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A rock on Bennu

A rock on Bennu
Click for full image (which is rotated 180 degrees).

Cool image time! The OSIRIS-REx science team today released a close-up image of the surface of the asteroid Bennu. The image on the right is a cropped and rotated section of that image, focusing on the image’s star, its largest rock.

The boulders on Bennu’s surface sport a variety of surface textures, from smooth, to hummocky, striated, and crumbly “cauliflower” in nature. The large boulder in the image center is ~92 ft (~28 m) across and has a somewhat round shape, though many smaller boulders surrounding it are very angular. Some of these appear to be fragments that may have disaggregated from the central boulder and display layering effects that may reflect some of the properties of their mineral composition. Other boulders show signs of surface exfoliation and fractures that may have been caused by impacts, mechanical weathering, and other forms of rock breakdown active on Bennu’s surface.

The image was taken from less than a mile away, and shows a spot near the asteroid’s south pole.

Why the larger boulder has a rounded look, but the pebbles around it are jagged, is a puzzle.

The science team also revealed today that they have detected plumes of particles being released from the asteroid’s surface. They have also found Bennu to present them with the same problem faced by the Hayabusa-2 team at Ryugu: The asteroid is far rougher than expected.

The higher-than-expected density of boulders means that the mission’s plans for sample collection, also known as Touch-and-Go (TAG), need to be adjusted. The original mission design was based on a sample site that is hazard-free, with an 82-foot (25-meter) radius. However, because of the unexpectedly rugged terrain, the team hasn’t been able to identify a site of that size on Bennu. Instead, it has begun to identify candidate sites that are much smaller in radius.

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

 
Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

One comment

  • Ryan Lawson

    This makes me think about eating Frosted Flakes as a kid. Even then at a young age I noticed how the larger, more intact flakes were at the top of the bag and the smaller broken bits were packed at the bottom. I always loved getting to the bottom of the bag because that’s where the highest concentration of sugary powder was.

    I suppose on Bennu, a captured dense metal-rich asteroid would slowly be absorbed into the center with the lighter rocks remaining on top.

    You could also move Bennu around by picking up small rocks and throwing them away. I need to patent a modified baseball pitching machine for this. :-p

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