Gamma-Ray Spectroscopy on an Asteroid Could Help Find the Mother Lode

Now that President Obama has signed the U.S. Commercial Space Launch Competitive Act into law, also known as the SPACE Act of 2015, the concept of mining asteroids has taken another step from the realm of science fiction into the real world. Such companies of Planetary Resources, Inc. can now start making more firm plans to utilize asteroids for their raw materials.

Of course, space mining isn’t going to start anytime soon. That’s because the infrastructure to get people and mining equipment out to an asteroid isn’t exactly in place. But, with the successful launch and soft landing of the Blue Origin rocket, and the continuing tests of other boosters and launch services by such companies as SpaceX, and space agencies such as NASA and ESA, figuring out HOW to get to space (and get mining equipment to an asteroid) will happen in the not-too-distant future.

Seeing Inside a Rocky Body

Once you get “out there” to do some mining, how do you tell which asteroids are mother lodes and which ones will be just barren rocks in space? It’s going to take new tools. For example, a team of scientists at Vanderbilt and Fisk Universities, NASA’s Jet Propulsion Laboratory, and the Planetary Science Institute have been working on an instrument that could let a mining company know which rocks are worth going after. It’s called a gamma-ray spectroscope — a technology that’s been around for a while. In fact, missions to the Moon, Mars, Mercury, and asteroid Vesta (for example), have used low-resolution versions of such a spectrometer. This new one is a next-generation design that can be set to detect veins of gold, platinum, rare earth metals and other useful materials hidden within asteroids.

How it Works

Planetary gamma-ray spectroscopy depends on the idea that all objects in the solar system are continually bombarded by cosmic rays. They strike the exposed surfaces at relativistic velocities. That smashes atoms in the top layers apart, which creates a secondary shower of particles. That includes neutrons, which collide over and over again with the atoms in the material. The repeated smashing produces gamma rays. These are a form of electromagnetic radiation like light, but considerably more powerful and penetrating. The decay of long-lived radioactive elements is a secondary source of gamma rays.

The gamma-ray spectroscope records the intensity and wavelengths of the gamma rays coming from the surface of an object bombarded by cosmic rays. Its data can be analyzed to determine how much (if any) important rock-forming elements are in the asteroid. This includes oxygen, magnesium, silicon and iron, as well as precious metals like gold and valuable crystals  like diamonds.

Future Missions to Asteroids

Now that the legal way is cleared for asteroid mining, the first missions using this new method of “long distance detection” of valuable materials could come as early as the 2020s.  Of course, we have already visited asteroids with science missions, and those will continue. Mining operations will take longer to put in place. In the meantime, scientists studying moons, asteroids, comets, and other objects in the solar system will find the newly developed gamma ray spectrometer a handy tool to help them understand what those objects contain.

Exploitation is the Future — and It Raises Questions

Scientifically, this is an amazing new step — the chance to study objects and really learn about them from their interactions with cosmic rays. Legally and culturally, however, I wonder if we’re ready. This new law could open up the floodgates of space “claim grabbing” by any country with a space-faring ability.  Are the laws in place to protect the planets from contamination enough to induce the asteroid mining companies to proceed with caution? What happens if two companies from two different companies want the same asteroid? Or lay claim to vast swaths of space containing potentially valuable ones? Farther down the line, how will this space race for resources change our societies? These are all questions that will need to be answered as we make our moves to space in the next few decades.