(Source: Touchstone Pictures)
The mother of all bombs would sit in wait in an orbitary platform

Purdue University Geophysics Professor H. Jay Melosh has spent his career studying massive impact craters such as Chicxulub, a massive, partially underwater impact region in the Yucatan.  

Thanks to Professor Melosh's research, scientists now feel reasonably confident that it was this massive asteroid impact that triggered the extinction event that killed the dinosaurs.  And for the last two decades, Professor Melosh had been chief evangelist for a campaign urging the U.S. and other spacefaring nations to adopt a plan to design asteroid diverting devices to make sure the same thing doesn't happen to mankind.

I. To Nuke?

Opinion on how exactly to end an extinction-event size asteroid is sharply divided in the research communities of Russia and the U.S. -- the world's veteran space superpowers.

One camp was formerly led by Edward Teller, a veteran U.S. researcher referred to as the "father of the [American] hydrogen (fusion) bomb".  Before his passing he urged lawmakers in the 1990s to consider the use of a massive nuclear warhead, the mother of all bombs, to literally blow an asteroid off its orbit-crossing impact course with Earth.  At a 1995 meeting at Lawrence Livermore National Laboratory (LLNL) in Calif., he pitched the idea to a collective of U.S. and Russian ex-Cold War weapons designers and space engineers.

Nuclear fiery explosion
[Image Source: YouTube]

On the other side is a coalition of experts who believe a non-nuclear solution is possible, and that those on the other side are willfully overlooking the potential security risks of a space nuke for their own self-interest.

Nukes and asteroids... where have we seen this before??? Oh, right...
[Image Source: Touchstone Pictures]
George Mason University (GMU) anthropology Professor Hugh Gusterson is cynical about the effort, remarking, "It was a response to the loss of the weapons lab mission, it was not a response to the asteroid threat."

In his 1998 book about the effects of the Cold War on nuclear weapons testers at LLNL "Nuclear Rites: A Weapons Laboratory at the End of the Cold War" he argues that interest peaked when nuclear researchers feared that if they did not convinced the government to switch gears and develop nukes to target asteroids, they might lose their jobs.  But after they obtained jobs maintaining the U.S. nuclear weapons stockpile, he says, these clamoring calls largely died down, save for a few holdouts like Ed Teller.

II. Not to Nuke?

Professor Melosh is also a skeptic of those who advocate a nuclear answer.  He is leading a campaign to use an alternate, non-nuclear solution.  In a recent interview with The Center For Public Integrity he recalls the 1995 meeting at LLNL, complaining, "It was a really bizarre thing to see that these weapons designers were willing to work together—to build the biggest bombs ever."

He points out that no very large asteroids are in near-term orbits that overlap with the Earth.  He adds, "The remaining smaller objects can be dealt with by non-nuclear means, kinetic detection being the most straightforward [feasible].  I think that the need for deflecting very large objects that might require nuclear detonations is waning and that a reevaluation of realistic needs is very much in order."

Purdue University Geophysics Professor H. Jay Melosh [Image Source: Purdue University] 

His plan is to shoot large mechanical impactors -- battering rams of sorts -- at the meteorite, which could come with ion boosters to further "push" the asteroid post-impact with the object.  Together, he argues, this mechanical solution could prove far more safe and effective than his nuclear alternative.  The disadvantage is that mechanical solutions would admittedly take more time.

Asteroid event
Researchers believe mankind must find a way to prevent an extinction level asteroid from htting the Earth. [Image Source: LANL]

Others like Princeton University Professor Christopher Chyba -- a nuclear weapons expert and a member of President Obama’s 18-person Council of Advisors on Science and Technology -- sit somewhere in the middle.  He argues that the U.S. and its allies need to increase spending for asteroid surveys to predict potential threats, which could be averted with mechanical solutions such as Professor Melosh's.  On the other hand, since surveys could miss a dangerous asteroid, he supports a nuclear solution too.

He comments, "This is a hazard I take seriously, and I think this civilization needs to take it seriously.  I have no qualms with research on deflection strategies, including nuclear deflection strategies.  Nothing will be done to jeopardize existing arms control treaties. There, the game’s not worth the candle.  Nobody’s talking about testing."

III. Obama, Russia Leaning Towards Mega Space Nuke

The deck seems stacked against the nuclear camp.  Today there are several major international treaties that ban nuclear weapons testing including the 1963 Limited Test Ban Treaty (LTBT) which forbids nuclear weapons tests underground and the 1996 Comprehensive Nuclear Test Ban Treaty (CTBT) which prohibits all tests.  The former treaty was signed by the U.S. and ratified by Congress, while the latter test was signed by President Bill Clinton, but not yet ratified by Congress.

And then there's the 1967 Outer Space Treaty -- a treaty that prohibits the use of or testing of weapons in space.  That treaty has been signed by 129 nations in total -- including China, Russia, and the U.S.  Every spacefaring nation, in fact, has signed it except for Iran.

But despite its possibility to breach international treaties, the Obama administration has come to support the nuclear idea.  Last month the U.S. Secretary of Energy Ernest Moniz and Russian nuclear agency (Rosatom) Director Sergey Kirienko signed a shadowy agreement to collaborate on "defense from asteroids" and other topics.  The 47-page document, published in both English and Russian was not made public, but the Center of Public Integrity managed to obtain a copy and make it publicly available.

Russia and U.S. deal
Energy Secretary Ernest Moniz (left) and Russian atomic agency (Rosatom) Director Sergey Kirienko claims their collaboration will be for peace. [Image Source: State Dept.]

Strangely, there's no mention of asteroids at all in the "agreement" (a semantics game used by recent Presidents to circumvent the authority of Congress, whom are required to sign all "treaties").  Instead the actual text only describes peacetime efforts to improve nuclear fission power, study the potential for nuclear fusion power, safeguard nuclear stocks against terrorists, and come up with more effective means of disposing of nuclear waste.

But some experts believe the agreement may be an opening overture in an agreement between the world's two largest nuclear nations to breach both space weapons and nuclear testing treaties, testing warheads in space.

In February the Russia's deputy Prime Minister Dmitry Rogozin received a proposal from the Russia’s Academy of Sciences to spend $2B USD on asteroid defense.  The academy told Russian state-support television channel RT, "Destruction of an asteroid in emergency cases may be performed by a rocket with a powerful megaton-class nuclear warhead.  If the threat is detected early, more advanced means of changing an asteroid’s orbit may be considered."

David Dearborn
David Dearborn, a LLNL researcher, is America's senior anti-asteroid researcher and key advocate of a nuclear solution. [Image Source CFPI]

Rosatom's deputy director Oleg Shubin -- an attendee at the 1995 LLNL meeting -- is his country's counterpart to Ed Teller.  He has authored several papers exploring the idea.  A March article by state-owned news agency RIA Novosti said that Mr. Shubin was campaigning among Russia's leadership to develop space nukes.  The article states, "In the opinion of Oleg Shubin, a departmental director at Rosatom, nonnuclear ways of deflecting and destroying Earth-bound asteroids may be exotic but ineffective."

IV. U.S. is Backing Nuclear Option With Research Funding

In the U.S. funding for examining nuclear deterrents to an asteroid is gaining ground.  Government-funded research scientists at Los Alamos National Laboratory (LANL) in New Mexico have been studying the effect of a nuclear warhead on an asteroid using simulations.

Robert Weaver and research physicist Cathy Plesko are among the small collective of government researchers at the lab working at least part time to study the idea using the LANL's Cielo supercomputer.  The researchers are trying to determine -- whether "an energy source of this magnitude" could "really disrupt this asteroid and prevent the hazard to the entire Earth," in Mr. Weaver's words.

Catherine Plesko
Catherine Plesko, LANL researcher [Image Source: Santa Fe Radio Cafe]

University of Washington (UW) engineering professor has received a $1.25M USD grant from the U.S. National Aeronautics and Space Administration (NASA) to study a ballistic impactor designed to deliver a nuclear warhead into an asteroid.

A 1997 concept for a nuclear interceptor to be used on an incoming asteroid

He says in an interview, "When we first started looking at this about a dozen years ago, very early on, the nuclear option was the one that everyone said, ‘Hey, we can do this.'  But that was politically incorrect, so there was a lot of hesitation for anyone to say that this is a solution."

Iowa State University (ISU) is another key player in the nuclear effort, with Professor Bong Wie launching the Asteroid Deflection Research Center, a center looking to model and build model impactors.  Professor Wie and the center received a $600,000 USD grant to investigate a "hypervelocity nuclear interceptor system", which would rocket towards an asteroid, fire a secondary impactor, which would create a crater, which would serve as landing site for the warhead in the main missile, preventing the missile from "bouncing" off the asteroid and corralling the blast.

Asteroid attacker
A rendering of the anti-asteroid missile by ISU Professor Bong Wie's group.

Professor Wie estimates a two-stage launcher based on his design would cost $500M USD and could be launched in coming years to demonstrate the technology he's currently developing.

The senior U.S. research studying the nuclear solution is nuclear weapons designer David S. P. Dearborn, who was working on the problem on his own time until 2012, when he obtained a grant to make it his full time project at LLNL.  You fragment it with enough force so that the pieces spread out ... [and most] miss the Earth.  Small bits of rock would burn up in the atmosphere, or fall as dust. Fragmentation may reduce a catastrophe to an inconvenience.

V. Feasibility Concerns Remain

A nuclear explosion would look much different in space than Earth, taking a spherical shape, rather than the mushroom cloud we know.  It's unclear whether a nuclear blast could destroy a large asteroid, and if so what size blast would be necessary.

Russian researchers in February mentioned a 1-megaton device, but by March Oleg Shubin said he believed a multi-megaton device might be necessary.  (Russia's "Tzar Bombs" built in the 1960s packed 50-100 megatons of explosive energy.)  The effect on the asteroid could depend somewhat on its composition as the electro magnetic pulse (EMP) could result in complex magnetization and heating if the asteroid was rich in certain metallic elements, such as iron.

Even if research can hash out what size device they need, there's the question of how to deliver it.  Mr. Dearborn and Professor Wie want to deliver it directly.  But Ed Teller prefered an orbital platform with the nuke onboard -- and some nuclear advocates think that's a good solution.  Such a platform could make for a slightly faster response (due to less launch prep) and more precise targeting (due to the effects of atmospheric exit versus space launch) -- but critics like Mr. Dearborn complain that such a platform could pose a security risk, could be damaged by space debris, and would require regular maintenance by astronauts.

A similar "orbiting platform" non-nuclear solution has been proposed by University of California physics Professor Phillip Lubin who wants to build a six-mile (10 km) wide targeting mirror (dubbed "DE-STAR"), combined with a network of laser satellites, which together could focus over a megaton of force a day to a target object.

Prof. Phillip Lubin's "DE-STAR" laser system [UCSB]

A final feasibility problem is what to do with the remains.  A shot at a far away object could safely remedy a threat, but a shot near enough to Earth could create a small flock of asteroids that could prove only slightly less dangerous.  It's possible such smaller targets could be dealt with by land-based missile defenses, but it's a topic researchers are taking seriously.

At the end of the day of these technologies remain proven, so mankind is as vulnerable as ever to an asteroid strike.  But some are working to change that, even if they remain bitterly divided on the topic of nukes in space.

Sources: The Center for Public Integrity [1], [2], DOE, Rosatom

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