A successor to the ISS, built to validate artificial gravity and closed-loop life support.

Promethea Station addresses the two most critical unknowns of human deep-space travel: what sustained partial gravity does to the body over years, and whether biological systems can replace resupply chains entirely.

The AG habitat rotates at 5.6 rpm to simulate 0.38 g — equivalent to Martian surface gravity — so the station becomes a long-duration testbed for crew physiology before any Mars transit is attempted. The four ICELSS greenhouse modules provide a fully closed loop of oxygen, water and food per crew unit, eliminating dependence on Earth resupply for those basic necessities.

The commercial sector is not decorative. Four short-stay tourism berths generate the operational funding that makes the research mission financially viable — a deliberate design constraint that shaped the station's modular structure.

Promethea is designed to remain operational for a minimum of 20 years, with modules replaceable on-orbit via Starship cargo flights. It is intended as the operational predecessor to any permanent Martian habitat: every system it tests is a system that Mars will require.

The final configuration shows the four Space Crusader habitation arms extending symmetrically from the central hub. The ICELSS modules are separate inflatable volumes connected to the microgravity backbone. The large solar array truss provides power for the full station, and the backbone itself allows zero-g research.

Two distinct zones serve different gravity levels and user groups. The outer ring of Space Crusader modules provides Martian gravity, while the backbone provides a microgravity environment.

The Space Crusader is the primary habitation unit. Four modules extend from the central hub in a cross configuration and rotate together at 5.6 rpm, generating 0.38 g at the habitat floor through centrifugal force. The station accommodates 12 individuals across 4 modules — 8 permanent crew separated in 2 modules and 4 tourists in the remaining 2.

The cross-shaped plan allows four equal arms to extend radially, creating a balanced rotation system that takes advantage of the resulting Coriolis force. The modules are arranged parallel to the rotational axis to favour movement along it and mitigate the effect of Coriolis force on crew motion.

The ICELSS — Inflatable Controlled Ecological Life Support System — consists of separate inflatable modules connected to the microgravity backbone. The units complete the biological loop: plants absorb the CO₂ and water produced by the crew, return oxygen, and yield food. Waste is preferably composted back into the growing medium.

The toroidal geometry creates a continuous growing surface. 40 m² of cultivated area per person is achieved through aeroponics and felt/NFT harvesting units, and autonomous robotic harvesting operates independently of crew schedules.

Living at 0.38 g in a rotating habitat is unlike any prior human spaceflight experience. The interior is designed to make this condition legible: curved floors follow the rotation radius, sightlines extend into the greenhouse, and natural light cycles are simulated to support circadian rhythm.

A booklet chapter by Beliz Bayraktar, Christopher Egg and Luka Pejic, from the HB2 Orbital Shift studio.