A few centuries ago, there were just a few widely used materials: wood, brick, iron, copper, gold, and silver. Today’s material diversity is astounding. A chip in your smartphone, for instance, contains 60 different elements. Our lives are so dependent on these materials that a scarcity of a handful of elements could send us back in time by decades.
If we do ever face such scarcity, what can be done? Not a lot, according to a paper published in PNAS. Thomas Graedel of Yale University and his colleagues decided to investigate the materials we rely on. They chose to restrict the analysis to metals and metalloids, which could face more critical constraints because many of them are relatively rare.
The authors’ first task was to make a comprehensive list of uses for these 62 elements, which was surprisingly difficult. Much of the modern use of metals happens behind closed doors in corporations under the veil of trade secrets. Even if we can find out how certain metals are used, it may not always be possible to determine the proportions they are used in. The researchers’ compromise was to account for the use of 80 percent of the material that is made available each year through extraction and recycling.
Rare earth elements also hold tremendous strategic potential. About 130,000 metric tons are produced a year. And there may be about 150 million metric tons in reserve to mine. So 100 years max.
But this paper looks at more than just rare earth elements. It looks at the amount that is being used and the reserves. So there are many other elements to be worried about.
Here are the 12 for which there is no adequate substitute: rhenium, rhodium, lanthanum, europium, dysprosium, thulium, ytterbium, yttrium, strontium, thallium, magnesium, and manganese.
Here is a nice graph showing the relative amounts of these elements, in comparison to silicon (number of atoms per million atoms of silicon):
See that orange blob. The first 6 purple names represent the platinum group metals. A single 500 meter asteroid might have 1.5 times the entire world reserves of these metals. A single asteroid with more than the entire planet.
Now, it is not quite so amazing for the other elements but they are found at levels very close to what we have found on Earth. So asteroids present a ready source.
By my rough calculation, an asteroid 30 meters in diameter and massing about 40,000 metric tons (a metric ton is 1000 kilograms), like 2012DA12), would have 4.8 million kg of magnesium, 360,000 kg of strontium and so on. There would be about 3200 kilograms of thallium. The US currently consumes about 1000 kilograms a year.
From one 30 meter asteroid. How many of these are there? Well, lets just say there are a lot. Almost 900 of them close to Earth’s orbit that are over 1000 meters in diameter, not 30. There are about 10,000 asteroids near Earth.
Lots of resources close to us.
Now, these are very loose numbers and we need much better to be totally accurate. But they do show that asteroids can well provide us with many of the high tech elements we need.