Saturday, September 4, 2010

GraviTmod: Spacecraft Gravity Room

Weightless Astronaut - Physiological Effects
CONCEPT: At the moment, what is presented here is based on unproven assumptions, but have a reasonable potential to be a plausible and effective solution. The solution is the provision of 1G gravity environments for astronauts who are traveling in deep space for prolonged (greater than 180 days) periods of time at ZeroG (weightless).

KEY ASSUMPTIONS: The fundamental physiological assumption here is that the astronauts must experience a 1G environment at least 6 hours out of every 24 hours. This interval is expected to offset physiological conditions that generally weaken the astronauts overall physical profiles with strong potentials for direct impact on cognitive functioning as well. At the same time, it is recognized that the daily moving in and out of a gravity environment can also be destabilizing. What is not yet understood is whether this daily transition can eventually be tolerated by spacecraft crew without disorientation or discomfort.

SPACECRAFT CONFIGURATION: The spacecraft in this regard is essentially an extremely large, traveling space station that includes several interconnected modules. The central module is the gravity room (GraviTmod) that is a centrifuge system that gradually places astronauts into a 1G environment. As noted above, they remain in this environment for a total of 6 hours each day. The image of the Stanford Torus is one design example of a large centrifuge system that serves as the GraviTmod of the spacecraft.

Stanford Torus
MAJOR DESIGN AND OPERATIONAL CHALLENGES: Certainly the most obvious is the huge size of the space station/craft. The size is dictated by the space considerations for an artificial gravity system that uses the centrifuge concept.  To insure a 1G environment at a non-disturbing rotational velocity, the GraviTmod must accommodate a rotational arm(s) that is approximately 200 meters (600 feet) in length, This length is increased by the attachment of a rotational tube-room that must rotate at approximately 1-2 rotations/minute to achieve the desired gravity effect. This configuration is also essential, as stated above,  to insure that the crew inside experiences correct artificial gravity without it inducing disorientation, motion sickness, light-headedness, and other physical reactions to the rotational forces.

  • The 600 ft length is only the arm radius so the entire GraviTmod is more than 1200ft in diameter.
  • Another critical question is whether a centrifuge of this size will induce the gyroscopic effect that could effect both the maneuverability of the spacecraft-spacestation, and astronaut physical sense of balance. An excellent presentation on this issue was done by NASA. You may review that document here (pdf file download).
  • Another important consideration is long-term astronaut explorations of planetary and asteroid bodies with little or no gravity. This does not seem either wise or productive considering the physiological and possible neurological impact of prolonged weightlessness.  One technique would be to deploy robonauts instead of human astronauts for explorations in these environments. Another would be to consider the construction of a "on-the-ground" gravity module that served as home base for astronauts involved in long-term planetary explorations. In this concept they could at least be in a 1G environment for a safe daily interval to sustain their physical well being.
This author is a dedicated advocate for deep space exploration, but at the same time he recognizes the many human factor challenges that must be considered and met to insure a safe and productive exploration program. Weightlessness is only one vital consideration. In some of our solar system planets, there is little or no atmosphere and little or no protection from the solar winds and high cosmic radiation. These considerations must also be addressed before we can plan on sustained and safe human exploration of these planetary bodies.

Stanford Torus spacecraft design
Weightless Astronaut annotated image:: Courtesy Daniels and Daniels/Scientific American/Astrobiology


  1. A footnote comment. Since assembly of spacecraft in LEO is an active consideration, it would seem that either the expansion of the ISS or its eventual replacement with a space station that offers an artificial gravity environment is essential.

  2. Additional and current data on compensatory methods for coping with micro-gravity environments. Astrobiology, NASA, ISS