There is optimism in the air that a new Strategic Arms Reduction Treaty (START), signed by the presidents of Russia and the United States on April 8 in Prague, Czech Republic, will be successfully concluded by the end of this week’s Global Nuclear Security Summit in Washington. Over 1,500 warheads and even more delivery systems are planned to be decommissioned jointly by Russia and the United States.

So what are we going to do with the surplus nuclear arsenal? Do we simply destroy the nuclear weapons, or could we put them to good use for some other mission?

Some of the nuclear surplus could be used to generate power in nuclear reactors, but what of the delivery systems and infrastructure? What about the launchers?

Last April, at the “Overcoming Nuclear Dangers” conference in Rome, former Soviet President Mikhail Gorbachev suggested that one way to rid the world of these horrendously expensive weapons and their delivery rockets might be to collect them under a United Nations umbrella, modify them appropriately, and prepare them for use against a rogue asteroid. Early this year, the Russian Space Agency announced that it was looking at options to neutralize such a threat. (Note that Russia had a close shave with disaster in 1908 when an extraterrestrial object devastated the Tunguska Taiga.) Such a project could involve the whole world and might even be used to align several national defense and civilian space agency efforts, including those of India and China.

In a study called Project Icarus at the Massachusetts Institute of Technology in the 1960s, nuclear warheads atop Saturn rockets were proposed to confront rogue asteroids. In a study in my studio at the University of Southern California (USC) some years ago, we concluded that it might be possible to avoid the radioactive dust and fallout issue if we took out the potential impactor with existing nuclear weapons a few years and several orbits before anticipated impact. This concept of taking out asteroids using nuclear weapons was corroborated in a January report by the American National Academy of Sciences called “Defending Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies.” The authors recommend testing this strategy on practice targets to make sure of the end-to-end viability of such a complex mission.

We are constantly refining our understanding of the various classes of asteroids and comets, and NASA’s Jet Propulsion Laboratory and other space agency and astronomy divisions and even private foundations, such as Space Guard, are continually accumulating more detailed knowledge on these objects. Some are monolithic, rich in nickel and iron, and many near Earth objects (NEOs) are carbonaceous chondrite piles of rubble left over from the time of solar system genesis, just held together by weak gravity.

Our mission planners and trajectory optimization experts routinely command and control complex systems in deep space, tweaking spacecraft to put them accurately in spots hundreds of millions of miles away with split-second timing and hairpin precision, so deadly accurate nuclear warhead delivery and detonation are clearly possible. In fact, the Deep Impact mission did just that on July 4, 2005, when a nonexplosive projectile struck comet Tempel 1 to help reveal its constitution.

In the direct-confrontation strategy using nuclear surplus arsenal, the first reconnoitering missions, spearheading the armada, would carefully characterize the body and identify weak spots such as crevices, deep craters, cleavages or fractures where a nuclear device might be detonated most effectively.

Then we could perhaps direct volley after volley of these surplus nuclear weapons, in a complex but carefully choreographed series of missions, repeatedly hammering the asteroid, hoping to shatter the aggressor into much smaller and less-dangerous fragments, in several successive stages. Once fragmented, it would be necessary to reacquire the multiple targets and reprogram and retarget these missiles during flight, all in real time. This strategy of multiple sequential strikes may thwart the body from re-accreting through gravity.

The resulting nuclear debris and dust would be dispersed by solar photonic pressure or natural solar system perturbations, or blown away by the solar wind over the several orbits, long before our tryst with E-Day (E for extinction). Moreover, the radioactive danger of the dust cloud would have diminished to a harmless level by then. E-Day could end up being Exhilaration Day or Entertainment Day, a global event when these pulverized asteroid remnants burn up in our atmosphere and light up the skies in a magnificent pyrotechnic display.

While many fear that such a strategy might backfire, showering Earth with debris, radioactive dust fallout and so on, I still think it warrants detailed investigation and experimentation.

We do not have to wait for a potential aggressor to get going on this mega project. We could begin testing, evaluating and certifying the system as soon as the new START is finalized. We must first test this capability on a NEO test target. Eventually, we might even base an armada of such rockets on the Moon, from where volley after volley may be dispatched at much higher-energy trajectories toward the aggressor. Yes, we have other experiments to do as well, such as placing continuous thrusters on the asteroid or testing the Yarkovsky effect, which proposes albedo modification by solar photonic pressure to alter the trajectory of an NEO. Alas, these will not help to get rid of nuclear weapons.

Cometary impacts are another matter. These denizens, especially those lurking deep in the outer solar system, approach the sun at over 10 times the speed of NEOs. They may also be much larger. We do not have anything in our arsenal at this time to dodge a cometary impact.

Statistics and probability are used to give us some idea of how often NEOs and comets collide with the Earth; two major events are predicted every million years. Comets are far less likely to take us out, statistically, but in reality, if one appears out of the blue, there is nothing we can do to avoid a cataclysm. And there is mounting evidence that asteroids and comets have decimated life and human populations in the past.

Amid the doom and despair that prevailed during this exercise in the USC studio, I recall one young Air Force officer/student who proposed using tough, reliable, fully self-sufficient biospheres, built and buried deep underground, to help communities survive even after such a cataclysmic event. I recall she pointed to enclosed malls, skyscrapers, subways and other deep tunnels and mines that we burrow into, build and service routinely as precedent structures for such facilities.

And that is precisely one of the reasons why I think space technology and space habitat engineering are critical for humanity’s survival — not only to preserve our species by extending and spreading out among the stars, but also to protect us here on Earth if, God forbid, something goes terribly wrong. 

Rockets with conventional armaments are a weapon of choice for defense. Nuclear weapons by themselves can wreak untold havoc in population centers. The cocktail of multiple nuclear weapons atop intercontinental missiles, precision-guided by military satellite communication networks, is perhaps the most wicked weapon of mass destruction ever devised. So it is ironic indeed that these agents of annihilation could be turned toward an extraterrestrial aggressor, if the need arises, in an effort to save all life on our planet.

The surplus nuclear arsenal and launchers from START II could be that first block in a complex and evolutionary architecture for defending Earth from such an extraterrestrial threat.


Madhu Thangavelu is conductor of the Graduate Space Concepts Studio in the Astronautics Division at the Viterbi School of Engineering and the School of Architecture at USC.