Russian physicists make toy asteroids and blast them with a laserMarch 13, 2018
A large team of Russian researchers from Rosatom, joined by three MIPT physicists, has modeled the impact of a nuclear explosion on an Earth-threatening asteroid. They manufactured miniature asteroids and blasted them with a laser. The modeling technique developed in this study is a way of experimentally evaluating asteroid destruction criteria such as the explosion energy needed to eliminate a dangerous object on a collision course with Earth. The English translation of the paper reporting the results will appear in the upcoming issue of the Journal of Experimental and Theoretical Physics.
Asteroids are celestial bodies consisting of carbon, silicon, metal, and sometimes ice. Scientists usually classify objects larger than 1 meter as asteroids, although this lower limit is disputed. On the other end of the scale, asteroids get as big as 900 kilometers across. Traveling at 20 kilometers per second, such giants pose a threat of obliterating all life on Earth.
There are two basic options when it comes to protecting the planet from a collision with an asteroid: It either has to be deflected or blown into pieces most of which will miss us or burn up in the atmosphere. The authors of the paper explored the second option by modeling the effects of a powerful shock wave released by a nuclear explosion on the asteroid surface. The research team showed that a brief laser pulse aimed at a miniature replica of an asteroid produces destructive effects similar to those of a nuclear explosion on an actual space rock. The distributions of heat and pressure predicted for the real event generally matched those measured in the scaled-down experiment.
For their laser model to be accurate, the researchers made sure the density and rigidity of the small-scale asteroid -- and even its shape -- mimicked the real thing, and controlled the shock-wave pressures. Thanks to this precise correspondence, the researchers had a way of directly calculating the required energy of a nuclear explosion on the actual asteroid from the energy of a laser pulse destroying its miniature replica. Thus, for example, to eliminate a 200-meter asteroid, the bomb needs to deliver the energy equivalent of 3 megatons of TNT. This was calculated once the team measured that it took a 500-joule laser pulse to destroy a model 8-10 millimeters in diameter. For the sake of comparison, the most powerful explosive ever detonated -- Tsar Bomba, or "king of bombs," built by the Soviet Union in 1961 -- had an energy output of about 58.6 megatons, though accounts vary.
The research team came up with a technology for manufacturing artificial asteroid material. Its composition corresponds to that of the chondrite (stony) meteorites, which account for about 90 percent of asteroid remains reaching the surface of the Earth. The properties of the model asteroid, including its chemical composition, density, porosity, and rigidity, were adjusted during manufacturing. The replicas were made using the data on the chondrite meteorite recovered from the bottom of Lake Chebarkul. It is the largest fragment of the asteroid that entered the Earth's atmosphere in February 2013, exploding over Chelyabinsk Oblast, Russia. The asteroid material was manufactured using a combination of sedimentation, compression, and heating, imitating the natural formation process. Out of cylinder-shaped samples, imitation asteroids of various shapes were made, among them spherical, ellipsoidal, and cubical ones.
To confirm that their laser modeling fits in with reality, the researchers also did compressible flow calculations. They showed that a lab asteroid 14-15 orders of magnitude less massive than its space prototype requires almost twice as much energy per unit mass to be completely disrupted.
The experiments made use of three laser devices: Iskra-5, Luch, and Saturn. The laser beam was first amplified to a predetermined power and then directed at the asteroid replica fixed in a vacuum chamber. Model destruction was monitored from behind as well as from the side, and fragmentation dynamics were registered. The laser affected model asteroids for 0.5-30 nanoseconds.
To estimate asteroid destruction criteria, researchers analyzed the data available from the Chelyabinsk meteorite. It entered the Earth's atmosphere as a 20-meter asteroid and fractured into small fragments that caused no catastrophic damage. It therefore makes sense to say that a 200-meter asteroid has been eliminated if it is fractured into pieces with a diameter 10 times smaller and a mass 1,000 times smaller than the Earth-threatening rock itself. For obvious reasons, this conclusion only holds for a 200-meter asteroid entering the atmosphere at a similar angle and for fragments traveling along trajectories similar to that of the Chelyabinsk meteor.
The researchers were also interested in whether the explosion effect is cumulative -- that is, can one powerful explosion be replaced by a succession of smaller ones? They found that multiple weaker laser pulses provide no significant advantage over a single pulse combining their power in terms of the general destruction criterion. This holds for simultaneous as well as consecutive pulses.
In some of the experiments, the laser was targeted at a cavity made in the miniature asteroids ahead of time. By exploiting the cavity, the researchers spent less energy -- namely, 500 instead of 650 joules per gram. Similarly, the effect of a buried nuclear bomb is expected to be more pronounced.
Calculations accounting for the scaling effects indicate that it takes a 3-megaton bomb to eliminate an Earth-threatening nonmetallic asteroid measuring 200 meters across. The research team now plans to expand the study by experimenting with asteroid replicas of different composition, including those containing iron, nickel, and ice. They also intend to identify more precisely how the shape of the asteroid and the presence of cavities on its surface affect the general destruction criterion.
"By accumulating coefficients and dependencies for asteroids of different types, we enable rapid modeling of the explosion so that the destruction criteria can be calculated promptly. At the moment, there are no asteroid threats, so our team has the time to perfect this technique for use later in preventing a planetary disaster," says study co-author Vladimir Yufa, an associate professor at the departments of Applied Physics and Laser Systems and Structured Materials, MIPT. "We're also looking into the possibility of deflecting an asteroid without destroying it and hope for international engagement."
Moscow Institute of Physics and Technology
Related Nuclear Articles:
The US Nuclear Regulatory Commission relied on faulty analysis to justify its refusal to adopt a critical measure for protecting Americans from nuclear-waste fires at dozens of reactor sites around the country, according to an article in the May 26 issue of Science magazine.
Extraordinary decontamination efforts are underway in areas affected by the 2011 nuclear accidents in Japan.
Scientists at Rice University, the University of Illinois at Urbana-Champaign and the University of Chile offer a glimpse into a possible new path toward the production of energy through nuclear fusion.
Researchers from Ludwig-Maximilians-Universitaet (LMU) Munich have, for the first time, measured the lifetime of an excited state in the nucleus of an unstable element.
The main type of nuclear fuel is the uranium oxide pellet composition.
Determining if an individual has handled nuclear materials is a challenge national defense agencies currently face.
The article, published recently in Open Chemistry may lead to the development of a process to remove uranium from wastewater at the front-end of the nuclear fuel cycle, or even extracting natural uranium from sea water.
In a new paper, University of California, Riverside theoretical physicist Flip Tanedo and his collaborators have made new progress towards unraveling a mystery in the beryllium nucleus that may be evidence for a fifth force of nature.
The atomic nucleus is highly complex. Understanding this complexity often requires a tremendous amount of computational power.
The theoretical view of the structure of the atom nucleus is not carved in stone.
Related Nuclear Reading:
The Doomsday Machine: Confessions of a Nuclear War Planner
by Daniel Ellsberg (Author)
Shortlisted for the 2018 Andrew Carnegie Medal for Excellence in Nonfiction
Finalist for The California Book Award in Nonfiction
The San Francisco Chronicle’s Best of 2017 List
In These Times “Best Books of 2017”
Huffington Post’s Ten Excellent December Books List
LitHub’s “Five Books Making News This Week”
From the legendary whistle-blower who revealed the Pentagon Papers, an eyewitness exposé of the dangers of America's Top Secret, seventy-year-long nuclear policy that... View Details
Command and Control: Nuclear Weapons, the Damascus Accident, and the Illusion of Safety
by Eric Schlosser (Author)
**The documentary Command and Control, directed by Robert Kenner, finds its origins in Eric Schlosser's book and continues to explore the little-known history of the management and safety concerns of America's nuclear aresenal.**
The documentary will air on PBS's American Experience on January 10th.
A myth-shattering exposé of America’s nuclear weapons
Famed investigative journalist Eric Schlosser digs deep to uncover secrets about the management of America’s nuclear arsenal. A groundbreaking account of accidents, near misses,... View Details
Fallout: Disasters, Lies, and the Legacy of the Nuclear Age
by Fred Pearce (Author)
An investigation into our complicated 8-decade-long relationship with nuclear technology, from the bomb to nuclear accidents to nuclear waste.
From Hiroshima to Chernobyl, Fukushima to the growing legacy of lethal radioactive waste, humanity's struggle to conquer atomic energy is rife with secrecy, deceit, human error, blatant disregard for life, short-sighted politics, and fear. Fallout is an eye-opening odyssey through the first eight decades of this struggle and the radioactive landscapes it has left behind. We are, he finds, forever torn between technological hubris... View Details
U.S. Armed Forces Nuclear, Biological And Chemical Survival Manual
by Dick Couch (Author)
Military experts teach you how to survive an attack on American soil, from North Korean missiles to weaponized smallpox
North Korean nukes. Dirty bombs in train stations. Chemical warfare. Americans have more reasons than ever to be afraid. If a nuclear missile strikes, will you know what to do? If a nerve agent is released in your subway system or office building, will you be safe? The U.S. Armed Forces Nuclear, Biological and Chemical Survival Manual gives you the information you need to survive a terrorist attack. It contains the best practices of all the United... View Details
The Logic of American Nuclear Strategy: Why Strategic Superiority Matters (Bridging the Gap)
by Matthew Kroenig (Author)
For decades, the reigning scholarly wisdom about nuclear weapons policy has been that the United States only needs the ability to absorb an enemy nuclear attack and still be able to respond with a devastating counterattack. So long as the US, or any other nation, retains such an assured retaliation capability, no sane leader would intentionally launch a nuclear attack against it, and nuclear deterrence will hold. According to this theory, possessing more weapons than necessary for a second-strike capability is illogical.
This argument is reasonable, but, when compared to the empirical... View Details
Nuclear War Survival Skills: Lifesaving Nuclear Facts and Self-Help Instructions
by Cresson H. Kearny (Author), Don Mann (Introduction), Edward Teller (Introduction), Dr. Eugene P. Wigner (Introduction)
A field-tested guide to surviving a nuclear attack, written by a revered civil defense expert.
This edition of Cresson H. Kearny’s iconic Nuclear War Survival Skills (originally published in 1979), updated by Kearny himself in 1987 and again in 2001, offers expert advice for ensuring your family’s safety should the worst come to pass. Chock-full of practical instructions and preventative measures, Nuclear War Survival Skills is based on years of meticulous scientific research conducted by Oak Ridge National Laboratory.
Featuring a new introduction by... View Details
Atomic Accidents: A History of Nuclear Meltdowns and Disasters: From the Ozark Mountains to Fukushima
by James Mahaffey (Author)
A gripping narrative of nuclear mishaps and meltdowns around the globe, all of which have proven pivotal to the advancement of nuclear science.
From the moment radiation was discovered in the late nineteenth century, nuclear science has had a rich history of innovative scientific exploration and discovery, coupled with mistakes, accidents, and downright disasters.
Mahaffey, a long-time advocate of continued nuclear research and nuclear energy, looks at each incident in turn and analyzes what happened and why, often discovering where scientists went wrong... View Details
Nuclear Physics for Babies (Baby University)
by Chris Ferrie (Author), Cara Florance (Author)
Simple explanations of complex ideas for your future genius!
Written by an expert, Nuclear Physics for Babies is a colorfully simple introduction to what goes on in the center of atoms. Babies (and grownups!) will learn all about the nucleus and the amazing process of nuclear decay. Co-written by Cara Florance, who has a PhD in Biochemistry and a BS in Chemistry with work experience in astrobiololgy and radiation decontamination. With a tongue-in-cheek approach that adults will love, this installment of the Baby University board book series is the perfect... View Details
Nuclear Weapons: 1945 Onwards (Strategic and Tactical Delivery Systems)
by David Baker (Author)
Much misinformation has been published by those who support, as well as those who are against, the continued deployment of nuclear weapons as instruments of deterrence. This book provides an apolitical description of strategic nuclear weapons, how they are designed, how they work, and how they are assigned to different targets in the event of conflict.
As well as a Workshop Manual, this book would be a guide to public understanding expressed in a dispassionate and factual manner for information which many people find hard or impossible to obtain. Nuclear weapons do exist, and they... View Details
Atomic Awakening: A New Look at the History and Future of Nuclear Power
by James Mahaffey (Author)
“Persuasive and based on deep research. Atomic Awakening taught me a great deal."―NatureThe American public's introduction to nuclear technology was manifested in destruction and death. With Hiroshima and the Cold War still ringing in our ears, our perception of all things nuclear is seen through the lens of weapons development. Nuclear power is full of mind-bending theories, deep secrets, and the misdirection of public consciousness, some deliberate, some accidental. The result of this fixation on bombs and fallout is that the development of a... View Details