We use metals for so many different purposes that a list would go on page after page. The most common and most well known are iron and aluminum. It just happens that these are the two most abundant metals in Earth’s crust.

I have always found it interesting that these abundant metals are also the most useful for our purposes. Iron has strength and, when properly treated with carbon, becomes steel, which is the backbone of our cities and our transportation.

Aluminum has properties that make it essential for lightweight applications. Yet, both of these metals develop different properties when alloyed with other metals. In addition to carbon, other transition metals such as chromium, vanadium, and nickel combine with iron to make different varieties of steel. Aluminum-titanium alloys form structures of supersonic airframes.

As abundant as these metals and other metals are, the supply is running out. The remaining resources are sparse enough that the cost of extraction is becoming prohibitive. In addition, the geopolitical climate is such that finding new deposits of the ores for these and other metals involves skillful diplomacy.

An asteroid 130 feet across decimated 800 square miles when it exploded above a Siberian forest on June 30, 1908, which is the reason for International Asteroid Day and renewed discussions on the potential devastation that space rocks can cause.

But asteroids contain metals and other minerals. Potential mining of them has been a topic of discussion for decades, but the technology has been inadequate until now.

With NASA’s cooperation, by the 2020s, for-profit space-mining companies will be sending swarms of tiny satellites to assess the composition of asteroids. Two U.S. companies and several others worldwide have developed prototype spacecraft to identify the most lucrative ones and harvest them.

And lucrative they are!

In the asteroid belt between Mars and Jupiter are millions of rocks ranging in size from minor planets to dust grains. One of the 10 largest is 16 Pysche, which is 120 miles across and contains a little less than 1 percent of the total asteroid mass.

Radar reflections indicate that it is mostly iron and nickel, similar to Earth’s deep interior. Extractable iron alone would be worth an astounding 10,000 quadrillion dollars. This compares with the estimated value of all money in circulation on Earth of $70 trillion (a quadrillion is a thousand trillion).

Although such a massive supply could drive prices down, it is still an enormous amount of wealth. Aside from the question of how it would affect the world economy are the legal issues relating to space mining. It was difficult enough establishing the law of the sea relating to mining.

In 2014 the International Institute of Air and Space Law formed the The Hague International Space Resources Governance Working Group to recommend a stringent space policy to the United Nations that includes space mining.

Meanwhile, the U.S. and Luxembourg passed bills giving companies the rights to resources extracted from celestial bodies such as asteroids, despite being signees of the 1967 Outer Space Treaty that specifically prohibits it.

Considering that a single platinum-rich asteroid could contain more palladium and other platinum-group metals than all the reserves on Earth, the world economics of the coming decade should be interesting.

Richard Brill is a professor of science at Honolulu Community College. His column runs on the first and third Fridays of the month. Email questions and comments to brill@hawaii.edu.