The Taste of Space?
The Taste of Space?
Your journey to the brave new world will probably take some time (even Mars is several months away), so of course you will pack a few sandwiches and probably stock up on astronaut rations: freeze-dried delicacies in little silver packets that you suck through a built-in straw.
Astronauts on the International Space Station recently made history by baking the first ever space cookies (chocolate chip). But once you reach your destination, what are your long-term culinary plans?
Astronauts on the International Space Station recently made history by baking the first ever space cookies (chocolate chip). But once you reach your destination, what are your long-term culinary plans?
Naturally you will want to grow and produce Earth food in your new colony, and if you are settling on a lifeless rock like Mars this will be your only option.
Make sure you have enough water (from the polar ice caps, or possibly underground), make sure you filter out any toxic chemicals (such as percholates). Make sure you have brought plenty of seeds with you. Set up some UV lights if the distant Sun is not pulling its weight and with a bit of luck you'll be a successful interplanetary farmer...
But what if the planet DOES have its own life? Sci-fi is full of planets with Earth-like atmospheres where our heroes can stroll around unencumbered by spacesuits or biodomes, breathe the air and even stop to smell the flowers...
All of which is great for a flying visit, but if you plan on putting down roots then the question you need to ask is:
All of which is great for a flying visit, but if you plan on putting down roots then the question you need to ask is:
CAN HUMANS EAT ALIEN FOOD?
To answer this question we need to look into the very basics of human nutrition. What does your body actually need to survive?
The seven major classes of nutrients (substances in food essential to human life) are:
Macronutrients (which we need in bulk):
1 - Water
2 - Carbohydrates
3 - Protein
4 - Fat
5 - Fibre
Micronutrients (which we need but in smaller doses):
6 - Minerals
7- Vitamins
Let's look at each one in turn...
1 - Water
GOOD NEWS: Water is everywhere! The universe is full of it. And this is excellent because it makes up 60% of the human body and is quite definitely the essence of life. We need a constant supply of it.
It is a fairly simple molecule; one oxygen atom with two hydrogen atoms, and it has been detected in many different places outside of our planet. For example, our own Moon contains huge amounts in craters at the poles (which never see sunlight), good news for anyone wanting to live and/or work on the Moon, plus it can also be used as fuel (by splitting the H2O into hydrogen and oxygen).
It is a fairly simple molecule; one oxygen atom with two hydrogen atoms, and it has been detected in many different places outside of our planet. For example, our own Moon contains huge amounts in craters at the poles (which never see sunlight), good news for anyone wanting to live and/or work on the Moon, plus it can also be used as fuel (by splitting the H2O into hydrogen and oxygen).
It doesn't stop there. The dwarf planet Ceres, located in the asteroid belt between the orbits of Mars and Jupiter, has a surface which is 40% water ice. The rings of Saturn are composed of fragments that are 99% water ice. We also know that comets contain water ice (80% of the gasses released from Halley's Comet, for example).
We can be sure that the same conditions exist in other star systems. Spectroscopy shows us that all stars are made of the same basic elements and therefore so will be their planets, comets and other objects. Indeed, water has been detected spectroscopically on the exoplanet K2-18b.
Drinking water from an alien world should present no problems providing it is filtered first to remove any toxins.
2 - Carbohydrates
Carbohydrates (simple and complex sugars) are the main food source of energy consumed here on Earth, although we could actually survive without them if we had to. Nevertheless they are a very convenient and versatile food type, as grain-based products such as bread and noodles are widely used.
The high energy content of sugar found in fruit encourages seed dispersal by animals, and if a similar organism to a strawberry bush is found on an alien planet the carbohydrate content will quite likely provide monosaccharides (glucose, fructose, galactose), disaccharides (sucrose, lactose, maltose) or polysaccharides (starch and glycogen, cellulose) which humans can digest and, depending on which type, also has a sweet taste.
The high energy content of sugar found in fruit encourages seed dispersal by animals, and if a similar organism to a strawberry bush is found on an alien planet the carbohydrate content will quite likely provide monosaccharides (glucose, fructose, galactose), disaccharides (sucrose, lactose, maltose) or polysaccharides (starch and glycogen, cellulose) which humans can digest and, depending on which type, also has a sweet taste.
So, carbohydrates from an alien source would be safe to eat and a good source of energy. Again, however, they would have to be isolated from any toxic or indigestible substances that might also be present.
3 - Protein
Proteins are complex macromolecules that form much of the structure of our bodies and also perform a variety of functions such as catalysing metabolic reactions and transportation of molecules within the body. Proteins are made of chains of amino acids, often called "the building blocks of life" (they are also the main component of DNA). All amino acids are composed essentially of carbon, hydrogen, oxygen, and nitrogen, with other elements found in their "side chains".
The human body contains 21 different amino acids, eleven of which are made within the body. The nine which the body cannot manufacture itself are called essential amino acids (EAAs) and must be sourced from food.
This is where the picture looks less rosy; the chances of those nine complex molecules existing in an alien biosphere are impossible to predict. We have found some amino acids in meteorites, so we know that they do occur naturally outside of Earth's atmosphere, but this only gives us a little hint at how common ALL of them are in the universe.
We have evolved on Earth alongside the food sources available and our digestive systems reflect these specific biochemical pathways. There are around 500 naturally occurring amino acids found on Earth. If an alien world has a similarly rich level of diversity then the chances may be good that the EAAs are among them... somewhere!
If they are not, the question then becomes: could we survive on alternative amino acids to the nine that are currently essential to us? It would seem unlikely, though experiments with bacteria using synthetic amino acids have demonstrated that, at least on a unicellular level, this is a possibility.
4 - Fat
Fats (lipids) are a source of energy and contain fatty acids, two of which are essential for the human body and cannot be created within it: a type of omega-3 and a type of omega-6. These are involved in various vital functions including metabolism, synthesis of cell membranes and hormones.
Like proteins, these molecules are very complex and we cannot predict how prevalent they may be on an alien planet.
5 - Fibre
Fibre is carbohydrate that our bodies cannot easily break down (digest), such as cellulose (from plant cells) and is an important component of human digestion. Its bulking effect allows various processes to operate efficiently. It regulates blood sugar, balances intestinal pH and lowers cholesterol.
Is it possible that these sources of fibre might arise on an exoplanet? Possibly, yes. If they do not, could we replace it with whatever alternatives we might find there?
Well, finding something which is resistant to digestion may not be difficult, but it would be unlikely to be a GOOD replacement. Our bodies have evolved to make complex uses of specific sources of fibre. Introducing something different would probably be disastrous.
6 - Minerals
In a biological context, a mineral is a chemical element apart from hydrogen, oxygen, carbon or nitrogen which is essential to the organism. For example, we need calcium for bone formation, iron for blood chemistry, etc.
The good news here is that, just like water, these elements are present wherever there are planets. For a star to have terrestrial ('rocky') planets, it and its planets must have formed from a cloud of matter thrown out by a supernova originating from a star which produced 'heavy' elements. Any form of life on that planet would probably use those elements in a similar way to life on Earth, and would therefore be readily available.
7 - Vitamins
A vitamin is a complex organic molecule and there are thirteen required by the human body: A, B1, B2, B3, B5, B6, B7, B9, B12, C, D, E and K. They are necessary for a wide variety of different physiological processes and are essential for health.
A healthy, varied diet will provide you with all the vitamins you need (tablets are of benefit only to those who are ill or malnourished), so we have evolved to source them from food. Is it likely that we can get all of these from another world? Possibly, but I think we would be very lucky to find all of them readily available.
- - -
The answer to our question - Can humans eat alien food? appears to be: a resounding MAYBE.
On the one hand, water and minerals will very probably be present on any planet that has life. Simple sugar carbohydrates are fairly likely. Fibre of some kind is fairly likely, but probably quite different to that found on Earth. More complex molecules such as proteins, fats and vitamins are probably less likely.
Of course, all of this could be irrelevant if we discover a world with biochemistry so VERY different to that of Earth that NOTHING is compatible with us: Silicon-based instead of carbon-based? Ammonia as a solvent instead of water? Methane poly-lipids instead of proteins? We just do not know.
Personally I think that we would be extremely lucky to find a planet that can provide us with ALL of the specific, complex molecules that our bodies need. We will probably need to take seeds with us wherever we go and grow our own Earth-origin food to keep our Earth-origin bodies alive, though exotic biospheres may provide a few interesting compatible alternatives. There may be some pleasant surprise out there...
Who knows what the future will really look - or taste - like?
LINKS:
Would humans be able to derive nutrition from foodstuffs found on alien planets?
https://worldbuilding.stackexchange.com/questions/47787/would-humans-be-able-to-derive-nutrition-from-foodstuffs-found-on-alien-planets
An Alien Diet
https://www.newscientist.com/article/mg15921452-100-an-alien-diet/
Water on the Moon
https://www.theverge.com/2018/8/23/17769034/nasa-moon-lunar-water-ice-mining-propellant-depots
Origin of water on Earth
https://en.wikipedia.org/wiki/Origin_of_water_on_Earth
Earth's Water Is Older Than the Sun
https://www.discovermagazine.com/the-sciences/earths-water-is-older-than-the-sun
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