There are some things we must do before we make an attempt on Mars, though.
- We need to make sure there is no life already on Mars. Once we start sending human beings to Mars, it will be impossible to prevent some microbes from making it to the surface, and there is every chance that some of them would find niches on Mars in which they could survive. Their presence could mask the presence of any native microbes. It's not likely that there is any life native to Mars, but we have to be sure; this could be our only chance to study them. Any Mars life would probably lie deep underground, so we will have to find a way to drill robotically and explore aquifers and the sites of ancient hot springs. This will take decades.
- We need to make sure humans can live on Mars long-term. The gravity on Mars is only about 1/3 what it is on Earth. Microgravity (the weightlessness experienced by astronauts in orbit) is known to have bad health consequences. Can we adapt to the low gravity of Mars, or will Mars always remain a place where we can visit, but not settle?
The best way to find out would be to establish a permanent station on the Moon. The Moon's gravity is even weaker than that of Mars, and it's conveniently nearby in case there is a medical problem. Presumably the first team on the Moon would stay for 2 years, the next for 4, the next for 6, etc., until we could be sure people could survive with no serious health problems for at least a decade. We would also bring some animals to see if low gravity affects the development of young -- we must not let the first families on Mars be guinea pigs.
- We need to solve the problem of energy generation by fusion so that energy constraints will no longer limit us. This will make it at least conceivable that we could move spacecraft with the massive (probably lead) shielding necessary to spend several months in space unprotected by the Earth's magnetic field, to send enough people and machinery to Mars to make a small city, and eventually to begin terraforming Mars to a less deadly environment. People are working on fusion now, but we are still decades away from it becoming a practical power supply.
Taking all these considerations into account, it is hard to know what to make of NASA's plans to go to Mars in the 2030s. It may be naive, it may be dishonest, or they may have goals entirely different from those I have laid out.