Traveller Universal World Profiles to M-Space Planets

Traveller is well known for it is various universal codes.” The Universal Character Profile/Universal Personality Profile was a shorthand method to quickly describe a character’s characteristics. The Universal Planetary Profile/Universal World Profile (UWP) describes the qualities of a world. In this article I want to take at look at how you can map a UWP to an M-Space Planet so that you can reuse Traveller-specific mapping tools with M-Space. It will not be always be a one-to-one mapping and there will be some judgements you’ll have to make for your game.

Uwp Code in a Nutshell

A UWP code looks like this: C77A9A9-6

  1. Starport: C
  2. Size: 7
  3. Atmosphere: 7
  4. Hydrographics: A
  5. Population: 9
  6. Government: A
  7. Law level: 9
  8. Tech level: 6

There are some other details sometime included separately from this main code sequence but these are the primary attributes we will be considering.


Starports map over fairly cleanly. Traveller has some specific ideas about annual maintenance” that may or may not fit into your own M-Space game depending how closely you are tracking such details.

UWP Starport Code UWP Descriptor M-Space Shipyard Capacity Maintenance
A Excellent Full Build & Repair Yes
B Good Standard Repairs & Upgrades Yes
C Routine Local Simple repairs Yes*
D Poor Emergency None No
E Frontier Emergency None No
X None None None No
  • Typically Routine/Class C Starports were not capable of performing annual maintenance” but could do simple maintenance.


Traveller world sizes starting at size 6 map over cleanly to M-Space, but sizes 0-5 are not covered. To help explain the lack of designations at the lower sizes, it is important to note that world sizes 1-4 would have such low gravities that walking in a straight line would be problematic.

UWP Size Code Traveller World Size Traveller Gravity M-Space
0 800 km (typically an asteroid) Negligible -
1 1,600 km 0.05 -
3 3,200 km 0.15 -
5 4,800 km 0.25 -
7 6,400 km 0.35 -
9 8,000 km 0.45 -
2 9,600 km 0.7 Extra Small
4 11,200 km 0.9 Small
6 12,800 km 1.0 Medium
8 14,400 km 1.25 Large
10 (A) 16,000 km 1.4 Extra Large


M-Space includes some tables for Atmospheric Pressure and Breathability which we will use to translate back to a UWP code.

UWP Atmosphere Code Descriptor M-Space Pressure M-Space Breathability
0 None None None
1 Trace None None
2 Very Thin, Tainted Too thin Vacuum Suit
3 Very Thin Too thin Vacuum Suit
4 Thin, Tainted Thin Breathing mask
5 Thin Thin Breathing mask
6 Standard Earth like Earth like
7 Standard, Tainted Earth like Breathing mask
8 Dense Dense
9 Dense, Tainted Dense Breathing mask
10 (A) Exotic Varies Vacuum Suit
11 (B) Corrosive Varies Vacuum Suit
12 (C) Insidious Varies Vacuum Suit
13 (D) Dense, High Dense
14 (E) Thin, Low Thin None
15 (F) Unusual Varies Varies

It is important to note that while Dense worlds may not require a particular Breathing mechanism they would be rather hot and have violent electrical storms, continent-sized hurricanes, or massive hailstones.


Traveller does a whole thing with Hydrographics and has a system for generating a climate profile given a few inputs. For example, a Size code of 6-8, an Atmosphere 5, 6 or 8 and Hydrographics 5-7 might give you a Garden World.”

There is no easy conversion here other than to provide some guidance on the codes and allow you to think about how close the planet might be to the habitable zone and what effect that would have on the climate.

UWP Hydrographic Code Descriptor
0 Desert world
1 Dry world
2 A few small seas.
3 Small seas and oceans.
4 Wet world
5 Large oceans
7 Earth-like world
8 Water world
9 Only a few small islands and archipelagos.
10 Almost entirely water.

Here’s some general guidance as to how you can fit all of the codes together:

World Class Size Atmosphere Hydrographics Temperature
Rock 0 0, 1, 2, 3 0 -
Harsh 1, A+ 4, 7, 9, A, B, C, D, F 1, 2, 9, A Freezing, Boiling
Marginal 2, 9 5, 8 3, 4, 8 Hot, Cold
Garden 3, 4, 5, 6, 7, 8 6, E 5, 6, 7 Temperate


At this point we need to jump out of M-Space’s World Building chapter and head to the previous chapter on Alien Creation. Mapping Traveller’s population code to M-Space’s population descriptors requires a bit of judgement as to what medium” means in your universe. Here’s an idea as to how one might do that:

UWP Population Code Descriptor M-Space Descriptor
0 None None
1 Few Very Low
2 Hundreds Very Low
3 Thousands Low
4 Tens of thousands Low
5 Hundreds of thousands Medium
6 Millions High
7 Tens of millions High
8 Hundreds of millions Very High
9 Billions Very High
10 (A) Tens of billions Super-dense


Governments in Traveller are rather specific compared to the broader terms used in M-Space. Additionally M-Space’s Circle mechanic provides a richer way to represent these planetary governments within your game world and how their actions can influence or impact your players. There’s no reason why you could not use Traveller’s label in your M-Space game. Some GM fiat is necessary to determine what these labels mean in your game, but here’s a sample mapping if you wish to preserve M-Space’s labels.

UWP Government Code Descriptor M-Space Ruler
0 None None, Anarchy
1 Company/Corporation Dictatorship, Semi-Democratic
2 Participating Democracy Democracy
3 Self-Perpetuating Oligarchy Dictatorship
4 Representative Democracy Semi-Democratic
5 Feudal Technocracy Council
6 Captive Government Council, Dictatorship
7 Balkanization Many
8 Civil Service Bureaucracy Council
9 Impersonal Bureaucracy Council
10 (A) Charismatic Dictator Dictatorship
11 (B) Non-Charismatic Leader Dictatorship
12 (C) Charismatic Oligarchy Dictatorship
13 (D) Religious Dictatorship Dictatorship
14 (E) Religious Autocracy Dictatorship
15 (F) Totalitarian Oligarchy Dictatorship

M-Space provides two additional layers of descriptors called Foreign Policy and Conflict Intensity that would require you to know a bit more about your world’s backstory in order to determine how your planetary governments are functioning with their neighbors.

Law Level,

M-Space has a 1:1 mapping for Traveller’s Law Levels 0-9. These can be found in M-Space on page 134 in the Alien Creation chapter.. The table presented here could be slightly cleared that the Weapons column is saying what is restricted.” So, Level 9 does not mean Any Weapons” are allowed but that all weapons are restricted by the government.

Tech Level

M-Space has a 1:1 mapping for Traveller’s Tech Levels 0-15, and you can read a bit about this on page 135, of M-Space’s Alien Creation chapter.

So there you go, M-Space is not shy about pointing out its roots from Traveller. In many cases mapping the terminology is not strictly necessary but it can be helpful to your players if they are not familiar with Traveller but own their own copies of M-Space.



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