Planetary science isn't all telescopes and spectral lines. Sometimes you need 40-foot cranes, advice from a dude named A-Ray, and a pair of 2,800-pound granite balls. Literal ones.
Dan Durda, a research scientist at Southwest Research Institute in Boulder, Colo., wanted to verify the mechanics of space-rock collisions, which can help explain the formation of asteroids and planets. Drawing inspiration from an artsy water fountain in Boulder, he ordered a pair of 3-foot-diameter granite balls and put them to the test.
When small rocks collide, they bounce off each other like billiard balls, and physicists use mathematical models to extrapolate this rebound property to larger scales, which can help them study asteroids and planet formation processes. They use the ratio of the outgoing speed to the incoming speed in a collision, known as the coefficient of restitution. This is a measure of how much energy is used up in a collision.
When it comes to boulders, you might expect the numbers to change, because some of the collision energy might be absorbed and cause fractures in the rocks. But the existence of massive rocks in landslide piles suggests that rocks are pretty tough. Durda wanted to test whether the coefficient of restitution would be the same across a wide spectrum of ball sizes, verifying current asteroid and planet models. He needed some big balls to figure it out.
"It involves the outcomes that we model when we model the destruction of asteroids, or big particles in the rings of Saturn," Durda explained. "It was out of the box for sort of the standard research that goes on in this community. When you have to rent two 40-ton cranes to do your planetary science experiment, you're doing something unusual."
A new outdoor mall near Durda's office features a water fountain with a sculpted granite sphere, and he was intrigued. He looked up the designer, waterfountains.com, and ordered a pair of 1-meter-diameter granite spheres of his own. They were quarried and milled in China, he said.
Durda's office is in a pretty chic district of Boulder — the spa next door might object to a couple huge cranes parked outside for a week — so he took the experiment to the Southwest Research Institute's main office in San Antonio, Texas. The two cranes he rented also came with operators Alan Rawlings (a.k.a. A-Ray) and Chris Vest, who are listed as co-authors (along with scientists Naor Movshovitz, Derek C. Richardson, Erik Asphaug and Alex Morgan) on Durda's paper. Durda said he was impressed with their interest in his unusual experiment, and was indebted to them for their suggestions about how to secure the spheres and release them for proper clacking. A-Ray came up with the idea to use zip ties to secure the balls at a set distance, for instance, and snip them with wire cutters to release the tension.
All told, the researchers smacked the balls together 108 times at up to 3.5 mph. See them in action in the video below.
"In the speed at which we were able to safely operate the experiment, the number turns out to be very similar," Durda said. This will help inform models of collision physics, which can help scientists learn more about asteroid impacts, space debris accretion, and more in the annals of planetary science. The findings are published in the January issue of the journal Icarus.
After the clacker study, Durda and colleagues ended up doing the spheres in, he said. They needed small pieces of the same granite to do follow-up studies, such as examining their composition.
"Rather than take a hammer to them, we thought we would do something more useful to planetary science, which was do a high-speed impact," he said. "We ended up shooting them with a big cannon, and making big craters on the sides of them."
The results of those experiments have not yet been published, but Durda said he got some surprising results.
Its job complete, now one of the Death-Star-ized spheres sits at SWRI's San Antonio headquarters, a testament to the weird experimental evidence — and the granite balls — that scientists sometimes require.
Oh, sooo many jokes! Begin......NOW!
credendo02/08/11 at 5:10 pm
Oh, sooo many jokes! Begin......NOW!
OK! I begin: It takes balls to do that kind of experiment.
He's good for a Igg Noble.
they should have pulled them back as far as they would go, and THEN let go.
That's some set of knockers!
Stunt man practicing for a scene from amazon women on the moon?
they sure like smacking their balls together... hey, anything for science!
Space balls. Unleash the force! umm... Ball force!
Why oh why did they paint nipples on them?
Ixnay on the allsbay!
How 'bout Wackamole?! Can you beat my score?
Well, that is at least one American who has bought his balls back from China. Shame that they still own the rest of ours.
Q: Hows it hanging?
A: From a crane! 2 Cranes!
"Why oh why did they paint nipples on them?"
I think that's to easily track the speed/distance via the video recording.
Man, I thought they were gonna drop the balls from a lot higher. I wanted to see what a high speed collision would do. And yes, I do find it odd that they would face the nipular area toward the camera.
I give this video 1 star wont play on android because i am one of those this article and video sucks cuz my device is not supported kind of people rawr nerd rage!!!!
They needed some big balls to pull of that one!
ahhahahahah thats hilarious! Man, theres so many jokes i dont know whwere to begin! Oh man, theyre even hanging, lol omg!
I got it! Its a ball-istics experiment!
This is nothing new. The film undustry has been doing research into ball smashing for years ;)
what a waste. i thought they were going to pull those balls so high up and far apart from each other. what a boring experiment. couldn't they of just used to pool balls then multiplied their outcome?
Read the article. Part of what they wanted to find out, is whether the "coefficient of restitution" changed, with the scale of the rock -- so that they would know what multipliers to use, when estimating the effects of asteroid impacts.
As for using pool balls -- how many pool balls are made out of granit? How many asteroids are made out of resin or ivory?
They could have saved a lot of money and time performing this experiment if they had just started by calling Chuck Norris. Of course, his are brass, but still.
I'll bet they would work well for crushing nuts! ;)
Balls are touching.
Well if they are not going to name that
building in Fort Wayne after Harry Baals,
then why not rename this experiment . . .
"The Harry Baals Buster".
"But we've got the biggest
balls of them all!"
Holy Balls Batman! If they had another 4 balls that size they could make the worlds largest perpetual motion toy!
1. They could have just studied me when i run.
2. My wifes been doing this busting my balls experiment for years.
So they wanted to "verify the mechanics of space-rock collisions" by testing on Earth? With the myriad of differences between the two environments, this experiment is fundamentally flawed, not to mention a complete waste of time. Cheers.
@JayAre: Perhaps you could explain why you think that the properties of the rocks change in space. The experiment is investigating the "coefficient of restitution" of granite. Why would the space environment change that?
Is that a chubby sasquatch at 00:45 left side?!