One iconic image expresses our existential condition: the pale blue dot. That photograph of Earth the Voyager 1 spacecraft took in 1990 from 6 billion kilometers away told us how small we are. What worries me is that dot may be all we ever have, all we can command, for the indefinite future. Humanity could become like rats stuck on the skin of our spherical world, which would look more and more like a trap.

Imagine: we've had our burgeoning history here and used up many resources…so what happens when they run out? Valuable things like metals, rare earths, fertilizers and the like are already running low. More things will join the list.

Voyager has flown outward for over 35 years, huge return on the taxpayers' investment. It is the first probe to leave the solar system and is the farthest man-made object from Earth. Voyager is now exploring the boundary between our little solar system and the vast interstellar space beyond.

It can instruct us still, about our more pressing problems, as Sagan pointed out: "Think of the rivers of blood spilled by all those generals and emperors so that in glory and triumph they could become the momentary masters of a fraction of a dot."

They fought over resources we could exhaust within the next century or two. Voyager's perspective also suggests an answer: there's a whole solar system out there. Sagan pondered that aspect, too: "There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet."

That is still true, but the vast solar system can help us. I worry that we will miss this opportunity.

After all, great civilizations have turned away from horizons before. In the 1400s China stopped trading and exploring in Africa and Arabia out of concern that this introduced unsettling elements into their society. Their 9-masted ships were a hundred meters long, and carried animals like giraffes back to China to amuse the emperor. China could have found America and ruled the oceans, but it chose to stay home.

We may be entering a similar age. This century will doubtless see our population rise from its current 7 billion souls to 9 or 10 billion. Climate change will wrack economies and nations. The bulk of humanity has large economic ambitions that will strain our world to satisfy. With the USA imitating Europe in its evolution into an entitlement state, it will have less energy to maintain world order. Amid constant demands for more metals, energy, food and all the rest, it seems clear we can expect conflicts among those who would become "momentary masters of a fraction of a dot."

But we can see in our skies the resources that can aid the bulk of humanity. With entrepreneurs now pulsing with energy, we have plausible horizons and solutions visible. SpaceX (Space Exploration Technologies Corporation), founded by former PayPal entrepreneur Elon Musk, now delivers cargo to the International Space Station. SpaceX became the first private company to successfully launch and return a spacecraft from orbit on 8 December 2010, and Musk remarked on his larger agenda, the economic opening of space, "We need to figure out how to have the things we love, and not destroy the world."

The black expanses over our heads promise places where our industries can use resource extraction, zero-gravity manufacturing, better communications, perhaps even energy harvested in great solar farms and sent down to Earth. Companies are already planning to do so—

Bigelow Aerospace (orbital hotels), Virgin Galactic (low Earth orbit tourism), Orbital Technologies (a commercial manufacturing space station), and Planetary Resources, whose goal is to develop a robotic asteroid mining industry.

Barely visible now is an agenda we can carry out this century to avoid calamity, those rivers of blood, and anguished need. We Americans especially know from history how to open new territory.

Historically, coal and the railroad train enabled much of the industrial revolution. Both came from the underlying innovation of steam engines. Coal was the new wonder fuel, far better than wood though harder to extract, and it made continental scale economies possible. Synergistically, coal drove trains that in turn carried crops, crowds and much else.

A similar synergy may operate to open the coming interplanetary economy, this time wedding nuclear rockets and robotics. These could operate together, robot teams carried by nuclear rockets to far places, and usually without humans, who would compromise efficiency. Mining and transport have enormously expanded the raw materials available to humanity, and the rocket/robot synergy could do so again. As such fundamentals develop in space, other businesses can arise on this base, including robotic satellite repair/maintenance in high orbits, mining of helium 3 on the moon, and metal mining of asteroids. Finally, perhaps snagging comets for volatiles in the outer solar system will enable human habitats to emerge within hollowed-out asteroids, and on Mars and beyond.

Nothing has slowed space development more than the high price of moving mass around the solar system. Using two stages to get into Low Earth Orbit may make substantial improvements, and beyond that the right answer may lie in nuclear rockets. These have been developed since the 1960s and could be improved still further. Lofting them into orbit "cold"—that is, before turning on the nuclear portion—may well erase the environmental issues. Fuel fluids can be flown up separately, for attachment to the actual rocket drive. Then the nuclear segment can heat the fuel to very high temperatures. Economically this seems the most promising way to develop an interplanetary economy for the benefit of humanity.

Such ideas have been tried out in the imaginative lab of science fiction, exploring how new technologies could work out in a future human context. Kim Stanley Robinson's 2012 visionary novel, 2312, portrays such a solar system economy. Another 2013 anthology, Starship Century, has more chapter and verse on this. Our reborn entrepreneurial space culture emerged from an earlier epoch that saw space as the inevitable next horizon. The fresh industrial reality is already making a larger cultural echo in novels, films and much else. It's a space era again.

Sagan spoke often of how the view from space gave us perspective on our place in the cosmos. That started with Apollo 8's 1968 swing around our moon and its backward look at the Earth. Many felt, looking at those photos, that future exploration of space should focus on ways to protect Earth and to extend human habitation beyond it. Sagan had the idea of turning Voyager to look back at ourselves, and tried to tell us to take the larger perspective in his Pale Blue Dot: A Vision of the Human Future in Space.

That first flowering into space set a tone we should embrace. In the end, history may resemble a zero-sum game ruled by resources. We can only win such a game by breaking out of its assumptions.

Babylonian astrologers thought the stars governed our fates. A thousand years ago, societies were largely religious and prayed to the skies for their salvation. We can seek our futures there now as well. And an age might come when we shall govern the fate of stars.