A journey to Mars is not going to be easy and there are a number of problems that need to be solved before we go. One interesting problem is how do we monitor the astronauts themselves. Of course, it is easy to monitor their heart rate and blood pressure, but is it possible to monitor what is going on inside their heads?
Source:
https://phys.org/news/2020-01-brain-mars-scientists-track-astronauts.html