Bennu

Details

Bennu is a carbon-rich near-Earth asteroid explored by NASA’s OSIRIS-REx mission. Returned samples contain carbon-rich material, water-related minerals, and unexpected phosphates, hinting that Bennu’s parent body may once have been part of a small primitive ocean world.

Bennu is important because it is no longer just a distant asteroid seen through cameras and spectra. Thanks to NASA's OSIRIS-REx mission, material from Bennu has been brought to Earth, turning the object into a direct source of laboratory evidence. That changes the relationship completely. Bennu is not only something we observe. It is something we can chemically inspect at close range.

What makes Bennu especially valuable is the kind of material it carries. The returned samples contain carbon-rich matter, water-related minerals, and chemically revealing compounds that point back to a much older and more altered parent-body history than Bennu's current small size might suggest. In other words, this rubble-pile asteroid may preserve the broken remnants of a more complex early environment.

That is why Bennu matters on this scale. It shows how a modest-looking asteroid can function like a time capsule from the early Solar System. Bennu is not scientifically rich because it is large. It is rich because it gives us uncommonly direct access to primitive material shaped by ancient chemical and watery processes long before Earth became the world we know.

182m
Visual creditNASA / Goddard / University of Arizona / Public domainSource: Wikimedia Commons

Key facts

Category
Asteroids
Object class
Carbonaceous near-Earth asteroid
Mass
~73 million tonnes
Scale fact
490 mmean diameter
Estimated age
~4.5 billion years
Composition
Carbon-rich rock and boulders

Scale context

Where Bennu sits on the full axis

By size on the journey, Bennu sits between Dimorphos and Ryugu. The band below compares Bennu with nearby Carbonaceous near-Earth asteroid objects so the size jump stays easy to read.

Shared physical scale
585m
Bennu490 m
Ryugu900 m

Together, these objects make the size change around Bennu easy to compare at a glance.

Between the smallest and the largest, perspective is everything.

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