Stephen Hawking has called for a massive investment in establishing colonies on the Moon and Mars, arguing that the world should devote about 10 times as much as NASA’s current budget — or 0.25% of the world’s financial resources — to space.

“A goal of a base on the Moon by 2020 and of a manned landing on Mars by 2025 would reignite the space program and give it a sense of purpose in the same way that President Kennedy’s Moon target did in the 1960s,” he said.

Over the next 200 to 500 years, humanity should try to expand to Earth-like planets around other stars, he added.