“Chemical propulsion is obsolete to go anywhere other than the moon. Three days – that’s acceptable. But for Mars, we need propulsion technologies to get us there in, say, 60 days – then spend whatever length of time we want to spend and return when we want to come home.”

“Chemical propulsion is obsolete to go anywhere other than the moon. Three days – that’s acceptable. But for Mars, we need propulsion technologies to get us there in, say, 60 days – then spend whatever length of time we want to spend and return when we want to come home.”

— Gene Cernan