Readers!
 

Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.


 

Regular readers can support Behind The Black with a contribution via paypal:
 


 

Or with a subscription with regular donations from your Paypal or credit card account:


 

If Paypal doesn't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to
 

Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652


Avalanches on an asteroid

A new analysis predicts that when the asteroid Apophis flies past the Earth in 2029, the close fly-by will cause avalanches on the asteroid.

If asteroids pass close to Earth, they begin to experience the effects of our planet’s gravity. Just like the moon pushes and pulls the oceans, creating the tides, asteroids are susceptible to tidal forces from our planet. To judge what effect this will have on Apophis, scientists need to know what it’s made of. Their best guess is based on photos taken by a Japanese spacecraft named Hayabusa, which took detailed pictures of an Apophis-sized asteroid named Itokawa. Those images revealed that the asteroid wasn’t a solid mass of rock spinning through space, but rather a giant clump of debris held together loosely by gravity. “You look at the [Hayabusa] pictures and you’re like, ‘Uh, that’s a pile of rocks, dude.’ It’s very likely that Apophis is similar,” says astrophysicist Derek Richardson of the University of Maryland, College Park.

To show that Earth’s gravity could cause some of these rocks to tumble, Richardson and his colleagues developed a computer model that allowed them to place virtual sand piles across the surface of a model asteroid with roughly the same dimensions as Apophis. By factoring in the gravity from the asteroid, the tidal force from Earth, centrifugal force caused by the asteroid’s rotation, inertial forces, and other effects, the team was able to predict how the particles on the surface of the asteroid would behave on approach. The results confirm that Earth’s tidal forces would be strong enough to cause tiny avalanches on the asteroid, the team reported online ahead of print in Icarus.

Need I note that there are a lot of uncertainties here? Because they are using what is known about a different asteroid, all of their assumptions about Apophis’s properties in their computer model could be very wrong.

Still, this is interesting, because it does demonstrate that an asteroid could be significantly disturbed simply by flying past a planet.

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

Readers: the rules for commenting!

 

No registration is required. I welcome all opinions, even those that strongly criticize my commentary.

 

However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.

 

Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.

Leave a Reply

Your email address will not be published. Required fields are marked *