Samuel T. Cohen had a different view of warfare than most, and it’s no surprise—he invented one of history’s most controversial weapons, the neutron bomb. He died on Sunday.
Cohen’s ingenious, deadly device actually packed far less destructive power than typical nuclear weapons (which he worked on with the Manhattan Project during World War II). The neutron bomb’s detonation sent out a barrage of neutrons, the neutral subatomic particles in atoms, that passed right though inorganic material but killed living things within its blast radius.
All nuclear explosions produce a rain of potentially lethal neutrons, uncharged particles from an atom’s nucleus, and Mr. Cohen, by adjusting components and reshaping the bomb shell, limited the blast and released more energy as neutrons. [The New York Times]
After the Manhattan Project, Cohen went to work for the RAND Corporation, where he developed his bomb.
He said the inspiration for the neutron bomb was a 1951 visit to Seoul, which had been largely destroyed in the Korean War. In his memoir, he wrote: “If we are going to go on fighting these damned fool wars in the future, shelling and bombing cities to smithereens and wrecking the lives of their inhabitants, might there be some kind of nuclear weapon that could avoid all this?” [Los Angeles Times]
Between murders and leaked documents, there’s disarray and intrigue all around Iran’s burgeoning nuclear program.
Yesterday, two prominent nuclear scientists in Iran were attacked in car bombings.
According to [Iranian new service] Fars, scientists Majid Shahriari and Fereydoun Abbasi were parking their cars in separate locations near the university campus about 7:45 a.m. local time when they were attacked.Witnesses said each car was approached by a group of men on motorcycles, who attached explosives to the vehicles and detonated them seconds later, the news agency reported. Shahriari was killed instantly. Abbasi was wounded. Both men were with their wives, who were also wounded. [Washington Post]
Unsurprisingly, Iranian President Mahmoud Ahmadinejad quickly pointed the finger of blame at the West and Israel. Both of the targeted scientists are reportedly connected to the Iranian nuclear program, which the government maintains is for the purpose of energy, but the United States and other nations oppose out of fear of an Iranian bomb.
Abbasi-Davani, whose handful of publications on neutron physics are mainly in Iranian journals, is a key figure in Iran’s nuclear programme. He is reported to be a scientist at the country’s defence ministry, and a member of Iran’s revolutionary guards since the 1979 Islamic Revolution. He was also named as being among “Persons involved in nuclear or ballistic missile activities” in the 2007 UN Security Council Resolution 1747, which imposed sanctions on Iran over its refusal to stop enrichment of uranium. [Nature]
If a country fires an airborne nuclear missile, the source of the attack is obvious. But what about the more fluid threat that hangs over the 21st century—terrorists sneaking a nuclear device into a city and setting it off? In a study in the Proceedings of the National Academy of Sciences this week, researchers suggest that even in the charred aftermath of a nuclear explosion, there could be evidence left behind that helps to identify the source of the bomb.
Physicist Albert Fahey and company went back to the beginning of the atomic age, to the United States’ first atomic bomb test in New Mexico in July 1945. As that bomb test was called “Trinity,” the glass left behind by the blast is called “trinitite.” Fahey obtained some of that glass to show that all these years later, it still contained evidence of the bomb’s makeup.
“Prior to this study, people didn’t realise that other components of the bomb could be discerned from looking at ground debris and seeing what’s associated [with it],” said Dr Fahey. “But there are some distinctive signatures that were in the bomb other than fission products and plutonium, and that gives you hope that you can get some additional information out of it – like where it was made.” [BBC News]
After decades of development, Iran’s first nuclear power plant is close to operational. This week the country’s TV service announced that engineers have begun loading the fuel rods into the core of the Bushehr plant in southern Iran.
The 1,000-megawatt Bushehr plant has been under construction since before Iran’s 1979 Islamic Revolution. It was first contracted to a company that later became German industrial giant Siemens; more recently work was done with the help of Russia’s state-owned atomic energy company. [Los Angeles Times]
Iran‘s power plant was reportedly one target of the Stuxnet computer virus that emerged several weeks ago, but apparently that didn’t impair the final steps of preparing Bushehr.
Shahram Amiri is at the Pakistani embassy in Washington D.C. Unless he’s not.
The missing Iranian nuclear scientist is no stranger to intrigue and indecision: Last month we covered dueling YouTube videos in which two men, both claiming to be Amiri, say that either he was being held against his will in the United States or was studying freely and happily here. Today his case took more strange turns, as government officials in Pakistan claimed that Amiri is currently at their embassy in Washington, awaiting a return trip to Iran.
Today Amiri was quoted by Iranian official media as claiming that the US government had intended to return him to Iran to cover up his kidnapping in Saudi Arabia. “Following the release of my interview in the internet which brought disgrace to the US government for this abduction, they wanted to send me back quietly to Iran by another country’s airline,” he told state radio from the Iranian interests office in Washington. “Doing so, they wanted to deny the main story and cover up this abduction. However, they finally failed” [The Guardian].
Have you seen this man? If so, please ask him to make up his mind.
Shahram Amiri, a 32-year-old Iranian nuclear scientist, is at the center of an episode of United States-Iran intrigue that just got weirder, thanks to YouTube. Amiri disappeared during his pilgrimage to Saudi Arabia last year, and anonymous U.S. officials confirmed that he defected, presumably bringing information about Iran’s nuclear program. Now he—or someone purporting to be him—appears in two contradictory videos that claim he was either abducted and tortured by the United States or is living happily here and going about his studies.
The first video:
The dark-haired man, appearing unshaven and disheveled, said he was being held against his will in Tucson. “I was kidnapped in a joint operation by the American intelligence, CIA terror and kidnap teams, and Saudi Arabia’s Istikhbarat” spy service, the man said in a grainy video aired in Iran on Monday night. He said he had been drugged before being smuggled out of Saudi Arabia, adding that he had been subjected to “severe torture” and “psychological pressures” [Washington Post].
A very different Amiri showed up in a second video today. He, or someone like him, appears in a professionally shot video sitting in front of some parlor with a globe and a chess board, as if he wants to have a few minutes of our time to talk about life insurance.
As DISCOVER’s Bad Astronomer reported, Norwegians spotted some seriously strange lights in the night sky early yesterday morning. Since it appeared to be a real phenomenon (as opposed to a Photoshopped delight) and as there was no indication that the little green men had finally come, astronomers and aviation experts immediately began investigating what could have caused such a light show. The Bad Astronomer suggested that it looked like a rocket spinning out of control, and a day later he was proven right.
It turns out the bizarre fireworks display was caused by a missile test that originated in Russia, however the heralded Bulava missile turned out to be a dud–again. The submarine-based Bulava (Mace) missile has been billed as Russia’s newest technological breakthrough to support its nuclear deterrent, but the repeated test failures are an embarrassment for the Kremlin [Reuters].
Federal experts believe that a major earthquake could trigger fires at Los Alamos National Laboratory, releasing radioactive materials and endangering lives. The rupture of a seismic fault that runs underneath the lab would shake the ground more than scientists previously thought, according to a new report (PDF). A natural disaster here would be bad news, since the lab, just west of Santa Fe, is the main plutonium factory in the United States, believed to hold thousands of pounds of plutonium for use in nuclear weapons(the actual amount is classified).
Researchers study plutonium inside glove boxes—a Hollywood movie staple, consisting of a sealed enclosure with gloves so that someone outside the box can work on dangerous materials inside. A major earthquake would shake the ground enough to topple the glove boxes, says the new study. Some glove boxes are enormous and even contain furnaces to cast and mold plutonium. If one of these were to crash, the resulting fire would be uncontrollable and would create a vaporized plutonium cloud that could drift outside of the lab, says the safety report. In a worst-case scenario, a fire could release so much airborne plutonium that a person on the boundary of the lab would get a dose of radiation—potentially many thousands of times greater than a chest X-ray—that could be fatal in weeks, according to individuals knowledgeable about the study [Los Angeles Times].
Here’s one direct and obvious effect of the economic stimulus package passed in February: The toxic sites where scientists ushered in the nuclear age are getting cleaned up. In Los Alamos, New Mexico, a dump that contains refuse of the Manhattan Project and that was sealed up decades ago is finally being explored, thanks to $212 million from the American Recovery and Reinvestment Act.
But experts aren’t sure what they’ll find inside the dump. At the very least, there is probably a truck down there that was contaminated in 1945 at the Trinity test site, where the world’s first nuclear explosion seared the sky and melted the desert sand 200 miles south of here during World War II [The New York Times]. It may also contain explosive chemicals that could have become more dangerous over the years of burial.
When North Korea announced on May 25th that it had conducted its second underground test of a nuclear weapon, scientists weren’t surprised: They had already picked up seismic readings indicating a subterranean explosion. While seismologists say the readings carried subtle signatures that strongly suggest that the blast was caused by a nuclear device rather than conventional explosives, scientists were still waiting for one more piece of evidence–detecting radionuclide evidence in the form of radioactive gas is the “smoking gun”. And the big news here is that they have not found that signal [BBC Two].
Unlike other nuclear debris, xenon, an unreactive noble gas, can filter out through fissures in the rock after an underground test. Once in the atmosphere, plumes of xenon isotopes can be blown for thousands of miles. In 2006, for example, a [nuclear monitoring] station in Yellowknife, Canada, detected traces of xenon-133 two weeks after North Korea’s first test [Nature News]. But monitoring stations set up by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) have failed to detect any trace of xenon following the May blast, and now it may be too late. Researcher Lassina Zerbo of the CTBTO notes that these xenon isotopes rapidly decay in the atmosphere. This long after the blast, he says, “there is very little chance that we will pick up anything” [Nature News].
Even before North Korea announced that it had conducted its second underground test of a nuclear weapon, scientists around the world were putting together a picture of what had happened. With a combination of seismic and radiation monitoring, scientists expect to soon have a working idea of how far the rogue nation’s nuclear program has advanced.
At 9:55 a.m. local time on Monday, two seismic monitoring stations on the Japanese coast detected seismic waves coming from the area where North Korea last tested a nuclear weapon, in 2006. The region has little natural seismic activity, and experts noted that the waves didn’t match patterns produced by earthquakes. Movements along natural fault lines transmit most of their energy through ‘s-waves’, whereas explosions at a single point release a greater proportion through compressional p-waves. In the waves detected in Japan, the s-wave component was just one-fifth that of the p-wave. “You can’t say it’s impossible for a natural earthquake, but it would be very rare,” says Gen Aoki of the Japan Meteorological Agency in Tokyo [Nature News].
Experts note that the network of blast detectors intended for the Comprehensive Test Ban Treaty, which has not yet come into force, seems to have perfectly identified the explosion as a nuclear test, despite its small size. [In 1998, the U.S. Senate] rejected the CTBT partly over fears that countries could cheat, by claiming small covert weapons tests were earthquakes. The detection of the North Korean test raises hopes that the Senate will no longer be able to object [New Scientist]. But scientists had to do more than simply show that an underground explosion had sent ripples through the earth; they also have to determine how big the bomb was, and prove that the tremors weren’t caused by conventional explosives.
To explore the dark reaches of the solar system, NASA is going to need a lot more plutonium-238, the space agency has told the Department of Energy. NASA‘s deep space probes are powered by pellets of the plutonium isotope: The electricity that powers onboard instruments comes from devices called radioisotope power generators. The RPGs make electricity with the heat from the radioactive decay of small amounts of plutonium-238 carried on board [Los Angeles Times]. Such devices are the only option for probes that voyage far from the sun and can’t absorb enough solar energy to power their operations.
But a new report from the National Research Council notes that the world’s stockpile of Pu-238 is rapidly dwindling, and explains that NASA only has enough left for a couple more missions. The isotope isn’t found in nature, and its production is at a dead halt all around the world. The United States stopped making Pu-238 at the end of the Cold War; although the isotope cannot be used in nuclear weapons, it’s a byproduct of the production of weapons-grade Pu-239. For the past few years NASA has been buying its supply from Russia, but Russia’s plutonium-making reactors were also shut down years ago. NASA will soon receive its last shipment of the isotope from Russia, after which the space agency will be looking for a new supplier.
By tracing radioactive pollution created by the nuclear tests of the 1950s, researchers have settled the question of whether the human heart creates new cells during a person’s lifespan. “The dogma has always been that cell division in the heart pretty much stops after birth…. In medical school, we teach that you’ll die with the heart cells you’re born with” [Science News], comments cardiovascular expert Charles Murry. However, a new study has overturned this dogma, and found that the heart does regenerate, albeit slowly.
Cell turnover rates can easily be measured in animals by making their cells radioactive and seeing how fast they are replaced. Such an experiment, called pulse-labeling, could not ethically be done in people. But Dr. Frisen realized several years ago that nuclear weapons tested in the atmosphere until 1963 had in fact labeled the cells of the entire world’s population [The New York Times]. The Cold War tests produced a radioactive form of carbon called carbon-14, which was absorbed by plants and worked its way up the food chain; in humans, carbon-14 gets into the DNA of new cells and remains unchanged for the cells’ lives.
Once nuclear tests ended in 1963, levels of carbon-14 began to gradually decline. Because the level of carbon-14 in the atmosphere falls each year, the amount of carbon-14 in the DNA can serve to indicate the cell’s birth date [The New York Times], says lead researcher Jonas Frisén. His team found that people’s hearts have cells that are younger than the people themselves, indicating that new cells have grown since birth. Heart experts say it’s a remarkable use of the nuclear tests’ impacts. “I am very excited about how they have used this novel technology to get something useful out of such a terrible environmental disaster” [Technology Review], says Murry.
Israeli researchers say they’ve developed a way to modify nuclear fuel so that it can be used only in power plants, and can’t be recycled later to build nuclear weapons. Lead researcher Yigal Ronen says the work could help “de-claw” some countries if nuclear fuel producers – the US, Russia, Germany, France and Japan – agree to put the denaturing additive they have proven effective into all plutonium [Jerusalem Post].
Israeli scientists suggest in their study that the element americium be added to the fuel at a level of 0.1 percent [Israel National News]. According to their research, the addition would neutralize the fissile plutonium produced by nuclear reactors, making that “denatured” plutonium unusable in a weapon. The research will be published in the journal Science and Global Securitynext month.
Ronen explains that when a country purchases a nuclear reactor from one of the five nuclear fuel producers, the sale includes nuclear fuel for the reactor. “Thus, if the five agree to insert the additive into fuel for countries now developing nuclear power – such as Bahrain, Egypt, Kuwait, Libya, Malaysia, Namibia, Qatar, Oman, United Arab Emirates, Saudi Arabia and Yemen – they will have to use it for peaceful purposes rather than warfare” [The Register], says Ronen. However, the researchers say that countries with more advanced nuclear programs, like Iran, have other ways to produce weapons-grade fuel.
The North Korean government announced yesterday that it’s preparing to launch a communications satellite on a North Korean-made rocket, a move that has been widely interpreted as a test firing of its long-range missile. South Korea and the United States say any test-firing, whether a purported satellite launch or a missile test, would be provocative since the technology is dual-use, and would breach UN resolutions [AFP]. Experts say that the long-range Taepodong-2 rocket has a range of about 4,200 miles, which gives it the theoretical capacity to hit Alaska. But in the only previous test of the long-range rocket, in 2006, it exploded 40 seconds after launch.
North Korea has insisted that the launch is a purely scientific endeavor. “The preparations for launching an experimental communications satellite … are now making brisk headway,” North Korea’s KCNA news agency said. “When this satellite launch proves successful, the nation’s space science and technology will make another giant stride forward in building an economic power” [Reuters]. South Korean news sources have reported that the rocket has not yet been moved to the launch pad, but that there is a great deal of activity around the site.
80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles on the day's most compelling topics.
80beats is written by Veronique Greenwood and Valerie Ross. This team darts through each day's science news faster than the ruby-throated hummingbird that beats its wings 80 times per second. Send ideas, tips, suggestions, and complaints to [azeeberg at discovermagazine dot com].
Samuel T. Cohen had a different view of warfare than most, and it’s no surprise—he invented one of history’s most controversial weapons, the neutron bomb. He died on Sunday.
Between murders and leaked documents, there’s disarray and intrigue all around Iran’s burgeoning nuclear program.
If a country fires an airborne nuclear missile, the source of the attack is obvious. But what about the more fluid threat that hangs over the 21st century—terrorists sneaking a nuclear device into a city and setting it off? In a 
After decades of development, Iran’s first nuclear power plant is close to operational. This week the country’s TV service announced that engineers have begun loading the fuel rods into the core of the Bushehr plant in southern Iran.
Shahram Amiri is at the Pakistani embassy in Washington D.C. Unless he’s not.
Have you seen this man? If so, please ask him to make up his mind.
As DISCOVER’s 
Federal experts believe that a major 
Here’s one direct and obvious effect of the economic stimulus package passed in February: The toxic sites where scientists ushered in the nuclear age are getting cleaned up. In Los Alamos, New Mexico, a dump that contains refuse of the Manhattan Project and that was sealed up decades ago is finally being explored, thanks to $212 million from the 
When 
Even before 
To explore the dark reaches of the 
By tracing radioactive pollution created by the nuclear tests of the 1950s, researchers have settled the question of whether the human heart creates new cells during a person’s lifespan. “The dogma has always been that cell division in the heart pretty much stops after birth…. In medical school, we teach that you’ll die with the heart cells you’re born with” [
Israeli researchers say they’ve developed a way to modify nuclear fuel so that it can be used only in power plants, and can’t be recycled later to build nuclear weapons. Lead researcher Yigal Ronen says the work could help “de-claw” some countries if nuclear fuel producers – the US, Russia, Germany, France and Japan – agree to put the denaturing additive they have proven effective into all plutonium [
The North Korean government announced yesterday that it’s preparing to launch a communications 
