The Personal Pressure Port

Concept Paper II · Series: Uniphase Planetary Surface Operations

The vision here is not about a room that gets evacuated, or a cycle that takes thirty minutes, or a calendar entry that blocks out the hour before you leave. It is about something more fundamental: imagine deciding, in the moment, that you want to go outside. Not scheduling it. Not spending four hours breathing pure oxygen. Not waiting for someone else to finish their EVA because the airlock is occupied. Just deciding — and sixty seconds later, standing on the surface of Mars, because the suit you put on in the corridor is already at the right pressure, and the wall behind you is already a door.

And when your colleague inside realises you forgot something, they place it in the small hatch beside your port. Thirty seconds. It is in your hand. The airlock does not interrupt the thought. It completes it.

The PPP is not a faster airlock. It is what an airlock becomes when the reason it was slow no longer applies.

Why the Conventional Airlock Is the Wrong Answer at 1 atm

The conventional airlock serves two functions: it inflates the suit to operating pressure, and it removes the atmosphere between the suited astronaut and vacuum. At 29.6 kPa suit pressure, both functions are necessary — the astronaut must transition between two different pressure environments, and that transition takes time and atmosphere.

At 101.3 kPa — if the suit operates at the same pressure as the habitat — the first function disappears entirely. There is no inflation cycle, no suit pressurisation check, no pressure adaptation, no pre-breathing. When the astronaut puts the suit on inside the habitat, they are already at their operating pressure.

The airlock's only remaining job is the second function: remove the atmosphere enclosed around the suited astronaut before the outer hatch can open. And the question that follows immediately is: how small can that atmosphere be?

The ISS Quest crew lock is approximately 4.25 m³. At 101.3 kPa, venting that volume unrecovered wastes approximately 5.1 kg of atmosphere per EVA cycle — gas that took significant energy to process. A 30–60 minute pump-down cycle recovers most of it, but the time cost is fixed by the room's volume.

The Fluid Lock patent (US4828207) demonstrated that geometric conformation alone reduces residual gas by approximately 90%: a form-fitting enclosure cuts residual mass from ~7.3 kg to ~0.64 kg, without any active mechanism. The PPP goes further. The enclosure conforms to the suit. An active displacement membrane fills the remaining clearance. The residual gas that must be managed drops to 10–50 litres — less than 0.03 kg per cycle. A 170× reduction in atmosphere loss compared to the Quest crew lock.

The gas mass equation:

m_loss = (P_hab × V_residual) / (R_specific × T_hab) × (1 − η_recovery)

where V_residual is the clearance volume after membrane actuation. Reducing V_residual is the primary lever. Everything else — pump efficiency, gas composition, temperature — is secondary.

The Suit-Shaped Wall Cavity

The PPP is a socket embedded in the habitat wall, shaped to the external geometry of the suit, with the suit stored in the socket when not in use. The astronaut retrieves the suit, dons it inside the habitat, and steps backward into the socket. The inner hatch seals. The displacement membrane advances around the suit. Residual gas returns to the habitat storage manifold. The outer hatch opens.

The socket is not a room. It does not need to accommodate movement, suit donning infrastructure, benches, storage, or maintenance equipment. Its job is to hold one person in one orientation for sixty seconds while a small volume of gas is managed.

The displacement membrane is not a sponge and does not absorb gas. It is an active volume-displacement structure driven by habitat-side actuators. As it advances, it pushes gas back into the habitat manifold rather than leaving it to be evacuated. The membrane has two layers: an inner compliant layer that conforms to the irregular geometry of the suited astronaut — helmet, backpack, tools, limbs — and an outer structural skin that faces vacuum and provides mechanical constraint and environmental protection for the inner layer.

Critically, the outer skin does not expand toward vacuum under differential pressure. Its position is commanded by the actuator, not governed by the pressure gradient.

Why the Airlock Must Not Disappear

The suitport — patented by Marc Cohen at NASA Ames in 1989 (US4842224A) — solves the airlock problem more aggressively: it mounts the suit permanently outside the habitat, and the astronaut enters it from inside through an aperture in the hull. No intermediate volume, near-zero gas loss, fast preparation. Its limitation is that the suit becomes the habitat's primary pressure boundary. Any failure of the suit or its seal during ingress is directly a habitat pressure event. Rescuing an unconscious astronaut requires managing the suit-habitat interface in emergency conditions from the exterior.

The PPP retains an independent pressure boundary — the port chamber — between suit and habitat:

Suitport: HABITAT ↔ SUIT ↔ VACUUM

PPP: HABITAT ↔ PORT CHAMBER ↔ SUIT ↔ VACUUM

This changes the safety philosophy from "the suit must not fail" to "suit failures must be contained." Three scenarios illustrate the difference:

Unconscious astronaut — With a suitport, a colleague must manage the suit-habitat interface in emergency conditions, outdoors, with an incapacitated occupant. With the PPP, the colleague maneuvers the astronaut into the port, closes the outer hatch, and the chamber repressurises from the manifold. The PPP was designed for this operation; it is its normal function in reverse.

Suit leak — With a suitport, a leaking suit during ingress is a habitat pressure event. With the PPP, the suit is inside the port chamber when the leak is detected. The inner hatch stays closed. The habitat is never in the leak path.

Decontamination — With a suitport, decontamination must occur on the exterior of the habitat before ingress. With the PPP, after the outer hatch closes and before the inner hatch opens, the chamber is an isolated volume. UV exposure, gas purge, and mechanical brushing can run automatically before the inner hatch opens. On Mars, where regolith contains perchlorate compounds, this inter-stage matters.

The Port Hierarchy

The PPP concept generalises to a distributed system of atmospheric interfaces, each optimised for a different throughput class.

Personal port — one astronaut plus suit plus immediate personal equipment. Displacement membrane. Approximately one-minute cycle. Multiple units distributed around the habitat perimeter for independent parallel egress.

Tool port — individual items: flashlights, wrenches, sample containers, cameras. Fixed small volume, approximately 2–5 litres. Approximately thirty-second independent cycle. Operable without interrupting adjacent ports or the astronaut's position on the surface.

Equipment port — batteries, orbital replacement units, replacement modules. Medium fixed volume. Parallel operation with personal ports.

Bulk cargo lock — panels, structural members, machinery. No volume minimisation. Conventional full cycle. Human egress is completely decoupled from cargo timing.

The forgotten tool scenario at a conventional airlock costs thirty to sixty minutes. At the PPP, it costs thirty seconds, and the astronaut does not need to return. This is not a minor improvement in operational tempo. It changes the kind of work that is feasible.

For a crew of six preparing for EVA: with six personal ports distributed around the perimeter, all six cycle independently in approximately one minute each. The last person is outside within six minutes of the first. They do not need to leave together — individual readiness determines departure, not the airlock's schedule.

Comparison with Prior Art

Attribute	Conventional Airlock (Quest)	Suitport (Cohen 1989)	Fluid Lock (US4828207)	Personal Pressure Port (PPP)
Enclosed pressure volume	4.25–10.0 m³	Near-zero	~0.5 m³	10–50 L
Volume minimisation	None	External suit mounting	Rigid geometric conformation	Active displacement membrane
Nominal egress cycle	30–60 min	<15 min	5–10 min	~1 min
Atmosphere loss per cycle	~5.1 kg	<0.01 kg	~0.6 kg	<0.03 kg
Habitat pressure boundary	Dual hatch room	None (suit IS the boundary)	Dual hatch rigid frame	Dual hatch + independent PPP chamber
Unconscious crew ingress	Straightforward (pull into room)	Complex (external manual docking)	Moderate	Fast: external insert + rapid repressurisation
Decontamination	Internal (habitat potentially contaminated)	Exterior only	Internal (chamber contaminated)	Automated inter-stage: UV, purge, brush before inner hatch opens

Engineering Challenges

Suit-conforming seal — the outer hatch must achieve a gas-tight seal at 101.3 kPa differential against the complex, variable three-dimensional geometry of a fully equipped suited astronaut, including backpack, helmet, tools, and differing operator body sizes. Dynamic fluid-filled active seal rings that conform to irregular surface protrusions are the candidate approach.

Membrane actuation speed — a one-minute cycle requires rapid membrane advance, sensor-mediated contact detection without applying damaging force to the suit, and equally rapid retraction on return.

Body and equipment diversity — different operators, tools, and life-support configurations produce different external geometry. The fixed cavity is sized for the largest configuration; the membrane fills the remaining variable gap. Optimising this tradeoff across the population of likely suit configurations is a system-level design problem.

Regolith seal lifetime — the sealing interface contacts a dust-laden suit surface on every ingress cycle. Sub-micron abrasive particles degrade elastomeric seals progressively. Electrodynamic dust shields — high-voltage electrostatic traveling-wave arrays embedded in the port frame — clear particles from the sealing perimeter before hatch closure. Sacrificial fluoropolymer surface layers absorb residual abrasive wear.

Parallel port contamination paths — the tool port creates a pressure interface for objects passing in both directions. Outbound objects are clean; inbound objects from the surface may be contaminated. Managing this boundary without a full decontamination protocol for every tool exchange requires careful port design.

Secondary Benefits

Waste management — the conventional MAG (maximum absorbency garment) exists partly because returning through a conventional airlock takes up to an hour. With a one-minute return cycle, the operational calculus changes. Routine habitat-proximal EVAs may not require continuous waste management provision.

Suit maintenance — the PPP socket is a natural suit docking interface. On return, the suit stays in its recess. Power, oxygen, cooling, data, and diagnostics connect through the port wall. The astronaut steps out of the suit directly into the habitat. The suit recharges and undergoes automated inspection without being carried through living spaces.

Habitat architecture — distributed personal ports change the habitat's relationship to EVA. Rather than a single bottleneck, EVA access becomes a distributed utility. Multiple crew members can exit and return simultaneously. Emergency evacuation paths multiply. Ports on different faces of the habitat enable directional access to different surface work areas.

Part of the OASIS Architecture

The PPP makes sense only in the context of a 1-atm suit — which is the PCVV paper. The PCVV suit makes full use of its potential only in the context of a 1-atm habitat — which is the Lava Tubes paper. These three papers form a connected physical architecture: the environment, the mobility system, and the access interface.

DXN provides the communications backbone that connects these habitats to each other and to Earth. PAAS provides the governance layer that determines how people in these environments make decisions together. Together, they describe not just survival on other worlds, but the physical and social infrastructure of life there.

Citation

Okitoi, O. S. (2025). The Personal Pressure Port: A Distributed Atmospheric Interface Architecture for Planetary Surface EVA: Concept Paper II. Independent Research, Kampala, Uganda.

BibTeX:

@article{okitoi2025ppp,
  title={The Personal Pressure Port: A Distributed Atmospheric Interface Architecture for Planetary Surface EVA: Concept Paper II},
  author={Okitoi, Samuel Oumo},
  year={2025},
  publisher={Independent Research},
  address={Kampala, Uganda}
}