Celestia Forums

I started a mid-year NaNoWriMo a few weeks ago, and have found Celestia to be a great help in pinning down the occasional detail.

Is there any chance someone here could write a quick location-object or two, within a day or so, to help me with more visualizing? I'm not worried about what they look like, I'd just like to be able to easily see where they are as I zoom the viewpoint around.

One of the spots is the Earth-Moon L4 point. The other two are directly opposite the sun from 70 Ophiuchi A and B, 550 AU out.


In case you're curious, in the current draft, the protagonist's ship launches from a station at the L4 point on 2150-07-03, with a steady 0.2G acceleration. After getting to about a quarter AU from the sun, it makes a close pass of Titan, on the Saturn side; and then will be passing 2005 RL43, then 2006 SQ372, before making it to about 275 AU after about two and a half months, at which time it turns around and decelerates at 0.2G for the rest of the trip until arriving at the sunlens observatory for 70 Ophiuchi B. (And, eventually, it'll be heading back to Titan.) I've mostly been using pure eyeballing and a simple calculator to work out timings.

It would be nice to find out if any other known bodies are near this course, but when I tried loading the larger sets of asteroids from the Celestia Motherlode, my decade-old laptop sputtered and died.

DataPacRat wrote:One of the spots is the Earth-Moon L4 point.

There is a Lagrange points addon; the download links seem to be missing but it's included in Celestia Origin (I can put it in a zip file and send it if you want).

DataPacRat wrote:The other two are directly opposite the sun from 70 Ophiuchi A and B, 550 AU out.

The easiest way to define that is using a barycenter, like this:

DataPacRat wrote:It would be nice to find out if any other known bodies are near this course, but when I tried loading the larger sets of asteroids from the Celestia Motherlode, my decade-old laptop sputtered and died.

If you have a trajectory file, maybe I can check and see...

SevenSpheres wrote:There is a Lagrange points addon; the download links seem to be missing but it's included in Celestia Origin (I can put it in a zip file and send it if you want).

I'd appreciate that; 8.3 gigabytes seems a little much to download to get such a small addon.

If you have a trajectory file, maybe I can check and see...

I'm afraid I don't have such a file. At a constant 0.2G, launching on 2150-07-03 gets her to Titan around 2150-07-21; given that that's faster than just about anything moving at merely orbital speeds, I've mostly just been zooming the viewpoint between Earth and Saturn between those dates. (And occasionally trying non-Celestia visuals, such as fourmilab.ch's orrery.)

DataPacRat wrote:I'd appreciate that; 8.3 gigabytes seems a little much to download to get such a small addon.

Here it is:

Good for you SevernSpheres, I was just doing a post of that.
Just in case it is different, here is what I found anyway.



This is supposed to show all legranges in our system.

To create your own powered flight xyzv file, here are the basics.
You need the position in xyz of your starting point. {I have a fork that shows them in realtime if you need it, at least one is posted somewhere on the forum, but I lost track of where.}
You need a unit of time between samples.
You need the distance traveled in this sample, dx,dy,dz.

This means keeping track of your speed, including planetary effects if you want a real looking trajectory.

The following are borrowed from huygens.xyzv

# Records are <jd> <x> <y> <z> <vel x> <vel y> <vel z>
# Time is a TDB Julian date
# Position in km
# velocity in km/sec

2453364.58408 -2678111.3235 -1619946.70639 807564.757047 -0.38810156 -1.7344566 0.87737208
2453364.6063 -2678851.1813 -1623272.95209 809247.424125 -0.38245277 -1.7306717 0.87551753
2453364.96185 -2689197.26216 -1675582.3471 835715.879432 -0.29164558 -1.6749484 0.84771755
2453365.31741 -2696800.57637 -1726185.25953 861332.807521 -0.20383635 -1.6195637 0.82007488
2453365.67297 -2701748.743 -1775091.13355 886102.538186 -0.11874181 -1.5644514 0.79255503

The start of each new entry should match as close as feasible to the end point of the previous entry.
Be sure to include turnover/deceleration in planning your course, pilot sober, planets don't move over.
Always include the gravity/influence of the sun in your calculations.
Be sure to include the gravity/influence of any planetary bodies while near them.
Ideally keep a log of velocities at every loci, then plot it to see how it looks.

Not everything of course, but I hope it gets you started.

I use asterisms to plot journeys between stars myself.
Doesn't work for planets because it stores the endpoints in a static array.


Janus.

the file of SevenSpheres is the module of lua_applications with also the ssc file.

the file of janus is only the ssc file of Lagrange point.

In my lua_universal_tools, I have deconnected the part lua of the addon because I couldn't get it to work. ( and I didn't know what he was supposed to do )

I was a little nervous when I started reading the instructions in the readme of SevenSpheres' .7z, but Janus's .ssc slipped into my extra folders without any effort at all, and is working just fine.

I seem to have missed a step in SevenSpheres' Barycenter suggestion; I'll be spending a bit of time today trying to dig through Celestia's docs and FAQs to see what else I might need to do to get it to work. (And to then try adapting it to having two points, opposite 70 Ophiuchi A and B, to see if my initial estimate that their 550-AU opposition points are 1.4M km apart in 2150 is anywhere near accurate.)

I'm a little hesitant to spend all the time I'd need to figure out all the numbers to put together a proper powered-flight file for the 0.2G-accel spaceship; I'd prefer to be spending my time on more direct writing activities, such as dialogue and plot.

Perhaps somebody reading this, with a better computer than mine, might be willing to load up every known asteroid, comet, and dwarf planet into your copy of Celestia, set the date to July, 2150, and just eyeball the straight-line path between Earth and Saturn for anything that comes close?

DataPacRat wrote:Perhaps somebody reading this, with a better computer than mine, might be willing to load up every known asteroid, comet, and dwarf planet into your copy of Celestia, set the date to July, 2150, and just eyeball the straight-line path between Earth and Saturn for anything that comes close?

If anyone is crazy enough to load the entire minor planet database, with over 950 thousand minor planets, its me!
I will be glad to help you in this interstellar journey.

Say, does anyone have an SSC for the Martian trojans, such as 1999 UJ7?

It looks like the Sol-Mars L4 point might be close enough to my spacecraft's course to be interesting, and I'd like to double-check that.

DataPacRat wrote:Say, does anyone have an SSC for the Martian trojans, such as 1999 UJ7?

Celestia Origin does.

Added after 7 minutes 45 seconds:
Here's an ssc for Mars trojans copied from CO (it does use CO's models/textures, not the standard ones):