Those dreaming of a trip to Mars will be waiting least 15 years, the head of the European Space Agency (ESA) says.
"If there was enough money then we could possibly do it earlier but there is not as much now as the Apollo programme had," ESA Director-General Jan Woerner said.
Woerner says a permanent human settlement on the moon, where 3D printers could be used to turn moon rock into essential items needed for the two-year trip to Mars, would be a major step toward the red planet.
US space agency NASA hopes to send astronauts to Mars in the mid-2030s and businessman Elon Musk, head of electric car maker Tesla Motors, plans to put unmanned spacecraft on Mars from as early as 2018 and have humans there by 2030.
The ESA's Woerner said it would take longer.
A spacecraft sent to Mars needs rockets and fuel powerful enough to lift back off for the return trip and astronauts would need protection from unprecedented physical and mental challenges as well as deep-space radiation.
Woerner wants to see a cluster of research laboratories on the moon, in a "moon village", replacing the International Space Station when its lifetime ends.
That could be funded and operated by a collection of private and public bodies from around the world, he said.
"There are various companies and public agencies asking to join the club now, so they want to do different things, resource mining, in situ research, tourism and that kind of stuff."
The ESA, working with Russia, in March sent a spacecraft on a seven-month journey as part of the agency's ExoMars mission, which will sniff out signs of life on Mars and deploy a lander to test technologies needed for a rover scheduled to follow in 2020.
