The journey from Earth to Mars takes about 300 days. Every two years Mars is at its closest point, only 55 million km from Earth, and it's the ideal time to send a spacecraft.Travel time depends on the positions of the planets and how much fuel you're willing to burn.very two years Mars is at its closest point, only 55 million km from Earth, and it's the ideal time to send a spacecraft. Travel time depends on the positions of the planets and how much fuel you're willing to burn.