But since our spacecraft won't have the capability to travel at or even near the speed of light, or be equipped with human hibernation technology, starting out with a crew of adult astronauts would be impractical for interstellar space travel.
I propose that in order to maximize the life expectancy of all astronauts in generational space travel, most of the initial crew would have to be very young - ideally children between the ages of 5 and 6. The thought of sending children into outer space might seem horrifying to some, but think of it this way: It's every child's dream to become an astronaut, so why not make the dream a reality early on in life? The children would be raised and further trained by the few adults who departed with them on the original trip. Those children would grow into adults and be able to care for themselves, their children (born and raised onboard the generational spaceship), and the spacecraft by the time the original adult astronauts grew elderly. The children born and raised aboard generational starships would consider their environment as perfectly "normal," because they had not been exposed to anything else. This would virtually eliminate any potential problems with claustrophobia.
Life expectancy on board the spacecraft would be drastically prolonged due to the unpolluted atmosphere and lack of chemically altered foods humans have been accustomed to consuming in their diets. Gravitational stress, UV radiation, and other factors that take a toll on human bodies on Earth wouldn't exist for this crew. Some might live to be 150 years old, but look like they're 40. The only visible sign of age would be white hair. However, the astronauts, both young and old, would have to keep up a regular exercise routine in order to avoid problems associated with living in space, such as the affects of living in a mostly weightless atmosphere. Foods might also be modified to help maintain bone density.
Conceivably, the first spacecraft to
embark on such a voyage would have to be designed to accommodate and
sustain enough passengers to maintain genetic diversity through several
generations when the astronauts begin producing new generations. A minimum
of 10 individuals would accomplish this, but more would
obviously be better because of the genetic variety the larger pool would
offer. To avoid the stress of overpopulation, reproduction among crew
members would have to be carefully planned.
Given the nature of the voyage (interstellar migration), having a large, frozen repository of plant seeds would be imperative. These seeds could be used on other planets both to grow food and potentially for terraforming. This could be achieved through a process called vitrification. Originally used to make glass, vitrification has become a relatively new way to preserve living tissues at very low temperatures. Specially engineered, small, light-weight freezers capable of subzero temperatures between -80°C to -196°C (the boiling point of liquid nitrogen) would be required to preserve this living databank of plant life over hundreds of years. At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death, is effectively stopped. Vitrification provides the benefits of conventional cryopreservation, but without the organic damage due to ice formation. When defrosted, seeds can still germinate to produce healthy plants.
A Theoretical Space Journey
A spacecraft left Earth more than three centuries ago bound for the nearest star outside our solar system: Alpha Centauri. But time has no meaning in space. We count "our time" from the moment the initial crew stepped into the spacecraft and took off from Earth. In the meantime, nine generations have been born and died aboard the spacecraft. The original astronauts with memories of having lived on Earth have long ago passed on. The voyage has included "pit stops" along the way to gather supplies from a few isolated asteroids and a comet or two. There have also been numerous new scientific breakthroughs - the results of which have been transmitted back to Earth.
But finally, the original destination of the voyage is realized: we arrive at the triple star system of Alpha Centauri. The first two stars, known as Centauri A and B, are situated very closely to one another, while the third star (a red dwarf called Proxima Centauri) is far from the other stars. Our star charts have been pretty accurate up until now, but once there, our instruments might detect many unexpected small objects the size of the Moon orbiting the Centauri A and B stars. Obviously we are surprised by the inaccuracies in our star charts, but we don't care because we are thrilled to have found small Earth-like planets in the vicinity of our destination. Our instruments also detect smaller objects that look like asteroids orbiting these small planets. Our task is to choose one that best suits our needs. From all of these small planets, one of them attracts our attention due to the presence of a thin atmosphere with a similar mixture of gases to Earth. Since we don't yet know what to call it, we'll temporarily refer to this new world as planet Alfa. Because this planet has less mass than Earth, the gravitational pull is also much less.
On parts of the surface, our onboard instruments detect the presence of oxygen, silicon, magnesium, titanium, manganese, sodium, potassium, and calcium. It's enough to make us choose this planet for our first settlement attempt. Before we use up the limited energy that we currently have by sending expeditions to this planet, we first create dome-shaped ecosphere outposts (bubble habitats) in the craters of nearby orbiting asteroids. These outposts will house launching pads, telecommunications stations, stock supplies and possibly yield valuable metals and minerals through mining. The crew must work synergistically to get the job done as efficiently and quickly as possible.
We first create outposts on two of the asteroids orbiting the planet. Sending more sophisticated probes to planet Alfa gives us a more accurate idea of what we'll need to establish a successful settlement that can become our permanent home. We determine that we can terraform part of the planet without disturbing the existing ecosystem. Apart from the elements already detected in both the surface and atmosphere, our instruments also show a lot of unidentified elements or substances. Down below we also see many meteor impact craters, and a lot of small lakes with a mauve tint. Interesting... strange... amazing.... All of our readings indicate that it's safe, and so we continue with our plans.
Since meteor craters are ideal for mining, we create our first live colony on planet Alfa by building an enclosed domed ecosphere - our first small town - over a crater. Because of the thin atmosphere, we have to use oxygen masks frequently when we get tired. We begin to think of creative ways to solve the fact that there's not quite enough oxygen in this atmosphere. While we will continue to use oxygen masks until we can grow enough plants to provide us with adequate oxygen, eventually our galactic explorers may look for ways to change their genetic makeup to adapt to new worlds. For instance, on Earth birds have lungs that allow air to flow through from one side to the other, meaning that their lungs are used with maximum efficiency. Humans only use about half of their lung capacity. If we could genetically engineer ourselves so that our lungs allow air to flow through like the lungs of birds, then we could easily live in such a thin atmosphere.
While prospecting the surrounding environment, we are astonished to discover that what we thought were mauve-colored lakes are actually silicon-based organisms that move like the Earth's continents - so slowly that their movement is difficult to detect. Human science has never encountered anything like them, and we patiently observe, document, and begin to learn about these fascinating new life forms. At the same time we discover several new elements not part of the known elements found on Earth's periodic table.
So much of human science is obsolete on planet Alfa that new scientific theories based on discoveries from these new worlds begin to emerge. We mine newly discovered elements that allow us to create technologies that are very different and more flexible than any ever seen on Earth. By accident in zero gravity we discover how to create new synthetic metallic alloys with incredible strength and lightweight properties that become highly valued in domed ecosphere construction and space travel.
A few generations have passed by since we arrived at Alpha Centauri, and having started with one domed habitat we now have 10 habitats scattered across planet Alfa. Our diet has changed due to a new strain of genetically engineered plants we created on the planet. Our children are accustomed to taking short space trips within this solar system, and there is talk of sending expeditions to new areas of the galaxy. Most of us want to stay on planet Alfa. But others would like to explore other worlds.
And so eventually we build a larger and better modular-type spaceship that can take our people beyond 4.3 light years. The new crew is better equipped and trained than "Generation One" from Earth. Since this trip is out of curiosity, telecommunication relay stations and supply outposts will be set up along the way. New communications technologies will enable us to better keep in touch with these space voyagers than was possible with the group that left Earth more than five centuries ago.
The planet this second generational spaceship
reaches will be called Beta. As time goes by, the people on Alfa get
word that life-colonization was successful on planet Beta. Eventually,
descendents of the original travelers build more generational spaceships
and also create - exponentially! - settlements on planets Gamma, Delta,
Epsilon, Zeta and Theta. Like this, conceivably, the entire galaxy could
be "colonized" in only ten million years.
Within just a few dozen generations, having lived on different planets, the original human has gradually changed into something else. Our stature and looks begin to slowly alter as we adapt to various new environments. In the future, the symbiosis of star travelers will be a blend of nanotechnology and organic matter into what will be called cybernetic life forms - the realization of cybergenesis. Our descendants are so different from how humans on Earth have evolved that they could easily be considered aliens.
Since we can't assume success for every mission, two generational spaceships are sent from Epsilon to explore the possible colonization of a new planet, Theta. However, the life forms encountered on this planet are more advanced than on previous expeditions, and present new challenges. What happens if some of these life forms have enough intelligence to create a social structure of some kind - or even advanced to a tribal mentality?
On planet Theta we have no choice but to land in a world dominated by predators and beings with tribal behaviors. Interfering with the evolution of a localized species creates new issues in the life-colonization plan. Either we stay and try to create a stable world, or simply replenish our supplies and leave. The second option is much safer in the long run. However, while visiting the planet, we cannot help but study the natives, and the cruelty of this primitive world forces some members of the expedition to take sides with some of the inhabitants.
We protect them while we ready our spaceships for another long journey and gather new supplies. We also try to teach them better survival skills, and we can only hope they'll retain the knowledge. But the inevitable happens and when we leave, our protected and newly "domesticated" natives are left to think and fend for themselves. What will happen to them, some members of the expedition wonder? Will they self-destruct in their own ignorance or allow themselves to fall victim to other predators? They could survive and advance if they successfully implement the knowledge we gave them during our visit.
The incident on planet Theta produces a paradox, because we are now - falsely - revered by the original inhabitants as protective deities, or gods. Spiritual rituals have been created around our presence, which have transformed the natives in many ways. Yet our departure and the sudden return to self-responsibility comes as a shock to the local inhabitants, who had become accustomed to being guided by and taken care of by "the gods."
In the time immediately following our departure, the "spiritual leaders" try to maintain social stability by creating new rituals in their futile attempts to bring the gods, as they saw us, back. Many of those rituals include creating art replicas of the objects we brought with us, or building structures mimicking the technologies of the gods, completely ignoring the fact that we were flesh and blood beings.
When primitive cultures try to copy the technologies and practices of more-advanced cultures they are referred to by anthropologists as cargo cults. This phenomenon began to be well-documented on Earth in the 20th century, and more than 100 cargo cults have been recorded worldwide.
The outcome on planet Theta has made us question some of the ancient mysteries on planet Earth. Could there be a parallel between the "gods from the sky" described by the ancient cultures of Earth and what we experienced as generational space travelers? How would the present human interpret generational space travelers revisiting Earth? The likelihood that primitive humans mistook space travelers for gods becomes much more probable.
If generational space travelers visited our world, they would most likely have created outposts on the Moon before coming to Earth. Wouldn't be ironic if we were to find some structures on the Moon like in "2001: A Space Odyssey" by Arthur C. Clarke? Another interesting and pragmatic theory for space colonization is presented by Marshall T. Savage in the book "The Millennial Project: Colonizing the Galaxy in Eight Easy Steps".
Since the galaxy, much less the known universe, has billions of stars, the probability of diverse life-forms is not only plausible, but probable. Our own planet that slowly drifts with the solar system around Milky Way galaxy has an incredible range of diversity. In this galactic soup, are WE part of the past of ancient star travelers who dropped by on Earth? Or what if it's the other way around? What if THEY are our past and we are their present and future? These paradoxical questions can help us rethink the meaning of alien intelligences. In this, a pattern emerges from the creation myths in which beings from the sky, although different, shared a basic genetic fingerprint - the humanoid form. If the gods from the most enigmatic civilizations on Earth were just a variation of a humanoid that evolved in very different planetary environments, then would they be EBEs? And are we?
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