Can We Eat Rocks? Imagine you’re an astronaut, floating in the cold, infinite void of space. The isolation is overwhelming, the stars are your only company, and every prepackaged meal reminds you of the tether that ties you to Earth. Bid a farewell to the crusty steak and crunchy toast — nothing is worse than life without the delicious Maillard reaction. Yet, an even more daunting scenario could be the future of dining for astronauts as we explore the possibility of turning asteroid material into sustenance. None of the people on Earth would ever think to ask, "Can we eat rocks or dirt?" — unless you are running out of money. However, always relying on Earth-dependent resupply missions is impractical for prolonged journeys to deep space. Innovative approaches, such as bioregenerative systems that grow plants, algae, mushrooms, or even cultured meat onboard spacecraft, could be promising. However, these systems require a significant amount of resources, including water, light, and nutrients [1, 2]. In comparison, applying the mining concept to food is tantalizing. Could the vast resources of space itself provide sustenance? Scientists are now exploring the possibility of mining asteroids to create food. The carbon-rich asteroids may hold the key, offering a potential source of organic materials that could one day be converted into food for astronauts [2]. The Science Behind Asteroid Food These carbon-rich asteroids, including the famous Murchison meteorite that crash-landed in Australia in 1969, contain organic substances in various forms, such as aliphatic hydrocarbons and insoluble organic matter (IOM) [2]. The food mining process involves feeding relatively short hydrocarbons to bacteria, ideally with carbon lengths from 10 to 40 [2]. Previous studies have identified bacteria that can convert the thermal breakdown products of high-density polyethylene plastic to human edible biomass [3]. Given the similarity in composition between the breakdown products of the plastic and the asteroid material, the microbial consortium is expected to work like a team of microscopic chefs, converting raw asteroid material into food rich in carbohydrates, proteins, and other nutrients humans need to survive [2–4]. Let’s Do Some Math! In the following calculation, asteroid Bennu is chosen to illustrate how much food an asteroid can offer [2]. Bennu is a small, near-earth carbon-rich asteroid with a mass of 7.329 × 1013 g. It was also the target of NASA's first asteroid sample collection mission [5]. A few assumptions are made for the calculation: First, the proportion of organic substances is based on data from the more extensively studied Murchison meteorite. Second, the maximum amount of food is calculated by considering the total amount of insoluble organic matter (IOM) in the asteroid, assuming that they can be extracted and converted into edible biomass. Let’s first find out the mass of IOM in Bennu: The extraction and conversion processes are expected to be somewhat inefficient. Assume the proportion of mass extractable for food production e is 0.32 [3], the conversion efficiency by the bacteria a Food Source for 成為太空 人 小行星能 Can Asteroids Serve as Mass of Bennu × Proportion of IOM = 7.329 × 1013 × 0.096 = 7.036 × 1012 g
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