Most of us think of an asteroid as a rough, uninteresting, grey rock moving through space. That's quite close to the truth, for the most part. However, NASA's historic OSIRIS-REx mission has shown us that some of these space rocks are concealing some extremely colourful secrets.
Bennu is one such asteroid that has been the focus of extensive research, and the pure samples returned to Earth are changing our understanding of the early solar system and even the beginnings of life. The reason why Ryugu, a comparable carbon-rich asteroid, appears reddish whereas Bennu has a little bluish hue was one of the first straightforward problems scientists solved.
The Colorful Case of Two Asteroids
The colour variation was first thought to be caused by "space weathering." Over time, a celestial body's surface may change because to the continuous bombardment of micrometeorites and the solar wind. It made sense to assume that Ryugu and Bennu were going through this process in different ways.
Analysis of the returned Bennu samples, however, contradicted this theory. As it happens, the weathering of the two asteroids is nearly identical. Time is the true factor that makes a difference. While Bennu's surface has been enduring the emptiness for tens of thousands of years, Ryugu's surface has only been subjected to the harsh conditions of space for a few thousand years.
Scientists are now examining two distinct phases in the same cosmic life cycle rather than two distinct processes. The "colour" of these carbonaceous asteroids—the way their surfaces reflect light—variates with age. Simply said, Ryugu's red stage is less developed than Bennu's blue.
A Time Capsule Carrying the Building Blocks of Life
The colour wasn't the only thing that was revealed. Researchers discovered something astounding as they delved deeper into the 4.5-billion-year-old material: the building blocks of life. A range of amino acids and nucleobases, the basic building blocks of proteins and genetic material, as well as phosphates, an essential part of DNA, are present in the Bennu samples.
The long-held hypothesis that asteroids and comets would have served as cosmic delivery services, providing a young Earth with the water and chemical ingredients required to initiate life, is greatly strengthened by this discovery. A pure look into the chemical inventory of the solar system's dawn is provided by the material in Bennu, which has been maintained in the vacuum of space.
A Mosaic of the Early Cosmos
The most recent research keeps revealing how unique Bennu is. It is a distinctive mosaic of components from all around the early solar system, not just a relic from one region. According to studies, the parent body of Bennu was created from a combination of ice and cosmic dust that came from the solar system's frigid outer regions. Even more remarkably, the samples contain stardust grains of material that are older than our own sun and solar system.
From solving a simple color mystery to providing profound clues about our own existence, the small fragments from asteroid Bennu are proving to be one of the most valuable scientific treasures ever returned to Earth. It's a powerful reminder that even the most seemingly drab and distant objects in space can hold the most vibrant and vital of secrets.
Frequently Asked Questions
What is the OSIRIS-REx mission?
OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer) is a NASA mission to study and return a sample from the near-Earth asteroid Bennu. It successfully brought the sample back to Earth in September 2023 for analysis.
Why was Bennu chosen for this mission?
Bennu was chosen because it's a carbon-rich, relatively old asteroid that hasn't changed much since its formation, making it a perfect time capsule from the early solar system. Its orbit is also relatively easy to reach from Earth.
What are the "building blocks of life" found on Bennu?
Scientists found high concentrations of carbon, water-bearing minerals, phosphates (a key component of DNA), and various amino acids, which are the molecules that form proteins.
Sources and Further Reading
- Popular Science: "Some asteroids are more 'colorful' than others. Here's why."
- NASA: "NASA’s Bennu Asteroid Sample Contains Abundant Water & Carbon"
- Purdue University: "Planetary scientist decodes clues in Bennu’s surface composition..."
- Natural History Museum: "Material necessary for life on Earth may have been delivered by asteroids like Bennu"
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