Report: A Review of Challenges and Opportunities – Variable and Partial Gravity for Human Habitats in LEO (2022)

Overview

The environment encountered in space presents significant unrealized and unrecognized opportunities for research, manufacturing, discovery, and industry. And that environment poses stiff challenges that hinder the realization of potential opportunities. Balancing the tension between the advantages and hurdles of operating in a weightless environment is particularly acute with human habitation. Gravitational variability from microgravity (ug) to hypergravity is one of the most notable and potentially exploitable for operations, research, and manufacturing.

This report reviews the literature and discusses the implications for creating artificial variable gravity habitats for humans in Low Earth Orbit (LEO) and cis-lunar space.

Artificial gravity through rotation was first proposed in 1883, by the Russian rocket scientist Konstantin

E. Tsiolkovsky. Decades before space flight was a reality, designs for artificial gravity systems using rotational structures were proffered as many experts believed that humans would not be able to survive in the weightlessness of space. However, today we know humans can survive in zero G. The overwhelming majority of human space experience has been in weightlessness, which does have definite damaging effects on human physiology and performance if left unaddressed by countermeasures.

Rotational artificial gravity structures are being proposed as single solutions to long duration and interplanetary space travel. It is also a consideration for accommodating everyone-from professional crew to researchers to tourists to protect health, facilitate operations and optimize time on orbit.

Major challenges to successfully designing, building, and operating rotating artificial gravity habitats is that ground-based studies of humans in rotational artificial gravity are hindered by the fact that Earth’s gravity is always present, so studies may not translate to space; however, these studies do provide data to guide development. The reality is that there is little direct human evidence that artificial gravity will protect human health, but animal studies combined with ground-based studies provide important clues.

Including the possibility that continuous, full 1 G Earth gravity may not be required to be an effective single solution countermeasure; intermittent 1 G or even 0.5 G may be effective. Further, the design and maintenance of equipment and the habitat may benefit from artificial gravity because dust, crumbs, etc. settle to the floor.

Coriolis acceleration produces unexpected sensations and actual movement of objects in unexpected ways and must be addressed by engineering, architectural, and human factors design to successfully live and operate in a rotating environment. Ground based studies do provide helpful direction for designs.

Factors critical to achieve a successful design recognize that human operations in artificial gravity inside a rotating structure must be approached with the same rigor and meticulousness as is applied to the engineering, launch, assembly, and maintenance of structures in this dynamic environment.

This study is authored by the Olabisi Lab at the University of California, Irvine in collaboration with the 100 Year Starship in Houston, Texas.

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