Exploring Bennu, the $670 billion asteroid headed toward Earth

About a week after Mars InSight touched down on Mars, another NASA space probe, OSIRIS-REx, arrived in orbit around an asteroid headed toward Earth called Bennu. The probe will spend the next two years mapping and examining Bennu.

OSIRIS-REx’s mission will not only offer insights into the origin and evolution of the solar system — but also may interest future asteroid miners. One estimate suggests that Bennu contains $670 billion worth of material.

The climax of the probe's stay around the asteroid will feature the extension of a sample-gathering arm that will take about 60 grams of particulate material from Bennu’s surface. The probe will blast out of orbit around the asteroid and bring its priceless cargo back to Earth.

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In September 2023, OSIRIS-REx will eject a capsule with the samples, which will then land via parachute at the Utah Test and Training Range. The sample capsule will then be taken to a lab at the Johnson Spaceflight Center in Houston, Texas for study.

One goal of the OSIRIS-REx mission will be to study the material from the carbonaceous asteroid, containing clays, some organic material, and volatiles (nitrogen, water, carbon dioxide, ammonia, hydrogen, methane and sulfur dioxide.) Key information for both planetary science and possible future mining projects.

The second main science mission will study how the so-called Yarkoysky effect determines Bennu’s path in orbit around the sun. The effect involves the absorption of radiation from the Sun and its subsequent emission as heat, creating a tiny but measurable amount of thrust.

A measurement of the Yarkoysky effect will be vitally important to future generations. Scientists believe there is a significant chance that Bennu could impact the Earth sometime in the 22nd century. The impact, were it to happen, would not be the world-killing catastrophe of the asteroid that destroyed the dinosaurs 65 million years ago — but it would hit with 1,200 megatons of force, creating massive devastation.

OSIRIS-REx’s studies will refine understanding of the forces affecting Earth-approaching asteroids, thus aiding the defense against Earth impactors.

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So far, missions to other asteroids have not returned a lot of gorgeous images. An asteroid up close looks like a rock with various shades of gray. The images cannot compete with the alien landscapes of Mars, the glorious rings of Saturn, or even the “magnificent desolation” of the lunar surface. However, from both a scientific and commercial perspective, NASA’s voyages of discovery like OSIRIS-REx have an importance that is beyond evaluation.

Asteroid science will help humankind gain a better understanding of the little part of the universe where our home planet orbits the typical, commonplace star that we called the sun. The knowledge won by such missions is as valuable, in its own way, as the gold sought by the Conquistadors in the last age of exploration. Science illuminates our civilization, making it better, opening paths to improve the human condition.

If we have the will to acquire them, the resources that asteroids consist of can become the basis of a new, space-based industrial revolution, creating an abundance of wealth that could vanquish poverty and want. Undertakings like OSIRIS-REx are not only a sign of American greatness, but evidence of what human beings can accomplish when they set out to do great and difficult things. 

Mark Whittington is the author of space exploration studies “Why is It So Hard to Go Back to the Moon? as well as “The Moon, Mars and Beyond.”