At the Nuclear Security Summit in Washington this spring, U.S. President Barack Obama reaffirmed the United States’ commitment to nuclear disarmament, nuclear nonproliferation and strengthening nuclear security worldwide to prevent nuclear weapons and enriched materials from falling into the hands of terrorists and other non-state actors.
It’s been 71 years since the detonation of the first nuclear weapon. Humankind, far from becoming a less belligerent species, is crafting 21st Century weapons of increasing efficiency, precision and lethality. A new generation of smaller nuclear warheads are being developed with the goal of achieving an arsenal that’s easier and cheaper to maintain, while research continues into newer inventions such as expendable drones and other, much more sophisticated robotic fighting machines.
At the World Economic Forum in Davos, Switzerland in January, speakers sounded the alarm about the impending rise of combat robots bestowed with artificial intelligence yet lacking the on-the-fly judgment human soldiers bring to the battlefield. Lasers, a ubiquitous technology that has found rich and varied use in such diverse areas ranging from fundamental science and astronomy to medicine, communications and consumer electronics are now being shaped for war. With rapid development in high density power storage and greater portability, high energy lasers are coming of age and could soon become the battlefield weapon of choice. High energy lasers (HEL) — are part of a broader category of directed energy weapon systems that also included kinetic and acoustic devices — are now being tested for battlefield application.
Think light sabers and laser blasters, except that the action is invisible, instantaneous and very lethal.
Mounted on warship, aircraft, and ground vehicles, lasers offer many advantages over conventional artillery including rapid target acquisition, point-and-shoot capability, and low operational cost. The snipers and infantry of tomorrow may very well carry deadly accurate laser guns running off power sources that fit in their backpacks.
Ongoing tests show that HEL systems today are approaching the capability to destroy targets hundreds of miles away, and all this without firing projectiles — just intense, lethal beams of energy at the speed of light. Straight forward line-of-sight ranging, target acquisition, quick friend or foe verification, instantaneous and highly reliable lock-on and target engagement, as well as immediate damage assessment and reengagement all become possible with lasers.
Sophisticated optical technologies such as beam combining and phased arrays with multiple, lowerpowered laser modules ganged together can deliver lethal power to targets far away. Anything you can see through a high-power telescope suddenly becomes a viable target. Adaptive optics, routinely used in groundbased astronomy, could be used to compensate for atmospheric distortion effects and technologies are being perfected to narrow losses due to phenomena like thermal blooming, produced by the scorching heat of the laser beam.
The power that HEL systems can deliver to the target is so intense that the thrust from the resulting plume of vaporized material act like rocket jets, resulting in an abrupt physical shock that pounds the target with the reactive force of Thor’s hammer.
As with all deadly powers that mankind discovers, invents and wields — amid all the wicked warfighting uses, with all the gloom-and-doom dark clouds in the horizon — there are some silver linings, too.
Recently, a small laser mounted on NASA’s Lunar Atmosphere and Dust Environment Explorer spacecraft, was able to transmit data to Earth at 600 megabits per second — a rate far superior to regular radio frequencies normally used for space missions, heralding a new era in low-power, wide-band civilian space communication. Several other space-based laser systems are being proposed and tested for interplanetary and deep space communications.
Among other concepts for using lasers in space, NASA is studying laser propulsion as a way overcome the speed barrier posed by conventional chemical rockets. Recent literature suggests using lasers to power spacecraft to velocities approaching 10-20 percent the speed of light using lasers — a prospect that bodes well for new interstellar probe missions.
HEL systems can be an effective tool for removing orbital debris. There are some ideas on mounting such a system on the International Space Station to clear its orbital track of incoming debris. And as we design larger and faster spacecraft to shorten interplanetary transit times, and since impacts with natural debris are far more energetic at higher velocities, a laser cannon could become a vital system for keeping the spacecraft’s trajectory clear.
High energy lasers could be one very effective arrow in our quiver for another progressive and peaceful humanitarian use: Planetary Defense. The technologies, strategies and global policy governing ways to thwart an asteroid or cometary fragment from colliding with Earth and causing a cataclysm is now being addressed at the United Nations as well as among the spacefaring nations of the world. We have the technological and operational know-how to start mitigating such extraterrestrial threats. The forces of nature are so great that we are able only to engage a narrow range of potentially hazardous objects at this time. At the request of Congress, NASA is scaling up budgets for Planetary Defense every year. And work is ongoing on improving sensors that can detect hazardous objects early to provide enough warning.
The earlier we detect them, the more time we have, to ready and field threat-mitigation systems. The further out we detect and ascertain the threat, the less energy we need to nudge them out of an Earth collision path. But even so, given the energies needed to thwart collision with large objects, most of the current planetary defense strategies involve early detection — years in advance — in order to gradually nudge the threatening object off its collision course with Earth. Unfortunately, the precise impact region cannot be accurately pinpointed until a few months or weeks before impact.
Whether we should even intervene if the impact is projected to occur over unpopulated areas, such as deserts or oceans, is a matter of some debate. After all, we now know that impacts and so-called air bursts — where the object vaporizes in the atmosphere, dissipating most of its energy while creating an intense and deadly shock wave with the capacity to cause widespread havoc were they to occur over cities — happen with disconcerting frequency, albeit (so far, at least) in remote regions and with no consequence to civilization or the biosphere.
But as populations grow and new cities rise up around the world, humanity faces the potential of just such a tryst, with all the more probability, as we saw in Chelyabinsk, Russia, in 2013. Without warning, an airburst damaged buildings and shattered windows, leaving over 1,400 people needing medical attention. Unlike hurricanes and other natural disasters that we can see coming, without early detection assets in place, asteroid impacts offer little advance notice, though we are improving our assets to detect and warn of such events.
A recent chart from NASA’s Center for Near Earth Object Studies at the Jet Propulsion Laboratory clearly shows that our planet is being bombarded by potentially hazardous objects more frequently than previously estimated. NASA has begun a series of International Planetary Defense workshops and JPL now hosts the Planetary Defense Coordination Office for NASA to bring together the various data gathered from diverse organizations, including the International Asteroid Warning Network and the European Space Mission Planning Advisory Group. Even the U.S. Federal Emergency Management Agency is now involved in studying how to handle asteroid impact aftermath issues. And a series of international Planetary Defense Conferences hosted by the International Academy of Astronautics continues to draw attention to this issue with global consequences, seeking ways to make nations aware of the threat while continually updating progress in both technologies and policy. The University of Southern California, where I teach, presented their case called Eden Shield at the 2015 conference.
What if we are faced with a threat that requires a response at short notice ? This is a question that was posed to a group of young professionals at the International Space University’s Space Studies Program held last summer at Ohio University. In their report titled “READI: Roadmap for Earth Defense Initiatives” students from around the world surveyed the topical literature, quizzed experts during their nine-week intensive program, and concluded that high energy lasers offer a new way to tackle just such a threat. Comets, much more lethal than asteroids, composed mainly of water ice, are particularly vulnerable because lasers can easily sublimate them. Modulating the laser beam could also cause resonance excitation on monolithic asteroids, fracturing them and rendering the smaller fragments easier to deal with, to avoid serious impact damage.
But putting up such deadly systems in space pose serious policy issues since they could be turned toward the Earth. Therefore, the far side of the moon — which never faces toward Earth — could be an ideal site to host such a system.
In Hindu mythology, Lord Shiva’s third eye was used in anger, like a laser, to incinerate. In reality, as we quickly approach the threshold of technologies that allow us mastery of weapons that make us the purveyors of death at the speed of light, it warms the soul to see a silver lining in those dark clouds on the horizon. Like the double-edged sword of nuclear technology in the 20th Century, there are peaceful, humanitarian uses for this deadly 21st Century high energy laser technology that makes us both purveyors of death at the speed of light and the protectors of our species and stewards Earth’s biosphere from external threats like asteroids and comets.
Madhu Thangavelu teaches the graduate-level Space Exploration Architectures Concept Synthesis Studio within the University of Southern California’s Department of Astronautical Engineering and is a graduate thesis adviser in the School of Architecture. The ISU READI report can be found at: bit.ly/ISU_READI