There's a better way.
Send a robotic mission to check out Phobos, including digging into it to make sure it isn't dangerously radioactive beneath the surface.
Send a nuclear powered robotic fuel factory to Mars surface, with the ability to launch enough rocket fuel and oxygen to orbit for a return mission.
Send supplies to Mars surface and to Mars orbit. Include tele-operated robots and a relay sat network.
Once you're sure they've arrived and deployed safely, launch the fuel factory back to orbit with enough fuel for a human return mission.
If that works ok, send a human crew to Phobos, where they land and dig in for radiation protection.
Dispatch a new fuel factory ship to Mars at the same time as the crew.
The crew's first task will be to secure the first fuel ship, for their eventual return mission.
From Phobos, the crew controls the robots on the surface to explore, prospect, set up infrastructure.
Each human should have at least 3 robots on the surface - most of the time the robots will be moving from point A to point B on their own, while the human controls the remaining robot.
Instead of a human that can only tolerate an hour or two in a suit on the surface each day, you get humans working in comfort at least 8 hours a day - making up for any loss in productivity from tele-robotics over being there in an awkward spacesuit. The crew works in shifts to make full use of the robots.
A relief mission arrives 2 years later, allowing anyone who wants to, to go home.
But it also brings more equipment for use on Mars, to start building a base for humans in some convenient location.
Two or three such missions later, with lots of experience landing and launching fuel factory rockets, the first human colonists land.
They find a well established base, already stocked with and producing fresh food and air and fuel.
They've got lots of smart tele-robotic helpers controlled from up above to keep them safe and make the mission a success.
The colonists mostly work via robots themselves - only going out in suits and rovers for special tasks and missions.
Most of their work is science or making stuff - in a shirt-sleeves environment - for the robots to deploy.
They don't plan to return to Earth, at least not for many years. They're colonists, not adventurers.
But very likely, some years later, a modified fuel factory ship will lift off to take the first Mars ambassador back to the old world.
The overall aim is to totally AVOID a flags and foot-prints model, that would lose support after 2 or 3 missions as happened with Apollo, dooming us to another 50 year gap.
It takes advantage of 35-50 years rapid progress in computers, software, robotics/AI, chemistry, manufacturing technologies, instead of blindly trying to repeat Apollo for Mars to show how wonderful and powerful and bold a nation we are. This time, it should be an international effort, even if one nation could do it.