Astronaut standing on Martian landscape, looking through a telescope.
In a recent lecture on Mars colonization, Elon Musk, CEO of SpaceX and Tesla Motors said, “I think that Mars is gonna be a great place to go. It will be the planet of opportunity.” Mankind’s first mission to Mars is getting ever closer — SpaceX hopes to get there by 2022. Extraterrestrial colonization is a challenge worth rising to, but getting to Mars is only a small part of the equation. The bigger problem to solve is how will we survive once we get there? In theory, surviving on Mars will be possible — and thanks to a fervor of recent research, many of the challenges we will face may be helped by engineered biological systems. It’s time we talk about synthetic biology in space!
Why synthetic biology?
It sounds obvious, but one of the main challenges behind any manned space travel is keeping the astronauts alive so far away from Earth and its resources. When the first Mars astronauts land, all they will find is dust and rocks, and maybe some water. Everything they need to survive will have to be carried with them to the red planet. But it’s not as simple as packing everything. Transporting anything to Mars will cost about $300,000 per kilogram, so reducing the weight of the load is the difference between Mars being economically feasible, or just a pie-in-the-sky fantasy.
This is where synbio could be a gamechanger. Synthetic biology is all about reprogramming organisms, such as bacteria, to make them useful in new ways. Scientists can create and recombine modular DNA parts that snap together like LEGO® bricks. When combined, they can encode useful cellular functions, like degradation pathways or chemical synthesis. Using synbio we can simply develop biological solutions for many of the problems our astronauts will need to solve on Mars.
Since engineered bacteria are microscopic and can rapidly propagate themselves, they can be brought to Mars frozen in small tubes, making them perfect candidates for light weight resources on a space mission.
How will microbes help us colonize Mars?
How will synbio best be employed once astronauts have landed on Mars? Water would likely already be available, frozen at the poles on Mars (see this article for more information on how water would be managed on a planet that has no running sources). Some food brought with the astronauts would also be available as rations while “setting up”. Therefore, the biggest initial need would be to construct a shelter — the first Mars base may have to be made biologically, as working with Martian dust would be difficult. To accomplish this goal, the astronauts would need to be equipped with a large 3D printer.
Humans have already 3D printed a house and we have plans for 3D printing a lunar base. However, with current printing methods, a heavy mixture of salts would have to be carried from the Earth that would be then combined with Martian soil to make a kind of printable concrete. This is possible, but not really practical given the cargo costs. A far more effective way would be using bacteria to produce the printer’s “ink” — for example, a synthesized bioplastic could be used to print resources from buildings to tools.
A recent quantitative study showed that using bacteria to produce building material will cut up to 86% of the shipped mass for habitation. One organism of choice could be the cyanobacterium Arthrospira platensis. It naturally produces a bioplastic called polyhydroxybutyrate (PHB) for energy storage (equivalent to humans storing fat). Why not exploit this pathway to mass-produce the structural components of a Mars base?
Kitchens will be aquariums on Mars
Moving beyond shelter, food rations brought to Mars will eventually run out. Constantly delivering food from Earth to a crew on Mars is highly unrealistic, again because of cargo costs, and each delivery would take between 3 and 6 months to arrive. Instead, our Martian astronauts will have to become self-sustainable green-fingered gardeners — and do so on a planet where nothing grows!
The soil on Mars — and by extension everything grown in it — is toxic to humans and animals. As an alternative, astronauts could use cyanobacteria or algae as a renewable food source. For one, they are perfectly safe to eat, and have been eaten by humans since the 70s in a supplement called Spirulina. Cyanobacteria and algae also need very little resource input to reproduce — sunlight, carbon dioxide (plentiful in the Mars atmosphere), water and elements like nitrogen and phosphorous present in the soil, serving as an ideal green-blueish food supply. They even produce oxygen in the process, which could provide a source of replenishing breathable air.
A culture of cyanobacteria that could make a blue-green food source (source: wikicommons, author: Joydeep)
Using synthetic biology methods, we could increase nutritional value of these organisms, introduce new flavors, or even generate medicines. By introducing new genes, the cyanobacteria could make plenty of human-essential dietary supplements, vitamins, and essential amino acids when they are growing.
That isn’t our only food option, though. Using synbio, it’s also possible to mitigate the toxins that are found in Martian soil.
Toxic tomatoes? No thanks.
If you have watched or read Mark Weir’s The Martian, you will know that the main character, Mark Watney, was able to survive on Mars by growing potatoes on Mars soil. What author Andy Weir didn’t consider were perchlorates, the toxic compounds that permeate the Martian soil. Too much chlorate will disrupt the function of the human thyroid, causing severe fatigue and even mental damage.
In order to grow anything in Martian soil, we need to remove perchlorates before they bio-accumulate in crops. Luckily, Dechloromonas aromatica is a harmless bacteria that is able to degrade these compounds, though unfortunately it is incredibly slow-growing.
Our astronauts will need to grow food to become self-sustaining. (Author: Manon Poliste)
Instead, by introducing the perchlorate-degrading genes into faster-growing bacteria, yeast, or the roots of plants, we would be able to detoxify some of the soil (with much more on this topic in our previous blog) and start growing crops that are edible. Dutch researchers have even prepared a dinner from vegetables grown on simulated Martian soil to prove it is, in theory, possible to grow Mars crops.
An apple a day — the doctor is a six-month trip away
What happens when our Martian astronauts get sick? There would definitely need to be a doctor on on the team of initial colonizers, but it would be impossible to stock all the required medicines. Even if you could anticipate every medical need, complex molecules lose their function faster in space due to the increased radiation, making medicines hard to store on Mars.
Biologically produced antibiotics can save you from an infection. (Source: wikicommons, author: CDC)
Many of the medicines we use are naturally produced by a bacterium, fungus or plant, or are based on such compounds. Synthetic biology could help develop just a handful of species that can produce them all. To become useful micro-pharmacists, we could equip bacterial strains with a number of existing genetic pathways that encode the complex medicinal compounds.
What challenges will our Micro-Martians have to face?
Space colonizers will come across many challenges during their adventure to build new worlds, and synthetic biology will be able to help solve an amazing amount of them. That doesn’t mean synbio in space will be easy, however. The microscopic organisms we will send with them will have a hard time surviving and functioning well on Mars. But don’t lose hope, there’s a lot of interesting research going on in this area.
Currently, most organisms have to be grown in huge bioreactors, up to 2000 liters in size. Huge tanks mean a huge shipping load. Successful synbio in space will require light-weight bioreactors that can also shield the bacteria from swings in temperature, low pressure and increased radiation.
Another challenge that we know little about is how bacteria will behave in space, seeing as they have evolved in a world with gravity. Research on board the International Space Station (ISS) showed that some bacteria replicate quicker, and even become more virulent when subjected to low-gravity conditions — but is their metabolism affected also? Will it affect any carefully implemented or useful pathways that we hope to use? Hopefully near-future research will begin to provide answers to these crucial questions.
Living on Mars could soon be possible thanks to synthetic biology
Mars, here we come!
The European Space Agency is currently working on a permanent human base on the moon. Here, researchers would be able to perform many experiments without being so far away from Earth. It is hoped that the moon will become a testing ground for our future mission to Mars. As the field of synthetic biology keeps developing, its application to a Mars mission becomes a matter of common sense. Let’s make this giant leap for mankind happen!
What else for synthetic biology in space?
So far, we’ve only scratched the surface of possibilities offered by synthetic biology when it comes to inter-planetary colonization. There are many other ways synbio can help us live on Mars:
- Bacteria that can extract metals from Martian dust, so we can make electronic devices — especially in combination with bioplastic producing microbes that can produce the electronic housing.
- Bio-fuel cells can provide us with renewable energy, and our bio-electronics could be powered by synthetic biology. Typically, bio-fuel cells are powered by organic compounds, like human waste.
- Not all bacteria are able to produce their own food, as cyanobacteria can, but synthetic biology can create a symbiosis in which cyanobacteria produce the necessary sugars for other useful bacteria currently under development.
- We could create “breathing walls” with bacteria that can convert exhaled CO2 into breathable oxygen. Adding extreme radiation resistance to these bacteria, like from the Deinococcus radiodurans, would give walls a self-healing radiation barrier.
- Autonomous, self-replicating robots and solar-panels might be on their way, but certain compounds for these machines are hard to produce from the available materials. The best reproducing 3D printer can make 73% of itself anew. Synthetic biology could possibly supply the materials for the other 27%, including materials like rubber for the drive belts.
This post was originally published on DNA by Design, the Twist Bioscience Blog. It was written by Valentijn Broeken of the 2016 Leiden iGEM team, which is the first team from Leiden University (the Netherlands) participating in the international Genetically Engineered Machine competition — with a killer application for synthetic biology! Their project makes sure that we can start a garden on Mars, without being poisoned by the perchlorates from the soil. More information and a video on their mission can be found here!
