Partial G Health Experiment

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The mission: research the long term impact of partial gravity on human health.

  • What is the impact of partial gravity on human health?
  • How much gravity does a human body need to stay healthy?
  • What kinds of exercise are needed to keep the human body healthy at partial gravity?
  • How much exercise is needed to keep the human body healthy at partial gravity?
  • Specifically: what is the health impact of Moon and Mars gravity?


The impact of zero gravity on human health has been studied for decades on Russian and US space stations. We know the human body needs gravity to stay healthy, but nobody knows how much gravity is needed. We need research on the health impact of long term living in partial gravity environments, especially the 0.17G on the Moon and 0.4G on Mars.

One way to test the long term impact of lower gravity on the human body would be to set up stations on the Moon and Mars and have people live there for a long time. However, this is very expensive and could be dangerous - sending people to another planetary body without the right exercise equipment could seriously impact their health.

Testing the impact of partial gravity on human health in low earth orbit has several advantages:

  • Astronauts could be brought back to earth quickly if health problems come up.
  • The gravity on a space station can be adjusted, so various levels of gravity can be tested in one laboratory.
  • As usual the equipment would require expensive launch on rockets to orbit, but the cost of design and fabrication for things launched into orbit is usually a number of times greater than the launch costs .

The impact of the last item cannot be underestimated because the lowest estimate that could be made is likely to be greater than the impact of the experiment as a whole. If an experiment like this is too expensive, it will not be done. However, if it can be designed privately at no cost whatever to the government and offered freely to NASA, it is still unlikely to be done. Using off the shelf components as much as possible could reduce development costs but is likely to increase launch costs by resulting in a heavier experiment package.


See Also: Partial G Todo

The details involved in a partial gravity health experiment are being discussed in IRC chat room [1].

Initial back-of-the-envelope idea:


There is no need to have this experiment done before establishing a robotic colony on Luna. Once robotic industry is established one g gravity can be provided if it is found to be necessary. A centrifuge can be constructed on the Moon out of lunar materials to provide for the health of personnel that maintain the base.


If such an experiment is undertaken by NASA it is likely to incite claims that NASA is just making busy work to justify the large appropriations rather than attempting to accomplish anything. Indeed such claims are already made and this would be another case of a program going in circles and getting nowhere.


The primary Partial G Experiments will be focussed on the impact of partial gravity on human health.

Secondary research objectives should focus on areas that are not adequately studied on the ISS, for example space agriculture.

Space Station

In order to simulate partial gravity, the space station will need to rotate or contain a large centrifuge. A rotating space station needs to be of a sufficiently large diameter or consist of components mounted in a "dumbbell" arrangement.

A current idea is to modify a Bigelow inflatable space station by assembling a floor from smaller rigid components inside the inflatable walls. See Partial G Space Station.


To save costs, only off the shelf launch vehicles will be used: Partial G Launch Vehicles.

Cost estimates

Unlike zero gravity workshops, which are used for all kinds of experiments, the partial gravity research laboratory is useful only for a smaller set of experiments. To put it bluntly, costs will need to be lower.

In order to ensure that constraint, the Partial G Cost Estimates page will be used to track cost estimates during every phase of planning the experiment.

See Also


  1. in in #space