
We read many quotes from various sources about humans traveling to the Moon, Mars, or some distant moon of Jupiter or Saturn. Most media stories seem to indicate that all astronauts would need to survive the journey is a space suit. They overlook the fact that the human body is carefully engineered to survive on Earth, but studies from the International Space Station show a new challenge for astronaut eyes in space.
We can address the damage to the heart and some other organs by providing enough cardiovascular activity on treadmills. However, new data on astronaut eyes in space show that long periods of weightlessness affect ocular biomechanics. More than 70% of astronauts on the International Space Station have Spaceflight-Associated Neuro-Ocular Syndrome (SANS).
NASA collected data on 13 astronauts who spent between 157 and 186 days in a weightless environment. The studies detailed a 33% decrease in ocular rigidity, an 11% decrease in interocular pressure, and a 25% reduction in ocular pulse amplitude. These changes caused decreased eye size, an altered focal field, optic nerve edema, and retinal folds. The researchers point out that some of these effects can produce long-lasting changes in the eye’s mechanical properties.
Science shows that the human body is engineered and designed for the gravitational effects of our planet. If only one or two things were essential for life on Earth, you might attribute it to chance. We are not talking about one or two things but the human body as a total unit. Every organ has to adjust when the body is subjected to weightlessness, but most organs cannot change. When NASA put Scott Kelly in space and his identical twin Mark stayed on Earth, it provided a comparison. Scott was in space for 340 days during 2015-16, and there were changes in his DNA and numerous changes in his body.
Now, we have additional data showing the effect of weightlessness on astronaut eyes in space. Some items like ocular pressure have potential complications like glaucoma. It is obvious that our bodies are engineered with many individual characteristics essential for life. The more variables that must be “just right,” the less likely it is that the final product could exist by chance.
For an airplane to fly, thousands of features must be carefully engineered. That requires engineers, not chance. That is even more true for the human body. God carefully designed us to live on planet Earth, and the media often oversimplifies what we need for space travel. Look in the mirror and behold the handiwork of God. (See Psalms 139:14.)
— John N. Clayton © 2025
References: National Institutes of Health, NASA, and Glenn Research Center