Engineering Gravity: Werner Grandl's Vision for Rotating Space Habitats at ACES Worldwide Workshop

The ACES Worldwide Living in Space Workshop featured an extraordinary presentation by Werner Grandl from Space Renaissance International (SRI), who unveiled comprehensive engineering solutions for simulating gravity in space through rotating habitats. His November 13th presentation, "The Simulation of Gravity in Rotating Space Habitats," offered detailed blueprints for humanity's gravitational future beyond Earth.

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From Science Fiction to Engineering Reality

Grandl began by acknowledging the visionary concepts that have inspired generations, from Hermann Noordung's 1928 "Weltraumrad" (space wheel) with its parabolic mirror for collecting sunlight, to the iconic rotating station from Stanley Kubrick's "2001: A Space Odyssey." These early concepts, once pure imagination, now serve as the foundation for serious engineering proposals.

The presentation addressed a fundamental challenge of space habitation: the devastating effects of microgravity on human physiology. Loss of bone density, reduction in red blood cells, fluid shifts, and cardiovascular deconditioning make long-term space residence without artificial gravity medically untenable. Grandl's solution? Harness centripetal force through rotation to create artificial gravity that could provide up to 1g—Earth-normal gravity.

The Comfort Box: Finding the Sweet Spot

One of Grandl's key insights involved what he called the "Comfort Box"—the optimal parameters for rotating habitats that balance gravity simulation with human comfort. Drawing on NASA research from Jesco von Puttkamer (1987), he demonstrated that rotating space stations need:

• A minimum radius of 30 meters

• A rotation rate no faster than 4.5 rounds per minute

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• Careful management of Coriolis forces that can cause disorienting traverse motion

These parameters ensure inhabitants can move naturally without experiencing debilitating motion sickness or spatial disorientation—crucial for productive life in space.

AGOS: The ISS's Potential Successor

Grandl presented the Artificial Gravity Orbital Station (AGOS), developed with C. Böck in 2017, as a possible successor to the International Space Station. This ambitious yet practical design features:

Modular Construction

• Hard-shell aluminum cylinders, 18 meters long and 7 meters in diameter

• Each module weighing 20 metric tons, fully equipped with furniture and systems

• Transport via reusable SpaceX launchers to Low Earth Orbit (450 km)

Phased Assembly

The initial stage would include:

• 4 rotating living quarter modules providing 0.9g

• 4 zero-gravity modules for research

• 1 docking module for spacecraft

• Total diameter: 102 meters

• Rotation rate: 4.2 rpm

• Initial crew capacity: 24 persons

The final configuration would expand to 32 living quarter modules, supporting approximately 180 inhabitants—a true city in space.

Living Quarter Design

Each module accommodates 6 persons across two floors:

• Upper floor: living areas, cooking facilities, and workspaces

• Lower floor: private dormitories connected by ladders

• Diameter: 7 meters, Length: 16 meters

The Engineering Marvel: The Roto-Joint

Perhaps the most crucial engineering challenge Grandl addressed was the connection between rotating and non-rotating sections. His solution: a Magnetic Liquid Rotary Seal using ferrofluid—an oil-based liquid suspended by permanent magnets. This hermetic seal includes:

• Rotor and stator components

• Auxiliary ferrofluid tanks

• Ball bearings for centering

• Airlocks and fire doors for safety

• Zero atmospheric leakage

This elegant solution, adapted from industrial applications, solves one of the most persistent challenges in rotating habitat design.

Mining the Sky: Asteroid Habitats

Looking beyond Earth orbit, Grandl presented a vision for converting mined-out Near Earth Asteroids (NEAs) into rotating habitats. Using asteroid 2008EV5 as an example (450m diameter, 1.43 billion tons), he outlined how the hollowed interior could house a rotating colony while the non-rotating rocky shell provides natural protection against cosmic rays and meteorites.

His prototype design for 3,000 inhabitants features:

• Rotation rate: 3 rpm on electromagnetic levitation bearings

• Gravity simulation: 90% of Earth gravity

• Minimal Coriolis acceleration: 0.05g

• Vertical farming and aquaculture for nutrition

• Closed air and water cycles

Deimos: A Gravitational Oasis at Mars

In perhaps his most ambitious proposal, Grandl outlined plans for habitats within Mars's moon Deimos. Since Mars itself provides only 38% of Earth's gravity—insufficient for long-term human health—rotating habitats inside Deimos could provide full Earth gravity for Martian colonists.

The Deimos habitat plan involves:

1. Docking a manned station to Deimos's surface

2. Building mining and processing facilities

3. Drilling central tunnels and excavating caves

4. Constructing three rotating toroidal structures

Each torus would feature:

• Rotation radius: 980 meters

• Total diameter: 1.96 kilometers

• Full 1g gravity simulation

• Rim speed: 98 m/sec

• Rotation rate: 0.96 rpm (exceptionally comfortable)

• Population capacity: 7,000 persons per torus

The scale is breathtaking:

• Living area: 220,000 m²

• Landscape areas: 693,000 m²

• Agricultural zones: 550,000 m²

• Water mass: 17,000 tons

• Air volume: 114 million m³

From Asteroids to Astropolis

Grandl concluded with a nod to the grand visions of Gerard K. O'Neill's Island 3 colonies from 1976 and his own work with Antonio Germano on the "Astropolis" concept at Princeton in 1993. These massive free-floating rotating colonies represent the ultimate expression of artificial gravity habitats—entire worlds spinning in space.

Engineering Tomorrow's Gravity

What makes Grandl's presentation remarkable is its progression from proven engineering principles to increasingly ambitious yet feasible applications. Each design builds on established technologies while pushing the boundaries of scale and complexity.

The AGOS station could be built with today's launch capabilities and materials science. The asteroid habitats require advances in mining and construction techniques but no fundamental breakthroughs in physics. Even the Deimos colonies, while requiring massive infrastructure investment, operate on well-understood principles.

By solving the gravity problem through rotation, Grandl addresses one of the most fundamental barriers to permanent space settlement. His detailed engineering solutions—from ferrofluid seals to optimal rotation rates—transform the rotating space station from science fiction trope to actionable blueprint.

A Future That Spins

As humanity prepares for its multi-planetary future, Grandl's work demonstrates that we need not abandon the gravitational environment in which we evolved. Through careful engineering and bold vision, we can carry Earth's gravity with us to the stars—not as a limitation, but as a tool for human flourishing.

His presentation at the ACES Worldwide workshop represents more than technical specifications and engineering drawings. It's a roadmap for creating true space settlements where children can grow with normal bone development, where water flows predictably, and where humans can live not just as visitors to space, but as permanent residents of the cosmos.

The simulation of gravity through rotation isn't just about comfort—it's about creating spaces where humanity can truly live, work, and thrive for generations. Werner Grandl and Space Renaissance International are engineering that future, one revolution at a time.

The Living in Space Workshop continues to showcase groundbreaking solutions for humanity's expansion beyond Earth. For more information about Space Renaissance International and their rotating habitat designs, visit their website at spacerenaissance.org.

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