A good futurist can come up with all kinds of outcomes for humanity, but for those of us consumed by space exploration, a recent article in The Economist sketches a particularly bleak possibility. Forget about the stars. For that matter, forget about Mars, even the Moon. The new reality is emerging in the symbolic end of the Space Shuttle program and the eventual de-orbiting of the International Space Station. It’s a reality based on a space program that fares no higher than geostationary orbit and the growing technosphere that encloses us like a planetary ring.

The End of the Space Age is a cautionary tale about an all too real possibility, one that dismisses those anxious to move into the Solar System as ‘space cadets,’ while invoking the space ideas of the 1950s and 60s as an almost surreal excursion that quickly gave way to the outright fantasy of ‘Star Trek.’ The Economist will have none of the old optimism, the vision of ever expanding humanity pushing out to build an infrastructure throughout the inner planets and beyond. The view is stark. Declaring that the Space Age is probably over, the article adds:

The future… looks bounded by that new outer limit of planet Earth, the geostationary orbit. Within it, the buzz of activity will continue to grow and fill the vacuum. This part of space will be tamed by humanity, as the species has tamed so many wildernesses in the past. Outside it, though, the vacuum will remain empty. There may be occasional forays, just as men sometimes leave their huddled research bases in Antarctica to scuttle briefly across the ice cap before returning, for warmth, food and company, to base. But humanity’s dreams of a future beyond that final frontier have, largely, faded.

I bring you this counterbalance to our usual explorations as a way of pointing out that missions to the stars — or even the outer planets — are by no means inevitable, even if people like myself operate with a conviction that they will happen. One of the things that confounds predictions about when and if a true interstellar mission will fly is that history does not always follow a straight path. Cultures can turn inward, technologies can be turned to frivolous ends or disappear altogether, learning can be all but lost as it was for a lengthy period in the European dark ages.

But what The Economist is talking about isn’t a new period of darkness as much as a coming era of content with our own planet. After all, what the Space Age has delivered so far is impressive, and not just in our far-flung robotic missions. Out there at 36,000 kilometers where the telecommunications satellites orbit and extending down to low Earth orbit, our satellites give us global positioning systems and finely tuned weather forecasts, not to mention spy capabilities that change the equations of war. What if the sheer cost of space and growing public indifference put an end to further explorations?

An exhausted world economy, thinks The Economist, will pull us back to Earth:

With luck, robotic exploration of the solar system will continue. But even there, the risk is of diminishing returns. Every planet has now been visited, and every planet with a solid surface bar Mercury has been landed on. Asteroids, moons and comets have all been added to the stamp album. Unless life turns up on Mars, or somewhere even more unexpected, public interest in the whole thing is likely to wane. And it is the public that pays for it all.

There are answers to all these ideas, but the point is that those of us who believe in a human future throughout the Solar System are going to find ourselves challenged at every turn to explain why such an outcome is even possible, much less desirable. We’re at that juncture where government space efforts are being supplanted by commercial ventures like those of Elon Musk and Sir Richard Branson, a time when we have to find something on which to hang the space program beyond expensive space tourism. Maybe Robert Zubrin has found one way forward through his suggestion of using a bevy of SpaceX heavy-lift vehicles to haul materials to Mars for an early human outpost there. But SpaceX has to succeed with that vehicle first.

As commercial space efforts move forward, a broader defense of a human future in space has to take the long-term view. Given the dangers that beset our planet, from ecological issues to economic turmoil and the potential for war, can we frame a solution that offers a rational backup plan for humanity? Planetary self-defense also involves the need for the tools to alter the trajectory of any object with the potential to strike the Earth with deadly force, and that means expanding, not contracting, our space-borne assets. Such work is not purely technical. It also teaches the invaluable lesson of multi-generational responsibility and holds out the promise of frontiers. Such challenges have enriched our early history and provide us a clear path off our planet.

We’re also a curious species, and it’s hard to see us pulling back from the challenge of answering the crucial question of whether we are alone in the galaxy. There is a huge gap, as The Economist points out, between where we stand with space technology today and where we fantasized being as we looked forward from the Apollo days. But a case can be made for steady and incremental research that gives us new propulsion options and broadens our knowledge of how life emerges even as it protects our future. A future that includes gradual expansion into space-based habitats and the exploitation of our system’s abundant resources is an alternative to The Economist‘s vision, and it’s one the public needs to hear. The infrastructure that it would build will demand the tools and the skills to move ever deeper into our system and beyond.