What are the problems scientists are trying to solve in order to get to Mars?

Accessing water is the biggest problem I would say, it is obviously one of the things humans can’t live without and Mars lacks of water. Another problem would be the colder weather and the carbon dioxide atmosphere.
Scientist are also trying to find a safer way to get the astronauts to Mars, because taking a trip there causes them to be exposed to radiation.

Do you have more info about it ? i doubt this is the answer because i don't have all the information but if trouble was brewing in a clinic maybe it was an argument as to which clinic was better or smth of that nature