NASA's first look: Tiny asteroid is studded with boulders

[left-of-center2012]

NASA’s first look at a tiny asteroid shows the space rock is more moist and studded with boulders than originally thought.

Scientists on Monday released the first morsels of data collected since their spacecraft Osiris-Rex hooked up last week with the asteroid Bennu, which is only about three blocks wide and weighs about 80 million tons (73 million metric tons). Bennu regularly crosses Earth’s orbit and will come perilously close in about 150 years.

There’s no liquid water on the asteroid, but there’s plenty of it in the form of wet clay. Project scientist Dante Lauretta of the University of Arizona said the blueish space rock is “a little more rugged of an environment than we expected” with hundreds of 33-foot (10 meter) boulders, instead of just one or two.

Scientists think Bennu is a leftover from the beginning of the solar system 4.5 billion years ago when planets tried to form and some failed. Lauretta said it looks like Bennu was once a chunk of a bigger asteroid that probably had water in it.

https://www.bostonherald.com/2018/12/10/nasas-first-look-tiny-asteroid-is-studded-with-boulders/

[gtar100]

1. I wonder what it's origin was when it formed into rock.

A previous planet from a time before this solar system even existed? Are there clues within that would reveal some of its past?

[Nitram]

2. The origin: an enormous cloud of dust gradually coalescing in clumps here and there,

some continuing to get larger, and others bumping into each other and returning to dust. As clumps gained mass, they gre bigger more ropidly because more mass means more gravitational attraction of dust and small clumps.

[gtar100]

3. That's interesting, but how would that explain the rocks within?

That picture looks very much like sedimentary rock. Wouldn't the smaller rocks contained in the larger mass require some geological process in order to form and get worn down to to their present shape? This cloud "dust" must have been composed of something that was broken up if that's the case. Granted my very limited knowledge is based on what I see on Earth. Thank you for your reply.

[Nitram]

4. As the mass increases, the pressure heats and compacts the dust into stone.

Early on there must have been many collisions between the many coalescing bodies, breaking them apart. Smaller rocks wouild be attracted by larger bodies.