Surviving En Route to a Beta World
I did a LOT of research for Tangled Planet. This is the second of three posts on how I used some of it in the book.
DISCLAIMER! I have stretched, tweaked and in some places rabidly mauled the current tech in my book – the second half of science fiction is the fiction part, after all. Astrophysics shouldn’t be allowed to get in the way of a good story.
Suspended Animation or Generation Starship?
A direct, manned interstellar flight that will take hundreds of years gives you two main options: suspended animation or a generation starship. Suspended animation would either take the form of adult passengers in sleeper ships, or frozen embryos. While both have fascinating narrative possibilities, I was drawn to the generation starship idea because I’ve read/seen so many variations on the theme – generation starship as dystopia, generation starship as luxury liner, generation starship as hoax, generation starship as world that has forgotten that it is actually a generation starship. Frankly, in fiction, it’s rare to have a generation starship just be a straight-up generation starship that actually reaches its destination.
Yet that was a fascinating concept to me. You have a society that has, as far back as their equivalent to the Tudors, never been outside. It would be a hell of an adjustment – and people generally don’t take to change well.
Also, one of the images that led to this story was that of an alien forest, with a big, bad wolf stalking among the trees. There is more power to that if my Little Red Riding Hood had never seen a tree before, never mind ventured into the deep, dark woods.
In my research, I fell down a bit of a Google hole while reading about gravity and using the toilet in space (it’s fascinating, and I recommend you start Googling it as soon as you’re done reading this). One of the many disgusting things I found out was that only know when we need to pee because of the downward pressure on our bladders caused by the liquid in it. So, in zero-g there is no urge to pee. And if you don’t pee in zero-g, you don’t just wet yourself, because again, you need gravity for that. And if your bladder gets too full a urinary obstruction is likely, and then you can’t pee at all.
If that happened on a flight to Mars and couldn’t be fixed, it could threaten the whole mission – but you can rest easy. We know how to fix it, thanks to a team of doctors who drained pee out of an unconscious pig on a parabolic flight, which is something I like to try to picture when I’m bored.
But, more important than the peeing issue, there are serious long-term impacts on the body of traveling in zero-g. Muscle atrophy would be a huge problem and some estimates suggest you could lose 50% of your bone density in just the 2 years it would take to travel to Mars and back. It certainly wasn’t practical for my characters to spend their whole lives in zero-g, much as I would have enjoyed writing the awkward bathroom scenes, so I had to find some way of simulating gravity on board my ship.
When the Venture was speeding up or slowing down, they could angle their carriages to allow the acceleration/deceleration to simulate gravity, but this force would not be constant throughout the voyage, and when the story opens, they have reached their destination, and are in orbit around Beta. Although, like the International Space Station (whose distance from Earth and speed of orbit I based the Venture’s on), they would be close enough to Beta to be subject to about 90% of its gravity, their orbit essentially means they are in free fall, so it would feel like zero-g.
Therefore, the Venture’s ‘gravity’ is generated by rotation. The ship is shaped like a giant wheel – the spokes of the ship are about a kilometer long, and the Venture rotates at almost one rotation a minute (1 rpm) – which generates about 9.89 m/s2 of centrifugal acceleration, equivalent to about 1G – making it feel like Earth around the rim of the ship.
However, using rotation to simulate gravity results in a couple of notable differences. One of these is the Coriolis force. This is the force that is supposed to make water drain different ways down the bathtub in different hemispheres (it’s too weak to actually do that – I’ve tested it). But the Venture is a lot smaller than the Earth, and rotates faster, so this force would be stronger and more noticeable – affecting balls thrown, and the inner ear. I considered giving my characters a little planet sickness as they adjusted to a lack of Corilolis effect after a lifetime on board ship, however, rotations of 1 rpm are well within human comfort ranges, (we can adjust to up to around 20 rpm) and so would likely require little adjustment.
Another difference is in the ship’s spokes. If something fell ‘down’ one of the spokes toward the rim, it would not fall straight down, but be pushed toward one of the walls, in the opposite direction to the ship’s rotation. Gravity would lessen the ‘higher’ up the spokes you got, and right at the heart of the ship there would be no gravity.
So you’d probably want to pop to the bathroom before heading there for any length of time. Just in case.
Food on board the Venture
With a crew of around 500 traveling for 400 years, ensuring enough food for the crew would be a major issue. I wanted my generation starship to be reasonably small (since mass is a huge issue when it comes to fuel for an interstellar voyage). I also didn’t want it to be too complex, or even as futuristic as the society it originated from – I wanted a ship that the crew could fix themselves, as they would have no help out in deep space. So there would be no room for livestock, and few resources to sustain such an energy-inefficient food source (not to mention the disease issues that livestock can cause. My crew are vegan (but they’ve never eaten cheese or bacon, so they don’t know what they are missing.)
As Mark Watney discovered in The Martian, you need a lot of space and soil to grow potatoes. But there are better ways that allow a greater yield in a smaller area, if, unlike Mark, you have the advantage of forward planning. Fogponics is a space-efficient means of production (sometimes known as Aeroponics 2.0). Aeroponics is already used in space. Instead of growing plants in soil or water, you grow them in a chamber filled with misted air, laden with nutrients. I’ve tweaked the basics, but this kind of agriculture features heavily in the ecocarriages aboard the Venture.
One way of reducing the amount of energy needed to grow plants is to limit the visible spectrum that they use when they are growing – plants do not need the full spectrum to flourish; they do well under red, blue and UV lights. However, this does mean that the salad eaten by the crew of the Venture would be purple, and that the green of vegetables in the natural world might seem rather odd to the crew.
Algae is a vast, untapped source of protein with an excellent nutritional profile. It’s already starting to sneak its way into our food. The biggest problem right now is that it tastes really gross. However, I’ve assumed that my future society have genetically modified algae’s flavour profile enough to make it a staple for the crew of the Venture.
Fermentation vats used to produce compounds using genetically modified yeasts
This is one that sounds futuristic, this kind of synthetic biology is already in use. While naturally-occurring yeasts can turn sugar into alcohol, the DNA in yeasts can be edited to produce other molecules through fermentation – artificial vanilla is one of these.
In theory, almost any molecule could be produced via fermentation, with the right edits to yeast DNA. Obviously, this causes all kinds of potential problems, now and down the line, especially since the regulations are not moving nearly as fast as the technology.
But for my crew, fermentation using genetically modified yeasts can solve issues of nutritional shortages, and allow them to produce rare compounds they would not otherwise have access to in deep space.
Which would probably make a nice change from all that algae.
Disease & Medical Issues
In a closed environment disease would be a concern, however, without livestock and with a small community, epidemics on the scale of those seen in the modern world would be rare. But if a virus/bacteria did mutate to infect the crew, it would quickly spread through them. The crew have a genelab on board, with technology based on much more advanced versions of our current vaccine programs to protect them. However, in 400 years it is likely that at least one pathogen would mutate to devastate the ship before a complete medical response could take place – so the Venture’s history has been shaped by the ‘Great Virus’ that happened long before my story begins. Such an event would be traumatic for the ship, and result in permanent changes to the society on board – much as the Black Death did to the societies of Europe, and the smallpox epidemics brought by settlers did to First Nations societies. The resulting population collapse would mean the ship would be undermanned for generations, resulting in a long-term maintenance backlog, the impact of which would still be felt on arrival at Beta.
Also, with no sunlight for most of their trip, limited resources and rationing during the later generations, there would only be so much that supplements and technology can do. The hard work, limited diet and small spaces of the ship would take their toll on the crew.
There is quite a bit of debate on what size population would be required to prevent long-term inbreeding. While 160 may be enough for a 200-year space journey, it would not be enough for populating a new planet.
In Earth’s past, we’ve had genetic bottlenecks – possibly as low as 1,000 breeding pairs – so 2,000 people may be enough to populate Beta. However, my spacefarers would not want to risk having only the lowest possible amount of genetic material to form a long-term population.
As I mentioned previously, I wanted to keep my ship relatively small. Obviously, not all of this genetic diversity has to be represented among the crew, and if the population of the planet relied upon only the genetic material of those who lived on board, one major population collapse (such as the ‘Great Virus’ en route, or a catastrophe soon after arrival), could quickly bring those numbers below a viable amount.
Therefore, my crew has a Genebank – genetic material from 60,000 Earth donors selected for their health, who did not want to go on the voyage, but liked the idea of their offspring living on a distant planet. Each member of the crew is made from a random selection from the Genebank, so families on the Venture are related not by genes, but by upbringing, resulting in a diverse crew. Sperm and eggs are harvested from the crew when they are of age, and added to the Genebanks. Targeted contraceptives in the ship’s food prevent conception, but allow pregnancy. Reproduction is only through implantation, to keep crew numbers at an optimal level.
The Great Virus would likely result in changes to how the ship’s population was managed. After the dramatic population collapse, my society chose to implanted fetuses to ensure a 2:1 women to men ratio – partly because women use fewer calories and food was in short supply, and partly because having more women on board meant that the population could be replenished faster in the case of another catastrophic event.
The ship has no spare capacity to keep injured or aging crew members alive, and premature aging is the norm. This means life spans are relatively short, because when age starts to make a crew member less efficient, they face the ‘Exit': a compulsory euthanasia program, and after death, the recycling of their bodies into fertilizer. But on arrival at Beta, on a planet with abundant resources, population control is no longer necessary, which probably comes as something of a relief to the older crew members.
Which brings us to next week’s post – which will be on the bioengineering of their new home – Using Science To Create a New World – Part 3 – Building a Beta World