airlocks

When we consider the environment of space, and the habitable interior of a spacecraft there are some clearly marked differences, and necessarily a series of complex mechanisms are involved in making sure that when personnel or equipment have to transfer from one to the other they do not open up for equilibrium the internal environment and the rest of space.

Though there is no single 'Universal Airlock' in use in the Federation but they all have certain common features, and must obey the strict safety regulations applied to everything in craft design. A standard mechanically separating airlock must have at least two doors, this is somewhat obvious if we consider what would happen when a door is opened between inside habitable environment and vacuum. In most Federation craft a three-door system is used where possible, this allows airlock operation even if one door fails to function properly.

The operation of the doors is initiated via keypad or spoken command (via suit interface in case of vacuum), and the doors together work on a logic that is both commanded by the central computer system, a separate airlock computer system, and finally a set of mechanical failsafe mechanisms. The logic is fairly simple:

Not at any time must all three doors be open when a pressure difference exists between internal and external environment (can be overridden), and is allowed by control when internal and external pressures are the same (eg when in atmosphere or if internal pressure is lost).

When system is not in use all three doors will but set to closed position.

For a standard airlock operation the space between innermost and middle doors will remain at internal pressure, only the space between external and middle doors will be depressurized.

For airlock operation where the object(s) exceed the room offered between the first two doors, the whole airlock will be depressurized but all three doors must not be open at same time (as above)

The construction materials used for the external door are nearly always the same material as the rest of hull, in this way, combined with high degrees of precision in manufacture, airlocks do not significantly reduce the overall resilience of the hull that would have been in its place. In addition the middle and interior doors have a degree of protection beyond what is really needed, to offer additional protection to the ship’s integrity if the external door fails.

The seals for the airlocks are also of very high precision, a combination of near perfect machining during manufacture, and a thin polymer/silicon film act as a perfect seal without compromising on durability of the total door, or making it impossible to open. The rate of leakage from a typical external door which has been MLN coated is effectively zero, molecular loss is in the order of thousands or less molecules per day. This ensures that even derelict ships, or badly damaged ones will often maintain internal environment, and even if net interior environment fails the airlock itself will be pressurized if not broken, and therefore offer at least one computer terminal to any docking crew without them having to enter the potentially hazardous interior.

Though potentially superior and more exotic methods are possible to replace the current airlock doors, they are simply not as failsafe, Force-field systems alone are vulnerable if power to these units fails, likewise smart nanite portals also are a risk if the nanites lose power, either freezing solid, or dispersing like dust, whereas a big solid door with a good seal and locking mechanism is all but immune to anything short of severe damage.