Sustaining Human Life in Space: The Role of Centrifugation as a Countermeasure

Sustaining Human Life in Space: The Role of Centrifugation as a Countermeasure George W. Freas II1 and Dr. Narasimha S. Prasad2, 1Supernal Technical Innovations LLC, [email protected], 2NASA Langley Research Center, [email protected]. Background: Over the years, researchers have created a substantial body of research investigating the effects of space and the microgravity environment to gain insight into the effects upon humans and space craft. The majority of these studies were performed on Earth, using centrifuges, clinostats or other test configurations to simulate low-gravity conditions. Human life sciences studies have been conducted on the ground using short-radius centrifuge facilities or with head-down bed rest (HDBR) to simulate the effects of microgravity on humans. [1] In the context of publicly accessible research, there are no documented instances of on-orbit centrifuges of sufficient size to generate artificial gravity (AG) for appliances similar to those on Earth. [2] Similarly, no human studies within orbital centrifuges exist. [3] Early experiments in SkyLab (M-131) explored the use of a chair that rotated 64 degrees in each direction to test the human vestibular function. This investigation was the closest analogue to a centrifuge performed on humans. The data indicates “astronauts were no longer susceptible to motion sickness when exposed to Coriolis, cross-coupling stimulation on or after the sixth day of their spaceflight.” and “further research is needed to better understand motion sickness susceptibility and vestibular adaptation.” [4] Although the International Space Station's (ISS) centrifuge facilities are not equipped for large-scale investigations like those involving conventional appliances or human beings, past research has investigated the potential of utilizing centrifuges for these tasks, and suggested utility in the use of such facilities. Despite centrifuge’s recognized potential and recommendations from advisory bodies like the National Research Council (NRC) [5] and COSPAR [6], dedicated, appropriately scaled AG research facilities have remained largely absent from orbital platforms. This paper will explore the potential of the use of the described centrifuges within the scope of the on-going development of space stations and space probes. Purpose: This paper brings forth a centrifuge concept specifically tailored for low gravity settings within orbiting space stations or in other extraterrestrial settings such as the moon or mars habitats. Two similar short-radius centrifuge configurations will be presented: one to facilitate the use of conventional terrestrial appliances in low gravity with little modifications, and another to address the health of astronauts while on extended missions away from Earth’s gravity. Consequently, the centrifuges presented here are larger than any in the ISS, one being 1.25m3 volume, and the other being large enough for humans to be within it (4.2m x 3m). These centrifuges are meant to fit within the volume of an orbital station and/or a human habitat on the surface of another planet. These centrifuges may be used in LEO to research the optimal configurations of rotating spacecraft, in order understand the limitations of short arm centrifuges in low gravity for all the use cases presented. Simulations of these centrifuge concepts are being implemented to gain insight into the validity of the designs, prior to their finalization. Objective: Two primary objectives are: 1) to increase the work volume of centrifuges in orbit to expand the use cases; 2) allow variable artificial gravity level for testing other simulated extraterrestrial environments such as the Moon, Mars, etc. The larger centrifuge would accommodate humans or larger scale investigations. One potential investigation could study the use of centrifugation within an Astronaut’s daily routine to observe if any of the known health issues of long duration missions are mitigated