On January 4 this year, the US National Aeronautics and Space Administration (NASA) announced the Psyche mission, which will study a metal asteroid called 16 Psyche that has never been visited before.

This asteroid is one of the 10 most massive asteroids in the asteroid belt that is located between the orbits of Mars and Jupiter, and the most massive metallic M-type asteroid. It is located about three times further away from the Sun than is the Earth, measures approximately 210km in diameter and contains a little less than 1% of the mass of the entire asteroid belt. Unlike most other asteroids that are rocky or icy bodies, it is thought to be comprised mostly of metallic iron and nickel, similar to Earth's core.

NASA stated in its announcement: "Scientists wonder whether Psyche could be an exposed core of an early planet that could have been as large as Mars, but which lost its rocky outer layers due to a number of violent collisions billions of years ago."

The Psyche robotic mission is targeted to launch in October of 2023, arriving at the asteroid in 2030, following an Earth gravity assist spacecraft manoeuvre in 2024 and a Mars gravity assist in 2025. Over approximately 20 months, the spacecraft will collect data about Psyche's composition and topography, and send back images of the asteroid. The mission aims to help scientists understand how planets and other celestial bodies separated into layers, including cores, mantles and crusts, early in their histories.

Lindy Elkins-Tanton from Arizona State University, and principal investigator of the Psyche mission, commented: "This is an opportunity to explore a new type of world - not one of rock or ice, but of metal. 16 Psyche is the only known object of its kind in the solar system, and this is the only way humans will ever visit a core. We learn about inner space by visiting outer space."

While NASA's objectives are research, the scientific study of 16 Psyche could indirectly help to make asteroid mining a reality.

Asteroid classification There are many types of asteroids that have been identified, but the three main classifications are C-type, S-type and M-type asteroids.  C-type asteroids, which are the most common type (approximately 75% of known asteroids), are carbonaceous asteroids - in other words, they consist of clay and silicate rocks. It is estimated that they can contain up to 22% water, as well as organic carbon, phosphorus and other elements used in fertiliser. S-type asteroids are siliceous asteroids with a stony composition. They have little water, but can contain numerous base and precious metals, including nickel, iron, cobalt, gold, platinum and rhodium. This is the second most common asteroid type, representing around 17% of known asteroids. M-type asteroids have a metallic composition, and many are made up of nickel-iron. They are the rarest type of asteroid, and can contain up to 10 times more metal than S-type asteroids.

Costs

NASA also has a goal of sending humans to Mars in the 2030s. However, in 2014, the NASA Advisory Council issued a recommendation that "the mismatch between NASA's aspirations for human spaceflight and its budget for human spaceflight is the most serious problem facing the Agency. NASA should carefully consider what steps would have to be taken in the years ahead in order to meet the national goal of sending humans to Mars in the 2030s with a realistic budget".

The price of spacecraft is dropping though, as demonstrated by SpaceX's recent re-use of rocket segments, and the price of new rockets is falling over time as well.

According to Business Insider, the multinational finance company Goldman Sachs is bullish on space mining with "asteroid-grabbing spacecraft". The news website stated that it had seen a 98-page note for Goldman Sachs' clients arguing that mining platinum from asteroids is getting cheaper and easier and that the rewards are also becoming greater.

It quotes the report as saying: "While the psychological barrier to mining asteroids is high, the actual financial and technological barriers are far lower. Prospecting probes can likely be built for tens of millions of dollars each and Caltech has suggested an asteroid-grabbing spacecraft could cost U$2.6 billion."

It also points out that while US$2.6 billion sounds like a lot of money, it is approximately a third of the amount that has been invested in the transportation app Uber.

In addition, the rewards reaped from successful mining of asteroids could be substantial. Peter Diamandis, co-founder of Planetary Resources, told Reuters in 2012 that a 30m-long asteroid can hold as much as US$25-50 billion worth of platinum (as calculated in prices at the time).

However, MIT's ‘Mission 2016 - The Future of Strategic Natural Resources' review pointed out that one 500m-wide platinum-rich asteroid could contain nearly 175 times the annual global platinum output (equivalent to 1.5 times the known world reserves of platinum group metals) - this would likely tank the global platinum market.

The price of spacecraft is not the only cost barrier, however; the price of fuel or propellant is another obstacle. Planetary Resources, one of the frontrunners in the quest to make asteroid mining a reality, is targeting water from asteroids as it sees this as a potential solution to the problem.

As the company explains in its 2013 video ‘The Market Problem and Radical Solution', we are at the bottom of the Earth's gravity well, which means that a much larger amount of energy is needed to get rockets or spacecraft past the first 300km than it takes for them to go the next 300 million kilometres - spacecraft burn the majority of what they can carry exiting this first 300km.

In the example given in the video, it takes 50kg of propellant to deliver just 1kg to low Earth orbit (LEO), 4kg of propellant to drive it another 35,000km, and just 2kg to transport it up to 300 million kilometres (meaning that Mars and many asteroids would be within reach). However, in the traditional model of spaceflight, each kilogramme of propellant used beyond LEO would require 50kg to get it there. Planetary Resources notes in the video: "This exponential nature of the rocket equation has us stuck hugging our planet".

As travel beyond Earth's gravity well requires much less energy, the company states that sourcing fuel from space avoids this exponential problem altogether. It says: "Fortunately, rockets run most efficiently on hydrogen and oxygen, which is just electrolysed water… These future oilfields in space are also ultra-high grade precious metal mines that lie unperturbed as the low-hanging fruit of our solar system, energetically closer than the Moon, just waiting to be harvested. Mining asteroids could provide a fuel source 1,000 times more efficient than the brute force ‘bring everything with you' approach used by the Apollo Moon programme."

Asteroid mining progress

Planetary Resources announced plans back in April 2012 to mine near-Earth asteroids (NEAs) for raw materials such as water and precious metals. In the intervening five years, it has come on in leaps and bounds, successfully deploying its first spacecraft, the Arkyd 3 Reflight (A3R) spacecraft, in July 2015. It also partnered with engineering, construction, and project management company Bechtel in 2013 and with the Luxembourg government in 2016. It also secured US$21.1 million in funding in May last year for Ceres, an advanced earth observation capability designed to use infrared and hyperspectral sensors to help manage natural resources on Earth.

Despite this, not all of its endeavours have been successful. The company raised US$1.5 million on crowdfunding website Kickstarter in 2013 with the aim of launching ARKYD, which it called ‘the first publicly accessible space telescope' as it would be controlled by members of the public through pledges and community involvement. However, in May 2016 Planetary Resources announced that it had been unable to obtain the additional support needed, saying: "The follow-on interest from the business and educational sectors to expand the ARKYD campaign into a fully-supported mission did not exist as we had anticipated." The company cancelled the project and refunded its 17,614 backers on Kickstarter.

The other major player looking into asteroid mining is Deep Space Industries (DSI), which announced its original asteroid prospecting plans in January 2013. The company states that it is "developing the technologies to find, harvest, and supply the asteroid resources that will transform the space economy", as well as delivering technology products for demanding space applications, which are also available to government and commercial explorers that are interested in developing low-cost missions of their own. The company describes its approach to spacecraft design as "focusing on minimising cost while maximising results".

Last year, the company partnered with the Luxembourg government on Prospector-X, its mission to test technologies for asteroid mining. DSI intends to launch a small spacecraft to a NEA to assess its geotechnical properties and suitability for mining - but first, Prospector-X, which is an experimental small nano-spacecraft, will be used to test several key enabling technologies in the familiar environment of LEO. It is scheduled to launch later this year.

In August 2016 DSI announced its Prospector-1 mission, which aims to survey and land on an asteroid to determine its value as a source of space resources. The destination asteroid has not yet been chosen, but the plan is to use an autonomous spacecraft to map the surface and subsurface, taking visual and infrared imagery and mapping overall water content. Following this step, the Prospector-1 will touch down on the asteroid and measure the target's geophysical characteristics.

The Prospector-1 mission is projected to be launched between 2019 and 2022. The company says: "Water will be the first asteroid mining product, so using water as propellant will provide future DSI spacecraft with the ability to refuel in space".

So while asteroid mining is not yet a reality, it seems clear that the next few years will have exciting developments in this field - we should all watch this space, literally.