The leading proponent of the nuclear solution is David S.P. Dearborn, a research physicist and nuclear weapons designer at Lawrence Livermore National Laboratory in California, presently engaged in refurbishment of the U.S. W-87 warhead — a weapon with an explosive force estimated at more than 375 kilotons, or 29 times the power of the bomb that flattened Hiroshima (it has about a third of the explosive power of the largest bomb in the U.S. arsenal).
Wie called Dearborn “the sort of senior person in this community” of those studying the nuclear option. “I am just following in his footsteps.” Melosh said Dearborn “is reasonable, he tends to be pretty persuasive, he comes across as not being a rabid advocate of nuclear weapons for their own sake. He’s quietly persistent.”
Dearborn said he was inspired to study the nuclear option a decade or so ago when he heard other researchers tell the media that nuclear weapons wouldn’t work against asteroids. “That’s just not true,” he said in an interview, saying he was offended by their “indefensible” claims.
Until two years ago, Dearborn worked on the problem on his own time. But since 2012 he said he and a colleague have had a small Livermore discretionary grant, amounting to perhaps several hundred thousand dollars, for their work on asteroids. He estimated that about a dozen scientists at the weapons labs have worked on the problem, but none is dedicated to it full time.
Nuclear explosives could work in two scenarios, he said. Where adequate time exists to divert the oncoming boulder, meaning a decade or longer, a “standoff” nuclear blast could knock it off course. When the time to impact is just a few years, he says, it would be too late for deflection but a carefully executed nuke strike would prevent most damage.
“You fragment it with enough force so that the pieces spread out ... [and most] miss the Earth,” he said. Small bits of rock would burn up in the atmosphere, or fall as dust. “Fragmentation may reduce a catastrophe to an inconvenience,” he said in a 2010 video of a lecture he gave to high school students at Lawrence Livermore.
Dearborn says there is that no need to develop new weapons and therefore no testing would be required. “The current, existing devices that we have provide all of the energy that is necessary,” he said. But he acknowledged that a large asteroid close to hitting Earth would probably require a weapon with the yield of about a megaton, one million tons of TNT, roughly the largest in the current U.S. arsenal.
Teller’s vision of placing these devices in orbit would not be practical, he said, because they would require periodic maintenance and would have to constantly shuttle between Earth and Space. He said major uncertainties remain, because some asteroids are like solid rocks, others like a handful of pebbles held together by gravity, and still others are porous like pumice. Different materials would react differently to being hit with either a nuclear explosive or an impactor — a crucial issue, because if one broke up in large pieces and remained on a dangerous path, the Earth could still get pummeled.
Melosh and Dearborn disagree, with Melosh asserting that since no large, Earth-killing, near-term threats are on the horizon, “the remaining smaller objects can be dealt with by non-nuclear means, kinetic detection being the most straightforward” and technically advanced.
“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,” Melosh said.
Dearborn says however that he understands the issues better than others because he is privy to classified data. “A truly accurate understanding … of the impulse caused by a standoff nuclear explosion depends on having access to information that is available only to the nuclear laboratories,” he wrote in an email.
Dearborn said he is eager to compare notes on the issue with his Russian counterparts. “The Russians that I have met at conferences have certainly strongly considered nuclear a likely option,” he said.
The mysterious new deal with Russia
During the Cold War, nuclear weapons scientists on both sides dreamed up many civilian uses for nuclear explosives, including mining, harbor dredging and even for oil and gas extraction -- like fracking on steroids. But after the demise of the Soviet Union, almost all of these schemes fell out of favor, with the singular exception of defending Earth with a nuclear shield.
Hugh Gusterson, a Stanford-trained anthropologist who wrote a 1998 book about Lawrence Livermore titled “Nuclear Rites: A Weapons Laboratory at the End of the Cold War,” said in an interview that weapons designers in both the U.S. and Russia first began talking about a nuclear defense against asteroids as the decades-long standoff between superpowers ended.
In Gusterson’s view, the timing was not coincidental. The weaponeers, he said, were searching for new ways to use their highly-specialized skills and the labs needed a new mission. “It was a response to the loss of the weapons lab mission, it was not a response to the asteroid threat,” Gusterson said. After the U.S. labs found work maintaining the nation’s nuclear weapons stockpile without testing, he said, “interest in asteroids faded into the background” in this country.
Nevertheless, the agreement that Secretary of Energy Ernest Moniz signed last month in Vienna with Sergey Kirienko, director of the Russian nuclear agency Rosatom, opens the door to cooperation on many projects — and according to a Sept. 16 DOE press release posted on the Web, one of these is “defense from asteroids.”
Oddly, the actual 47-page U.S.-Russian agreement — which the Energy Department has not publicly released but which the Center for Public Integrity obtained — does not mention asteroids. Instead it calls for the two countries to use the “experience and expertise gained by organizations of the respective nuclear weapons complexes,” and lays out broad areas for potential cooperation on civilian nuclear power, nuclear nonproliferation, fusion power research and the development of new nuclear security and safety technologies.
It also lists a host of highly sensitive sites where joint research can occur. U.S. scientists can propose work on high-energy lasers and plutonium-fueled breeder reactors, for example, some of it at Russia’s main weapons design centers in Sarov and Snezhinsk. Russian scientists, meanwhile, can propose joint projects using Livermore’s Vulcan supercomputer, one of the world’s ten fastest, or at Los Alamos’ Dual-Axis Radiographic Hydrodynamic Test facility, which makes x-ray pictures of materials imploding at speeds above 10,000 mph — speeds at which the cores of warheads smashed together to cause a nuclear blast.
In response to questions from the Center for Public Integrity, the Energy Department said in a statement that specific projects are to be agreed in talks between labs as well as in the White House’s U.S.-Russia Joint Working Group on Nuclear Energy and Nuclear Security, one of 19 bilateral panels set up several years ago by the administration as part of its “reset” of relations with Russia. A Rosatom statement said specific research proposals would be agreed by the end of the year.
The Department of Energy has not disclosed the panel’s full membership but its co-chairs are Rosatom’s Kirienko and Deputy Secretary of Energy Daniel Poneman. During its first meeting in Sept. 2009, the group visited the government site in Oak Ridge, Tenn., where scientists work with uranium weapons components and conduct other nuclear research.
“We are making the implementation of the agreement a priority and will be reviewing possible projects soon,” Energy department spokeswoman Keri Fulton said in an email, after declining to address the press release’s mention of asteroid defense.
The Russians will likely eagerly embrace the opportunity to work with the U.S. nuclear labs on planetary defense. Oleg Shubin, a Russian weapons scientist who is now Rosatom’s deputy director for the development of nuclear weapons, was among those who attended Teller’s 1995 “Planetary Defense” asteroid conference, according to the official proceedings. Shubin co-authored several of the Russian papers exploring the nuclear option presented at the conference.
The state-owned Russian news service RIA Novosti reported March 25 that some Russian officials are weighing the use of nuclear weapons to counter the asteroid threat. “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,” the Novosti article said.
The state-supported Russian news channel RT, aimed at foreign, English-speaking audiences, reported a month earlier that Russia’s Academy of Sciences had given Russian deputy prime minister Dmitry Rogozin a plan for spending $2 billion to bolster an asteroid defense program.
“Destruction of an asteroid in emergency cases may be performed by a rocket with a powerful megaton-class nuclear warhead,” the RT said, citing the Academy as its source. “If the threat is detected early, more advanced means of changing an asteroid’s orbit may be considered.”
According to a separate article by the Interfax news service, Shubin warned members of Russia’s Federation Council, the upper chamber of parliament, at a March 12 roundtable on planetary defense that the world could find itself with less than a year to prepare for a large asteroid strike. “It will take a nuclear device much bigger than one megaton to intercept an asteroid of more than one kilometer in diameter,” he told the roundtable, according to Interfax. “This scientific and technological task has a solution in principle,” he said, apparently referring to building a bigger warhead.
Rosatom spokesman Denis Perkin declined in an email to offer details about Russia’s research agenda, but a Russian official with knowledge of the new agreement with DOE, speaking on condition of anonymity, said that “personally, I do not exclude anything.”
So why exactly did asteroid defense appear in the U.S. press release given out by Moniz? Fulton declined to say. But according to a former DOE official who stays in close touch with the agency, an important proponent for new, joint work on the asteroid threat between U.S. and Russian nuclear weapons scientists was Donald L. Cook, deputy administrator at the Energy Department’s National Nuclear Security Administration, where he oversees the nation’s weapons labs.
Cook served for three years as the chief executive of Britain’s Atomic Weapons Establishment before joining the Energy Department in 2009. Earlier, he was an administrator at Sandia National Laboratories in New Mexico, which makes the nonnuclear components for nuclear weapons. Fulton said she could neither confirm nor deny his role in the deliberations.
A vigorous scientific debate
No one disputes that the threat posed to Earth by large rocks is real. Scientists first recognized this in the 20th century, when they concluded that many large craters — and geologic features like the Chesapeake Bay — were not the result of volcanic or other planetary forces but had been formed in part by the past impacts of mammoth asteroids.
A major U.S.-led effort to detect Earth-bound asteroids began in 1995, and NASA says astronomers so far have detected 10,200 with orbits that bring them close to Earth, including about 859 believed to be boulders at least six-tenths of a mile long — longer than two Queen Elizabeth-sized ships docked stem to stern.
The largest of these, which might strike only once every 700,000 to 100 million years, could threaten civilization. A blast caused by a six-mile-wide asteroid that slammed into a spot near the Yucatan Peninsula is thought to have wiped out the dinosaurs and most other animals 65 million years ago. But even smaller rocks — between 460 and 3,170 feet wide — can flatten cities or wreak havoc.
The 60-foot asteroid that exploded over Chelyabinsk had the power of half a megaton of TNT, damaging 4,000 buildings and injuring at least a thousand people, Russian officials said. Objects this large slam into the Earth on average about once every 100 years. Impacts involving asteroids as tall as water towers occur once every 2,000 years or so, and would have a force of ten megatons. Rocks the length of naval destroyers, or about 460 feet, would land with 300 megatons of force, but these hit only about every 30,000 years.
Fortunately, none of the 859 interplanetary monsters spotted so far appears to be headed for collision with Earth, at least for the next hundred years; the timing of their orbital crossings do not coincide. But astronomers estimate there may be 20,000 smaller but still potentially destructive asteroids whizzing around out there, waiting to be detected.
To find and possibly track these more elusive asteroids, the National Academy of Sciences and Department of Energy are helping build the $390 million Large Synoptic Survey Telescope on a peak in Chile. The impetus for action comes a 2005 congressional directive, and from the 152-page report completed three years ago by a panel of the National Research Council — a federally-supported group of eminent scientists — entitled “Defending Planet Earth.”
The report said called for more scrutiny of the sky and said the nuclear option would be “a last resort,” but also said it was most powerful approach and the only one that could be used against very large objects — those a third of a mile across or larger — spotted less than a decade before they might hit.
“Nuclear explosives constitute a mature technology, with well-characterized outputs,” the report said. “They represent by far the most mass-efficient method of energy transport and should be considered as an option for NEO [Near-Earth Object, i.e. asteroid] mitigation.” But the report also supported Melosh’s approach, ramming an asteroid with a heavy object.
Livermore’s Dearborn was a member of the panel, as was Mark Boslaugh of Sandia, who has also modeled the effects of nuclear blasts on asteroids. Many of the other members were from academic institutions, but several represented private firms with a financial stake in space research, such as Ball Aerospace & Technologies Corp., Orbital Sciences and Belton Space Exploration Initiatives LLC.