Water is one of the most sought-after natural resources in the world. Despite its seeming abundance on Earth, our planet’s available freshwater (usable water that isn’t locked away in glaciers, too polluted for use, or so deep underground it wouldn’t be feasible to extract) only constitutes 0.5%. To put that in perspective, if all of Earth’s water were shrunk down to 100 liters, the water accessible to humans adds up to half a teaspoon (0.003 liters). (1) The implications of water scarcity on Earth are devastating, and many countries largely concentrated in Africa and South Asia were indicated to have vulnerable water resources in the United Nations’ 2015 World Water Report. (2)
Other important resources like oil and coal are also becoming increasingly difficult to harvest due to diminishing quantity; the Millennium Alliance for Humanity and the Biosphere projected that we will run out of oil in 2052, natural gases in 2060, and coal in 2090. (3) The finite amount of natural resources currently at our disposal means that we will eventually run out of the materials needed to sustain life. At the current rate we’re gobbling up the Earth’s resources—1.75 times more than the ecosystems of the planet can regenerate per year—that time may be approaching quickly. (4) It is in part why we are looking beyond Earth to deep space for priceless reservoirs—asteroids, moons, even other planets—in search of rare metals such as platinum and, of course, water. Mining these resources from space may alleviate some of the strain we put on nature, giving it enough time to replenish its inventory for our continued use.
If space mining were to become a serious pursuit, our first target would most likely be the closest extraterrestrial body to us: the Moon. The Moon is a rich source of uranium, titanium, silicon, and other natural resources. Helium-3 in particular, found in scarce quantities on Earth but in abundance on the Moon, is of interest for its energy potential. (5)
Recently, NASA confirmed the existence of water on the Moon. In the early 2000s, several missions to the Moon, including NASA’s Cassini and Deep Impact, identified hints of hydrogen on the lunar surface but were unable to confirm whether or not that hydrogen belonged to water. Samples brought back from the Apollo Missions revealed hints of water molecules in the glass and rock, further supporting the belief that there might be water on the Moon. (6) While several other satellites detected signs of the molecule H2O, the locations of the water sources were always located on the permanently dark side of the Moon, where it remained trapped due to the extreme cold. However, NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) detected water in the soil of the Clavier Crater, which lies on the side of the Moon illuminated by the Sun. Unfortunately, the water discovered by SOFIA is measly, amounting to about 1/100 of the water found in the Sahara Desert. (7)
Unlike our Moon, Europa, one of Jupiter’s many moons, is (at least in theory) a global ocean. The entire moon is covered in a sheet of ice estimated to be up to 20 miles thick, under which lies what could be more than twice as much water than is in all of Earth’s oceans. (8) Scientists discovered signs of water on Europa in 2018, when old data from the Galileo orbiter and Hubble Space Telescope showed plumes rising up from Europa’s surface. The water on Europa is saltwater; it more so resembles the waters in our oceans than something we could use easily. The discovery of water on another planet is still remarkable, especially because of what it could suggest about life in space.
Our main source of metals besides the Moon would probably come from asteroids, which contain lots of raw materials like iron, nickel, and magnesium, and comets, which may contain water and carbon-based molecules important for life. (9)
The technicalities of actually harvesting these materials will require extensive research and development; we currently do not have technologies advanced enough to make space mining a regular industry. We also need to sort through a whole range of logistics. Who gets to do the mining? How are countries going to divide the “land” and “spoils”? Will we have to set up some sort of permanent settlement for harvesting full-time? What sort of harm would we do to our Earth and the masses we use? Still, the prospect of successfully extracting resources from space is exciting, and we would simultaneously be able to learn more about what’s in the universe with us. Wouldn’t that be fun?
(1) “Water Facts - Worldwide Water Supply” US Bureau of Reclamation California Great-Basin
(2) “The United Nations world water development report 2015” United Nations
(3) “When Fossil Fuels Run Out, What Then?” MAHB
(4) “Earth Overshoot Day 2019 is July 29, the earliest ever” Global FootPrint Network
(5) “The approach to sustainable space mining: issues, challenges, and solutions” Xu, ECMS 2019
(6) “There’s Water on the Moon?” NASA Science
(7) “NASA’s SOFIA Discovers Water on Sunlit Surface of Moon” NASA
(8) “Europa” NASA
(9) “NEO” NASA CNEOS