A new timeline from the billionaire underscores there are increasingly fewer windows to reach the red planet in his lifetime.

Elon Musk dreams of colonizing Mars in his lifetime, but the clock is ticking—and he knows it.Such is evident from a recent string of X posts about the precise timing required for interplanetary travel and the pesky regulations standing in his way.

Musk said SpaceX plans to launch five uncrewed Starship rockets to Mars in 2026, followed by the first manned missions either two or four years later.