Earth is a Spaceship Like the ISS – Let Me Explain

Imagine living in a place where your survival depends on living within your boundaries, where you consume no more food and energy than you produce, create enough fresh water and air to live on, waste to an absolute minimum limited, recycle everything you can, and avoid waste. polluting the environment around you. This is what astronauts face to some extent aboard the International Space Stationand what they would have to deal with to a greater extent in future settlements the moon or Mars.

But it is also the way we must live on Earth if we want to protect our environment, which is one of this year's themes World Space Week runs from October 4 to October 10.

A space station or a moon base is largely a closed system. What we mean by this is that it has to produce its own resources and then recycle them, putting them back into the system because they are limited. Consuming too much could leave astronauts without air, food, water or energy, which could be fatal. Of course there are occasional resupplies from Earth, so they are not 100% closed loop systems. What is a completely closed loop, however, is the Earth itself.

Spaceship Earth

Think about it. Our planet has a certain carrying capacity, or what the Club of Rome - a think tank of academics, business leaders and politicians - calls the ' limits to growth" in their famous 1973 report. They warned that the Earth was beginning to reach its carrying capacity, and that we would soon be generating too much energy, eating too much food, not producing enough fresh water, and pouring greenhouse gas emissions into the atmosphere, causing our global closed system is unsustainable climate change grows increasingly harmful year after year, leading to increasingly frequent droughts, famines, forest fires and extreme weather events, some might say we have already reached that stage.

Related: How satellite data has proven that climate change is a climate crisis

This is where learning to live in space can help us learn how to live sustainably on Earth. It is not a new idea, but a recent article by researchers from the German Aerospace Center in the journal Sustainable Earth Reviews succinctly summarizes how technologies designed for life in closed space habitats can be applied on Earth.

They described how a space habitat must perform several functions to remain a closed system, and how each of these can be reapplied to the larger scale of Earth.

First, resources must be cultivated and introduced into the system. In this case, resources mean everything a habitat needs to function, from food to energy. However, this concept must be managed carefully because, if left unchecked, it is open to exploitation. For example, if all the water ice were extracted from the lunar regolith too quickly, there would be nothing left to supply a lunar base for a very long time.

Secondly, there is the recycling of these resources so that they are not used up too quickly. In a closed-loop habitat, unrecycled waste is costly and can shrink the habitat over time because it means less and less of a given resource is available. It can also pollute the habitat's surroundings, again reducing its size.

Third is self-sufficiency. Aside from occasional resupply from Earth, a space habitat must be able to produce and repair everything it needs.

Finally, a closed habitat must be resilient enough to support the crew and any other animal or plant life indefinitely. If the system breaks down because it is misused, the lifespan of the habitat is severely shortened.

We can see how each of these can be applied to the Earth. Intensive farming, mining, fishing and so on show how we are exploiting the cultivation of resources on our closed Earth. Recycling can help us conserve our resources without polluting the environment with waste. If communities can become self-sufficient, carbon dioxide emissions can be reduced because resources do not have to be transported to communities from external regions.

The Earth has shown resilience to life for almost four billion years, but our careless treatment of the environment through overconsumption is testing that resilience.

Space on Earth

Interestingly, technologies developed for use in space can also help on Earth.

A classic example is solar panels. Invented in 1954, during the era of coal-fired power stations, solar panels weren't exactly a fad because photovoltaic cells weren't widely used on Earth at the time. On the contrary, solar panels first made their breakthrough in space, providing energy for satellites as early as 1958 with the Vanguard 1 satellite. The amount of money that spacefaring countries were able to put into R&D for solar cells made these cells capable enough to be used on Earth by the 1970s. Nowadays we find solar cells everywhere, with the average panel producing 1.5 kilowatts of electricity every day; and as of 2023, solar energy will generate a total of 5.5% of the world's electricity without the harmful emissions from coal-fired power stations or the toxic waste from nuclear fission reactors.

Another technology developed in space that could help support a more sustainable way of life on Earth is food-based. Crops are grown by astronauts on the International Space Station.

The experiment, known as the Vegetable Production System, produced lettuce for the first time in 2021, which was harvested by NASA astronaut Michael Hopkins. The experiment revolves around planting seeds in a 'seed cushion', along with the controlled release of fertilizer and clay and the use of specially designed LED lights to promote photosynthesis, emitting more red and blue light that stimulates plant growth . These lights are now being adapted for 'vertical farming' on Earth, which is a sustainable way to grow crops that don't take up too much land in urban areas and recycle their water, just like on the space station. By growing food in vertical farms close to built-up communities, people can reduce transportation costs and intensive farming, both of which produce high carbon dioxide emissions.

The water cycle

Speaking of water, it is of utmost importance that water is recycled on the space station because its weight makes it expensive to bring up from Earth. All water on the International Space Station is recycled through a water recovery system, as part of the space station's Environmental Control and Life Support System, which can convert the airborne water vapor that humans exhale, sweat, and even urinate into drinking water (which apparently, astronauts claim, tastes quite good!). The Urine Processor Assembly uses vacuum distillation to extract clean water from astronauts' urine, leaving behind a nasty-sounding "urine brine." A brine processor assembly has even been developed because there is still usable water in this brine; in a closed system, every resource must be used optimally.

Although we don't need to drink water from urine on Earth, there are many locations around the world where fresh, clean water is scarce. NASA's water reclamation technology has been licensed to companies to create portable filters that help communities obtain clean water from contaminated supplies.

Carbon cleaning

Together with water vapor, astronauts exhale carbon dioxide.

The astronauts on Apollo 13 learned firsthand the dangers of carbon dioxide buildup when they had to hastily build a carbon dioxide filter from spare parts on the way home from the moon. On the International Space Station, carbon dioxide must be washed out of the air in the same way.

Previously, oxygen was produced on the ISS by a system that extracted it from 400 liters of water brought from Earth each year. So it was not a closed system. Now the European Space Agency has developed the Advanced Closed Loop System (ACLS) capable of recycling 50% of the station's carbon dioxide into oxygen and no longer requiring large amounts of water to be taken from Earth. The ACLS Carbon Dioxide Reprocessing Assembly mixes hydrogen and carbon dioxide from the air to produce water and methane. The methane is blown into space as waste, but an Oxygen Generation Assembly can split the water into oxygen and hydrogen, the latter of which returns to the ACLS system to start the cycle again.

Before the ACLS, however, carbon dioxide was removed exclusively through a mineral called zeolite, which has pores small enough to trap carbon dioxide molecules and then flush them into space. Now Stefano Brandani and Giulio Santori from the University of Edinburgh are investigating ways to use zeolite technology to reduce carbon dioxide in the Earth's atmosphere. They envision giant fans drawing air filled with carbon dioxide into stations made of zeolite beds that remove the carbon dioxide from the air. The same technology could also be used closer to the source, removing carbon dioxide from waste gases produced by industry before they are released into the atmosphere. Although it cannot remove all carbon dioxide from the atmosphere and prevent global warming, carbon capture technology can help mitigate climate change and help the world meet its target of no more than 1.5 degrees Celsius of global warming to remain on earth.