Asteroids

The Asteroid Belt is roughly located between the orbits of the planets Mars and Jupiter, and this region is where the vast majority of asteroids, also known as minor planets, are found. Some asteroids orbit in near-Earth space and some occasionally migrate or are thrown out of the asteroid belt to the outer solar system by gravitational forces.

Overview
Around half of the mass of the entire asteroid belt is comprised of the asteroids Ceres, Vesta, Pallas and Hygiea. The mean diameters of Vesta, Pallas and Hygiea are over 400km, and Ceres has a diameter of 950km. Of all the asteroids in the belt, Ceres is the only one which is categorized as a dwarf planet. The remaining bodies range all the way down to objects as small as a dust particle. Because the asteroid belt is between the Mars and Jupiter orbits, it is around 2.2 to 3.2 Astronomical Units (AU) from the Sun – which is approximately 329,115,316 to 478,713,186 km. The average distance between objects is a massive 600,000 miles. To put that number into perspective, the circumference of planet Earth is only 24,901.45 miles which makes the distance between objects in the asteroid belt more than 24 times the circumference of Earth. With the growing consumption of key elements here on Earth, along with the known reserves of those elements, there is speculation that elements such as phosphorus, antimony, zinc, tin, silver, lead, indium, gold, and copper, could be exhausted on Earth within 50–60 years. Asteroid mining refers to the speculation that we could essential mine asteroids and other minor planets to exploit the raw materials found on them. There are a number of materials that could be mined from asteroids, including iron, nickel, titanium for construction, water and oxygen. As an example, they could be used to sustain the lives of prospector-astronauts on site. Also, water mined from asteroids could serve space colonies and hydrogen and oxygen could be used as rocket propellant. Minerals and metals mined from asteroids might also be used to build habitats and grow food for future space colony inhabitants. The biggest obstacle to asteroid mining is the financial feasibility of it. Space ventures are high risk, with long lead times and a lot of investment is needed. For it to be possible, affordable space flight technology will need to be developed in order to allow humans to reach the asteroids to mine. A number of potential mining projects are already under way, as companies announced their intention to mine asteroids as far back as 2012. Both Planet Resources and Deep Space Industries have begun prospecting asteroids, and NASA have their own projects in mind as well.