In 1945 British science fiction writer Arthur C. Clarke—now best known for 2001: A Space Odyssey—correctly predicted the invention of satellites, the first of which launched into space in 1958. Then in 1963, Clarke predicted that a man would land on the moon and safely return to Earth sometime around the year 1970—which Neil Armstrong and Buzz Aldrin did in the summer of 1969. In 1973, Clarke predicted a future where humans would be able to monitor outer-space threats such as asteroids and other near-earth objects—NASA established its Near-Earth Object Observations Program in 1998.

Much of what Clarke suggested about our future in outer space, however, has slipped further and further behind schedule in recent years. For example, he predicted commercial space flights by the year 2011 and a manned mission to Mars by 2021. He also spoke of a manned mission to Jupiter by 2099, which experts say looks pretty unlikely at this point.

Clarke was hardly alone in his optimism about what we could accomplish in outer space, and when we might accomplish it. Many others—including experts whose field was science rather than science fiction—have made predictions that we’ve failed, so far, to turn into reality. Why has the trajectory of our reach into space gone so far off course?

The challenges that stand in the way of achieving audacious goals outside the boundaries of Earth are many, including budgetary and technological limitations. But according to the experts who recently gathered to discuss the subject in Germany, the biggest obstacle standing in the way of our progress toward going where no man or woman has gone before is entirely in our heads.

Failure to launch

During the Asgardia Space Congress in Darmstadt, which focused on “paving the road to living in space,” experts from a range of disciplines presented their research into the various challenges that prevent us from living in space today, as well as potential solutions. They included the need for better artificial gravity and life-support systems, as well as a range of biomedical challenges; but the one most agreed would be the biggest barrier to a future in which humanity lives anywhere but its home planet is psychology.

“The hardest barrier to get over is the mindset,” argued Jeffrey Manber, the CEO of Nanoracks, which develops products for and conducts experiments on the International Space Station. “I get up on the planet earth, I work on the planet earth, I play on the planet earth, I go to sleep on the planet earth. Why do I need to do anything elsewhere?”

Manber considers how little progress has been made in the exploration of space since man first landed on the moon “a tragedy of the will of the species, not technical innovation, clearly.” He explains that while the advancement of technology over the 50 years since has been astounding, very little effort has been dedicated to the further exploration of space. “iPhones innovate every year, and yet we’re unable to innovate as quickly in what we do in space,” he says.