|Fig. 1: Rendering of an asteroid being captured for further study and sampling. (Source: Wikimedia Commons).|
Mining asteroids in space may seem like science fiction to many, but there is a very real conversation surrounding the prospect of mining raw materials from asteroids. The idea of exploiting asteroids for their materials dates back over a hundred years but only now in the 21st century is this once fictional concept becoming a reality with access to new technologies. There are many different materials that could potentially be found on an asteroid, with water and various metals being the most significant prospects. The prospect of being able to access this water during space travel could save organizations like NASA time and money as it is very expensive and inefficient to bring water into space.  Discovery of new natural resources have always allowed the human race to expand to new frontiers and the prospect of mining from asteroids should be no different. We will discuss the process of mining asteroids as well as take a look at the economic benefits before looking to what the future holds for asteroid mining.
The feasibility of asteroid mining is in large part due to the ability to find and categorize a large number of small enough asteroids that are near earth, also known as NEA's (Near Earth Asteroids).  The first step in capturing and mining an asteroid is actually finding viable candidates for the process. Using very powerful telescopes, one is able to determine the foreseeable composition of an asteroid, providing a clearer idea of whether or not it should be explored for mining. NEA's are the best prospects for mining as they are easier to access, saving time and money. It is also important to consider an asteroids velocity, as asteroids moving too fast will be much more difficult to survey and access. 
After an asteroid has been surveyed and chosen as a viable candidate for mining, the asteroid can either be mined for raw materials to be brought back to earth or those materials can be processed while in space, as could be the case for water extraction and conversion into Hydrogen and Oxygen for rocket fuel. These asteroids can also be captured and brought into the orbit of either the earth or the moon and controlled for further examination and use, as shown in Fig. 1.  If asteroids are brought into lunar orbit, it could lead to an increase in international space cooperation, as nations could work together to better understand methods for material extraction. 
However exciting the prospect of mining an asteroid may be, it is certainly a very expensive endeavor. According to an estimation done by the NASA GRC compass team, the full life-cycle of a mission to capture and return an asteroid could cost as much as $2.6 billion. The transportation of materials is one factor that pushes the price tag of a mission such as this through the roof, as it can cost around $0.1 million to transport 1 kg of mass from high lunar orbit.  It seems difficult to justify the economics of asteroid mining but finding precious materials on these asteroids could be economically advantageous and there may be benefits still unknown.
It's often the case that we over-predict what can be accomplished in the next year, but also common is to under-predict what will happen in the next 10 or 20 years. With companies like Planetary Resources exploring new technologies and leading the way, asteroid mining could become much more common in the next decade, leading to the discovery and familiarization with new materials as well as the expansion of an interesting market for asteroid exploration and the acquisition of rare metals.
© Brian Nana-Sinkam. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 A. Crerend, "Asteroid Mining," Physics 240, Stanford University, Fall 2014.
 "Asteroid Retrieval Feasibility Study," Keck Institute for Space Studies, April 2012.