Supercomputer takes on cosmic threat

By Leonard David

Senior space writer

updated 3:05 p.m. ET June 14, 2006

A super-powerful computer has simulated what it might take to keep Earth safe from a menacing asteroid.

Researchers have utilized the number-crunching brainpower of Red Storm, a supercomputer at Sandia National Laboratories in Albuquerque, N.M. Red Storm, a Cray XT3 supercomputer, is the first computer to surpass the 1 terabyte-per-second performance mark — a measure that indicates the capacity of a network of processors to communicate with each other when dealing with the most complex situations — in both classified and unclassified realms.

The massively parallel computing simulations have modeled how much explosive power it would take to destroy or sidetrack an asteroid that has Earth in its cross-hairs.

For the computer runs, asteroid 6489 Golevka was chosen. Golevka isn’t going to hit the Earth, explained Mark Boslough, a Sandia scientist and asteroid threat analyst. This particular asteroid was used as a “proxy” because solid geometry data about the object existed, he said.

Since its discovery in May 1991 by astronomer Eleanor Helin, asteroid Golevka has been repeatedly radar-scanned. It is about a third of a mile (one half-kilometer) across, but tips the scales at about 460 billion pounds (210 billion kilograms), according to asteroid experts at the Jet Propulsion Laboratory in Pasadena, Calif.

The Golevka asteroid has been a particular object of interest since 2003. That’s when NASA scientists discovered its course had changed.

Keeping tabs on Golevka has helped pin down the Yarkovsky Effect — a minuscule amount of force produced as the asteroid absorbs energy from the sun and re-radiates it into space as heat. Over time — lots of it — that force can have a big effect on an asteroid’s orbit.

Deflection and disruption
Boslough said the actual geometry from radar measurements of asteroid Golevka were used in the computer simulations.

Sandia National Laboratories The number-crunching Red Storm supercomputer has been used to simulate what happens when a nuclear device is used to change trajectory of asteroid.

“Of course we don’t know the internal structure, so we had to assume something,” Boslough said. He and his colleagues tried both heterogeneous and homogenous simulations, but selected the uniform strength and density for the high-resolution demonstration mainly for simplicity's sake.

The researchers applied the "Keep It Simple, Stupid" principle of avoiding unnecessary complications — don’t try the hardest thing first, Boslough added.

In general terms, several findings stood out in Red Storm computations that might be useful for future planetary defense systems.

Boslough first noted that there are two “end-member strategies” in the Golevka work:

• Deflection: Keeping the asteroid in one piece and changing its trajectory to miss Earth.
• Disruption: Blowing it to smithereens and making sure all the bits miss the Earth.

“There are a range of in-between options,” Boslough told Space.com, “but the deflection end of the spectrum is much more realistic.” On a kiloton-per-kiloton basis, small, shallow explosions are much more effective for moving the asteroid than large, deep ones.

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