In the Fourth Doctor story “The Ark in Space” (1975), the TARDIS materializes on an aged space station, and the Doctor realizes the ark is a generation starship.
There is no way back into the past; the choice, as Wells once said, is the Universe or nothing. Though men and civilizations may yearn for rest, for the dream of the lotus-eaters, that is a desire that merges imperceptibly into death. The challenge of the great spaces between the worlds is a stupendous one; but if we fail to meet it, the story of our race will be drawing to its close.
—Arthur C. Clarke, Interplanetary Flight (1950)
Roughly forty-five light-years from planet Earth sits a star in the famous constellation Ursa Major, the Great Bear, whose associated mythology likely dates back into prehistory. The star in question is 47 Ursae Majoris, formally named Chalawan. What makes 47 Ursae Majoris so special? In 1996, it became one of the first stars to have exoplanets discovered in orbit about it, and it is now thought to have at least three known planets. The light that reaches Earth from 47 Ursae Majoris is forty-five years old, given the distance between our two systems.
And when that light was leaving 47 Ursae Majoris, a Doctor Who story called “The Ark in Space” was televised for the first time. In the 1975 tale, the TARDIS materializes on an old space station. When the Fourth Doctor explores the old station, he realizes it’s a kind of ark. The idea of such arks, or generation starships as they’re sometimes known, is a good example of the way in which science and science fiction influence one another. That’s because many of the engineers and scientists who wrote about generation starships were also sci-fi writers. One of the earliest accounts of a “space ark” is in the 1929 essay The World, the Flesh, and the Devil. It was written by Irish scientist J. D. Bernal. Bernal’s essay was about the idea of human evolution and the human future in space. He described ways of living in space that included what we now call generation starships.
Pioneering rocket engineers also wrote about long-duration interstellar journeys. American rocket scientist Robert Goddard was among the first in his 1918 paper, The Last Migration. Here Goddard describes the death of our Sun and the journey of an “interstellar ark,” on which its crew would travel for centuries in suspended animation until waking at their ultimate destination—another star system.
Russian rocket pioneers were at it too. Konstantin Tsiolkovsky, the father of astronautic theory, wrote an account of the need for multiple generations of passengers in his 1928 essay, The Future of Earth and Mankind. Tsiolkovsky described a cosmic “Noah’s Ark”—a space colony kitted out with engines, which travels for thousands of years.
Human imagination is often light-years ahead of practice, of course. And, as the Doctor knows, we humans don’t as yet have too much experience of spaceflight. Space arks are one thing, but so far humans have only traveled to the Moon. Our Galaxy, the Milky Way, is about one hundred thousand light-years wide. And destination Moon, to which we’ve sent a number of manned missions, is a mere light-second away. You can see the distance problem with space travel quite easily.
Consider speed. At the moment, space travel is slow and expensive. In the Fifth Doctor story “Enlightenment,” the Doctor is aboard a spaceship that uses solar sails. In our real Universe, the fastest of these sail-ships work by aiming lasers (essentially beams of light) at specially made sails. When the laser hits the sails, it causes the ship to move more quickly than if they relied on the Sun alone.
Now, imagine we could launch such a solar-sailed ship from Earth. And imagine also that the ship aims a high-powered laser beam at the sails to propel it. That ship would take around forty years to reach the nearest stars. Not exactly quick, is it? Imagine how long a Doctor Who story would be at those speeds! And what about the stars and galaxies beyond? Now you can see why, from the very get-go, rocket pioneers and sci-fi writers realized humans would need generation starships to last long journeys.
Luckily, Whoniverse travel doesn’t depend on solar sails. And, generally speaking, space travel is thought to be one of the first steps a species takes in their development as a sophisticated civilization. Like us, the Time Lords realized that the vacuum of space is an extremely hostile place that can seriously mash up your genes. Earth scientists think that a mission to Mars is just about doable for humans, as the radiation sickness would be deadly if we tried to venture out any farther. The main problem is “galactic cosmic rays”—the nuclei of atoms traveling at ultra-high speeds. One solution to such rays could be the one used in the Doctor Who episodes “42” and “The Impossible Planet.” By the forty-second century, it seems that many human spaceships and bases have developed force fields to protect them from the harmful effects of space.
Rockets and spaceships are one way, but what other ways of space travel does Doctor Who suggest? Well, in the early Doctor Who story “The Seeds of Death,” we learn how humans stopped making rockets for spaceflight because of a new technology known as T-Mat. T-Mat stands for Travel Mat Relay. Using T-Mat tech, humans could be instantly teleported between the Earth and the Moon. But when humans stopped investing in rockets, we also lost interest in traveling beyond the Moon, then soon even forgot how to use rockets. Except, that is, for one guy who worked in a museum and was privately building his own retro rocket.
In later stories, the T-Mat tech is barely mentioned. Next, all we hear about is the Transmat, or matter transmitter. Transmat is used to transport humans between planets or space stations. And yet in one story a Transmat beam is used by the Time Lords to teleport the Doctor all the way to Skaro from future Earth. Transmat had considerable potential! So, according to the Time Lords, instantaneous space travel was possible. And before you say this is all nonsense, do remember that science is never finished. When so-called experts tell you that certain aspects of Whoniverse travel are impossible, remember to take their advice with a grain of salt. Science is always refining what we know. And if something seems impossible now, that doesn’t mean it’ll be impossible in the future.
Having said that, American sci-fi writer Kim Stanley Robinson revisited the question of the generation starship in a 2016 Scientific American article called “What Will It Take for Humans to Colonize the Milky Way?” Robinson’s novel Aurora, published in 2015, follows a gargantuan generation ship and its seven generations of humans as they make their way to the Tau Ceti system, twelve light-years away, to start a human colony.
And what did Robinson have to say on the topic of space arks? “The idea that humans will eventually travel to and inhabit other parts of our galaxy was well expressed by the early Russian rocket scientist Konstantin Tsiolkovsky, who wrote, ‘Earth is humanity’s cradle, but you’re not meant to stay in your cradle forever.’ ” But Robinson’s conclusion was cagey.
An interstellar voyage would present one set of extremely difficult problems, and the arrival in another system, a different set of problems. All the problems together create not an outright impossibility, but a project of extreme difficulty, with very poor chances of success. The unavoidable uncertainties suggest that an ethical pursuit of the project would require many preconditions before it was undertaken. Among them are these: first, a demonstrably sustainable human civilization on Earth itself, the achievement of which would teach us many of the things we would need to know to construct a viable mesocosm in an ark (a mesocosm is an outdoor experimental system that examines the natural environment under controlled conditions. In this way mesocosm studies provide a link between field surveys and highly controlled laboratory experiments.) Second, a great deal of practice in an ark orbiting our sun, where we could make repairs and study practices in an ongoing feedback loop, until we had in effect built a successful proof of concept; third, extensive robotic explorations of nearby planetary systems, to see if any are suitable candidates for inhabitation. Unless all these steps are taken, humans cannot successfully travel to and inhabit other star systems.