The Third Data Point

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.

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.