Elon Musk has clear plans to colonize Mars; he thinks that if we advance tech over the next 50 to 100 years, we might be able to get 1 million people over there.
Using reusable rockets, like SpaceX’s Falcon 9 Heavy and Falcon 9, which have been successfully landed and relaunched, ships would first be launched and then be fueled up for the trip to Mars while in space. The ship that Musk envisions going to Mars is called the ITS (Interplanetary Transport System); the ITS would in fact be using the Raptor engine that SpaceX is currently developing.
This ITS would have 42 Raptor engines making it the biggest rocket in history and also woule be capable of carrying a record 550 metric tons on an expendable mission.
The ITS, once fueled, would set off at the perfect time between the Mars and Earth orbits around the sun. While on this interplanetary journey, Musk says people will have great fun: there will be lectures to attend, one restaurant, cabins, and movies.
He says the ITS might carry 100 people or more, and he thinks 1,000 of these trips could be made to Mars over the next 50 to 100 years, hence the million people on Mars projection. Musk really wants to make this very affordable; currently it might cost $10 billion to get to Mars, per person. He wants to reduce this to a very affordable $200,000, so that if we need to explore a new planet, we have reduced the cost of doing so, primarily by making the rocket systems as reusable as possible.
With all this being said, and as ambitious as Musk might be, he is still relying on successful testing, which will continue to 2023, testing which is dependent on support from NASA.
At some point over the next 5 years, it might slowly become apparent whether future millionaire families could blast off in a cloud of smoke and go and visit or live on Mars.