Three ways to spin an asteroid

Posted by Daniel Pendick
on Thursday, July 10, 2008

The Galileo spacecraft photographed the binary asteroid Ida (the big one at left) and its tiny satellite Dactyl in 1993. Galileo Project/JPL/NASA
Spinning asteroids or skinning cats — there are so many ways to do it. Let’s look at three methods recently in the news:

One: The effects of sunlight
In today’s issue of Nature, several scientists outline a mechanism by which sunlight striking at an angle “spins up” loose, rubbly asteroids, causing them to cast off debris that eventually coalesces into a moon. This, they propose, is how binary asteroids — a drifting space rock with its own satellite — come to exist.

Two: Invoke Chicken Little
June 30 was the 100-year anniversary of the Tunguska event, during which a smallish asteroid or comet exploded over Siberia and made a hell of a mess. Fortunately, the area was sparsely inhabited. The explosion took out about 830 square miles (2,150 square kilometers) and was possibly about 1,000 times more powerful than the bomb dropped on Hiroshima, Japan.

But what if such a space rock (or snowball) exploded over a densely populated modern city — say, Los Angeles? Are we prepared?

Or at least that was the asteroid spin emanating from the offices of The Planetary Society in Pasadena, California, on the Tunguska centennial. Space-science supporter Rep. Dana Rohrabacher, R-Huntington Beach, joined the Planetary Society and several other interested parties to promote the importance of support for efforts to identify and track potentially Earth-threatening asteroids, lest they visit another Tunguska on us.

Three: Blame it on E.T.
The official line on what caused Tunguska may be “comet or asteroid,” but certain Russian scientists (and a few Russian pretend-scientists) say otherwise. They met in Moscow for the Tunguska anniversary to exchange ideas and reenergize their opposition to the pro-asteroid-or-comet lobby.

The lack of conspicuous fragments of the Tunguska impactor has spawned some hypotheses that a charitable observer might call “creative.” Or, if you are not feeling particularly charitable, “kooky” might work, too.
 Based on my brief Google search, the kookiness includes:
• Crash of an alien spaceship.
• Maverick physicist Nikola Tesla (1856–1943) detonated an underground volcano in Siberia by remote control.
• A really, really, really strong bolt of lightning, possibly originating at Earth’s core.
• Global warming.
• Something to do with an earthquake.
• Methane gas explosion.
• A tiny black hole from outer space that exploded on impact for some reason.
• A chunk of antimatter from an unknown extraterrestrial source

Predictably, the Russians asserted that the pro-asteroid-or-comet lobby was just trying to get money for their research by promoting the “danger from space” spin on the Tunguska event. I agree. That money would be better spent supporting research on giant UFOs and lightning bolts.

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