ADELAIDE, Australia — Elon Musk is revising his ambitions for sending people to Mars, and he says he now has a clearer picture of how his company, SpaceX, can make money along the way.

The key is a new rocket — smaller than the one he described at a conference in Mexico last year but still bigger than anything ever launched — and a new spaceship.

Speaking on Friday at the International Astronautical Congress in Adelaide, Australia, Mr. Musk said he had figured out a workable business plan, although his presentation lacked financial figures to back up his assertions.

Mr. Musk has long talked about his dreams of colonizing Mars, and at the same conference last year, he finally provided engineering details: a humongous reusable rocket called the Interplanetary Transport System.