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Beyond the Iris Valve

This article originally appeared in Cepheus Journal issue 007, and was reprinted in the July/August 2022 issue of Freelance Traveller.


We’re all familiar with classic starship blueprints. Apertures between rooms have either the “hatch” icon, or the “iris valve” icon. These are wonderful and thematic, and give a great “1950s battleship” feel to interior spaces that is the predominant aesthetic in this sort of role playing game. But this style and atmosphere may not suit all campaigns. And cultures can different within one game setting.

This article looks at a number of alternatives to how rooms are sealed off. It also deals with the special case of moving up and down, which isn’t often considered. Finally, it presents a number of adventure seeds where such choices may have relevance.

Between Here and There

When considering doors on starships, there are basically three classes.

The first class is just a partition. It is a mobile barrier between one place and another. It can be opened and closed, and possibly locked. It typically presents a visual barrier, a moderate sound boundary, and forms a climate control boundary.

The major difference in the middle class of doors is that they present a firm airtight atmosphere boundary. The lower class aperture may keep the temperature and humidity secure, but is not rated to prevent air leaking through when there is vacuum on one side! This door can remain stable and operable over a wide variety of pressure gradients such that if the structure is breached on one side, those on the other side are not in danger.

Although a middle class door may suffice to keep atmospheric integrity during an emergency, it is not rated for long term operation. The highest class of door is the equivalent of an external airlock. It can hold out a vacuum (or water, or other hostile environment) indefinitely, and also has the same rating for protecting against radiation, micro­meteorites, or whatever needs to be guarded against to the same level as the ship’s hull or facilities outer boundary.


The simplest arrangement for the basic barrier between rooms is a solid flat panel hinged on one side. It is possible to vary the shape, but physics makes rectangles the most widely chosen option. On spaceships, and other areas where space is a premium, the hinge may be dispensed with in favor of a “pocket door” that slides into a compartment. Although this saves the space of sweeping out an area that a hinged door takes, space has to be allocated in the wall for the door when it is open.

Higher tech options push these boundaries. Starting at tech level 9 or 10 such pocket doors may be hollow and quickly deflate to open up. Or they might be composed of ionized powder held open by a static charge, which retracts when the current is changed. These remove the need for wall space, and make for interesting scenarios when they are compromised or need maintenance.

There are non­rigid options as well. Beaded curtains, hanging strips of plastic, or magnetically suspended iridescent scales all make for a visual barrier that someone can walk through without a need for opening. They don’t form an acoustical barrier and can’t be locked, however.

Iris Valves

The classic iris valve is a usually round but occasionally rectangular aperture in a wall across the threshold. The door part itself is made of several triangular pieces that pivot together and apart to make a gap of various circular sizes. These, typically, do not fill the entire door frame, and a passer is required to lift and step to get past them.

Other variants of interior air­tight doors would be more robust versions of simple doors. Thicker, with interlocking edges and reinforcement to withstand pressure.

Often such doors are purely for emergencies and do not serve as general access barriers. A more common motif in this configuration is one that is not as obvious. It may form part of the ceiling, wall or floor and pivot into position when activated. These are usually noticeable if one is looking for them (and often marked) but in situations where presentation is important, they may be harder to spot. In other cases, they may double as security barriers and be deliberately disguised.


The classic exterior hatch is a large metallic circular panel, hinged on one side with a large hand crank in the middle to seal it. If a less submarine aesthetic is desired, the sturdy panels may be motorized and operated by buttons.

As this is as protective as a hull, some heft is expected. It will not be easily breached by accident or intention. At particularly high tech levels a door may be replaced with a force field.

Some hatches may also double as ramps. For person sized hatches, they may fold down into the long, slender, golden age era type ramp. Larger hatches for vehicles would be set up to allow the contained vehicles to ascend or descend.

Up and Down

One thing that is glossed over on classic floor plans is vertical movement. There are circles indicating hatches, a movement point cost, and the details are left to the imagination.

In the submarine aesthetic, vertical movement is done via ladders. Either there are specialized vertical supports, or the rungs protrude directly from the wall. Slanted ladders make more ergonomic sense, but they are messy to draw so you don’t see them on floor plans that often.

Much like pocket doors, at tech level 9 spaceships will have rungs that extrude as needed and retract otherwise. When tech level 11 is reached, protruding rungs become “rung strips”, and rungs protrude as a spacing appropriate to the physiology of the climber. Short, tall, child or alien, a “smart ship” will work out who is climbing and produce appropriate rungs. And just past that at tech level 12 the rungs themselves become mobile. Once the climber has started their traverse, the rungs themselves move, much like a vertical escalator, saving them effort. Other arrangements in high traffic areas have one set of rungs going up on one side, and one set going down on the other.

By the time tech level 14 is reached the rungs disappear altogether. Artificial gravity has advanced to the point where local gravitic fields can be adjusted. The climber can just be “wafted” up and down the chute with a simple verbal or visual queue.

Equipment Box

Door Spoofer

Many higher tech doors have sensors to prevent their operation or advise their operator when there are adverse conditions on the other side. Sometimes there are reasons that someone might want to override the choices an automated system makes. Other times they may want to deliberately deceive others. This is what the Door Spoofer is for.

The spoofer is a small, thimble sized suction cup. It is operated by placing it over the door sensor. At tech level 8, the interior can be evacuated to make the device register a vacuum, or it can be pressurized to spoof an atmosphere. At tech level 10, the spoofer can also be supplied with different cartridges to spoof sensors that detect the type of atmosphere on the other side. At tech level 11, a small radioactive element can mimic more conditions.

Most doors only have a single sensor, and anyone with Engineering skill can quickly spot it. Those without will need to make a simple check as the sensors are often discrete. Particularly secure installations may have more than one sensor per door.

Most spoofers are physical devices that operate mostly mechanically. Other classes of spoofers are entirely electronic and operate by manipulating the sensor through induced currents.

Such devices are seldom for sale in easy to find places. A few Streetwise rolls are often required to find a seller. They can run from Cr100 to Cr200 for a basic disposable model. Higher models are more expensive, and prices vary widely, especially on high law level worlds.

Game Hook

Doors are everywhere, but we seldom give them much thought in a game. And, yet, if an adventure is a series of barriers between the players and their goal, doors can play a part. And, because they are most often “invisible”, they can be more of a surprise adversary.

The Artful Spoofer

It all starts in a busy port with players who own a moderately high tech ship. The ship receives an invitation to an art show with a chance to purchase up and coming artists at low prices, with free hors d’oeuvres and live music. You may make a secret Computer check for the player with the best skill (or the computer itself) to notice the Trojan virus that slips in with the message. In any event they are bound to be suspicious when they arrive and find the address only has a down­and­out street artist and busker across from a soup kitchen who know nothing of any art display. (Although they will happily sell anything or perform for pocket change.)

Enter the Artful Spoofer. She presents as female, but her exact gender is up to the referee. She dresses in flamboyant shabby clothes and is prone to flashy dance moves even when she is just moving about. She has an array of devices at her fingertips to spoof all manner of door sensors. Her virus will also compromise the body language recognition system of the ship, allowing her exaggerated gestures to trigger a variety of reactions from the ship’s automated system, but at her timing.

She’ll happily stroll onto the ship, preferably while the characters are at the nonexistent art show, but their presence won’t stop her. The doors won’t block her or register her passage. Video cameras might, as she considers it beneath her to deal with surveillance.

Her intentions are not overtly criminal. She’ll pick up any loose change but is more interested in looting their refrigerator than their arms locker. Mostly she seeks to avoid confrontation, seeking to place obstacles in the path between any players and herself. If she is eventually cornered, she’ll surrender, happily holding her wrists out to be cuffed, proclaiming to be curious as to what the station reward is now for her capture. She’ll provide a running commentary on whatever restraints they might use, possibly slipping them off to check the model numbers before slipping them back on again. If they physically threaten her, she’ll quote them chapter and verse of the starport code about rendering violence to an unresisting prisoner.

Starport authority will respond quickly to any summons about trespassing, as they take that quite seriously. When they arrive and find out who is trespassing, they’ll grow less enthusiastic. The Artful Spoofer will greet the officers by name, and request a specific cell, because it has the most challenging security. She’ll thank the players and say she looks forward to seeing them in the future.

This is, mostly, a humorous side encounter. But it can serve the purpose of introducing players to the different ways in which their security might be compromised, or how they might compromise other targets. Particularly clever players might even try to befriend the Spoofer, to either get a rundown of the devices she uses, or to pay for training, or to hire her services.