Posts Tagged ‘human physiology’

Living in Microgravity

In Larry Niven’s The Integral Trees and its sequel The Smoke Ring, the crew of an interstellar exploration party settles an unusual habitat: a torus of gas containing plants, animals and water orbiting a neutron star.

Astronaut Pedro Duque watches a water bubble aboard the IS

While some of  the Smoke Ring colonists live on giant trees that provide pseudogravity, many live in free fall. Even though original crew that settled the Smoke Ring had been selected for their physiological tolerance of microgravity, their offspring did not develop normally.

Pregnancy was easy in low gravity. Women became pregnant many times during their lifetimes. Infant mortality (“lost ones”) was high, perhaps around sixty percent; the natives seemed to take it for granted.  [...] the growth of bones and organs was altered by altered gravity. Some children could not digest food. Some grew strangely, until their kidneys or livers or hearts or intestines would no longer work because of their shape
~ The Smoke Ring

However, those who survived childhood were quite tall and thin and functioned just fine with misshapen limbs in free-fall. Humans adapt well to new environmental conditions.

While Niven’s depiction of the biological effects of microgravity seem plausible,  we’re only beginning to understand the long-term effects of microgravity on the human body.  From studies of astronauts on Skylab, the International Space Station, and the Space Shuttle we know that the physiological effects of weightlessness include loss of bone density,  muscle weakness, and a reduction in immune system function. Those physiological issues haven’t caused serious complications to astronauts when they return to Earth. Human bodies are resilient.

But what about long-term human colonies in low gravity? That’s currently the realm of science fiction, and there are lots of aspects to consider.

Will people be able to have babies? One obvious concern is that human reproduction will be serious affected. While frog and fish embryos appear to develop normally, the lack of gravity appears to impair the early stages of mouse development. Clearly more research needs to be done before people consider having babies in space the old-fashioned way.  Could there be a technological solution?

And what about the other needs of colonists, who will be subject to the physical changes of aging and will have plenty of leisure time? There have been a few interesting inventions along those lines, such as special adjustable eyeglasses for free fall and the 2Suit, meant to “stabilize human proximity” for sex.  Other inventions are sure to be developed as soon as there is a market for them.

Astronaut Carl Walz performs on the space shuttle.

The colonists would also certainly develop new customs specific to their living conditions. Take, for example, the free-fall banquet in John C. Wright‘s story “Guest Law”:

[The Captain's] feast was arranged in a circle around her, little colorful moons of ripe fruit, balls of wine-jelly, spheres of lacy bread, meatballs or sausages tumbling end-over-end. As the feast progressed, she would rotate slowly clockwise, to let one delicacy after another come within reach of hand and foot (toe-foods for the foot, finger-foods for the hand) and the order of the orbiting food around her was organized by traditional culinary theory.

Since the captain’s head was always “up,” the feasters must be attentive, and match their rotations to the captain, eating neither too swiftly nor too slowly, nor grabbing for any favored food out of order.

Nothing like that could take place in gravity!

So while science fiction has indeed frequently touched on different aspects of living in free fall, there still many aspects of living in microgravity that are ripe for science fictional speculation.

  • Will medicine be able to prevent the effects of low gravity on bone loss and muscle tone? Would that even be necessary?
  • What advances in technology would make life in microgravity easier?
  • How could genetic engineering improve human life in microgravity?
  • What would childhood and old age in microgravity be like?
  • What sort of microgravity-specific rituals would develop?

Background reading:

Edited to add: A study released by NASA today shows “Astronauts can become as weak as 80-year-olds after six months at the International Space Station