"The first Starships to Mars will launch in 2 years when the next Earth-Mars transfer window opens. These will be uncrewed to test the reliability of landing intact on Mars. If those landings go well, then the first crewed flights to Mars will be in 4 years," Musk said on X.
The entrepreneur added that the frequency of flights will then begin to grow exponentially, with a goal to create a self-sustaining city on Mars in about 20 years.
"Being multiplanetary will vastly increase the probable lifespan of consciousness, as we will no longer have all our eggs, literally and metabolically, on one planet," he added.
The current cost of delivering a payload to Mars is estimated at about $1 billion per ton, Musk noted.
"That needs to be improved to $100k/ton to build a self-sustaining city there, so the technology needs to be 10,000 times better. Extremely difficult, but not impossible," he said.
Musk-led SpaceX is building a powerful Starship spacecraft for future long-distance space flights. So far, four test flights have been carried out, only the last of them, carried out in early June, was completed successfully.