Planetary Defense:
Catastrophic Health Insurance for Planet Earth

A Research Paper

Presented To

Air Force 2025


COL (Sel) John M. Urias (USA)
Ms. Iole M. DeAngelis
Maj Donald A. Ahern
Maj Jack S. Caszatt
Maj George W. Fenimore III
Mr. Michael J. Wadzinski

October 1996



2025 is a study designed to comply with a directive from the chief of staff of the Air Force to examine the concepts, capabilities, and technologies the United States will require to remain the dominant air and space force in the future. Presented on 17 June 1996, this report was produced in the Department of Defense school environment of academic freedom and in the interest of advancing concepts related to national defense. The views expressed in this report are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the United States government.

This report contains fictional representations of future situations/scenarios. Any similarities to real people or events, other than those specifically cited, are unintentional and are for purposes of illustration only. It should be duely noted that at this time Planetary Defense is not an assigned or approved mission for the United States Department of Defense or the United States Air Force.

This publication has been reviewed by security and policy review authorities, is unclassified, and is cleared for public release.


When we learned that our team had been assigned the topic of "Planetary Defense," we admittedly did what most people do when they first consider the subject: we laughed. This phenomenon is commonly referred to as the giggle factor, and we have seen it many times during the ensuing months of our research and briefings. However, once we immersed ourselves in the data and began to work directly with several of the growing number of astronomers and scientists actively working this problem, our laughs were quickly replaced with concern. Our concern was based not only on the prospects of the earth being confronted with the crisis of an impending impact of a large asteroid or comet but the fact that such impacts occur far more frequently than most people realize, and that the global community, although becoming increasingly serious about this threat, currently lacks the capability to adequately detect or mitigate these extraterrestrial objects. More importantly, however, is the fact that the impact of a relatively small asteroid would, in all likelihood, cause catastrophic damage and loss of life-even the possible extinction of the human race! Once we understood the magnitude and seriousness of the planetary defense problem, our initial laughs were quickly replaced with many hours of research and brainstorming as we pondered the issue of developing and deploying a planetary defense system, a goal that has become our personal crusade.

In accomplishing this team project, we received invaluable help from several people which was critical to the success of our study. We thank our faculty advisors, Col Vic Budura of the United States Air Force Air War College and Maj Doug Johnston of the United States Air Force Air Command and Staff College, for their insight and support throughout the project. We also thank Mike McKim of the Air War College for his dedicated assistance in our research efforts. Additionally, we wish to thank Col Mike Kozak, Lt Col Larry Boyer, Capt John Vice, and SSgt Brian Sommers of the 2025 Support Office for their dedication and responsiveness to our many administrative requirements. We also thank our foreign teammate, Ms Iole De Angelis of the International Space University, for her tireless energy and valuable European perspective, especially regarding the treaty implications of deploying a planetary defense system. From a technical perspective, we thank Drs Tom Gehrels and Jim Scotti of the Lunar and Planetary Laboratory, University of Arizona, and Ms Shirley Petty and John Plencner of the Lawrence Livermore National Laboratory for their willingness to share results of their recent research and workshops with us as well as to serve as sounding boards for our ideas. Finally, we extend a special thanks to our families for their understanding and patience during our many hours away from home. We could not have succeeded without them.

COL (Sel) John M. Urias (USA)
Maj Donald A. Ahern
Maj Jack S. Caszatt
Maj George W. Fenimore III
Mr Michael J. Wadzinski


Executive Summary

Concern exists among an increasing number of scientists throughout the world regarding the possibility of a catastrophic event caused by an impact of a large earth-crossing object (ECO) on the Earth-Moon System (EMS), be it an asteroid or comet. Such events, although rare for large objects (greater than 1 kilometer diameter), are not unprecedented. Indeed, the great upheaval and resulting ice age that marked the extinction of the dinosaurs is thought to have been caused by the impact of a 10 km diameter asteroid. In 1908 a stony asteroid of approximately 50 meters diameter exploded in the air above the Tunguska River in Siberia, producing an equivalent yield of 15-30 megatons of TNT, and leveling over 2,000 square miles of dense forest. Such an event is thought to occur approximately every century. It is only a matter of time before the world finds itself in a crisis situation-a crisis involving the detection of a large ECO, leaving little time to react and resulting in global panic, chaos, and possible catastrophe.

Collectively as a global community, no current viable capability exists to defend the EMS against a large ECO, leaving its inhabitants vulnerable to possible death and destruction of untold proportion and even possible extinction of the human race. In this regard, a planetary defense system (PDS) capability should be resourced, developed, and deployed. At this time Planetary Defense is not an assigned or approved mission of the Department of Defense or the Air Force. Such a system would consist of a detection subsystem, command, control, communications, computer, and intelligence (C4I) subsystem and a mitigation subsystem. There are many potential variations of these subsystems which, with advances in novel technologies, will be available by 2025 to develop a credible PDS. We propose a three-tier system developed sequentially in time and space. Such a system would serve not only as a means to preserve life on earth, but also help to unite the global community in a common effort that would promote peaceful cooperation and economic prosperity as related spin-offs and dual uses of novel technologies evolve.


Chapter 1

If some day in the future we discover well in advance that an asteroid that is big enough to cause a mass extinction is going to hit the Earth, and then we alter the course of that asteroid so that it does not hit us, it will be one of the most important accomplishments in all of human history.

-Sen George E. Brown, Jr.

The Earth-Moon System (EMS) and its inhabitants are in danger. It is not the kind of danger that most people are familiar with such as disease, pestilence, or the threat of nuclear war, but one that is rapidly moving to the forefront of scientific research, exploration, and analysis-the very real hazard of a large earth-crossing object (ECO) impacting on the EMS. As the Earth revolves around the Sun, it periodically passes close to orbiting asteroids and comets, producing near-earth-object (NEO) situations. When asteroid or comet orbits intersect the orbit of the earth, they are referred to as ECOs. Clearly, a global effort is needed to deal with this problem and to provide perhaps the only means of preserving the human race from possible extinction.

Building on the 1993 SPACECAST 2020 Study, this paper describes new research and analysis on the magnitude of the threat and possible mitigation systems.1 It then proposes a mission statement and outlines the basic capability required in a functional planetary defense system (PDS). This "system of systems" is described in detail, working through the detection, analysis, and mitigation subsystems that comprise the PDS. Included in this development are novel concepts using new technologies and capabilities expected to be available in the years prior to 2025, facilitating a variety of courses of action, and moving the community away from the less-than-desirable nuclear solution. It also provides, an overall concept of operations which describes how these subsystems work together to provide the needed capability against threat objects from space. A three-tier system is proposed. Several commercial applications and benefits are considered as spin-offs or as dual-use capabilities of the PDS. Finally, specific recommendations are provided which are keyed toward generating increased interest, emphasis, funding, research, development, and deployment of a PDS to deal with this rare but potentially catastrophic problem.

The Threat

The earth lies at the center of a cosmic shooting gallery consisting of asteroids and comets, racing through space at velocities relative to the earth of up to 75 times the speed of sound.2 These extraterrestrial objects are material left over from the formation of the solar system; basically, they are material that never coalesced into planets. Asteroids are rocky and metallic objects that orbit the Sun, ranging in diameter from mere pebbles to about 1,000 kilometers. They are generally found in a main orbital belt between Mars and Jupiter. Comets, on the other hand, contain ice, clay, and organic matter and are commonly referred to as "dirty snowballs" because of their opaque appearance. Like asteroids, comets orbit the sun, typically in highly elliptical or even parabolic orbits.

Although ECO impacts involving large asteroids or comets are rare, they do occur. When they do, they have the potential for causing catastrophic destruction and loss of life. It is currently estimated that more than 2,000 ECOs in excess of 0.5 km in diameter do exist. Given the inadequate deep space detection capability, only a small percentage of these objects have been classified. Disturbingly, a sizable number of these potential threat objects are quite large. Ceres, for example, is 974 km in diameter and is currently the largest of the classified asteroids. Approximately 20 other asteroids fall into this mega-threat category. With the natural gravitational perturbations created by the planets, it is inevitable that one or more of these objects will someday impact the EMS.

Geologic history is replete with examples of actual ECO impacts. Indeed, many scientists argue that it was the impact of a huge asteroid, perhaps as large as 10 km in diameter, that created a global dust cloud and ultimately triggered climactic changes that caused the extinction of dinosaurs and up to 75 percent of other species then on earth. This event, called the Cretaceous/Tertiary (K/T) Impact, is believed to have produced an equivalent yield of 108 megatons of TNT.3 Ancient writings and drawings contain numerous accounts of objects falling from the sky, causing death and destruction. A size and impact versus frequency graph is included as figure 1-1.

During the twentieth century, several impacts and near misses have been recorded. In 1908 a stony asteroid of approximately 50 meters in diameter exploded in the air above the Tunguska River in Siberia, producing an equivalent TNT yield of 15-30 megatons (MT) and leveling over 2,000 square miles of dense forest. Needless to say, had the Tunguska event occurred over a populated city, the results would have been catastrophic. In 1937 and again in 1989, large asteroids passed uncomfortably close to the earth. The 1989 asteroid would have unleashed the equivalent of more than 40,000 megaton of TNT had it impacted. More recently, in 1994, astronomers cautiously watched as a small asteroid missed the earth by only 60,000 miles. In 1996 comet Hyakutake passed within 9 million miles of earth (0.1 astronomical units (AU)), the nearest comet approach in six centuries, yet this body was discovered only three months prior to its closest approach to earth.4

Figure 1-1. Asteroid Size/Impact Versus Frequency

The earth continues to be struck by objects from space at irregular intervals, most of which are small pebble-sized rocks weighing only a few milligrams. Scientists estimate that a large number of meteoroids (asteroids that impact earth) enter the earth's atmosphere daily, amounting to several hundred tons of material each year.5 Based on recent analysis, coupled with the exploration of over 120 impact craters on earth, researchers now believe that collisions involving large objects occur within centuries and millennia versus millions and billions of years, as originally estimated.6 Additionally, data now indicates that multiple impacts are more common than previously thought. Although these frequencies of occurrence may seem to be inconsequential, requiring virtually no action or concern, the catastrophic effects associated with only one of these events demand that the global community unite to develop a defensive capability.


Due to a lack of awareness and emphasis, the world is not socially, economically, or politically prepared to deal with the vulnerability of the EMS-to-ECO impacts and their potential consequences. Further, in terms of existing capabilities, there is currently a lack of adequate means of detection, command, control, communications, computers, and intelligence (C4I), and mitigation.

Few people are even aware of an ECO problem, much less the potential consequences associated with its impact on the EMS. However, there are hopeful signs in correcting this deficiency as more frequent Planetary Defense workshops are being conducted with active participation by an increasing number of major countries. Nevertheless, other than a congressional mandate requiring further study of the problem, no further globally sanctioned action has been taken.

In terms of courses of action in the event of a likely impact of an ECO, other than a nuclear option, no defensive capability exists today. However, new technologies may yield safer and more cost-effective solutions by 2025. These authors contend that the stakes are simply too high not to pursue direct and viable solutions to the ECO problem. Indeed, the survival of humanity is at stake.

Chapter 2
Social, Economic, and Political Implications

Nearly every century, the earth is impacted by an asteroid large enough to cause tens of thousands of deaths if they were to hit densely populated areas. On millennial time scales, impacts large enough to cause destruction comparable to the greatest known natural disasters may occur.7

Social Implications

Most of the world's population does not know or care about the prospect of cosmic collisions, although this hazard from space is a subject of deadly concern to humanity. Unfortunately, there are fewer than a dozen people currently searching for ECOs worldwide, fewer people than "it takes to run a single McDonalds."8

Many experts wrongly believe there have been no recorded deaths due to asteroid strikes, acknowledging only that there have been some close calls from small meteorites striking cars and houses.9 However, planetologist John S. Lewis asserts in recent research that meteorites have in fact caused thousands of deaths throughout recorded history. Lewis details 123 cases of deaths, injuries, and property damage caused by ECO impacts reported over approximately a two-hundred-year period alone. Table 1 reflects known cases which caused injury or death.10

Table 1 - Injuries and Deaths Caused by ECO Impacts

1420 BC
 Israel - Fatal meteorite impact.
588 AD
 China - 10 deaths; siege towers destroyed.
 China - People & animals killed; homes ruined.
 Ho-t'ao China - Soldier injured; fire.
 Shansi, China - 10,000 deaths.
 Cremona, Italy - Monk, birds, & sheep killed.
 Milono, Italy - Monk killed.
 China - Tens of deaths; 10 homes destroyed.
 Indian Ocean - 2 sailors killed aboard a ship.
 France - Farmer killed; home destroyed; cattle killed.
 Oriang, India - Man killed; woman injured.
 Mhow, India - Man injured.
 Macao, Brazil - Oxen killed; homes damaged.
 Braunau, Bohemia - Home struck by 371 lb meteorite.
 Nedagolla, India - Man stunned by meteorite.
 Ming Tung li, China - Cottage crushed, child killed.
 Newtown, Indiana, USA - Man killed in bed.
 Dun-Lepoelier, France - Farmer killed by meteorite.
 Grossliebenthal, Russia - Man injured.
 West Virginia, USA - Walls pierced, horse killed, man injured.
 Weng-li, China - Whole family crushed to death.
 Tunguska, Siberia - Fire, 2 people killed. (referenced throughout paper)
 Aba, Japan - Girl injured by meteorite.
 Zvezvan, Yugoslavia - Meteorite hit bridal party, 1 killed.
 Santa Ana, Mexico - Houses destroyed, 28 injured.
 Colford, UK - Telephones knocked out, boy injured.
 Sylacauga, Alabama, USA - 4 kg meteorite struck home, lady injured.
 Mbole, Uganda - 48 stones fell, roofs damaged, boy injured.

More recently, on 8 December 1992, a large asteroid named Toutatis missed earth by only two lunar distances. This was a fortunate day for everyone on earth, because this asteroid was nearly 4 kilometers in diameter.11 If Toutatis had impacted earth, the force of the collision would have generated more energy than all the nuclear weapons in existence combined-equal to approximately 9 x 106 megatons of TNT.12

Finally, if you were standing on Kosrae Island, off the New Guinea coast on 1 February 1994, you would have witnessed a blast in the sky as bright as the sun. A small meteor traveling at approximately 33,500 miles per hour had entered the earth's atmosphere. Fortunately, the meteor exploded at high altitude, over a sparsely populated region; the blast equaling 11 kilotons (KT) of TNT.13

Regardless of the tendency to downplay the ECO threat, the probability of an eventual impact is finite. When it happens, the resulting disaster is expected to be devastatingly catastrophic. Scientists estimate the impact by an asteroid even as small as 0.5 kilometers could cause climate shifts sufficient to drastically reduce crop yields for one or several years due to atmospheric debris restricting sunlight. Impacts by objects one to two kilometers in size could therefore result in significant loss of life due to mass starvation. Few countries store as much as even one year's supply of food. The death toll from direct impact effects (blast and firestorm, as well as the climatic changes) could reach 25 percent of the world's population.14 Although it may be a rare event, occurring only every few hundred thousand years, the average yearly fatalities from such an event could still exceed many natural disasters more common to the global population.

Because the risk is small for such an impact happening in the near future, the nature of the ECO impact hazard is beyond our experience. With the exception of the asteroid strike in Shansi, China, which reportedly killed more than 10,000 people in 1490, ECO impacts killing more than 100 people have not been reported within all of human history.15 Natural disasters, including earthquakes, tornadoes, cyclones, tsunamis, volcanic eruptions, firestorms, and floods often kill thousands of people, and occasionally several million. In contrast to more familiar disasters, the postulated asteroid impact would result in massive devastation. For example, had the 1908 Tunguska event happened three hours later, Moscow would have been leveled. In another event occurring approximately 800 years ago on New Zealand's South Island, an ECO exploded in the sky, igniting fires and destroying thousands of acres of forests.16 If such an event were to occur over an urban area, hundreds of thousands of people could be killed, and damage could be measured in hundreds of billions of dollars.17

A civilization-destroying impact overshadows all other disasters, since billions of people could be killed (as large a percentage loss of life worldwide as that experienced by Europe from the Black Death in the 14th century).18 As the global population continues to increase, the probability of an ECO impact in a large urban center also increases proportionally.

Work over the last several years by the astronomical community supports that more impacts will inevitably occur in the future. Such impacts could result in widespread devastation or even catastrophic alteration of the global ecosystem.

During the last 15 years, research on ECOs has increased substantially. Fueled by the now widely accepted theory that a large asteroid impact caused the extinction of the dinosaurs, astronomy and geophysics communities have focused more effort on this area. Astronomers, with more capable detection equipment, have been discovering potentially globally catastrophic 1 km and larger ECOs at an average rate of 25 each year.19

The combined results of these efforts help us to realize that there is a potentially devastating but still largely uncharacterized natural threat to earth's inhabitants. A disaster of this magnitude could put enormous pressure on the nations involved, destabilizing their economic and social fabrics. Certainly, such a disaster could affect the entire global community. Historically, governments have crumbled to lesser disasters because of a lack of resources and the inability to meet the needs of their people. Often only the infusion of external assistance has prevented more severe outcomes.

What will happen when a significant portion--such as one-quarter--of the world's population is in need of aid, especially when it is not known how long the effects may last? Thus, the time has come to investigate development of the necessary technologies and strategies for planetary defense. While living in day-to-day fear is not the answer, there is a sizable danger to our planet from an ECO impact. Numerous other species may now be extinct because they could not take preventive steps. We must avoid delusions of invincibility. Humans must acknowledge that, as a species, we may not have existed long enough to consciously experience such a catastrophic event. But we currently have the technological means for detecting and possibly mitigating the ECO threat. We would be remiss if we did not use it.

Economic Implications

The cost for a PDS system could be compared to buying a life insurance policy for the world. Applying our three-tier defensive plan could offer the best answer in convincing the world purseholders to invest in a long-term program. Gregory H. Canavan, senior scientific advisor for defense research at Los Alamos National Laboratory, and Johndale Solem, coordinator for advanced concepts at Los Alamos National Laboratory, suggested a possible graduated funding approach. A few million dollars each year could support necessary observation surveys and theoretical study on mitigation efforts. A few tens of millions each year could support research on interception technologies and procure the dedicated equipment needed to search for large earth-threatening ECOs. And a hundred million dollars could create a spacecraft, such as in the Clementine I and II projects to intercept ECOs for the necessary characterization and composition analyses of ECOs of all sizes.20


Millions of dollars each year are spent to warn people of hurricanes, earthquakes and floods.21 Tens of millions of dollars to warn and mitigate a potential asteroid impact will be minor compared to what the costs will be in response to even a relatively small impact in a populated area. Responding to such an impact will require a concerted effort from many nations and will strain severely strain on the economic resources of the international community.22

In fact, recognizing the potential seriousness of such events, the Congress in 1990 mandated that the National Aeronautics and Space Administration (NASA) conduct two workshops to study the issue of NEOs. The first of these workshops, the International NEO Detection Workshop or "Spaceguard Survey," held in several sessions during 1991, defined a program for detecting kilometer-sized or larger NEOs. The second workshop, the NEO Interception Workshop, held in January 1992, studied issues in intercepting and deflecting or destroying those NEOs determined to be on a collision course. In related action, Congress also funded two asteroid intercept technology missions: Clementine I and Clementine II. Clementine I was launched in 1994 to demonstrate space-based interceptor "Brilliant Pebbles" technology. Clementine II is scheduled for launch in 1998. The United Nations has directed national labs, corporations, and universities to accomplish other studies.


Building a complicated PDS crash program at a cost of billions may not hold the answer. A proposed program of Air Force space surveillance and monitoring as well as such intercept tests as Clementine II will considered.23

No known ECOs are projected to impact the earth today. However, our inadequate detection capability due to inadequate resourcing and technology limitations place humanity at significant risk. The bottom line is the finite probability that we eventually will have a significant ECO impact. Indeed, one day it will be exactly equal to one. A modest but prudent program is justified and may buy us all substantial peace of mind.

The Spaceguard Survey Workshop's proposed observation network consists of six dedicated astronomical telescopes widely dispersed worldwide with all sites data-linked to a central survey clearinghouse and coordination center. The proposal offers a good start, but the limited rate of detection it can support would mean that the comprehensive census of 1 kilometer and larger ECOs would take 20-25 years. Development and operational costs for this system are estimated at $50 million (a one-time cost) and $10-15 million (annually), respectively. It is reasonable to assume these costs will be shared by the minimum of five nations where observatories are located and other where other states are directly involved.24

Development of this system will benefit from the experience gained by numerous space surveillance missions from man-made Earth-orbiting satellites, which in turn will benefit from technology developed specifically for detection and tracking of asteroids. Once such a system is in full operation and completes the initial catalogue, it may detect most large ECOs years or even decades in advance, which will provide time to prevent a collision. Then, the primary attention of the system may be changed to the hundreds of thousands of smaller near-earth asteroids and comets which also will cause considerable concern, while maintaining a perpetual watch for elusive long-period comets of any threatening size.

However, the system may also alert us to the prospect that our doomsday is closer at hand than we currently realize. Since the 1994 comet Shoemaker-Levy 9 impact on Jupiter, many experts have recognized that collisions with objects larger than a few hundred meters in diameter not only can threaten humanity on a global scale but have a finite probability of occurring. This recent public exposure to the consequences of a major planetary impact should encourage some willingness to invest more money into detection and mitigation technologies.

We should also realize that the technology required for a system to mitigate the most likely of impact scenarios is, with a little concerted effort, within our grasp. There are no current means for preventing many such natural disasters as earthquakes, tornadoes, and typhoons. Some of these disasters can not even be detected in time to give adequate warning to the affected population. Such is not the case with ECOs. Humanity certainly has the technology that, with a relatively modest investment, to warn of an impending catastrophe, maybe years or decades in advance. In most cases, an associated mitigation system could use the latest nuclear explosives, space propulsion, guidance, and sensing and targeting technologies, coupled with spacecraft technology. These technologies already are related to defense capabilities, but how they are developed for use in space (and what effects they have) will offer invaluable experience for defense efforts.

We can maximize our investment by turning to the commercial world for technology development and highlight opportunities for dual-use possibilities.25 Space operations will continue to grow at a rapid rate as a factor in United States military capabilities limited primarily by affordable access.

It is quite possible that the current assumption of "anything in space costs more than it would on the ground" may no longer hold true in 2025. With rapid progress being made in miniaturization and with a downward trend in spacelift costs, the option of placing detection system components in orbit rather than on earth may be a money saver. The orbiting components can be tasked around the clock without regard for the weather conditions on the surface.

Large savings in Department of Defense (DOD) spending could result by stopping military-only launch access to space and reducing investment in technologies the commercial world can develop.26 Beyond deflecting or fragmenting a threatening ECO, there may be some great advantage in capturing an asteroid into earth orbit. In addition to the scientific lessons learned in such a mission, many benefits could be gained by mining the asteroid's natural resources. Large-scale mining operations, from a single asteroid, could net upwards to twenty-five trillion dollars in nickel, platinum, or cobalt metals to offset the cost of the mitigation system (table 2).27

Parking an asteroid in orbit slightly higher than geosynchronous might be an ideal base of operations to maintain and salvage geosynchronous communication and surveillance systems used in surveillance of the near-earth environment.

Table 2 - Economic Analysis of 2-km diameter M-Class Metal Rich Asteroid28

 Fraction of Metal by Mass


 Estimated Current Market Dollar Value

(in trillion)

 2.7 x 1013

 3.0 x 1012

 1.5 x 1011

Platinum-group metals
 4.5 x 108

Total Value

Orbits occupying Lagrange points, L4 and L5 (to be discussed later), offer the most cost-effective orbits due to minimum energy required to maintain orbit. A captured asteroid also could be used for large space-based manufacturing or even as a space dock for buildup of interplanetary missions, eliminating the expensive need to launch large systems out of the earth's gravity.

Political Implications

Since planetary defense is a relatively new subject, there are no existing international treaties that specifically address it. However, in this section, we look at existing space treaties that offer relevance to planetary defense.29 The Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies, legally prohibiting weapons in space, provides perhaps the greatest restrictions to the concept of employing a Planetary Defense System (PDS).30 Article 4 of this treaty, which became effective on 10 October 1967, states:

Parties to the Treaty undertake not to place in orbit around the Earth any object carrying nuclear weapons or any other kinds of weapons of mass destruction, install such weapons on celestial bodies, or station such weapons in outer space in any other manner.31

Additionally, the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies, enacted on 11 July 1979, applies to the Moon and other celestial bodies within the solar system.32 Article 3 specifically restricts the use of nuclear weapons in space, stating:

Parties shall not place in orbit or around the Moon objects carrying nuclear weapons or any other kinds of weapons of mass destruction or place or use such weapons on or in the Moon.33

Legal Aspects of Planetary Defense

Therefore, even though no existing treaties specifically prohibit the employment of a PDS, collectively, they provide enough legal restrictions to seriously affect the ability of operators to use it effectively when faced with a major extraterrestrial threat. In our extreme case involving the impending impact of an asteroid or comet and where the survival of the human race is potentially at risk, we assume that appropriate exceptions would be approved, allowing the use of nuclear weapons or other weapons of mass destruction to mitigate the threat. Indeed, these weapons could serve as the only means of saving the earth.

Fortunately, none of the existing treaties restrict the employment of detection devices-- whether they be earth-, space-, or planet-based--that would serve as major components of the PDS. As discussed in the "Concept of Operations (CONOPS)" section, our three-tier PDS concept includes near-, mid-, and far-range detection systems. Obviously, early detection and classification of an asteroid or comet as an ECO allows more reaction time and permits greater flexibility in developing viable courses of action. Therefore, our PDS concept places significant emphasis on detection at the greatest possible range.

A decision to develop and ultimately deploy a planetary defense system will involve numerous developmental tests, both at the system and subsystem levels. Inevitably, however, politicians and engineers will be faced with the dilemma involving the need to test the system under realistic conditions using weapons in space. A limited number of these tests will involve nuclear weapons, predictably against a simulated or actual ECO. Such tests are currently banned by the Treaty Banning Nuclear Weapons Tests in the Atmosphere, in Outer Space, and Underwater, which became effective on 10 October 1963 and stated:

Parties to undertake to prohibit, prevent and not to carry out any nuclear weapon test explosion, or any other nuclear explosion, at any place under its jurisdiction or control: (a) In the atmosphere, beyond its limits, including outer space, or under water, including territorial waters or high seas; or (b) In any other environment if such explosion causes radioactive debris to be present outside the territorial limits of the State under whose jurisdiction or control such explosion is conducted.34

One of the biggest objections against nuclear testing in space involves radioactive fallout reentering the atmosphere with deleterious effects. In the case involving a nuclear intercept of an actual ECO, the potential for death or injury due to fragmented asteroid impacts poses equal concern. The decision to use such weapons of mass destruction (WMD) would obviously involve much dialogue and debate, but, from an acquisition standpoint, such testing would be necessary to validate system credibility. With the united commitment of the global community, it is anticipated that the treaty restrictions mentioned earlier could be waived to permit such a test.

As the planetary defense problem becomes better understood and accepted within the global community, and as potential solutions, including a PDS, are developed, it will likely become necessary to selectively renegotiate existing treaties that currently prohibit testing and using weapons in space. Perhaps a treaty specifically tailored to the evolutionary development of a planetary defense system as well as its use during an ECO threat crisis will be needed. Regardless of the outcome, however, it is safe to say that the use of weapons in space, especially WMD, will remain highly restricted.

European Perspective On Planetary Defense

If one nation, such as the US, attempted to place weapons in space, the world would likely oppose such an attempt. Therefore, the US would not likely attempt to forge a PDS alone. Realistically, the US would require a coalition with other nations, such as the Europeans, Russians, Japanese, and other aerospace nations of the future, before placing weapons in space. While discussing the interaction of each of these nations is beyond the scope of this paper, the political and economic issues are worthy of comment since these factors will affect all participants. In this section, our Italian co-author, Ms Iole M. DeAngelis, offers insight into this area, especially, from a European point of view.35

In analyzing the political structure and processes of the European continent, the first and most significant factor noted is that Europe is not a single political entity; hence policies reflect consensus among many different European countries. Similar to the democratic process in the United States, the European political organization allows for free-flowing discussion as issues are openly debated and agreements are ultimately reached. As is the case in the US, debate can be an extremely time-consuming process. In Europe, countries such as the United Kingdom (UK), have long enjoyed a close relationship and spirit of cooperation with the United States, while others, like France, have historically rejected US influence in European policy-making.

As discussed in this paper, the development, testing, and deployment costs of a planetary defense system likely will be staggering, especially if the three-tier PDS concept is adopted. However, we believe the catastrophic results of a large asteroid or comet impact, including the potential extinction of the human race, justify such an expenditure, especially if it can be incrementally funded. Obviously, since the planetary defense problem is global in nature, one should not expect that the PDS costs will be borne by one or even a few countries. Indeed, such an endeavor will certainly fail without the cooperation and commitment of the entire global community. In this sense, Europe must be a major player in the successful implementation of a PDS.

When considering future European involvement in space-related issues, it is important to include the activities of the European Space Agency (ESA), with its international perspective and influence. Without a doubt, the ESA will be critical to the successful development and deployment of the PDS, especially with its close ties to France as one of ESA's most influential members.

Since France does not favor the influence of the US on European policy decisions, the US should use caution as it identifies requirements and ideas for a PDS. However, considering the need for global funding to support the development of the technologies and capabilities required for such a system, the US also must maintain open lines of communication with every major player to achieve a viable solution to the planetary defense problem. Given the normal reluctance of most countries to accept solutions or direction originating from a superpower such as the US automatically, it may be more effective to use a neutral element as the lead to pull the global community together and develop a strategy that all parties can support. Further, since there will likely be reservations, mistrust, and possibly even rejection due to the dual-use potential of the PDS as a strategic weapon, a neutral element would help to alleviate such fears.

Because of its global charter, the United Nations is probably the best organization to assume the leadership role in pulling together the global community, educating it about the planetary defense problem, garnering support for the development of a global PDS strategy, and ultimately serving as the primary advocate for the evolution of a functional planetary defense system to protect the EMS against ECO impacts. Clearly, the international influence of the UN will serve as an important foundation for the global community to implement the PDS strategic plan.

Both education and communication will be crucial to the success of the PDS developmental process. The ECO threat must be presented in layman's terms, not using complex scientific jargon, for the program to gain public support. For example, an 80- year-old grandmother must be able to understand why a part of her pension will be used to pay for this system. Public opinion will influence political decisions regarding funding and research and development commitments.

In any case, it is important to distinguish between education and information, because, while we need to make people aware of ECO problem, we do not want to create panic or anxiety. One way to promote awareness is through the use of thought-provoking television documentaries and movies such as Meteor.36 The Internet offers another way to educate the public about planetary defense issues. However, since many people do not own a computer it is not as effective as television yet for reaching the large numbers we will need to educate.

Communication problems commonly exist between politicians, scientists, engineers, and the general public, not because these groups lack the desire to work together, but because of their inherent language differences. Realizing that the scientific community alone will not bring the PDS program to fruition, these groups must resolve their communication problems as early as possible and ultimately speak with one voice, especially when it comes to justifying commitments of limited resources.

Since private enterprises and not governments produce systems, it will be important to achieve the cooperation of the global community to ensure that the economic needs of these enterprises are fulfilled. In this regard, it may be beneficial to adopt the ESA policy of juste retour, despite its inherent drawbacks in efficiency and economies of scale, to promote global commitment and cooperation.37

Considering the general willingness of governments to participate in large space projects and with the ever-present uncertainty of the budget process, it is conceivable that a consortium-based PDS effort could become another International Space Station (ISS). In the latter case, the ISS project ended up with many ideas, studies, and proposals, but offered little to nothing in the way of actual development due to normal budget fluctuations, infighting, and the resulting inability of the participants to absorb the exorbitant developmental costs. Like ISS, a repeat of this approach might also cause the PDS project to be added to the list of failures.

Planetary Defense as a European Space Policy Priority

In this section, we will take a look at planetary defense as a European space policy priority.38 The ESA currently does not have an ECO detection program.. A possible near-term solution might be the Infrared Space Observatory (ISO). The ISO is a long-duration observatory of celestial radiation sources. Using this system, astronomers will be able to observe low-temperature stars (stars hidden by dust that only infrared light can penetrate) and can even detect planetary systems similar to earth by searching for life forms outside the solar system.

Initially, ISO will analyze the planets of the solar system and their satellites. In particular, it will focus on Titan, because astronomers suspect that its atmosphere may host complex chemical processes similar to those supporting life on earth. ISO will eventually be added to the growing number of observatories actively involved in detecting and classifying ECOs.39

Planetary defense is not a high priority in the minds of many Europeans today. This lack of concern is true especially at the political level, even with the projected ISO capabilities. Although ISO will serve as a valuable means of ECO detection, there is generally little awareness about the ECO impact threat within the European region. Yet, within Europe, there are significant scientific talents and resources that need to be integrated into the overall global effort. Hopefully, greater participation in planetary defense workshops will help to increase European awareness and, ultimately, stimulate interest in achieving a viable solution to the problem. Communications and education will be critical to obtaining European support and commitment and establishing planetary defense as a European space policy priority.

Alternate Futures and Political Outlook For Planetary Defense

We believe it is realistic to assume that the treaties governing operations and activities in space will change before 2025, because, like the treaties previously discussed, they depend on the international environment. They also depend on the evolution of technologies and changes in resource availability, as well as other needs, including for example, economic exploitation of NEOs for minerals and scarce resources.

The 2025 Project developed five alternate futures for the year 2025, plus one possible scenario for 2015, and based on that work, it is possible to imagine how treaties may evolve and whether the international environment will be favorable to the implementation of a planetary defense system.

In the first future scenario "Gulliverís Travails,"40 there is no place for a PDS, because each country is busy defending itself from the others, and there is no possibility for cooperation. There is not enough money for space exploration or issues as the states are too busy with national and international problems. In fact, this scenario suggests that the existing treaties are sufficient.41

In the second scenario, "Zaibatsu,"42 planetary cooperation is led by the UN to counter an asteroid threat to the earth in the year 2007.43 In this scenario the international situation is favorable to cooperation, mostly in the economic field, and it is rational to think that the treaties on outer space will change to allow economic exploitation of space and allow for a PDS to evolve. As the world was able to survive an asteroid threat due to technological development, it is logical to assume that the world will be able, sometime during the 1997 to 2007 time frame, to deploy a PDS to mitigate the asteroid.

In the third scenario, "Digital Cacophony,"44 it is difficult to envision a global PDS, because power is dispersed among many actors and governments. However, it is rational to suppose that more than one actor or government has developed a PDS because of the ultrahigh-technology capabilities. Furthermore, in this scenario, national defense tactics are based upon a strong strategic defense. Therefore, it is reasonable to foresee technical capability to deal with and survive an ECO encounter.45

Planetary defense in the fourth scenario, "King Khan,"46 strongly depends on the political will of the superpowers. The technological capability is present, but the ECO threat is unimportant to the elites who are more worried about maintaining the international equilibrium. It is possible to presume the existence of some kind of WMD deployment in outer space.47

In the fifth scenario, "Halfs & Half-Naughts,"48 there is a PDS system jointly developed by the US, China, Russia, and European Union. However the reexplosion of war in the Balkans, earthquakes in California, wars in Africa, crisis in Cuba--all happening at the same time--make the coordination difficult among these countries.49 But in case of a real and urgent menace, it is possible to insure the survival of the earth, thanks to the high level of technology.

In the 2015 scenario, "Crossroads,"50 the world seems to favor cooperation after the success of several UN operations. This international organization acquires new respect and new power that enables it to lead a cooperative effort to deploy a PDS and promote the exploitation of outer space.

In any case, these scenarios are just scenarios, and thus, they do not represent what will necessarily happen. They do provide options, however, and remind us that humanity still has time to choose a path of survival or a way of living and thinking about the environment, especially in regards to developing a PDS. The implementation of a PDS will offer nations a unique opportunity to cooperate in a legal fashion to provide for the survival of the EMS.

Planetary defense efforts need to be consolidated, coordinated, and expanded under international leadership. The US should not go it alone. The threat is global; detection efforts will require observation sites throughout the world, and other nations possess unique technologies, spacelift, and other space-related capabilities which also could be used to develop and deploy a PDS.

Any action should involve the international community. This thinking is particularly important as mitigation efforts could require nuclear capabilities, and these intentions could violate current arms control treaties. Furthermore, a handful of the thousands of nuclear weapons being deactivated under the Strategic Arms Reduction Talks (START) agreement might offer the most expeditious solution to this problem. START implications would require DOD involvement.

Why should the DOD take an active interest in the planetary defense issue? Given such a scenario, the effects could threaten the national security of the US, even if it were not physically impacted. Certainly, the international community cannot deal with a disaster in which a significant portion the world is destroyed. All surviving nations would be affected. The devastating blows to governmental and societal structures could be equivalent to those thought of when talking about a post-global-nuclear war holocaust, but lacking perhaps the lethal radiation effects. More importantly, once a threat is detected in advance, the nation and perhaps the entire planet will quite naturally look to the DOD to provide the means, technical expertise, and leadership, in addition to the required forces, to counter such a threat to its citizens' lives and well-being. A number of other US organizations and agencies will certainly be involved, including NASA, Department of Energy (DOE), Federal Emergency Management Agency (FEMA), and Office of Foreign Disaster Assistance (OFDA) and national laboratories and universities.

There will also most likely be an international effort to include the United Nations. Currently, Russia, Great Britain, France, Canada, Japan, Australia, China, Italy, the Czech Republic, and other nations have shown an interest in this topic. However, few organizations other than the DOD have the experience and capability to even attempt such an effort.

Russia, with its military and space infrastructure, is probably the only other nation capable of the task, but a consolidated effort will offer the best chance of survival. Suffice it to say that the DOD will form the core around which the others could organize.

The fact that it may only happen once in several lifetimes does not absolve the current defense team of at least a moral responsibility if it does happen, particularly if it had the means to prevent or at least mitigate it. Perhaps for the first time in not only human history but the entire history of the planet, the inhabitants of earth are on the verge of having such capability. Currently, the chemical and nuclear propulsion systems now in development offer the best options for planetary defense. Employment of nuclear devices in a standoff mode represents the gentle nudge of all the options available. Though technically much more difficult, nuclear devices exploded on or beneath the object's surface impart 10 or more times the impulse of a standoff explosion.51

International concern for use of these weapons leads to many political questions and misgivings. Ironically, these devices "could be notably straightforward to create and safe to maintain because they derive from vast research and development expenditures and experience accumulated during the forty-five years of the Cold War."52 Technically, without an appropriate reentry vehicle, these devices could not be used as ballistic weapons, though there is always the possibility of terrorism or misuse. In any event, effective international protocols and controls could be established through the United Nations to minimize downside potential.

The debate will certainly continue, however, as evidenced in The Deflection Dilemma: Use vs. Misuse of Technologies for Avoiding Interplanetary Hazards: "The potential for misuse of a system built in advance of an explicit need may in the long run expose us to a greater risk than the added protection it offers."53 The greatest challenge involves the building of international coordination, cooperation, and support. The threat of ECOs is a global problem and one which the entire world community should be concerned with. Coordination between nations, international organizations, DOD, NASA, DOE, academia, and others in the scientific community is essential in establishing the building blocks for a credible PDS. It is necessary to build trust, coordinate resources, consolidate efforts, and seek cooperation with and support for similar efforts in the international community.

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