Let's Read “Traveller: Core Rulebook - Space Operations”

Space Ships Ain't Cheap and There's a Lot to Them

Last chapter, we read about Vehicles in Traveller and in this chapter we’ll learn about spacecraft and operations.


Traveller breaks down different spacecrafts based on tonnage, jump capabilities, and hull types. One displacement ton is based on the volume of hydrogen, and displaces roughly 14 cubic metres.

Buying a ship is expensive, we get details about taking out a loan to pay for ships. Some quick math on mortgage payments. Price divided by 240 for monthly payments for the next 40 years.

During character creation, Travellers may get full access to a Ship, Ship Shares, or even a significant part paid off. In my character creation examples, and each earned 1 Ship Share. The group can start with a ship and knock MCr2 off of the loan. I wonder how much ships cost? Let’s peak at a Free Trader on page 166 says it costs MCr45.342. I guess that puts ’s MCr1 medical debt and anagathics usage into perspective.

Space and Time

Given and skills having task completion times, we now get some quick units which would please your High School teacher.

Astronomic Unit
The distance between the Earth and the Sun – 149,597,870 kilometres
Light Second
The distance light travels in one second – 299,792 kilometres
Light Minute
17,987,547 kilometres
Light Year
9,460,730,472,580.8 kilometres
Parallax of one second of arc – 30.857 × 1012 km, or 3.262 light years.


For those of you reading along, Traveller frames a lot of specifics. Most of the time, as an Referee, I wouldn’t worry about these details. However, having these details available can help in moments where you and your fellow gamers zoom in on a scene. For example, an reactor leak flooding everyone with radiation. How long does it take to patch up the leak? While waiting on your crew members who are on a space walk? And a pirate ship just showed up on sensors.

In this case, using time and space could add to the tension.

A ship has at least one airlock per 500 tons. The average airlock is large enough for three people in vacc suits to pass through. An airlock takes ten seconds to cycle. Under normal circumstances, airlocks are locked down from the bridge and require a Very Difficult (12+) Electronics (computers) check to override. An unlocked airlock can be triggered from outside. Airlocks generally have vacc suits (see page 96), rescue bubbles (see page 115) and cutlasses (see page 117) in lockers nearby.

Ships with cargo space have cargo hatches, allowing up to 10% of their cargo to be transferred at any one time.

This is some specific detail, and I would imagine it could be important to have this information.

Atmospheric Operations

Different spaceship designs handle atmosphere differently. Some can operate like planes, others can operate without issue in thin atmospheres (or while skimming a gas giant). And finally, there are those that are ill-designed for flying in atmosphere. Referees, remember this exists but don’t dwell on it until you need to. After all, most episodes of Star Trek we don’t worry about its inability to fly in an atmosphere. But on those few occassions, these rules can help guide you.

Docking, Landing, and Boarding

These rules are a sibling to the Atmospheric Operations. As a Referee, knowing they exist can be important. Most landings and dockings you can skip over, but when your spaceship’s coming in hot or there’s a complication, then lookup these rules.

I would definitely say, if your pirate ship is preparing to dock and board its target, then go to the rules. If your pirate ship is landing at a safe port, please just say yes, and move on. This is based on Vincent Baker’s admonition: “Every moment of play, roll dice or say yes.” Think about it, when you go to the dice, you invariably slow down the table narration. That slowdown may be critical for determining what happens in the fiction.


In this section, Traveller introduces us to power requirements of the spaceships.

You need power for:

  • Basic Ship Systems - life support, artificial gravity, ship’s computer, and ship’s amenities
  • Manoeuvre Drive - your drive that moves you through normal spaces
  • Jump Drive - your drive that moves you into jump space
  • Weapons and Systems - lasers, turrets, and particle beams

Based on this section it looks like power management may come into play during critical moments. Some ships will have ample power for everything or may skimp and running close to maxium. And a critical hit can damage power production.

For example, you’re manuevering through space, minding your own business, when you detect a corsair accelerating towards you, launching a couple of missiles. You’re going to consider returning fire, calculating your jump, continuing to manuevering, and spinning up your jump drive.

This may well be a time for Chief Engineer Scotty to do his magic.

Running Costs and Maintenance

In some of my additional reading, I’ve seen styles of play in which you eschew tracking maintenance costs and loans. Instead, focus on the adventures, and keep some of those bookkeeping aspects out of play. For each group, your mileage may vary.

If you’re going to have a mortgage for your spaceship, it’s a safe bet there’s associated maintenance costs.

We get a quick table to that lists the monthly cost. Crew, life support, mortgage, fuel, and general repairs and maintnenance.

This looks like something you’ll want to calculate and record for future reference.

There’s rules for skipping or skimping out on maintenance. Namely systems have an ever increasing chance of faulty performance.

And if you’ve got a mortgage, you may consider skipping out on that mortgage. This sidebar provides a framework for Travellers wanted by larger organizations.

Let’s take a look:

Ship captains hoping to avoid crippling repayments on multi-million credit loans may be tempted to skip out on repayments, jumping to distant systems to make a new life for themselves. If the Travellers do so, they may be chased by ship tracers (bounty hunters) employed by the bank, or logged as criminals in the Imperial database and hunted down by naval vessels. For each new system, roll 2D and apply the modifiers below. If the result is an 8+, the Travellers will be hunted for their crimes.

Per parsec distant
-1, reset every time the Travellers are discovered
Changes to the ship (repainting, altering transponders, refits etc)
-1 to -6
Per MCr10 of value of ship stolen
If the Travellers have visited this system more than once in the past three months
Payment is less than one month overdue
Payment is one to six months overdue
Payment is seven to twelve months overdue
Payment is one year or more overdue
Law level
Add Law Level - 5
Traveller: Core Rulebook p144

Let’s frame this using the term Heat. The higher the dice modifier, the hotter the pursuit.

So, the further you travel from a last known location, the less heat you have. A ship that jumps multiple parsecs is a good ship to skip out on payments. After all, with non-FTL communication, messages travel only as fast as the postal service.

The more you owe, the more interest your creditors will have. The more you modify your ship, the less easy it will be to track. This sounds like you’ll need to make a plan to skip out. I’d imagine a standard procedure when you “pay your monthly mortgage” is for the banks to run a quick scan of your ship. Were I the Referee and Players, I’d make sure everyone knows the rules around how the Travellers may claim this tremendous dice modifier for skipping out on a loan.

If you keep revisiting your favorite haunts, it’s going to be easier to find you. Mechanically, this nudges you to continue diving into adventures and never quite settling down.

Banks are most interested in those who’ve skipped out in the last year. And the local system authorities also have a say.

Most notably, this bounty never goes away. Which means, if you want to skip out on your mortgage, you better run far away.


I have grown to love random encounter procedures. In years past, I looked at them as getting in the way of the campaign; I thought that I to present a situation and respond to the players’s actions.

Today, I see random encounter procedures as a means to model the world around the characters. It is these procedures that fold into the campaign story. These procedures are a tool to help a Referee more holistically respond to players actions.

So, let’s take a look!

First, space is massive. And has varying density of activity. Not much happens beyond the Oort Cloud, but a Starport on a trade route sees lots of action.

Each day roll a d6 🔍. On a 6, the Travellers have an encounter. As with all rules, these are here to use OR not.

For an encounter, roll D66 🔍 and modify the tens die by the following.

Highport (DM+3)
The space near an orbital starport
High-Traffic Space (DM+2)
The space near an industrial world with a high-class starport.
Settled Space (DM+1)
Most core worlds in settled or colonised space.
Border Systems (DM+0)
Outlying worlds near the border, such as the Spinward Marches.
Wild Space (DM-1)
Amber or Red worlds.
Empty Space (DM-4)
Untravelled space or unexplored systems.
Traveller: Core Rulebook p145

The Space Encounters table has entries and summaries including alien derelicts, navigational beacons, hostile vessels, grand fleet warship, noble yacht, and so forth. Lots of diffent types of encounters to bring life to space.

Also in this section are some tables for random results for mining and salvage. All good stuff. All of these tables help seed the shape and form of your campaign world.


You get fuel from hydrogen; Maybe skimming it from a gas giant or converting water. The fuel can be either refined or unrefined. Unrefined fuel is cheaper but more dangerous to use during a jump.

Refueling takes d6 hours. Again, consider that you don’t really care about how long it takes to refuel except when time matters. Scooping fuel from a gas giant requires a Difficult (10+) pilot check, and always produces unrefined fuel. For skimming, I’d always require a test. For the consequences, I might have it take longer or possibly inflict damage or be even more dangerous than unrefined. I’d of course tell the players the dangers ahead of the roll.

Jump Travel

Ships use their Jump drive to create a jump bubble—a short-lived universe all its own. To create a bubble you must be more than 100 diameters distant from any object larger than the ship. In other words, to jump from near Earth, your ship would need to be 100 diameters of Earth away from Earth. Again, only something I’d likely consider when time truly mattered. For example, you’re blasting off of a planet and need to jump out of the system, but there’s a few cruisers patrolling the area, possibly receiving orders to intercept.

The astrogator must plot the jump. They need a Easy (4+) Astrogation check with a penalty equal to the number of parsecs jumped. This takes d6 × 10 minutes, and failure means the astrogator needs to recalculate.

Let’s peek back at . You can make a quicker calculation, but that increases the chance of failure. Given that failure means start again, there’s a math game going on to optimize these calculations.

For this example, let’s assume we have an Astrogation-2 and attempt a 1 Parsec Jump. We have a 3% chance of failure. If we shift up three bands on the Timeframe we have a 67% chance of failure. However, we can keep re-checking. For lazy simplicity sake, we fail the first two times, then succeed. We’ll need about 3d6 × combat rounds to get a success, instead of the 1d6 × 10 minutes. This is some napkin-level probability calculations.

This I find quite interesting. If time doesn’t matter, don’t really worry about the roll. But if time does matter (e.g. there’s a firefight), it’s reasonable to try quicker calculations.

With the Astrogation completed, we divert power and engage the Jump drive.

Again, difficulty and timeframe for the Jump is Easy (4+) Engineer (J-Drive) and requires d6 × 10 minutes. We apply a few modifiers:

  • The Effect of the successful Astrogation check
  • A penalty for lack of maintenance ( Dice Modifier (DM 🔍)-1 per month)
  • DM-2 for using unrefined fuel
  • DM-4 for jumping within the 100-diameter

Unlike Astrogation, this is one you likely want to get right. Failure means a Misjump. Success means you spend 148 + 6d6 hours in transit and arrive just on the verge of the 100-diameter range of your destination.

Whereas Stars without Number has a Misjump Table, we instead get some rules that could be summarized in a table. I’ll present it that way:

Table 206: Summary of Traveller Misjump Consequences
-1Arrive 1d6 days later
-2Arrive an additional 1d6 × hundred-diameter further away from target.
-3 or worseMercifully, the Referee can send them 1d6 × 1d6 parsecs in a random direction.

Having just read the “Skipping out on a loan”, I’d check with your Referee about whether they’re using that rule. If so, maybe that’s your ticket to greatly reduce the chance of being caught by loan hunters.


In Traveller there are different classes of passengers, and if you though airlines were bad, wait until you learn about Low Passage. It’s even worse than Kermit and Fozy flying 17th class in the Muppet Caper.

High Passage
Great treatment, requires trained stewards
Middle Passage
Stand-by for high passage
Basic Passage
This is analogue to coach
Working Passage
You get a place in coach, but you also work during transit
Low Passage
Frozen in a cryoberth and you may die when they try to revive you

Remote Operations

Some quick rules for operating mining, probe, and repair drones.


Repairs break down into two categories: Critical Hits and Hull Damage. Repairs take spare parts, though a skillful Engineer or Mechanic might be able to shave off the amount needed; One ton of Spare Parts costs Challenge Rating (CR 🔍)100,000.

Repairs take time, and for critical hits the best you have in the short-term is a temporary jury-rig. Again, these rules appear to help model lots of the sci-fi tropes of someone patching something together for a bit, but those fixes don’t hold.


Traveller provides a list of sensor types, ranges, and sensor details. I find myself preferring Stars without Number’s sensor system. Traveller relies on range bands, but those are relative to other objects. Stars without Number focuses on regions, or more absolute maps. I suppose this preference is likely based on using maps that show geographic locations. Were I to have used more maps that show relative ranges that would be useful.

Ship Computers

Ship software provides basic control and library data. You also need jump control software to make jumps and assist in turret fire. You can also run software to assist with evading fire and repairing damage.

Spacecraft Security

This brief section speaks to the various security measures that keep a high-cost ship safe from would be thieves. This section also gives the rules for would-be thieves to lay claim to someone elses ship. This includes: Cameras, Sensors, Computers, Locks, and Security Systems.

Travel Times

Here we again have some information that would make a science teacher proud:

Time Required
2 × Square Root of (distance ÷ acceleration)
Acceleration Required
(Distance × 4) / Time2
Distance Travelled
(Acceleration × Time2) ÷ 4

In case you don’t have a calculator, you can reference the table on Page 153 for distance and acceleration.

Traveller also provides common distances for object to object (e.g. World Surface to Orbit, or World Surface to Close Neighbour World).


I suppose if your characters’s are going into quite a bit of debt, you may want quite a few rules around your asset. And we haven’t even read about . That’s for next chapter.