ship. Since I failed to get better than a D when I took calculus in college (3 times) I figured i was out of luck.

Then I found this site:

http://convertalot.com/relativistic_star_ship_calculator.html

I urge you to check it out.

I leave a sample chart for transit times for a Bussard ramjet at 1G = 9.80665 m/s and 1 parsec = 3.26156 ly and transit times in years

Dist---Aerth---Ship
01-----04.8-----3.1
02-----08.2-----4.2
03-----11.6-----4.8
04-----14.9-----5.3
05-----18.1-----5.7
06-----21.4-----6.0
07-----24.7-----6.3
08-----28.6-----6.5
09-----31.2-----6.7
10-----34.4-----6.9
11-----37.8-----7.1

I made these 'back of the envelope' calculations so I can chart ship movements. At first there are only four of them. My gear head instincts are taking over so real ship designs will be coming later.

 

[kilemall]

A real trick is dealing in power during even 'just a few years'. IMTU is either He³ or fission rather then 'standard' fusion.

Then you are left with either a real problem with reaction mass, even at a 100,000x more efficiency, or grav drives working against little interstellar mass.

Heat too if some of that fuel is for power exhaust.

Finally, interstellar debris impact at high frac-C. IMTU it's repulsor and a form of fusion bottle shielding, but have to have something to deal with that.

 

[Sifu Blackirish]

Doing research for these stories, i noted the fuel issue. I did a neat sidestep by declaring that anomalies are occurring, allowing hydrogen to show up in space. Rather than going through the mechanics of developing interstellar fuel depots. That high speed impact i still have to deal with. The last craft launched are streamlined but i do think i have to come up with a better solution.

 

[Keklas Rekobah]

Assuming a mission profile of "Accelerate --> Flip the Ship --> Decelerate", those times seem about right for an outside observer; but how much time passes for the occupants of the ship?

Time dilation, and all that...

 

[atpollard]

Assuming a mission profile of "Accelerate --> Flip the Ship --> Decelerate", those times seem about right for an outside observer; but how much time passes for the occupants of the ship?

Time dilation, and all that...

Aerth is the time passing on the worlds and Ship is the time passing on the ship. So a 1 parsec trip would be 4.8 years on the planets, but only 3.1 years for the people on the ship. A 6 parsec trip would be 21.4 years on the planet and only 6 years for the people on the ship.

 

[Timerover51]

One other thing about a slower-than-light interstellar travel universe, and that is you will not have any significant interstellar government, and each planet is going to develop in its own way.

 

[mike wightman]

CJ Cherryh's early Alliance/Union universe was like this.

STL ships taking years to push station modules to nearby systems - it is a lot easier to build a space habitat than try and colonise an unpleasant world. Over time the stations grew larger and the culture that developed on each station was different to the culture that developed on the STL ships.

Pell was discovered that had its own biosphere and intelligent natives, and far far away from Earth Cyteen was discovered that was also relatively Earth like and fit for colonization.

The people of Cyteen were scientists, engineers and the like, their culture diverged yet further and Union was born. When they unlocked the secrets of the FTL jump drive they used it to expand, cloning settlers and workers as needed.