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New research detects increase in Bennu’s rotation

New research using ground-based observations has detected a slight increase over time in the daily rotation of the asteroid Bennu.

The new research finds the asteroid’s rotation is speeding up by about 1 second per century. In other words, Bennu’s rotation period is getting shorter by about 1 second every 100 years.

While the increase in rotation might not seem like much, over a long period of time it can translate into dramatic changes in the space rock. As the asteroid spins faster and faster over millions of years, it could lose pieces of itself or blow itself apart, according to the study’s authors.

…The change in Bennu’s rotation could be due to a change in its shape. Similar to how ice skaters speed up as they pull in their arms, an asteroid could speed up as it loses material.

Nolan and his co-authors suggest the reason for the increase in Bennu’s rotation is more likely due to a phenomenon known the YORP effect. Sunlight hitting the asteroid is reflected back into space. The change in the direction of the light coming in and going out pushes on the asteroid and can cause it to spin faster or slower, depending on its shape and rotation.

Truth is, this is not a very significant finding. Asteroids don’t weight much, and thus have very weak gravitational fields. It is therefore very easy to change their orbit and rotation, as well as add or subject material from them.

In this sense, the conclusion above is likely incorrect. What they have found is that the asteroid’s rotation increased at a pace of about 1 second per century, during their study period. Their data only covers the period from 1999 to 2005. Bennu could easily slowed its rotation, or increased it even more, during other times.

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.

2 comments

  • Phill O

    The big question is the defining the propagation of error in the measurements!

    This is a measurement of 3 parts per trillion. If taken over a 5 year period, the measurement system must be able to detect a difference of near 1 part per 20 trillion.

  • Phill O

    Sorry, there was a calculation error, the precision would have to detect 1 part in 53 trillion

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