In the 1964 Cold War classic film, Dr. Stragelove, a device called the Doomsday Machine brings nuclear Armageddon to the world. It’s time we start building a Doomsday Delay Machine that will also use a powerful nuclear weapon — but for the opposite effect, to save life on Earth by blowing apart renegade asteroids.

As a complementary piece to its Asteroid Initiative for hijacking an asteroid and bringing it back to Earth for dissection, NASA recently announced an Asteroid Grand Challenge. One goal of the challenge is to harness public engagement and problem solving to find dangerous asteroids and deal with them appropriately.

This likely was spurred on by a letter on Near Earth Objects (NEOs) from the White House Office of Science and Technology Policy (OSTP) to the Congress in 2010. The OSTP strongly recommended that NASA take the lead in detecting NEOs and coming up with technologies to deflect them away from Earth.

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Astronomers have been cataloging NEOs and tagging the ones that could pose a potential threat to Earth. So far, 10,000 NEOs have been cataloged. The upcoming Large Synoptic Survey Telescope — essentially an all-sky surveillance camera — will find at least 100,000 more asteroids.

But, once you find one heading for Earth, what do you do?

There has been a lot of discussion about how to deflect an asteroid. Among the ideas: kinetic-energy impactors that give it a whack (as tested in 2006 on comet Temple 1, shown above), slow-pull gravity tractors and the staple of sci-fi disasters: nuclear bombs. But without testing these technologies in space it’s unlikely there will ever be a clear consensus on how to protect Earth in a timely manner.

Aeronautical engineer Alan Pitz and co-investigators at the Asteroid Deflection Research Center at Iowa State University say that we need to develop a knuckle-fisted asteroid interceptor. On short notice it is launched to sprint to an asteroid a blow it apart with a nuclear blast.

He reports that we need at least three space missions to test out the space interceptor concept. There would be an asteroid orbiter mission, sample return, and an impact mission with a dummy payload. Pitz estimates the total development and flight cost at about $3 billion. That’s a small insurance premium for defending an entire planet.

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“An intercept mission with nuclear explosives is the only practical mitigation option against the most probable impact threat of NEOs with a short warning time (much less than 10 years),” writes Pitz.

He’s calling for an innovative concept that is a one-two punch to the NEO. It blends a kinetic impactor with a subsurface nuclear explosion strong enough to break apart the asteroid. He proposes building a Hypervelocity Asteroid Intercept Vehicle (HAIV) that would disintegrate the asteroid.

One asteroid-killer mission design calls for an advanced rocket booster capable of propelling the interceptor vehicle to extraordinary speeds of roughly 60,000 mph. The 3-ton HAIV would quickly climb up the sun’s gravitational slope and onto an asteroid rendezvous.

PHOTOS: NASA’s Asteroid Capture Mission

One day before asteroid impact, the spacecraft detects the target NEO and the terminal control subsystems onboard the HAIV awaken. Cameras and laser radars home in on the primitive body. The images are used by the onboard flight computer to direct thrusters to guide the spacecraft to ground-zero.

Shortly before impact, the piggyback HIAV spacecraft separates with the impactor module taking the lead. It deploys a whisker-like 30-foot boom to touch the asteroid. An instant before the impactor does a kamikaze crash into the asteroid, the boom’s tactile sensor sends a signal to the trailing atom bomb vehicle to begin its detonation sequence.

The impactor vaporizes on contact. Seething hot plasma and debris blowtorch the heat shield on the front of the trailing companion spacecraft. Using onboard cameras for guidance, the bomb steers itself into the fresh crater. The heat shield deforms and melts as it passes through the plasma and ejecta. It burrows 15 feet into the roiling crater debris and the bomb detonates with a shattering 2-megaton yield.

The sudden unleashing of energy is equivalent to 70 percent of the total yield of all the explosives used in World War II, including the Hiroshima and Nagasaki atomic bombs. For the first time in human history a weapon of mass destruction will have used to save countries rather than obliterate populations.