The Dawn of Asteroid Mining is Here
Trillions of dollars of minerals are locked away in asteroids. For the first time we're about to bring some of that back to Earth.
The vision is tempting. A wealth of mineral riches , from iron to gold to platinum, are out there, just waiting for someone to grab them. There’s only one catch. These minerals aren’t on Earth; they lie deep in space, far out of our reach on distant asteroids.
Soon that will change. Two missions , one Japanese, one American , are aiming to bring back chunks of asteroids to Earth. The Japanese mission, Hayabusa2, is already enroute back to Earth, carrying a precious cargo of 35 pounds of rocks. The other, NASA operated OSIRIS-REx, is expected to grab up to five pounds from the asteroid Bennu later this year.
These two sample-return missions, as they are known, represent early steps towards asteroid mining. But they also give scientists a chance to study pristine materials from the early Solar System. The hope is that such studies reveal secrets about the formation of the planets, and even about the origins of life itself.
What Are the Essentials?
Hayabusa2, the Japanese mission, launched in 2014 and reached the asteroid Ryugu in 2018. After arriving the spacecraft dropped two rovers onto the surface of the asteroid, and then transmitted photographs and scientific data back to Earth. The probe spent more than a year mapping the asteroid from orbit before collecting a small surface sample.
Japan’s mission is a successor to the earlier Hayabusa mission. That probe visited a small asteroid in 2005, bringing back grains of dust to Earth. In doing so Hayabusa briefly landed on the asteroid, staying on the surface for around thirty minutes.
The second mission, OSIRIS-REx, forms part of NASA’s New Frontiers program. This is the third spacecraft in the program, following earlier missions to Jupiter and Pluto. The fourth probe, Dragonfly, will visit Titan, the mysterious moon of Saturn.
OSIRIS-REx left Earth in 2016 and reached its destination, the asteroid Bennu, two years later. Following five hundred days dedicated to surveying the asteroid, NASA executed a series of rehearsal manoeuvres over the summer of 2020. In October OSIRIS-REx managed to grab a chunk of Bennu, and will head back to Earth by 2023.
How Do They Grab Samples?
Both probes spent months mapping their asteroids, providing scientists with the information needed to pick the ideal spot for sampling. Once a spot had been chosen, both probes need to get close enough, within a few tens of meters, to collect a sample. After that, though, the two missions have different approaches to collecting samples.
Hayabusa2 used a funnel and high speed bullet to blast material up from the surface of the asteroid. After firing the bullet the probe was able to collect material in the funnel. But this approach only captured surface material — and the mission scientists also wanted to get rocks from deeper down.
For this, Hayabusa2 needed a bigger gun, and a bigger explosion. To prevent the explosion damaging the spacecraft, the probe first released the gun, and then shielded itself on the far side of the asteroid. Once the probe was safely hidden, the gun fired and blasted out a ten meter wide crater. After the dust had settled, Hayabusa2 returned from hiding, and collected a sample of the newly revealed rocks.
OSIRIS-REx took a different approach. Instead of firing a bullet into the asteroid, the probe will literally reach out and grab a piece. Engineers fitted OSRIS-REx with a three meter long arm that will extend away from the spacecraft as it hovers close to the surface. Once it makes contact with the asteroid, the arm will capture material and bring it back for storage.
Haven’t We Already Landed on an Asteroid?
Yes! Two previous missions have landed on asteroids. The first Hayabusa mission accidentally landed on Itokawa, a small asteroid, in 2005. Mission planners had intended to just touch the asteroid to collect a sample. But as it did mission control lost communication with the probe, leading to a much longer stay than planned. After thirty minutes on the surface, mission operators regained control and successfully took off.
The first landing on an asteroid came even earlier. NASA’s NEAR mission, visiting 433 Eros, spent more than a year in orbit studying the asteroid. At the successful end of the mission operators decided to attempt a landing. After a slow descent, the spacecraft touched down on Eros on February 12, 2001, and likely remains there today.
Other missions have touched down on the surface of comets — notably ESA’s Philae lander, which transmitted briefly after landing on Churyumov–Gerasimenko. NASA also obtained samples from a comet when Stardust passed through the tail of Wild 2 in 2004.
What Is Special About These Asteroids?
Both Bennu and Ryugu are near Earth asteroids. Both are also extremely old, forming billions of years ago in the youth of the Solar System. Astronomers hope that samples from these two asteroids can reveal important details about the early Solar System.
Scientists have another reason for investigating Bennu — it may be on a collision course with Earth. Simulations of its orbit show that several near misses will happen over the next two centuries. A key year is 2060 — depending on exactly how close to Earth it comes then, the asteroid may line up perfectly to strike Earth soon after.
To understand this risk better, astronomers need more detailed information about the asteroid. In particular, they are interested in something called the Yarkovsky Effect, a tiny force on the asteroid caused by the Sun’s heat. Some have suggested that we could use this effect to alter an incoming asteroids orbit. One strange idea is to paint the asteroid white , thereby cooling the asteroid and reducing the strength of the effect.
Why Is This Important?
While saving the Earth from a future asteroid impact is one benefit of these missions, the main goal is to better understand the early Solar System. Astronomers think that asteroids like Bennu and Ryugu were the building blocks for the planets. By studying them close up we can get a better understanding of how the planets formed.
The pristine surfaces of these asteroids are also of great interest. Rocks found on Earth are young in comparison. Thanks to our planet’s climate and biology, rocks tend to get eroded and remade over millions of years. Four billion year old rocks — like those found on Bennu and Ryugu — are extremely rare on Earth.
Scientists think they may find organic chemicals in these rocks. These chemicals, like their name suggests, are vital for life and may have helped life get started billions of years ago. If so, these two missions may shed light on our own ultimate origins.
The third reason these missions are interesting goes back to the idea of asteroid mining. For the first time two spacecraft will prove that we can indeed go to asteroids, and bring something back. They may one day be remembered as the first small steps towards reaping the riches of the heavens.
What’s Next?
Asteroids are attracting more and more interest from both space agencies and private companies. Several missions are coming up in the next few years. Two , Lucy and Psyche , are planned as part of the same NASA program to investigate the formation of the planets.
Others, notably Japan’s DESTINY+, will demonstrate advanced technologies for deep space flight. Asteroid redirection is another goal. NASA and ESA are planning a pair of missions to Didymos to study ways of deflecting potentially dangerous asteroids.
The Didymos missions, named DART and Hera, will also be notable for another reason. Hera will carry two cubesats — tiny but potentially much cheaper satellites — with it. These two probes will carry out dedicated observations of the asteroids, and relay back to Earth through the Hera mothership.
All these missions to asteroids may be early steps towards a revolution in mankind’s exploitation of space. Plans are already afoot for satellites to start mining asteroids — and to unlock the almost unimaginable wealth hidden in the Solar System.