Most space geeks would like to believe that all of the difficulties in interplanetary travel are to do with technology, and once you’ve cracked that, all you have to do is jump in your rocket ship and go.
The reality, unfortunately, is a little different. Hardware might be difficult, but human beings are frail and the solutions to their issues can be much more complex and challenging.
A lot of the reason why NASA has been parked in orbit in the ISS for the last twenty years is to research the human factors issues that a journey to Mars would present (okay, the ISS is a lot cheaper that Mars, as well).
At NASA’s request, the US National Academies of Sciences, Engineering and Medicine have just completed and published their latest review of NASA’s research in this area.
The report covers the areas you’d expect, physical impacts like muscle and bone loss, radiation damage and permanent damage to eyesite. It also looks at psychological impacts of living for long periods in a confined space, with only the same, few people to interact with, with no real time communications possible with family and friends back home.
These issues can only multiply when put together; if you’re having morale problems on the trip anyway, try throwing in having problems with eyesite and circulation.
Captain Kirk never had these problems!