The stars are so far, and humans’ current space-travel range so limited, that it could take 100 years or more to even design a ship to travel interstellar distances. This weekend in Florida, though, dreamers gathered at a DARPA conference to take the first step: Batting around crazy ideas for how humanity could colonize the galaxy.
The Defense Advanced Research Projects Agency (DARPA) is known for its ambitious timetables. But even the mad scientists there expect that just building humankind’s first ride to the stars will take 100 years. Although actually traveling to the stars remains a faraway dream, the experts at the DARPA-sponsored 100 Year Starship Symposium this past weekend in Orlando reached something close to a consensus on how to get started, and what it will take to realize their vision.
Top engineers, physicists, and even science fiction writers put their heads together in what physicist and conference track chair James Benford called the “finest, widest, deepest coverage of starships that has yet occurred.” The 205 papers submitted (of which about 40 were presented), explored propulsion possibilities, extraterrestrial habitats, the ethical implications of scattering humankind’s progeny through the cosmos and more. The result: a step-by-step roadmap for settling the galaxy.
Michael Belfiore is the author of Rocketeers: How a Visionary Band of Business Leaders, Engineers, and Pilots Is Boldly Privatizing Space.
First, Let’s Get Off This Rock
One planet is simply not enough. Today’s merely terrestrial economy can’t support what’s likely to be a multitrillion dollar, century-long project. Over the next 100 years, we’ll need to harvest the energy and materials of the entire solar system, and use our explorations to the other planets, moons and asteroids of our solar system as a springboard to the monumentally more complex task of launching a starship.
Plus, Jill Tarter, research director at the Search for Extraterrestrial Intelligence Institute, gave two compelling reasons for settling space and then pushing out beyond the solar system. “We need to solve the single-point failure that is our human civilization on this single planet Earth,” she said. “We need to think about colonizing other bodies in the solar system to protect ourselves against a failure from our own technology, from our misuse of our resources and environment, or from a wandering interstellar rock that creates a civilization-ending impact.”
For such a sustained, expensive effort, we’ll need more than the efforts of a beleaguered space agency like NASA, or even a larger bureaucracy such the Department of Defense. It’s got to be an organization with extreme longevity and massive fundraising power. Interestingly, when trying to come up with an example of such a group after which to model a starship organization, conference-goer James Schalkwyk, a graduate student at the University of Cape Town, could think of only one in modern history: the Catholic Church.
NASA and other space agencies have already sent unmanned explorers to photograph and study the other planets of our solar system, including MESSENGER to Mercury, Cassini to Saturn, and the Mars rovers and many others to the Red Planet. But tapping the resources of another world is an entirely different degree of difficulty.
Philip Metzger, research physicist at NASA’s Kennedy Space Center, favors sending swarms of self-replicating robots to asteroids and rocky planets to build massive solar power stations and collect the raw materials needed for interstellar travel (as well as for solving problems here on Earth). These machines would look after themselves, presumably manufacturing everything from small prospecting bots to big diggers and other mining equipment as needed, and shipping raw materials and microwave-beamed power back to Earth.
Today’s standard chemical rockets would take tens of thousands of years to reach even the nearest stars, and the craft would need to be enormous to carry enough propellant. No, to get to another star within 100 years—the time frame conference participants settled on as reasonable—a human spacecraft would need to get up to a decent fraction of the speed of light—say, 10 percent.
For a ship carrying its own propulsion system, nuclear power is the surest (known) path to success. Humans can do fission; it’s what powers terrestrial nuclear reactors. Nuclear fusion, of course, would be more efficient (if it weren’t perpetually five years away).
Beyond nuclear power, would-be star travelers must turn to more far-out energy sources. Antimatter-powered rockets would yield the best thrust and efficiency, but that technology, though theoretically possible, is centuries away from development. In 2011, the DARPA conference experts agreed, it’s best left in the realm of warp drives, faster-than-light travel and other potential breakthroughs we can’t count on.
Sailing on Light
There is one possible propulsion alternative on the table now. NASA and other organizations are currently experimenting with solar sails—large thin sheets in space that catch the physical pressure of sunlight to push themselves along. In theory, engineers could build a laser that’s launched into orbit and used to push the sail up to speed. But there are just a few hiccups here: The light sail would need to be about a third the size of the moon, and the laser would need to pump out around 10 terawatts of energy—about the consumption of the entire human race today.
The starship visionaries aren’t deterred. Based on the acceleration of humanity’s power output, they say it’s possible within a century to reach a level at which a laser of that power is feasible. It’s “just” a matter of scaling up.
Send Robots Without Us
Naturally, many of the people working on the 100 Year Starship project would like to travel to other stars themselves—or at least give their descendants a crack at it. But, frankly, sending humans into space is a pain. And so the debate going on today about the necessity of human spaceflight will kick into overdrive when it comes to interstellar travel.
Why pick robots? Robots don’t need food, shelter, air, entertainment or medical care, making a robot-based mission vastly simpler than a human-centered one. The very first interstellar missions probably will be unmanned probes, whether people follow them or not. But sending machines presents its own set of challenges. The computers on board will need to be completely autonomous, and in fact approach human-level intelligence to determine what to do once they arrive. They’ll need to evaluate the destination star system for signs of life and figure out where to drop off sub-probes and landers.
Actually, Send Humans After All
Let’s be honest: Nobody’s going to all this trouble just so a bunch of machines can go to the stars while we stay home on this rock. The sci-fi visions that inspire projects like DARPA’s 100 Year Starship include humans traveling interstellar distances to brave new worlds.
But just how hard is it to transport human life through vast reaches of space? A ship with humans on board will need to be a self-sustaining, perfectly recycling ecosystem—a mini-world in itself with an unending supply of food. No material could be allowed to go to waste as the ship hurtles through the interstellar medium, which is devoid of even rocks that can serve as raw materials. The human spacecraft we’re familiar with, such as the space shuttle, were designed simply to make it home to Earth if something went wrong. No such luck in the interstellar void: All repairs would have to be made en route, making easy-access panels and other user-friendly components a necessity, along with 3D printing technology for making spare parts out of a well-stocked onboard supply of raw materials. To top it off, the ship would need to be robustly shielded to keep cosmic radiation from harming the crew and their DNA—DNA which will have to produce healthy offspring to complete the 100-year trip.
These are the known unknowns of interstellar travel. The experts at DARPA’s conference know all of them must be answered before humans can leave the solar system. For one thing is clear: No one at the conference even envisioned how to pull off a return. This is a one-way trip.
Fabio Evagelista is a Brazilian writer.
Crossed Paths is the first book of the Myra-Hati trilogy, an epic adventure in a post-apocalyptic world, for the lovers of sci-fi / fantasy genre. This is the author’s first work published in America.