After more than 50 years of human spaceflight, it is clear that health issues associated with prolonged habitation in a microgravity/weightlessness environment pose a major problem. The human body is not adapted for such conditions and suffers from a variety of serious complications, including bone density loss, muscle atrophy, cardiovascular complications, immune system issues, visual impairment. While some of these can be partially mitigated to some degree, others currently cannot. Other negative factors like living comfort, crew psychology, and complications related to re-adaptation to natural gravity upon return to Earth have also been identified.

The cumulative effect of all the above remains one of the main obstacle in the pursuit of human exploration and habitation of outer space.

Rotational artificial gravity offers a solution to this obstacle and while by no means a new concept, it was  not technically or economically viable up until recently, due to the low capacity-high price of deploying such a solution. This is, however, no longer the case.

To fully replicate Earth’s gravity (1g) on a human body with the centripetal acceleration in a spinning/rotating habitat, the required structure would need to be excessively large (approximately 1 km in radius), so some compromises need to be made to achieve viable and satisfactory results. The compromises come in comfort and adaptability of inhabitants in smaller radius/higher angular velocity habitats and comprise the following factors: Gravity gradient, Coriolis effects and vestibular (canal) sickness. Some research has been carried out to identify and examine these factors, and while not rigorous, it offers a theoretical ‘comfort zone’ for adaptability in terms of rotating structure radius and angular velocity, as plotted in Figure 1.

As can be seen, GST-01 with an effective rotational radius of 42 m and an angular velocity of 3.5 rpm, delivering ~0.61g of artificial gravity, sits close to the ideal comfort zone.

While ‘artificial gravity’ habitation with proposed parameters should be regarded as experimental, it is reasonable to believe that it can significantly mitigate negative health effects of weightlessness and greatly improve crew comfort. This, in turn, will prolong crew service time, reduce the number of rotations required, and will ultimately open new possibilities for human presence beyond Earth.