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COMMON GROUND: and Planetary Defense BY JAMES C. HOWE

IMAGE CREDIT: © NASA/DON DAVIS

22 Summer 2015 AD efending from collisions with and looks outward from its planned station at the Earth- L1 emerged as a serious issue less than . Dtwo generations ago, as the community The same processes and procedures used for detecting increased its understanding of the Near-Earth Object (NEO) potentially hazardous objects in apply to the detection population within the . Interest in planetary of possibly resource-rich asteroids or comets. While the defense grew as evidence showed that a large asteroid strike space mining industry may eventually develop a robust 65 million years ago led the dinosaurs to extinction, and detection capability of its own, relying on existing NEO was enhanced during observation of the fragmented detection programs should serve it well into the future. Shoemaker-Levy 9 crashing into in 1994. The asteroid that exploded above Chelyabinsk, , in 2013 rekindled This is true also for the second step in both endeavors, debate, showing once again the vulnerability of our to the long-term tracking and accurate determination of celestial impacts. an asteroid or comet’s , and projections of when it will through the inner Solar System. Three main More recently, a nascent space mining industry has begun to variables affect orbit calculation accuracy: the number of take shape, with several commercial entities taking concrete observations, the time span over which they are conducted, steps to develop the systems needed to harvest water and and whether observations from optical or the mineral resources from asteroids and comets, as well as far more precise, but range-limited, Goldstone and Arecibo from the . While neither planetary defense nor asteroid telescopes are included in the data. For the planetary mining operations have yet been conducted, both disciplines defense community, a precise orbit is needed to determine may prove vital to humanity: the first by protecting the planet which asteroids constitute a potential threat, with the goal from a devastating collision, and the second by developing of identifying a hazard several decades before a forecast new sources of precious metals, raw material for in-space collision. manufacturing, and water for use as hydrogen- or oxygen- based fuel, expanding mankind’s reach into the For miners, knowing a precise orbit allows cost-benefit Solar System. calculations as to which asteroids can be reached most Finding Synergies advantageously: many mineral-or ice-laden bodies may have orbital parameters that preclude a cost-effective At first glance, planetary defense and interception, while more than 2,500 known asteroids can be appear to be markedly different activities, the first designed reached using less fuel than is needed to fly to and land on to deflect or destroy a hazardous asteroid and the second the Moon. NASA and other organizations publish the orbital to recover its resources. However, an examination of the parameters of all known NEOs—information that is available operational, logistical, and technological attributes of these at no cost to the space mining community. two disciplines shows a striking amount of commonality. Like fraternal twins, planetary defense and asteroid mining The third general shared attribute of both activities is the look different but share much of their DNA. remote characterization of NEOs. This step is essential in planetary defense, as it provides important information Notionally, most planetary defense and asteroid mining for guiding a mitigation strategy for asteroids or comets scenarios involve five discrete steps. The first step, bound for collision with Earth. Optical and radar telescopes, detection, locates previously undiscovered asteroids and when within range, are employed to determine the body’s comets from among the vast catalog of known celestial size, mass, shape, density, composition, albedo, and spin objects. An estimated billion asteroids and trillion comets characteristics, a process that sometimes can take years, revolve around the Sun: more than half a million of them depending on the orbital track of the object and the number have diameters greater than 30 meters and that and quality of the observations. Once these characteristics pass through the inner Solar System. Planetary defense have been established, decisions regarding the type of practitioners concentrate on those that will pass within 0.05 mitigation effort—a nuclear explosion, a kinetic impact, or Astronomical Units (7.5 million kilometers) of Earth’s orbit, one of many “slow push” techniques, such as laser ablation, posing the greatest threat of collision. tractors, or mass drivers—can be made. Without To date, terrestrial and Earth-orbiting telescopes have knowing the characteristics of the body, any deflection or discovered more than 12,000 NEOs: the ground-based fragmentation strategy would face a very high risk of failure. LINEAR, , and Pan-STARRS telescopes The mining community also depends on knowing the being the most successful. New are poised detailed characteristics of an asteroid or comet, and to greatly expand this number. The ’s would use remote characterization to winnow the field of proposed Sentinel space , if launched as planned potential targets. Small NEOs that may not be considered a into a -like orbit, should become the most prolific serious hazard to Earth could be targets for resource asteroid hunter in history. NASA’s NEOCam , exploitation. Conversely, many asteroids that at first glance still on the drawing board, could be a close second as it seem like likely mining targets may be discounted due to

Summer 2015 AD ASTRA 23 high spin rates, loose structures, or awkward shapes that On the opposite end of the spectrum for deflecting an make mining impractical. Precise remote characterization inbound body are the “slow push” methods, which would will help the asteroid mining industry determine the most deliver a minute but steady deflective force to the asteroid suitable candidates for further and, potentially, or comet, over time providing a cumulative change in resource extraction. velocity. With few exceptions, every proposed slow push technique would be dependent on extended operations in The fourth common step, in situ exploration, builds upon close proximity to the body. Gravity tractors would hover a the data collected through remote characterization. For near the asteroid for years or decades, slowly most planetary defense deflection or fragmentation efforts, imparting a deflective gravitational force; an enhanced information beyond what can be determined remotely would first collect boulders or from will be necessary for finalizing operational planning for the threatening body, to increase the mass and gravitational the mission. Robotic fly-bys, close orbits, or contact pull of the spacecraft. Laser or solar ablation methods would exploration can determine a number of vital parameters, require the stationing of a spacecraft near the asteroid to such as the amount of rubble orbiting near a threatening direct the ablative beam. Using thrusters or a space tug asteroid, the seismological characteristics and internal would require direct physical contact with the body for years structure of a body, and the depth of regolith on a body’s on end, nudging it to alter its velocity. systems surface. Assuming a hazardous asteroid is discovered well would land and anchor a robotic mining apparatus on in advance of collision, in situ exploration is essential for the asteroid’s surface, to cast a steady stream of regolith assessing the physical characteristics that will help drive the into space and produce a minute but steady deflective exact mitigation tactics to be employed. counterforce. In situ exploration is also vital for the asteroid mining industry, Similarly, asteroid or comet mining would rely entirely on as it would allow detailed analysis of a body’s chemical the ability to conduct reliable, long-term, repetitive proximity make-up, geological composition, and thermal structure. operations. Several mining concepts have been analyzed. Additionally, mechanical testing could establish the The most common concept would land and anchor robotic effectiveness of anchoring, surface excavation, drilling, or mining and support systems on the asteroid or comet; scooping—information that would be essential for assessing these systems would methodically drill, scrape, crush, lift, if an otherwise tempting asteroid is indeed suitable for metal, or scoop the desired minerals or ice from the body. Support mineral, or water extraction. systems would discard unwanted tailings and transport the Proximity operations constitute the fifth, and broadest, to a processing station or collection facility. The mining shared attribute of national planetary defense and asteroid operation could occur on the surface, in pits, or in caverns mining activities. These operations involve orbiting, hovering, cut into the interior of the asteroid or comet. landing/launching, anchoring, and extracting material, all in a Alternative mining methods include leaching minerals micro- or milli-gravity environment. The technical challenges through the injection of high pressure steam, fully of operating near a small celestial body are extreme: witness encapsulating a small asteroid or comet and capturing the Japanese mission to the asteroid Itokawa in the escaping water as the container is heated by the Sun, 2005, and the ’s ongoing mission and collecting water vapor from a passing comet using a to Comet 67P/Churyumov-Gerasimenko, both which spacecraft stationed in a trailing position behind it. Each of encountered severe difficulties with landing and, in the later these activities would require the ability to operate on and case, anchoring on the asteroid or comet. near the surface of the body for long periods.

Progress in Proximity The commonalities between planetary defense and Extensive and prolonged proximity operations will be asteroid mining are extensive for the wide range of proximity an essential element of most types of planetary defense operations. For both endeavors, hovering, orbiting, mitigation missions. The most technologically mature landing, and anchoring on the space body are essential method for fragmentation or deflection of a hazardous competencies. The same base technologies that can object is through a surface, subsurface, or stand-off be used to mine metals could be employed in burying a nuclear explosion: The tremendous impulsive force of the nuclear device to fragment an asteroid, or as a mass driver blast and resulting surface ablation could, in one moment, apparatus used in deflection. The technologies that could deliver the necessary velocity change to the body to miss be employed to secure thrusters or a to a tumbling its future collision with Earth. Time permitting, to assure asteroid to change its orbit could be adapted to anchor a exact positioning and maximum deflective or fragmentation full suite of mining equipment to the surface of a resource- effect, the nuclear device would be buried, anchored to the rich body. surface, or orbiting just above the asteroid, an effort that would involve precise proximity operations.

24 AD ASTRA Summer 2015 Advancing Two Fields generate civilization-ending collisions, they constitute From initial detection to detailed characterization to the vast majority of NEOs, can inflict significant regional operations on and around a NEO, the twin disciplines damage, and strike Earth far more frequently than larger of planetary defense and asteroid mining share a host of bodies; further, they represent a population ripe for resource common attributes. Because of this, advances in one field exploitation. Terrestrial and Earth-orbiting telescopes, also will lead to advances in the other. Building a robust while having performed admirably in this quest, should be space mining industry and developing the technologies augmented by much more effective telescopes and techniques to conduct extended operations in a micro- placed into orbit around the Sun. At a minimum, ensuring gravity environment would yield tremendous benefits for that the B612 Foundation’s Sentinel and NASA’s NEOCam future planetary defense operations. Likewise, advances spacecraft receive the private and public funding needed for in planetary defense-related detection, orbit calculation, deployment is vital. characterization, and mitigation capabilities would provide A second enhancement would more deeply intertwine a similar boost to the fledgling mining industry. mitigation and mining technological development with A constructive path forward would see increased government space operations. The planned Asteroid cooperation and collaboration between the planetary Redirect Mission (ARM), in which NASA will capture a defense and asteroid mining communities, the former small asteroid—or part of one—and place it into lunar overseen primarily by governments and academia, and the orbit, could yield significant technological advances for latter spearheaded by the private sector. While collaboration both the mining and planetary defense communities. currently exists, it is piecemeal and poorly resourced, with Increasing the involvement of the asteroid mining industry very limited government funding being used to develop in this endeavor could help jumpstart efforts to develop the collision mitigation technologies or kick-start the space landing, anchoring, and extraction technologies essential mining industry. Considering the consequences of a major for successfully harvesting resources in space. Further, asteroid or comet strike, as well as the immense promise focusing specific activities of ARM and future NASA of commercial mining in space, a greater focus on this missions on planetary defense capabilities could generate connectivity could be extremely beneficial to the long-term major operational and technological breakthroughs, such health, wealth, and survival of our species. as perfecting close-aboard orbiting and hovering techniques, key attributes of gravity tractor and other First Steps Forward deflection methods. In September 2014, NASA took an important step forward Third, government research activities related to planetary by holding a conference at the titled defense and asteroid mining activities should be increased “The Economics of NEOs,” bringing together leaders from dramatically over current levels, which barely exceed the space mining community, academia, and government $1.0 million per year—an almost invisible sum by federal to explore the contours of the industry, identify overlap standards. Vast improvements need not break the bank: with other federal activities, and find areas for further an aggressive program dedicated to developing asteroid collaboration. mitigation, proximity operations, and mining technologies The conference summary included a list of key findings, could involve cooperative cost-sharing arrangements the first of which very effectively framed the issue: “Great between industry and government, all for far less than what synergies exist between planetary defense, scientific is spent annually by NASA on agency management (about research, , and commercial space $365 million last year). activities—including mining of minerals and volatiles—that Building a functional space mining industry will yield more could be strengthened through public-private partnerships.” robust planetary defense capabilities, and developing the Further, the findings noted that government must play a enhanced technologies and methods to protect Earth from central role in nurturing the fragile asteroid mining industry, collision could enhance the growth of a commercial sector by serving as the “first customer” for water and minerals dedicated to harvesting the resources found on asteroids harvested in space. Finally, the conference established that and comets. Through close, continual, and expanded the significant technological challenges faced in operating collaboration between these two fields of endeavor, the on and near small space bodies, by both the planetary synergies of planetary defense and asteroid mining can best defense and asteroid mining communities, were achievable be leveraged to yield benefits for all mankind. in the near term, assuming a properly focused effort.

A first necessary action would be to increase detection Jim Howe is a writer and policy analyst who focuses on capabilities, particularly for smaller asteroids and comets space and national security issues. He works in the nuclear down to 30 meters in diameter. While these bodies cannot power industry.

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