Living in space, even just visiting for a few weeks or months, is tough. The environment out there can be deadly. Radiation will kill you slowly, and the lack of oxygen will kill you quickly. But those conditions can be mitigated. We build radiation protection into our spacecraft, and we carry oxygen, food, and water to keep us alive. But one dangerous aspect of space can’t be controlled: the lack of gravity. We currently have no effective artificial gravity.
You
might have seen videos of astronauts floating and spinning in their spacecraft
or sucking up blobs of water from mid-air. It may look like fun, but there are
long-term consequences of living for extended periods with no gravity.
Lack
of gravity causes unexpected and sometimes bizarre changes in the human body.
Astronauts who stay in space for too long develop puffy heads and bird-like,
thin legs. On Earth, gravity pulls your bodily fluids down to your legs, but in
space, that doesn’t occur. Your heart, for example, can more easily pump blood
up to your head and away from your legs. As much as a gallon and a half more of
various fluids can collect in and near an astronaut's head. Although that
problem disappears rather quickly after returning to Earth’s gravity, NASA is
working on ways to alleviate brain and eye strain during the time spent in
space.
As
their bodily fluids move toward the head of an astronaut, they can develop
neuro-ocular syndrome. The optic nerve swells due to greater fluid pressure,
causing the back of the eye to flatten. According to NASA, 70% of astronauts on
the ISS experience some amount of swelling in the back of their eyes. This may
cause blurry vision and the occasional headache. While glasses can help
alleviate this, researchers are concerned about how this might affect astronauts
on long-duration flights, such as a 1000-day trip to Mars.
On
Earth, your bones and muscles must constantly work to keep you upright against
the pull of gravity. With a lack of gravity, that’s no longer necessary, and
astronauts lose bone and muscle mass. NASA has developed exercises for
astronauts to do while in space, and although the effect reverses itself once
they return to Earth, doctors are again concerned about long flights to Mars.
In
space, your heart doesn’t need to work so hard pumping blood “uphill” to your
brain. As a result, the hearts of astronauts shrink a bit and become more
spherical. Upon returning to Earth’s gravity, they can have difficulty
maintaining normal blood pressure when standing. Again, this effect is reversed
on Earth, but long flights to Mars may be quite problematic for returning
astronauts.
As
the head swells and more fluids enter the astronaut’s brain, it can shift a bit
in their skull. This can lead to disorientation and issues with balance and
coordination. That effect fades with time in a weightless environment.
I,
for one, would be willing to deal with those issues for a chance to explore
Mars, but NASA must consider the health and safety of its astronauts and is
still seeking solutions to these problems.
Each month, I write an astronomy-related column piece
for the Oklahoman newspaper. After
it is published there, I post that same column to my blog page.
