Determining Orbits in world of Mongoose

[LtBennett]

I am perplexed and having difficulty grasping how to determine location of orbiting moons, asteroids, gas giants etc under Mongoose rules...Guidelines are provided in T5E...but not yet found in reading various Mongoose publications...any help available?

 

[ShawnDriscoll]

The MgT1 Scout book doesn't have much to say?

 

[BackworldTraveller]

Not really. MgT1 has a very abstract system.
LBB6 had a mechanism, but excluded minor elements (under 200km diameter) and places 50% of the moons very near in (which can be an issue if they are of any significant size)

 

[LtBennett]

about these orbit determiniations

I see two responses so far...
By BBB 5E is elsewhere right now...but even with that I get a bit confused...
So my ship approaches a world/system/star ??? coming out of jump...
Interested in going to gas giant first...but where is it...?
Then perhaps wants to go to asteroid...but where is it?
Over to the experts...

 

[tjoneslo]

Orbits are numbered 0 to 10 (2d-2). One of the orbits is the habitable zone. Usually orbit 3, which is also where the 100D limit of the Star is as well. If the main world is a habitable one (atmosphere 3-9, hydro 1+) put it into the habitable orbit . Otherwise roll for the orbit. Roll the orbits of the gas giants. Place the belts in the next orbit inward from the gas giants or otherwise roll them. Assume the rest of the orbit are occupied by airless rock balls or other useless worlds.

System completed

The actual habitable orbit depends on the primary. And for binary stars there are some additional complications.

 

[Werner]

Orbits are numbered 0 to 10 (2d-2). One of the orbits is the habitable zone. Usually orbit 3, which is also where the 100D limit of the Star is as well. If the main world is a habitable one (atmosphere 3-9, hydro 1+) put it into the habitable orbit . Otherwise roll for the orbit. Roll the orbits of the gas giants. Place the belts in the next orbit inward from the gas giants or otherwise roll them. Assume the rest of the orbit are occupied by airless rock balls or other useless worlds.

System completed

The actual habitable orbit depends on the primary. And for binary stars there are some additional complications.

Some potentially habitable orbits are closer than 0, we have found a number of exoplanets close than that, including in the Trappist system I believe. Proxima B is closer than 0. What should we do about that?

 

[BackworldTraveller]

I see two responses so far...
By BBB 5E is elsewhere right now...but even with that I get a bit confused...
So my ship approaches a world/system/star ??? coming out of jump...
Interested in going to gas giant first...but where is it...?
Then perhaps wants to go to asteroid...but where is it?
Over to the experts...

Is this a system Generation Question (what orbit should I expect it in about the target star) or
A survey Question (where, in its range of possible positions, is it at a given time relative to the nearest star) or
An Astrogation Question (how far from my projected jump-exit point do I want it, and how far from my jump entry point will it be in a week(ish) of time given the relative motions of the two star systems)

e.g. if the main world is in an orbit at 1.6 AU and the inner giant is in an orbit at 2.8 AU is it 1.2 AU from the main world or 4.8 (with a star in the way)? Would I do better going for the next gas giant because it is in an orbit at 5.2AU but is now only 2.8AU distant from the mainworld.

For astrogation purposes, the question "Which planet is most likely to be closer to the Earth: Mercury or Venus?" is not the same as the survey question "which planet's orbit is closer to earth's: Mercury or Venus?"

 

[tjoneslo]

Some potentially habitable orbits are closer than 0, we have found a number of exoplanets close than that, including in the Trappist system I believe. Proxima B is closer than 0. What should we do about that?

This is a quick and dirty system to answer basic questions. If you want a full detailed system generator I recommend GT:First In. Despite its age it has the most accurate system generator.

 

[ShawnDriscoll]

Some potentially habitable orbits are closer than 0, we have found a number of exoplanets close than that, including in the Trappist system I believe. Proxima B is closer than 0. What should we do about that?

Ha! Exoplanet does not mean habitable.

 

[Werner]

This is a quick and dirty system to answer basic questions. If you want a full detailed system generator I recommend GT:First In. Despite its age it has the most accurate system generator.

There ought to be a website. Press the button and you get a system randomly generated with 1 to 3 stars and with a planetary system for each. I tried making a spreadsheet on my tablet which could generated a random planetary system but it was too slow! What you roll next depends greatly on what you rolled last, so GM hands on involvement is constantly involved as you craft your spreadsheet for one particular star system, and then you start all over again for the next one. The funny thing is that the output doesn't take all that much space, but crafting it certainly does!

There must be a process to generate a planetary system without too much human gray matter involved. Imagine how long it would be to detail a complete subsector, 40 star systems and all!

I've seen some planetary map generators, one flaw is they tend to make one or two supercontinents, you don't get something like the Earth and its seven continents and four oceans.

 

[Werner]

Ha! Exoplanet does not mean habitable.

Most Traveller planets you'd generate using the basic system aren't habitable either with out a space suit or other environmental gear. If you need to wear a filter mask, the planet is not habitable for you. Red dwarf planets tend to be eyeball planets if they are in the habitable zone, they are tidally locked with the star they are orbiting, there is a zone on the planet's surface that is most habitable. PCs are going to see red alot.

Non habitable planets can be anywhere in the system, you need a spacesuit to survive on its surface so it doesn't need to be in the habitable zone

 

[Fovean]

You may like this one:

https://donjon.bin.sh/scifi/tsg/

There are others if you look around a bit.

 

[Werner]

You may like this one:

https://donjon.bin.sh/scifi/tsg/

There are others if you look around a bit.

Yeah, that's pretty good. I just have to assign orbit numbers to them, find whichever orbit number is the habitable zone, put the mainworld there, and any worlds that come before the mainworld are in the inner system, and the worlds after are in the outer system, and prior to that I just roll to see whether the system is solo, binary, or trinary, then roll for the orbit locations of the companion star(s) relative to the primary then I roll for system generation three times, the most massive star is the primary, and it is not always the brightest star, for instance the primary could be a black hole, white dwarf or pulsar.

 

[Werner]

Here are my standard orbits that I added to the ones in the Scouts book.
ORBITAL DISTANCES
Orbit
No. AU
-6 0.01
-5 0.03
-4 0.04
-3 0.05
-2 0.06
-1 0.13
0 0.20
1 0.40
2 0.70
3 1
4 1.6
5 2.8
6 5.2
7 10
8 20
9 40
10 80
11 150
12 300
13 600
14 1200
15 2400
16 4800
17 9600
18 19,200
19 38,400

 

[Werner]

Here is the table from the classic book 6 Scouts, that I have expanded to include orbits to -6 so red dwarf systems can be detailed.

Orbit Star Type (Bright Supergiant) Ia

No.	B0	B5	A0	A5	F0	F5	G0	G5	K0	K5	M0	M5	M9
-6	.	.	.	.	.	.	.	.	.	.	.	.	.
-5	.	.	.	.	.	.	.	.	.	.	.	.	.
-4	.	.	.	.	.	.	.	.	.	.	.	.	.
-3	.	.	.	.	.	.	.	.	.	.	.	.	.
-2	.	.	.	.	.	.	.	.	.	.	.	.	.
-1	.	.	.	.	.	.	.	.	.	.	.	.	.
0	.	.	.	.	.	.	.	.	.	.	.	.	.
1	-	-	.	.	.	.	.	.	.	.	.	.	.
2	-	-	-	-	.	.	.	.	.	.	.	.	.
3	-	-	-	-	-	-	.	.	.	.	.	.	.
4	-	-	-	-	-	-	-	.	.	.	.	.	.
5	-	-	-	-	-	-	-	-	.	.	.	.	.
6	-	-	-	-	I	I	-	-	-	-	.	.	.
7	-	I	I	I	I	I	I	I	I	I	I	.	.
8	I	I	I	I	I	I	I	I	I	I	I	I	I
9	I	I	I	I	I	I	I	I	I	I	I	I	I
10	I	I	I	I	I	I	I	I	I	I	I	I	I
11	I	I	I	I	H	H	I	I	I	I	I	I	I
12	I	H	H	H	O	O	H	H	H	H	H	H	H
13	H	O	O	O	O	O	O	O	O	O	O	O	O
14	O	O	O	O	O	O	O	O	O	O	O	O	O

 

[Werner]

Orbit Star Type (Weaker Supergiant) Ib

No.	B0	B5	A0	A5	F0	F5	G0	G5	K0	K5	M0	M5	M9
-6	.	.	.	.	.	.	.	.	.	.	.	.	.
-5	.	.	.	.	.	.	.	.	.	.	.	.	.
-4	.	.	.	.	.	.	.	.	.	.	.	.	.
-3	.	.	.	.	.	.	.	.	.	.	.	.	.
-2	.	.	.	.	.	.	.	.	.	.	.	.	.
-1	.	.	.	.	.	.	.	.	.	.	.	.	.
0	-	-	.	.	.	.	.	.	.	.	.	.	.
1	-	-	-	-	-	-	.	.	.	.	.	.	.
2	-	-	-	-	-	-	-	-	.	.	.	.	.
3	-	-	-	-	-	-	-	-	.	.	.	.	.
4	-	-	-	-	-	I	I	-	-	.	.	.	.
5	-	-	I	I	I	I	I	I	I	-	.	.	.
6	-	I	I	I	I	I	I	I	I	I	I	.	.
7	-	I	I	I	I	I	I	I	I	I	I	I	.
8	I	I	I	I	I	I	I	I	I	I	I	I	I
9	I	I	I	I	I	I	I	I	I	I	I	I	I
10	I	I	I	H	H	H	H	H	H	I	I	I	I
11	I	H	H	O	O	O	O	O	O	H	H	I	I
12	I	O	O	O	O	O	O	O	O	O	O	H	H
13	H	O	O	O	O	O	O	O	O	O	O	O	O
14	O	O	O	O	O	O	O	O	O	O	O	O	O

 

[Werner]

Orbit Star Type (Bright Giant) Il

No.	B0	B5	A0	A5	F0	F5	G0	G5	K0	K5	M0	M5	M9
-6	.	.	.	.	.	.	.	.	.	.	.	.	.
-5	.	.	.	.	.	.	.	.	.	.	.	.	.
-4	.	.	.	.	.	.	.	.	.	.	.	.	.
-3	.	.	.	.	.	.	.	.	.	.	.	.	.
-2	.	.	.	.	.	.	.	.	.	.	.	.	.
-1	-	-	-	-	-	-	-	.	.	.	.	.	.
0	-	-	-	-	-	-	-	-	.	.	.	.	.
1	-	-	-	-	-	-	-	-	-	.	.	.	.
2	-	-	-	I	I	I	I	I	I	.	.	.	.
3	-	-	I	I	I	I	I	I	I	I	.	.	.
4	-	-	I	I	I	I	I	I	I	I	I	.	.
5	-	I	I	I	I	I	I	I	I	I	I	.	.
6	-	I	I	I	I	I	I	I	I	I	I	I	I
7	I	I	I	I	I	I	I	I	I	I	I	I	I
8	I	I	I	H	H	H	H	H	I	I	I	I	I
9	I	I	H	O	O	O	O	O	H	H	I	I	I
10	I	I	O	O	O	O	O	O	O	O	H	I	I
11	I	H	O	O	O	O	O	O	O	O	O	H	H
12	H	O	O	O	O	O	O	O	O	O	O	O	O
13	O	O	O	O	O	O	O	O	O	O	O	O	O
14	O	O	O	O	O	O	O	O	O	O	O	O	O

 

[Werner]

Orbit Star Type (Giant) III

No.	B0	B5	A0	A5	F0	F5	G0	G5	K0	K5	M0	M5	M9
-6	.	.	.	.	.	.	.	.	.	.	.	.	.
-5	.	.	.	-	-	.	.	.	.	.	.	.	.
-4	.	.	-	-	-	-	-	.	.	.	.	.	.
-3	.	-	-	-	-	-	-	.	.	.	.	.	.
-2	.	-	-	-	-	-	-	-	.	.	.	.	.
-1	-	-	-	-	-	-	-	-	-	.	.	.	.
0	-	-	-	-	-	-	-	-	-	.	.	.	.
1	-	-	-	-	I	I	I	-	-	-	-	.	.
2	-	-	-	I	I	I	I	I	I	-	-	.	.
3	-	-	I	I	I	I	I	I	I	I	I	.	.
4	-	-	I	I	I	I	I	I	I	I	I	I	.
5	-	I	I	I	I	I	I	I	I	I	I	I	I
6	-	I	I	I	H	H	H	I	I	I	I	I	I
7	I	I	I	H	O	O	O	H	H	I	I	I	I
8	I	I	H	O	O	O	O	O	O	H	H	I	I
9	I	I	O	O	O	O	O	O	O	O	O	H	H
10	I	H	O	O	O	O	O	O	O	O	O	O	O
11	I	O	O	O	O	O	O	O	O	O	O	O	O
12	H	O	O	O	O	O	O	O	O	O	O	O	O
13	O	O	O	O	O	O	O	O	O	O	O	O	O
14	O	O	O	O	O	O	O	O	O	O	O	O	O

 

[Werner]

Orbit Star Type (Main Sequence) V

No.

B0

B5

A0

A5

F0

F5

G0

G5

K0

K5

M0

M5

M9

-6

.

.

.

.

-

-

-

-

-

I

I

I

I

-5

.

.

.

-

-

-

-

-

I

I

I

I

H

-4

.

.

-

-

-

-

-

I

I

I

I

I

O

-3

.

-

-

-

-

-

I

I

I

I

I

I

O

-2

.

-

-

-

-

I

I

I

I

I

I

H

O

-1

-

-

-

-

I

I

I

I

I

I

I

O

O

0

-

-

-

I

I

I

I

I

I

H

H

O

O

1

-

-

I

I

I

I

I

I

I

O

O

O

O

2

-

-

I

I

I

I

I

H

H

O

O

O

O

3

-

I

I

I

I

I

H

O

O

O

O

O

O

4

-

I

I

I

I

H

O

O

O

O

O

O

O

5

-

I

I

I

H

O

O

O

O

O

O

O

O

6

I

I

I

H

O

O

O

O

O

O

O

O

O

7

I

I

H

O

O

O

O

O

O

O

O

O

O

8

I

I

O

O

O

O

O

O

O

O

O

O

O

9

I

H

O

O

O

O

O

O

O

O

O

O

O

10

I

O

O

O

O

O

O

O

O

O

O

O

O

11

I

O

O

O

O

O

O

O

O

O

O

O

O

12

H

O

O

O

O

O

O

O

O

O

O

O

O

13

O

O

O

O

O

O

O

O

O

O

O

O

O

14

O

O

O

O

O

O

O

O

O

O

O

O

O

 

[Werner]

Orbit Star Type (Sub-Giant) IV

No.	B0	B5	A0	A5	F0	F5	G0	G5	K0
-6	.	.	.	-	-	-	-	-	.
-5	.	.	-	-	-	-	-	-	-
-4	.	-	-	-	-	-	-	-	-
-3	.	-	-	-	-	-	-	-	-
-2	.	-	-	-	-	-	-	-	-
-1	-	-	-	-	-	I	I	I	I
0	-	-	-	I	I	I	I	I	I
1	-	-	I	I	I	I	I	I	I
2	-	-	I	I	I	I	I	I	I
3	-	I	I	I	I	I	I	I	I
4	-	I	I	I	I	I	I	I	H
5	-	I	I	I	I	H	H	H	O
6	-	I	I	H	H	O	O	O	O
7	I	I	H	O	O	O	O	O	O
8	I	I	O	O	O	O	O	O	O
9	I	H	O	O	O	O	O	O	O
10	I	O	O	O	O	O	O	O	O
11	I	O	O	O	O	O	O	O	O
12	H	O	O	O	O	O	O	O	O
13	O	O	O	O	O	O	O	O	O
14	O	O	O	O	O	O	O	O	O