This summer, we will witness the beginning of a new era in spaceflight with the launch of the Artemis 1 unmanned mission to space. Like Apollo the Artemis program will enable human landing on the Moon. More importantly, the beginning of long term human activities will create a new opportunity. It will enable us to complete the study of the human body and zero‑G.
Why do I say complete? Admittedly, the International Space Station (ISS) studies of the human body and zero‑G have made a clear picture of the effects on human physiology. It is common knowledge that decalcification of the bones is an issue that is offset with exercise. Less well known is the deformation of the eyeball associated with the blood pooling in the upper body. Least widely known is the fact that many genes shut down while others turn on in minutes of the body reaching zero‑G.
These physiological changes could have even more profound impact over longer duration missions. I worry about the combined effects of these changes to the body for a mission to solar system destinations. A crew that could arrive at their destination crippled, blind, and fighting unknown disorders. I wonder if that crew could be effective. So why is the ISS studies incomplete? The answer is: we don’t know how much gravity is enough. Landing on the Moon will help us answer that question.
Human Body and Zero‑G and One-sixth G
The Artemis 3 mission enables a very useful data set. The day before launch and within the first day after launch, a blood sample can be taken. This has been done in the past for Shuttle and ISS missions. They use the blood to perform a genetic test to determine the genes that have been activated and deactivated as a result of entering zero‑G. The only thing different with Artemis 3 is that a third condition can be tested. Within the first day after landing on the Moon, a third blood sample can be taken. Also, this will enable knowing the genes activated and deactivated as a result of entering one-sixth G.
Having the third data point, a curve will begin to appear. The shape of the curve will give insight into the effects of gravity on the human body. It could be either that the body requires nearly one‑G to be healthy. Or at the other extreme, a very little gravity could be enough to counter the negative effects. Either way, we’ll be getting some of that insight with real data.
After longer missions to the lunar surface have been done, the effects of bone loss and blurred vision will be characterized. Ultimately, we’ll have a means to interpolate between Earth’s one G and the gravity of any destination. It will also give sense of the engineering challenges associated with interplanetary travel. If the Moon’s gravity is sufficient to offset much of the effects associated with the human body and zero‑G, a spin gravity of one-sixth G is sufficient to offset these effects. Engineering such a system is left for another discussion.