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Planetary Defense: Preventing a World of Trouble
(Released November 2005)

 
  by Salvatore A. Vittorio  

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  1. AIAA Paper 2004-1428

    Anonymous

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Sooner or later we will detect an asteroid on a collision course with Earth. If we are to have a reasonable chance of preventing that collision, it is essential that we have some prior experience manipulating asteroids. There are many unknowns surrounding how to go about deflecting an asteroid, but the surest way to learn about both asteroids themselves as well as the mechanics of moving them is to actually try a demonstration mission. Deflection methods can be broadly classified into instantaneous and gradual methods. Instantaneous methods such as kinetic impact or explosions run the risk of fracturing the asteroid, thereby possibly worsening the situation. This is conglomerations, or rubble piles. One major advantage of gradual deflection methods over instantaneous methods is that they are in principle highly controllable. The need for this is important since moving the impact point of an asteroid on a collision course necessarily moves the future impact point across the surface of the Earth until enough delta V is imparted to make it miss the Earth, so that the actual deflection trajectory must be carefully considered. Furthermore, randomly deflecting an asteroid may simply end up nudging the asteroid into a nearby resonance orbit that also later collides with the Earth. The next problem to contend with is that asteroids of this size can have rotation rates up to several times per day. In order to effectively use the thrust of the spacecraft to impart velocity, either the rotation must be stopped, or the spacecraft must be situated at one of the poles. Stopping the rotation runs the risk of disrupting the asteroid since the rubble pile structure of the asteroid is held together by a delicate balance between weak gravitational and centripetal forces. We are therefore proposing to land the spacecraft at one of the poles, and to torque the rotation axis to realign the axis of rotation while maintaining the original rotation rate. Amongst the gradual deflection methods, all of them have in common a requirement to transport a fairly large spacecraft to and rendezvous with the asteroid. Since the average delta V required to rendezvous with an NEO is of order 15 km/sec, some sort of high ISP propulsion system will be required. We are proposing to use that same propulsion system to both rendezvous with the asteroid as well as to gradually impart the delta V needed to change the trajectory of the asteroid. The mission we are proposing is to fly a spacecraft to an asteroid of size of order 200 meters, rendezvous and land, rotate the asteroid spin vector, and thrust to change the velocity of the asteroid by of order 0.2 cm/s. The amount of delta V required to avert a collision is a function of the orbital parameters and the warning time, with 0.2 cm/s being sufficient for of order 50-year warning time.

  2. Planetary body maneuvering - Outbound propulsion and trajectory analysis

    Robert B. Adams, Joseph Bonometti and Tara Polsgrove

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This paper is part of a sequence of three documenting the work completed at the NASA Marshall Space Flight Center in the area of the defense of Earth from incoming Near Earth Objects (NEO). The work found herein can be found fully documented in Adams et al. (2004). The topics of outbound propulsion and outbound trajectory modeling are covered in this particular paper.

  3. Planetary body maneuvering - Study architecture and results

    Robert B. Adams, Randall Hopkins and Tara Polsgrove, et al

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This paper is part of a sequence of three documenting the work completed at the NASA Marshall Space Flight Center in the area of the defense of Earth from incoming Near Earth Objects (NEO). This work can be found fully documented in Adams et al. (2004). The sections of this paper cover the mission configurations and the parametric results.

  4. Determining probability upper bounds for NEO close approaches

    Salvatore Alfano

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Collision probability analysis is accomplished by combining covariances and physical object dimensions at the point of closest approach. The resulting covariance ellipsoid and hardbody are projected into the plane perpendicular to relative velocity. Collision potential is determined from the object footprint on the projected covariance ellipse. This paper shows how to calculate the upper bounds of probability by determining the worst possible covariance parameters and orientation. These methods can be used as a simple pre-filter or to determine worst-case scenarios when the actual covariances are not known.

  5. Conceptual design of an asteroid interceptor for a nuclear deflection mission

    Mark J. Barrera

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    A conceptual design was developed for an asteroid interceptor vehicle using a nuclear explosive to deflect Athos, a 200-m diameter threat object. A notional concept of operations is proposed for delivering the interceptor to the asteroid, detonating the nuclear device, and verifying the effectiveness of the intercept. Preliminary system requirements and constraints were derived based on desired performance and near-term available technology. The proposed requirements and constraints were used to establish conceptual designs for an interceptor and cruise stage including estimates for the nuclear device and vehicle homing instruments. Further discussion is provided regarding issues in mission design, vehicle guidance, and design adaptability for alternate threat scenarios.

  6. Obtaining long warning times on long-period comets and small asteroids - Extremely large yet extremely lightweight space telescope systems

    Ivan Bekey

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Obtaining long warning times for long-period comets is exceedingly challenging, for detection must take place far out in the solar system, comets are usually dark with low albedo and with no coma when far from the Sun, most are new and so their appearance cannot be predicted, and their velocities are great and increase as they approach Earths orbit. Current Spaceguard class ground telescope systems would likely provide less than one year warning time against 1 km sized long-period comets. A revolutionary optical space telescope concept is described in which precise and expensive optics and structures are replaced with information systems, which are very lightweight and inexpensive. Feasibility studies indicate that a 25 meter diameter aperture space telescope using these new techniques would weigh just 260 kg total in orbit, which is almost 2 orders of magnitude lower than were the same aperture telescope be built even using technologies of the James Webb Space Telescope. The cost of such telescopes would also likely be about 2 orders of magnitude lower. A 1 km size comet would be detected and tracked at 12 AU and yield five years warning time using just one 25 m space telescope. The technologies are applicable to space telescopes at least up to 75 meters diameter, yielding 16 years warning time. Thus the paper demonstrates that long warning times on long-period comets are attainable, and would cost only on the order of tens of millions of dollars compared to the several billions cost of same-sized space telescopes using any other technologies.

  7. Summary of the 2002 Arlington Workshop on the Scientific Requirements for Mitigation of Hazardous Comets and Asteroids

    Michael Belton

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Seventy-seven scientists, engineers and military experts from the U.S., Europe, and Japan participated in the Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids. Its purpose was to consider the scientific requirements for avoidance and mitigation of hazards to the Earth due to asteroids and comets, i.e., what should be done to ensure that an adequate base of scientific knowledge is created that will allow efficient development of a reliable, but as yet undefined, collision mitigation system when needed in the future. Eighteen major conclusions were formulated that provided the basis for five recommendations. In brief, these are: That NASA be assigned the responsibility to advance this field; That a new and adequately funded program be instituted at NASA to create, through space missions and allied research, the specialized knowledge base needed to respond to a future threat of a collision from an asteroid or comet nucleus; That the Spaceguard survey be extended to cover the hazardous part of the population of possible impactors down to 200 m in size; That the DoD more rapidly communicate surveillance data on natural airbursts; That governmental policy makers formulate a chain of responsibility for action in the event a threat to the Earth becomes known. All aspects of near-Earth objects were discussed. These included the completeness of our knowledge about the population of potential impactors, their physical and compositional characteristics, the properties of surveys that need to be done to find hazardous objects smaller than 1 km in size, our theoretical understanding of impact phenomena, new laboratory results on the impact process, the need for space missions of specific types, possible mitigation systems, education of the public, public responsibility for dealing with the threat, and the possible roles of NASA, the military, and other agencies in mitigating the threat.

  8. Preliminary design of feasible Athos intercept trajectories

    Eric T. Campbell and Laura E. Speckman

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    System-level mission design for Near Earth Object (NEO) mitigation requires a set of feasible intercept trajectories from the Earth to the NEO. Previous trajectory analyses in the literature optimize on time of flight and other classic trajectory design parameters. However, for trajectories to be used within a system-level mission design, a figure of merit based on systems design constraints is useful to select optimum intercept trajectories. It is shown in this report that such a figure of merit can be used to select best intercept trajectories for the Athos Defined Threat (DEFT) scenario constructed for this conference.

  9. The impact imperative - A space infrastructure enabling a multi-tiered Earth defense

    Jonathan W. Campbell, Claude Phipps and Larry Smalley, et al

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Impacting at hypervelocity, an asteroid struck the Earth approximately 65 million years ago in the Yucatan Peninsula area. This triggered the eventual extinction of almost 70 percent of the species of life on Earth including the dinosaurs. Other impacts prior to this one have caused even greater losses. Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most critical space challenge facing human civilization. This is the Impact Imperative. We now believe that while there are about 2000 Earth orbit crossing rocks greater than 1 km in diameter, there may be as many as 200,000 or more objects in the 100-m size range. Can anything be done about this fundamental existence question facing our civilization? The answer is a resounding yes. By using an intelligent synthesis of sensors, high-energy laser arrays, other secondary mitigation options, and near term space transportation technologies in an Earth/moon/space systems infrastructure, inbound asteroids, meteoroids, and comets can be deflected and prevented from striking the Earth. With lasers, this can be accomplished by irradiating the surface of an inbound rock with sufficiently intense pulses so that ablation occurs. This ablation acts as a small rocket incrementally changing the shape of the rocks orbit around the sun. One-kilometer size rocks can be moved sufficiently in about a month while smaller rocks may be moved in a shorter time span. We recommend that world space objectives be reprioritized to start moving immediately towards a systems infrastructure that will support a multiple option defense capability centered around a lunar base. Planning and development for lunar facilities should be initiated immediately in parallel with other options. Infrastructure options should include ground, LEO, GEO, Lunar, and libration point laser and sensor stations for providing early warning, tracking, and deflection. All mitigation options are greatly enhanced by robust early warning, detection, and tracking resources to find objects sufficiently prior to Earth orbit passage in time to allow significant intervention. Other options should include space interceptors that will carry both laser and nuclear ablators for close range work. Response options must be developed to deal with the consequences of an impact should we move too slowly.

  10. The Impact Imperative - A space infrastructure enabling a multitiered Earth defense

    Jonathan Campbell, Claude Phipps and Larry Smalley, et al

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Preventing collisions with the Earth by hypervelocity asteroids, meteoroids, and comets is the most critical space challenge facing human civilization. This is the Impact Imperative. We now believe that while there are about 2000 Earth orbit crossing rocks greater than 1 kilometer in diameter, there may be as many as 200,000 or more objects in the 100 m size range. By using an intelligent synthesis of sensors, high-energy laser arrays, other secondary mitigation options, and near term space transportation technologies in an Earth/Moon/Space systems infrastructure, inbound asteroids, meteoroids, and comets can be deflected and prevented from striking the Earth. All mitigation options are greatly enhanced by robust early warning, detection, and tracking resources to find objects sufficiently prior to Earth orbit passage in time to allow significant intervention. Other options should include space interceptors that will carry both laser and nuclear ablators for close range work. Response options must be developed to deal with the consequences of an impact should we move too slowly.

  11. Airborne-laser planetary defense against asteroids - Near-field aero-optical distortions and far-field space propagation

    Haris Catrakis, Roberto Aguirre, Jennifer Nathman and Nella Barrera

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The focus of this work is on the laser-beam distortions associated with the aircraft-generated turbulence which can degrade significantly the far-field laser-beam behavior. In particular, separated flows generated by the aircraft cause significant near-field aero-optical distortions. Preliminary findings indicate that large-scale flow structures dominate the aerooptical distortions, necessitating novel means to suppress or eliminate the large-scale flow structures and aero-optical distortions using flow control. Additionally, regularized aero-optical flow fields could facilitate tracking lasers. Airborne-laser turrets generate flow curvature that can be used to advantage to reduce aero-optical distortions.

  12. NEO impact scenarios

    Clark Chapman

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    To prepare for the unlikely discovery of an actual threatening NEO, the purpose of Spaceguard and the raison d'etre for designing mitigation, the world's "sentry" system must be reliably prepared to deal with events that are unexpected, indeed unprecedented. In particular, astronomical observing techniques, reporting procedures, the sifting of data and posting of ephemerides by the Minor Planet Center (MPC), the independent calculations of impact probabilities by Sentry and NEODys, and the process of public announcement of a potential impact...all must avoid missing the very unlikely signal, should one manifest itself. Yet the chance of an unprecedented real event happening is much smaller than that an error has occurred. So very careful judgments must be made, and quickly. For even though a predicted impact is likely to be decades away, rapid, reliable decisions are required to follow-up an NEO while it is still near the Earth, and to provide the fast-paced news media with accurate information to avoid hype. Some impact scenarios have substantial implications for the further design and operation of detection and warning systems as well as for disaster planners and crisis mitigation. For instance, if a real impact were predicted, plans for evacuating ground zero might be needed, even as efforts to divert the NEO were underway. One scenario actually played out just last month (13-14 January 2004). For nine hours, experts felt there was a credible chance (perhaps 1 to 25 percent) that a mini-Tunguska (or even Tunguska-scale) impact might occur the very next evening (just after President Bush's space policy speech), or at least during the next few days. The real object (much larger and farther away) missed the Earth by millions of km several weeks later. But the MPC posted on its Confirmation Page a nominal orbit, fitting undersampled LINEAR data, that actually impacted the Earth. Six hours later, some experts still thought that it might hit. Finally, amateur astronomer Brian Warner, with clear skies, found that the "virtual impactor" did not exist, so impact was ruled out. Had he been clouded out, when should a report have gone out, and with what consequences?

  13. The space elevator concept as a launching platform for Earth and interplanetary missions

    V. A. Chobotov

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The concept of a space elevator was examined as a potential launching platform for Earth and interplanetary missions. Keplerian parameters were obtained for payload separation from the space elevator at various radii (altitudes) from the Earth's center. It was found that Earth reentry results at separations lower than 23390 km altitude and that hyperbolic orbits result for releases above 46749 km altitude. Velocities at infinity were calculated and found to be up to 12 km/s at release radius of about 4 times GEO. The resultant solar system apogees were as high as 14 AU. Applications to a potential planetary defense mission were examined. It was found that an intercept of an Earth orbit-crossing asteroid (Athos) could be performed by the release of the interceptor at twice the GEO radius. This results in a 5 km/s velocity at infinity that is sufficient to perform the intercept. Practical issues related to the use of the space elevator as a launching platform were outlined.

  14. Using a gas-blast warhead to perturb a DEFT body orbit

    Guy Cooper

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    A non-impact, unmanned missile to deflect the DEFT target bodies is the most flexible and least expensive system. A gas blast warhead is proposed as the most versatile means of transferring momentum change to any target type (a rock pile, a snowball, or a single large rock). Direction of the momentum change vector is dependent solely upon the missile aiming and approach velocity vector relative to the target body at the instant of warhead detonation. The best example of deliberate gas blast modification of a space trajectory is the Space Shuttle, which relies on an upper atmosphere relative wind for de-orbiting.

  15. Asteroid, Comet and Planetary Defense: The Joke's On Who?

    Liara M. Covert.

    55th International Astronautical Congress 2004; Vancouver; Canada; 4-8 Oct. 2004. pp. 1-13. 2004; 55th International Astronautical Congress 2004; Vancouver; Canada; 4-8 Oct. 2004

    At present, national and international security issues drive emerging policy and law, but the threat of cosmic collisions is rarely noted or integrated. Is this purely an economic issue? Does it mean historical resources only suggest meteorite collisions have been catastrophic? Do people ignore all the general media broadcasts about asteroid and comet sightings near Earth? Are scientists debating the research value of near-earth objects (NEOs)? Should international organizations discontinue cooperation in space debris studies? As it stands, actors who drive State policy are more reactive than proactive. Overlapping military or other national services are set up to mobilize for full-blown crises. They don't regard seriously a need for global military planning or concerted planetary defense. Further, agencies exist to collect and interpret data. States aim to preserve sovereignty, promote economic growth, national self-interests. and foster global competition. With this a given, global terrorism then evolved to be seen and budgeted for as the most pressing global threat over and above all other threats. That said, what might be the best way to combat terrorism that threatens security, economies and society, while also raising awareness, credibility and response to key environmental threats? What might convince leaders to define strategies that recognize common ground in different kinds of threats to security? This paper will address fundamental socio-political issues on national and international levels. The author contends the public, scientists, environmental professionals, military and government, all have roles to play in urging leaders to recognize benefits in dividing planetary defense into manageable initiatives that could be reflected in policy and law.

  16. 21st Century Steam for Asteroid Mitigation

    D. S. P. Dearborn

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The systematic requirements to divert an object on an Earth-impacting course are developed relating the minimum velocity perturbation (both magnitude and direction) to the time available before impact. This, coupled with the accuracy to which orbits can be determined, restricts the time available for any mitigation technology to operate. Because nuclear energy densities are nearly a million times higher than those possible with chemical bonds, it is the most mass efficient means for storing delivering energy with todays technology. The question is how to most effectively apply that energy. This paper examines the simple case of shattering the body, as well as a more controlled approach in which one or more small velocity increments divert a body. The optimal approach depends on the detailed circumstances, but in either case, already developed technology permits a successful diversion with a few years to decades of notice. The success of nuclear options on relatively short timescales permits consideration of other technologies that while not so well developed might be sufficiently improved to divert small (100 m) bodies.

  17. Mass drivers for planetary defense

    George Friedman, John S. Lewis, Leslie Snively, Richard E. Gertsch, Lee Valentine and Dennis Wingo

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Mass drivers do not require bringing along large masses of propellants. A major advantage of this approach is that all the energy can come from the sun and the reaction mass from the asteroid itself. We expect no design surprises; straightforward engineering should yield a mass driver of adequate performance for planetary defense. We focus on asteroids of 1 km in diameter or greater because those rare impactors are responsible for the large majority of casualties and economic damage expected from NEA strikes. To simplify the mining, we need large masses of finely comminuted regolith. That is most likely to be available on large rubble piles. Smaller asteroids may consist of bare rock and so are much more difficult to convert to usable reaction mass. This scenario shows what may plausibly be done with near-term systems. The plan uses only equipment that is off-the-shelf or in advanced development at NASA. Launch vehicle technology is limited to existing launchers, including the Delta IVH. Upper stages are limited to existing stages and a derivative of a commercial SEP tug. On orbit assembly avoids the development of a new large booster. Setting up a mine to provide thousands of tons of reaction mass on a body with complicated geology and geometry is a daunting task. Therefore, a human crew, with teleoperated robonauts, travels to the asteroid after pre-positioning of essential supplies and equipment. The crew inhabits a module developed for the ISS. ISRU is used to produce oxygen for the return to Earth and to provide consumable oxygen during the extended stay on the asteroid. In situ resource utilization decreases the necessary mass to be transported to the asteroid and offers the potential for cost savings in rough proportion to the mass savings. For most deflection circumstances, NEA translational kinetic energy is much greater than rotational energy. The most effective strategy is to kill the rotation as soon as possible. De spinning also permits full time use of the solar arrays and minimizes thermal cycling. The first missions are probes to map the gravity field of the asteroid, the thickness of regolith and internal structure. A beacon attached to a lander guides cargoes to precision landings. The 35 ton crew module with a four person crew arrives later. The crew lands the habitat, attaches it to the asteroid and shields it with regolith. A critical first task is to secure a robust cable to the surface of the asteroid and girdle the asteroid with it. A rudimentary web allows reliable mining and transportation on the asteroids surface. Using robonauts, the crew sets up the induction furnace, power supplies, mining and beneficiation equipment and mass driver at the equator and begin the despin operation. After despin is complete, the mass driver is lined up with velocity vector and translational thrusting begins. About one year later the velocity vector has been changed by 1 cm/s, and the deflection mission is concluded. The crew packs up and heads for home.

  18. Paving the way for an effective deflection mission - State of the art NEO precursor missions

    Andres Galvez, Jose Gonzalez and Juan Martin-Albo

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    In the event of the detection of an asteroid on a collision course with the Earth, a mission to collect in-situ information on the asteroid properties and to test the technologies required to perform the deflection will be mandatory. The mission proposed in this paper, which has been called Don Quijote, will consist of two spacecraft, which would be injected into separate interplanetary trajectories by the same Soyuz launch vehicle. The first spacecraft, called Hidalgo, would impact on the asteroid at a relative speed of at least 10 km/s. A second spacecraft, called Sancho, would have previously performed a rendezvous maneuver with the asteroid and would remain in orbit about it, observing the impact and analyzing any changes in the asteroid internal structure, shape, orbit and rotation state as a consequence of the collision. The objectives of the mission would be to determine the asteroid internal structure, to constraint its mechanical properties, to determine the feasibility of coupling devices onto its surface and measure the orbital deflection of the asteroid as a result of the impact of the Hidalgo spacecraft. As an illustration of the mission concept and its versatility, a candidate mission has been selected considering one of the proposed DEFT, Athos, with optimum spacecraft masses and delta-v, compatible with the asteroid detection and estimated Earth impact date. Hidalgo arrival at Athos on 2012 would take place more than four years before the Earth impact, which could be time enough to allow the adaptation of a second mission -according to Don Quijote mission results - in order to enable an optimal asteroid deflection.

  19. Deflecting asteroids by means of standoff nuclear explosions

    Donald Gennery

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    A nuclear explosion at a distance can deflect an asteroid primarily because of energy transmitted to the surface by neutrons and X-rays. If the surface material is nonporous, evaporation or spalling can produce the impulse. However, if the surface is porous, spalling caused by neutrons usually is not effective, so that the energy density must be great enough to produce evaporation. Based on some recently available information and some reasonable assumptions about the surface material, computed results are presented that show the impulse produced on a porous object as a function of total neutron energy, distance of the explosion, and diameter of the object. The deflection of an object by a sudden impulse such as that from an explosion may cause it to disperse, especially if the ratio of deflection velocity to escape velocity of the object is high. Although internal rubble may make the dispersion of an object more likely in some cases because it is already fractured, in other cases it may help to prevent dispersion because internal absorption of energy is aided by voids. Results are presented showing the maximum portion of fragments that would be expected to hit Earth, as a function of the amount of attempted deflection relative to Earths radius, in case the object disperses. These indicate that it is fairly easy to keep this portion below 10 percent and in some cases below 1 percent. Publicly available information about some current nuclear bombs and reasonable assumptions about custom-made bombs are used to estimate total neutron energy and bomb mass for some possible warheads that could be used for deflection. By using all of the information described above, examples (based on the Defined Threat scenarios recommended for this conference) are given of threatening asteroids that could be deflected successfully with existing technology, and in some cases even with existing hardware, by means of standoff nuclear explosions.

  20. Rapid and scalable architecture design for planetary defense

    Matthew Graham, John Olds and A. C. Charania

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    A modular/swarm architecture, based upon existing spacecraft buses and launch vehicles, is proposed to mitigate near-Earth object (NEO) planetary threats. Each spacecraft that is part of this swarm would utilize mass driver technology to remove mass from the object to yield an Earth-avoiding trajectory. Such a design philosophy focuses on developing rapid and scalable NEO mitigation plans incorporating the worlds current launch vehicle/spacecraft bus manufacturing capability. Three specific planetary threats (one comet, two asteroids) are examined, each with different impact times and masses, and based upon predetermined fictitious Defined Threat (DEFT) scenarios. Potential advantages envisioned in such an architecture design include: integrating the analysis of spacecraft development/deployment/launch, ability to complete the mission given the loss of part of the swarm, scalability of response for different size threats, and flexibility to initiate an immediate response leaving the option to develop more advanced systems.

  21. Deep surveys to discover sub-km NEAs

    Alan Harris

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    In anticipation of achieving the "Spaceguard Goal" of discovering 90 percent of NEAs larger than one km in diameter by 2008, two systems are under serious design and development. One is Pan-STARRS, a system of four 1.8-m telescopes planned by the University of Hawaii and funded through the USAF. The other is LSST, a single 8.4-m telescope, planned by the National Optical Astronomy Observatories (NOAO), intended to be funded by some combination of NSF, NASA, and private foundations. A few other 4-m class instruments are under design (e.g., Next-Generation Lowell Telescope) that can contribute to the next generation survey. Unlike current survey systems, these much larger instruments will share priorities with various other astrophysical programs, so we must design a survey strategy that can accomplish the NEO survey task with only a fraction of the total time, or with images not optimized for the NEO survey. Four factors promise substantial improvements in survey performance: (1) optimal design and location of telescopes and detectors to obtain higher resolution and larger fields of view; (2) sky subtraction of current images against a catalog of summed past images rather than comparing one image with another taken the same night (this is used successfully by supernova surveys); (3) more advanced linkage strategy along with better quality astrometry to obtain orbits with fewer observations over shorter time spans; and (4) optimizing the search area to cover less than "all sky" while retaining most of the discovery rate. Preliminary evaluations of these improvements suggest that a successful NEO survey can be accomplished using half or less of the total observing time of a single wide-field survey telescope, as opposed to about two such telescopes, as would be required by simply scaling up from present instruments and strategies. Thus it appears possible to design an NEO survey that is compatible with other uses of the same instrument.

  22. Deflection techniques - What makes sense?

    Alan W. Harris

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    A first step toward finding what makes sense in terms of asteroid deflection is to consider the deflection velocity needed to divert an asteroid (or its disrupted fragments) from impacting the Earth. A simple dimensional analysis yields that the deflection delta-v required to miss the Earth is (delta-v)(time) = (radius of the Earth), which translates to about (20 cm/s)/(t, years). Over a time long compared to orbit periods, the deflection delta-v is even less, about (7 cm/s)/(t, years). Thus with a lead-time of a decade, a delta-v of only about 1 cm/s is required. A second important relation is that if one were to disrupt a body (say by nuclear explosion) the residual velocity dispersion of the fragments would be at least of the order of the surface escape velocity of the undisrupted body, which is about (60 cm/s) x (diameter in km). From these two relations, it is clear that if one were to disrupt a 1-km diameter body, within only a few months the fragments would disperse over an orbital arc large compared to the dimension of the Earth. For non-nuclear options, the delta-v that may be achievable is of the order of cm/s, or perhaps even less, thus any such method requires at least a decade of application of force, and an even longer lead time to put it in place. Furthermore, precision tracking is required to assess the progress of the deflection, thus an active transponder on the asteroid is required in addition to the deflection "engine". For these reasons, non-nuclear deflection scenarios are of such long lead-time that the development time is short compared to the implementation time, so there is limited value in building any such system in advance of need. Only for the nuclear option is the response time short compared to the development time. However, this option leads to the "deflection dilemma", that the risk of having a deflection system "at the ready" may exceed the risk it is designed to obviate. Furthermore, short lead-time mitigation is problematic: either deflection or disruption may be difficult if the asteroid is a "rubble pile" or some exotic configuration like a contact binary object. Another often overlooked aspect of asteroid deflection is the claim that "NEAs are the easiest targets to get to" is only true if you get to choose the target. Technology that would almost certainly be required for a deflection includes heavy lift launch vehicles and advanced high-performance in-space propulsion systems. Development of such technology, and exploratory missions to better understand NEAs, would have great scientific value even if never needed for asteroid deflection.

  23. Psychological factors influencing responses to major near Earth object impacts

    Albert A. Harrison

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Plans to prevent or minimize a global catastrophe will be based on human judgment and will therefore involve a combination of reason and emotion. This paper draws from the behavioral science literature and from historical precedent to identify some of the sociological and psychological factors that are likely to influence the planning process. Characteristics likely to distinguish NEO impacts from more common disasters such as volcanic eruptions, hurricanes and floods include significant warning time, a greater potential for extensive global damage, and a post-impact environment that could prevent full recovery. Impediments to effective planning include the giggle factor, media distortions, supernatural interpretations, and interagency competition. The Janis-Mann conflict model of decision making suggests that effective decisions rest on a careful assessment of the situation, recognition of the complexities of various options, painstaking integration of new information as it becomes available, a sense of hope that a good course of action is available, and a conviction that there is time to find and implement it. This paper concludes with a brief look at the sociological and psychological aspects of survival communities, such as portrayed optimistically in the 1998 science fiction movie Deep Impact.

  24. An assessment of our present ability to deflect asteroids and comets

    Keith A. Holsapple

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This is a short summary of current thought and analyses regarding ways to divert threatening asteroids and comets that are on a collision course with the Earth. Such analyses have been presented by various authors, including the present author (Holsapple, 2004), in recent conferences and workshops, and in the Proceedings of the Planetary Defense Conference, 2004 of which this contribution is a part. Other papers (Kahle et al., 2004; Gennery, 2004) presented at this conference on diversion efficiencies have been included the present summary. The trend over the short lifetime of these deflection studies is to shift consideration to the smaller bodies that impact more frequently. Initially bodies in the 10-km diameter or global devastation size were being considered. Now, emphasis has shifted to bodies as little as 50 m in diameter. That increases the difficulties for the astronomers, but decreases the difficulties for deflection. There is little doubt we can deflect bodies up to about 200 m diameter if discovered a decade before an impending impact.

  25. Athos deflection mission analysis and design

    Ralph Kahle, Gerhard Hahn, Ekkehard Kuehrt and Stefanos Fasoulas

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    An asteroid deflection mission is analyzed and designed based on a fictitious threat scenario. The mission objective is to prevent the collision of the virtual binary asteroid Athos with Earth on February 29, 2016. Two alternative techniques are investigated both aiming on the diversion of Athos trajectory rather than on its destruction. These techniques are an inflatable solar collector and a kinetic energy projectile. Based on the results of a precursor mission to Athos and the outcomes of technology feasibility studies, one technology will be selected for mitigation. Mission constraints are identified as the time of collision, the physical and orbital properties of Athos, and the technology readiness level of the envisaged mitigation techniques and underlying launch system and spacecraft technology. The last point is of high priority because of the short time span from time of detection (February 22, 2005) to launch date of the deflection spacecraft. Detailed mission schedules, delta-V analysis, mass budgets, payload analysis, and cost estimates are derived to assess the feasibility of both mitigation techniques. We show that Athos can be deflected with non-nuclear concepts. Further, the threat posed by Athos satellite DeWinter, which might separate during mitigation, is assessed in terms of Earth atmosphere entry analysis.

  26. Orbit determination for long-period comets on Earth-impacting trajectories

    Linda Kay-Bunnell and Robert H. Tolson

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This paper presents a study of orbit determination capability and potential warning times for long-period comets in various inclination orbits detected at a distance of 5 AU, based on optical tracking accuracies equivalent to Hubble-type resolution. Comparisons are made for single observatories and multiple observatories placed at various locations in the solar system. The effects of non-gravitational perturbations due to comet outgassing are considered as both a random but constant bias throughout the orbit and a random, time dependent state noise. The comparison between observatories in several different circular heliocentric orbits shows that observatories in orbits with radii less than 1 AU result in increased orbit determination accuracy for short tracking durations due to increased change in parallax per unit time. However, an observatory in a circular heliocentric orbit at 1 AU will perform just as well if the tracking duration is increased. The orbit determination accuracy is significantly improved if additional observatories are positioned at the Sun-Earth Lagrange points L3, L4, or L5. At the time of closest approach, the dominant error in comet- Earth relative distance is along the trajectory of the comet. Observations from which the distance from the comet to the Sun can be inferred dramatically reduce this along track error and consequently reduce the orbit determination uncertainty.

  27. Comet, Asteroid, NEO Deflection Experiment (CANDE) - An evolved mission concept

    David K. Lynch

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    We propose a space mission to a small asteroid (1-2 km) that would carry a sophisticated remote sensing package and detonate a 10 MT nuclear bomb on or near the surface of the body. The goal is to demonstrate the technology of such a mission, measure detailed properties of an asteroid, provide real-world data on how nuclear radiation interacts with the surface, and determine how much the body was actually deflected. An asteroid or comet with a diameter of 1-5 km would be best because it would be deflectable (few cm/sec) with our existing ability to deliver energy to it. CANDE is a rendezvous mission equipped with remote sensing instrumentation that would be placed in orbit around the body to ascertain mass, shape, color/spectra, rotation and moments of inertia. Close monitoring of the bodys motion before and after detonation would provide unprecedented accurate measurements of perturbations, non-gravitational forces and the error ellipses. The CANDE payload would consist of two parts: an orbiting remote sensing package and a lander. The orbiter would carry the nuclear bomb and provide power for the remote sensing suite. The remote sensing suite would consist of imagers, spectrographs, dust particle collectors, gas analyzers, inertial navigation equipment, a laser altimeter, etc. The orbiter would have a complex orbit that would eventually produce nadir views of every part of the surface and provide information on jets, surface irregularities and of course the gravitational field. The lander would carry a radar beacon, corner cubes, surface analysis equipment including seismic sensors to plum the interior by using conventional shaped-charge explosives. After several months of measurements, the nuclear bomb would be maneuvered into position and detonated. Detonation would take place when the orbiter and lander were behind the asteroid to shield it from direct blast effects. Post-detonation orbital information would be obtained and relay back to Earth.

  28. Athos, Porthos, Aramis & DArtagnan - Four planning scenarios for planetary protection

    David Lynch and Glenn Peterson

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    For the 2004 Planetary Defense Conference: Protecting Earth from Asteroids, four fictitious Defined Threat (DEFT) scenarios were created where, without mitigation, solar system bodies (three asteroids, one comet) will strike the Earth. These scenarios were generated to encourage detailed designs of rendezvous, intercept, and deflection missions and to focus discussion of how the world community might prepare for mitigation efforts or possible disaster from engineering policy, public education, and other perspectives.

  29. Planetary Defense From Space: Part 1- Keplerian Theory

    Claudio Maccone.

    Acta Astronautica. Vol. 55, no. 12, pp. 991-1006. Dec. 2004, pp. .

    A system of two space bases housing missiles is proposed to achieve the Planetary Defense of the Earth against dangerous asteroids and comets. We show that the layout of the Earth-Moon system with the five relevant Lagrangian (or libration) points in space leads naturally to only one, unmistakable location of these two space bases within the sphere of influence of the Earth. These locations are at the two Lagrangian points L1 (in between the Earth and the Moon) and L3 (in the direction opposite to the Moon from the Earth). We show that placing bases of missiles at L1 and L3 would cause those missiles to deflect the trajectory of asteroids by hitting them orthogonally to their impact trajectory toward the Earth, so as to maximize their deflection. We show that the confocal conics are the best class of trajectories fulfilling this orthogonal deflection requirement. An additional remark is that the theory developed in this paper is just a beginning of a larger set of future research work. In fact, while in this paper we only develop the Keplerian analytical theory of the Optimal Planetary Defense achievable from the Earth-Moon Lagrangian points L1 and L3, much more sophisticated analytical refinements would be needed to: (1) Take into account many perturbation forces of all kinds acting on both the asteroids and missiles shot from LI and L3; (2) add more (non-optimal) trajectories of missiles shot from either the Lagrangian points L4 and L5 of the Earth-Moon system or from the surface of the Moon itself; (3) encompass the full range of missiles currently available to the US (and possibly other countries) so as to really see "which asteroids could be diverted by which missiles", even in the very simplified scheme outlined here. Outlined for the first time in February 2002, our Confocal Planetary Defense concept is a Keplerian Theory that proved simple enough to catch the attention of scholars, representatives of the U.S. Military and popular writers. These developments could possibly mark the beginning of an "all embracing" mathematical vision of Planetary Defense beyond all learned activities, dramatic movies and unknown military plans covered by secret.

  30. Automatic Planetary Defense Deflecting NEOs By Missiles Shot From L1 And L3 (Earth-Moon)

    Claudio Maccone.

    55th International Astronautical Congress 2004; Vancouver; Canada; 4-8 Oct. 2004. pp. 1-13. 2004; 55th International Astronautical Congress 2004; Vancouver; Canada; 4-8 Oct. 2004

    We develop the mathematical theory for an automatic, space-based system to deflect NEOs by virtue of missiles shot from the Earth-Moon L1 and L3 Lagrangian Points. A patent application has been filed for the relevant code dubbed AsterOFF (=Asteroids OFF !). This code was already implemented, and a copyright for it was registered. In a paper published in Acta Astronautica, Vol. 50, No. 3, pp. 185-199 (2002), this author proved mathematically the following theorem (hereafter called the "confocal conics theorem"): "Within the sphere of influence of the Earth, any NEO could be hit by a missile at just an angle of 90 degrees, was the missile shot from the Lagrangian Points L 1 or L3 of the Earth-Moon system, rather than from the surface of the Earth". As a consequence, the hitting missile would have to move along a "confocal ellipse" (centered at the Earth) uniquely determined by the NEO's incoming hyperbola. Based on the above theorem, the author further shows in this paper that: 1) The proposed defense system would be ideal to deflect NEOs that are small, i.e. less than one kilometer in diameter. Small NEOs are just the most difficult ones to be detected early enough and to such an orbital accuracy to be positively sure that they are indeed hazardous. 2) The traditional theory of Keplerian orbits can successfully be applied to get an excellent first-order approximation of the (otherwise unknown) mathematical formulae of the energy-momentum requested to achieve the NEO deflection. Many engineering details about the missiles shot from L1 and L3, however, still have to be implemented into our simulations, partly because they are classified. 3) Was one missile not enough to deflect the NEO completely, it is a great advantage of the "confocal conies" used here that the new, slightly deflected NEO's hyperbola would certainly be hit at nearly 90 degrees by another and slightly more eccentric elliptical missile trajectory. A sufficient number of missiles could thus be launched in a sequence from the Earth-Moon Lagrangian points L1 and L3 with the result that the SUM of all these small and repeated deflections will finally throw the NEO off its collision hyperbola with the Earth.

  31. AsterOFF - A computer code to deflect NEOs by missiles shot from the Earth-Moon L1 and L3 Lagrangian Points

    Claudio Maccone

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    We develop the mathematical theory for an automatic, space-based system to deflect NEOs by virtue of missiles shot from the Earth- Moon L1 and L3 Lagrangian Points. The proposed defense system would be ideal to deflect NEOs that are small, i.e., less than one kilometer in diameter. If one missile is not enough to deflect the NEO completely, it is a great advantage of the system discussed here that the new, slightly deflected NEOs hyperbola would certainly be hit at nearly 90 degrees by another and slightly more eccentric elliptical missile trajectory. A sufficient number of missiles could thus be launched in a sequence from the Earth-Moon Lagrangian points L1 and L3 with the result that the SUM of all these small and repeated deflections will finally throw the NEO off its collision hyperbola with the Earth.

  32. A realistic approach to planetary defense using a modular in-space transportation architecture

    Daniel Mazanek

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    In recent years, the real and credible hazard of Earth impacting comets and asteroids has been identified. A dedicated planetary defense system actually capable of averting an impact is expensive to develop and maintain, and would likely not be used for decades or centuries due to the infrequent nature of this hazard. These factors make a dedicated system impractical from financial and political standpoints. This paper describes a different approach to planetary defense that can be achieved realistically in the future. The approach advocates developing a modular, reusable in-space transportation architecture that can support human and robotic exploration of the near-Earth neighborhood. These types of missions would provide unprecedented planetary scientific research and exploration, as well as validate many of the methods and technologies required to protect the Earth from a future catastrophic collision. Since the elements of this architecture would already be operational, they could provide a rudimentary on call planetary defense system, and even provide some level of protection against impactors that pose an immediate threat. Establishing a robust, adaptable infrastructure in cis-lunar space protects the region of space that we ultimately want to defend. Human and robotic space exploration will allow mankind one day to leave the cradle of Earth, and using the same technologies and infrastructure could allow us someday to save the nursery.

  33. Asteroid deflection - The mirror ablation approach

    H. Jay Melosh

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    I propose a method of deflecting Earth-threatening asteroids by means of a solar collector. The collector focuses sunlight on the surface of the asteroid, strongly heats a small spot, and vaporizes enough material that the thrust from the expanding jet of gas and dust can, over a period of years, divert the asteroid from collision with the Earth. This paper examines the limits on concentration of sunlight, evaporation of the surface rocks, expansion of the jet and operations in near-asteroid space. The primary difficulty with this scheme is the fouling of the last optical element in the system by evaporated material, for which several solutions are suggested. Overall, this scheme compares very favorably with other proposed deflection approaches and does not involve a large extension of present technology.

  34. Presentation at the 2004 Planetary Defense Conference

    Larry Niven

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This paper, presented by novelist/science fiction writer Larry Niven, addresses public reaction to the threat of near-Earth objects (NEOs) to life on Earth and what we should do about stopping the threat. The author concludes that we will not survive the next giant meteoroid impact unless we can build the devices for dealing with it that we have been designing. He also states that we need funding to build the spaceships needed to avert the threat.

  35. Satellite sensor detection of a major meteor event in the United States on 27 March 2003 - The Park Forest, Illinois bolide

    Dee Pack, B. B. Yoo and E. Tagliaferri

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    A major meteor explosion in Earths atmosphere occurred over Park Forest, Illinois on 27 March 2003 at 05:50 UT (11:50 PM local time). The event resulted in a large-scale meteorite fall over the southern suburbs of Chicago. This is the largest meteorite fall over a densely populated area in modern history. Several buildings had their roofs penetrated, though no injuries resulted. The explosive disintegration of the meteor lit up the night sky to daylight levels. Large sonic booms were heard over a wide area. The meteor explosion was detected by space-based infrared and visible sensors operated by the Department of Defense (DoD) and Department of Energy (DoE), as well as by ground-based infrasonic arrays, seismic stations, video cameras, and video camera microphones. A number of meteorites were recovered, and the object was classified as a type L-5 chondrite (stony meteor). The Park Forest event is one of only four meteors detected by satellite sensors that also resulted in a collected meteorite fall. A collaborative effort is underway between The Aerospace Corporation, Sandia National Laboratories, and the University of Western Ontario to fuse and analyze the space- and ground-based data. This report summarizes the analysis of the satellite data to determine the energy, temporal signature, trajectory, velocity, mass, and size of this extraordinary meteor. The total energy release was determined to be on the order of a 0.34 kT nuclear event. The derived velocity of the meteor was 20 +/- 1 km/s, decelerating to 14 km/s at lower altitude. The preatmospheric mass of the stony object is estimated as 7.8 tons, and its diameter is estimated as 1.6 m.

  36. Deflection of Earth-crossing asteroids/comets using rendezvous spacecraft and laser ablation

    Sang-Young Park and Daniel Mazanek

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Space missions are presented to deflect four fictitious Earth impacting objects by using an advanced magnetoplasma spacecraft designed to deliver a laser ablation payload. The laser energy required to provide sufficient change in velocity is estimated for one long-period comet and three asteroids, and an optimal rendezvous trajectory is provided for each threat scenario. The end-to-end simulations provide an overall concept for solving the deflection problem. These analyses illustrate that the optimal deflection strategy is highly dependent on the size and the orbital elements of the impacting object, as well as the amount of warning time. A rendezvous spacecraft with a multi-megawatt laser ablation payload could be available by the year 2050. This approach could provide a capable and robust orbit modification approach for altering the orbits of Earth-crossing objects with relatively small size or long warning time. Significant technological advances, multiple spacecraft, or alternative deflection techniques are required for a feasible scenario to protect the Earth from an impacting celestial body with large size and short warning time.

  37. NEO orbit uncertainties and their effect on risk assessment

    Glenn Peterson

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Threat assessment of approaching Near-Earth Objects (NEOs) is best based upon the probability of collision since it yields a more accurate measure of risk than simple miss distance. The probability is computed at the point of closest approach using the miss vector, the sizes of the objects, and the covariances. However, the ephemeris and covariance of the NEO is determined at the time the object is detected. To get the values at conjunction, both the trajectory and covariance must be propagated to the time of conjunction. Due to orbital dynamics, the covariance will grow in size as time progresses. Since the probability of collision is dependent upon the covariance, the dynamically induced covariance growth directly impacts the computation of the probability and hence the capability to conduct risk assessment for a conjunction in the future. In this study, approximate analytic expressions are developed that relate the largest possible probability at conjunction to any time before conjunction and to the NEO state uncertainty at epoch. This largest probability sets an upper bound that any actual probability cannot exceed, thus enabling decision makers to evaluate a conjunction more effectively.

  38. Delta-V requirements for DEFT scenario objects

    Glenn E. Peterson

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Mission design for Earth-NEO (Near Earth Object) encounters often focuses on the ability to impart an impulse to the NEO that will move the object so that the miss distance increases by an acceptable amount. However, this does not necessarily reduce the probabilistic risk that the NEO poses to an acceptable level. Dynamically induced (and therefore unavoidable) covariance growth between the time of last tracking and the conjunction time represents a significant uncertainty in the NEO trajectory, and hence the miss distance at closest approach. If this uncertainty is not accounted for, optimistic impulse solutions may result. In essence, proper maneuver analysis requires actual risk reduction, not simply increasing the miss distance. It is shown in this report that covariance-based maneuvering will yield significantly different answers than deterministic maneuvering for asteroid threats. The Defined Threat (DEFT) scenarios constructed for this conference are used as examples.

  39. Billiards shot against Artemis

    Jean Marc Salotti, Andrew Barton, Nicolas Peter and Douglas Robinson

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The billiards shot strategy consists in deflecting a smaller asteroid (the striker) so that it impacts and destroys the threatening asteroid (Artemis is the target in this case study) before the predicted collision with Earth. The main conclusions are: (1) The kinetic energy of a small striker is more powerful than nuclear weapons to destroy big NEOs. In the case of Artemis, a 100 meters diameter asteroid is sufficient. (2) Potential strikers of appropriate size and orbital parameters already exist in the databases of NEOs that have been built so far. Considering a plane change maneuver to match Artemis plane followed by a modification of the semi-major axis, it is shown that 1999 VK12 is the best striker of the billiards shot against Artemis. (3) The energy required for a plane change maneuver and the diameter of the asteroid (derived from its albedo) are the main parameters for the choice of the striker. Complementary studies remain to be performed to assess astronautic capabilities and to examine billiards shot without exact matching of the planes.

  40. Close proximity operations for implementing mitigation strategies

    Daniel Scheeres

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    Central to almost any characterization or mitigation mission to a small solar system body, such as an asteroid or comet, is a phase of close proximity operations on or about that body for some length of time. This is an extremely challenging environment in which to operate a spacecraft, surface vehicle, or human mission. Reasons for this include the a priori uncertainty of the physical characteristics of a small body prior to rendezvous, the large range that can be expected in these characteristics, and the strongly unstable and chaotic dynamics of vehicle motion in these force environments. To successfully carry out close proximity operations about these bodies requires an understanding of the orbital dynamics close to them, a knowledge of the physical properties of the body and the spacecraft, and an appropriate level of technological sensing and control capability onboard the spacecraft. To go the next step and implement some mitigation strategy can involve even more challenges, such as placing large structures or devices on the surface of the body, inside the body, or in close proximity to the body for extended periods of time. This paper will discuss the range of possible dynamical environments that can occur at small bodies, their implications for spacecraft control and design, and technological solutions and challenges to the problem of operating on and in close proximity to the surface of these small bodies.

  41. The mechanics of moving asteroids

    Daniel Scheeres and Russell Schweickart

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The fundamental problem for all asteroid mitigation concepts is how to best alter the trajectory of the hazardous body. This is a non-trivial issue and brings together many different aspects of dynamics, engineering, and small body science. This paper will focus on some select issues that pertain to this problem, and will attempt to define a coherent approach to a class of solutions to this problem. First, we will discuss what is currently known or suspected about the surface, interiors and spin states of small bodies, and the implications of these. Second, we will discuss the mechanics of altering an asteroids trajectory and spin state, incorporating realistic numbers for thrust levels available. Finally, combining these previous topics, we will discuss some possible approaches to implementing these maneuvers. Throughout we will focus on the use of continuous thrust devices for effecting these changes to the small body state.

  42. The real deflection dilemma

    Russell L. Schweickart

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The term "deflection dilemma" originated in articles in the early 1990s by Carl Sagan, Alan Harris, Steve Ostro and others to describe the reciprocity inherent in the capability of humankind to deflect asteroids away from collisions with the Earth. I.e., if one can deflect an incoming asteroid away from a collision with Earth, one can also deflect a passing asteroid toward a collision, presumably a collision with a specific Earth target. While the author considers this historic dilemma to be virtually non-existent there exists a "real" and significant deflection dilemma that cannot be avoided if the Earth is ever to be protected from asteroid impact. The dilemma arises in the Hobson's choice between doing nothing, thereby suffering the consequences of an impact, or pro-actively deflecting an asteroid which will, in the process of "protecting the Earth", necessarily place otherwise non-threatened people and property at risk. As the deflection is initiated the change of impact point (IP) from the original "act of God" IP becomes an "act of humankind" IP-path as the instantaneous IP moves across the surface of the Earth to a point where the asteroid just misses the Earth (the "lift-off point"). All points along this IP-path are placed in jeopardy by the possibility of system failure during the deflection operation. Given that the populations and property put in jeopardy will, in the general case, extend across international boundaries the planning and execution of such a deflection mission will necessitate international coordination and perhaps control. Grappling with these daunting issues by an appropriate international body should be undertaken immediately since the development of rational policies will be extremely difficult after an impact is announced and an IP specified.

  43. The precautionary principle as the law of planetary protection

    Evan R. Seamone

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This paper identifies the precautionary principle as the preeminent law of planetary protection. This principle requires governments to take action to prevent harm even when it is uncertain if, when, or where the harm will occur. The consequence of the precautionary principle is that agencies responsible for preventing harm must view the applicable law as one that requires adoption of the most effective measures. This view of effectiveness as law requires governments to implement specific frameworks for making decisions to deal with impending threats, which differ substantially from the standard approach to harm. The precautionary principle directs intergovernmental bodies to adopt a worst case orientation and requires planners to develop self-reinforcing standards by scheduling continuing simulations and updates to their technical guidelines. The principle also shields agencies from liability with Good Samaritan immunity when they attempt to rescue others. Finally, the principle mandates that governments coordinate the roles of all the different agencies that could foreseeably become involved in planetary protection in advance of any actual threat. Applying these rules to the Defined Threat (DEFT) scenarios results in a planetary protection plan that does not differentiate responses by time of impact or the category of the object (i.e., comet or asteroid). Instead, the precautionary principle dictates that planners develop interventions based on the most salient aspects of the asteroid and comet threats combined. The principle encourages efforts to deflect or destroy asteroids by immunizing failed attempts and accidents as long as agencies test defensive measures and employ them responsibly. The development of an Initial National Response Plan by the Department of Homeland Security as well as two lessons from the experience of governments in combating infectious disease offer further guidance.

  44. Deflecting a near-term threat - Mission design for the all-out nuclear option

    Patrick L. Smith, Mark J. Barrera, Eric T. Campbell, Karin A. Feldman, Glenn E. Peterson and G. N. Smit

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    In theory, exploding a nuclear bomb close to an asteroid will alter its trajectory. Material on the asteroids surface vaporized by radiation from the blast will be ejected, imparting a slight thrust. This paper looks at the practical aspects of mounting a nuclear deflection mission, summarizing in-depth analyses of intercept trajectories and interceptor designs as well as operational considerations and cost. The key finding is that only relatively small objects (about 200 m) can be reliably deflected with todays space technology, and even then several years of warning time is needed to allow enough time to build and launch nuclear interceptors. Several topics for future research are suggested.

  45. Earth-Moon defense management

    William L. Smith

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    In recent years, prudent, ground-based low cost steps, such as Spaceguard, have been taken to attempt to size the population of potential global threat for NEAs/NEOs/ECOs, which could lead to a development of an Earth-Moon Defense System. The ground-based effort is making strides in identifying NEAs and acquiring a more knowledgeable population database of what the flux is and therefore the potential associated threat (for large sizes). It is not just detection. It is mitigation. The need for a space based system of search, acquisition, and appropriate mitigation targeting can be space, Earth, or lunar based with a rich tool box set of mitigation techniques (which currently need to be explored). An Earth-Moon Defense Management System (E-MDMS) needs many of the same organizational characteristics and functions of military defense approach where the emphasis is clearly on the Engagement level. The Engagement Level approach includes four hierarchical levels: Strategic, Operational Tactical, and Engagement. Planning and execution of mitigation needs architecture context, surveillance and countermeasures. Operations tasks include observing, engagement, mitigation, and post mitigation follow-up. This paper will explore some prior proposals; propose some frameworks for planning, policy and operations; explore some organization options and propose an option; and propose some preliminary steps that need to be taken to assure viable mitigation techniques. E-MDMS permits a parallel approach that without massive international partnership investments and doing the initial steps to put into place a defense system to protect our home planet and its satellite will gain preparedness in a phased way, providing for scientific knowledge increase and experimental testing with various organizational sets to an optimum family of options and integrated operational mitigation modes which best serve our planets population general good.

  46. Planetary body maneuvering - Threat mitigation and inbound trajectories

    Geoffrey Statham, Randall Hopkins, Robert B. Adams, Jack Chapman, Joseph Bonometti and Slade White

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This paper is part of a sequence of three documenting the work completed at the NASA Marshall Space Flight Center in the area of the defense of Earth from incoming Near Earth Objects (NEO). The work found herein can be found fully documented in Adams et al. (2004). The topic of threat mitigation is covered in this particular paper.

  47. The SIMONE mission - Close reconnaisance of the diverse NEO population as a precursor to impact mitigation

    Roger Walker, Nigel Wells, Simon Green and Andrew Ball

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The paper summarizes a novel mission concept called SIMONE (Smallsat Intercept Missions to Objects Near Earth), whereby a fleet of microsatellites may be deployed to individually rendezvous with a number of Near Earth Objects (NEOs), at very low cost. The mission enables, for the first time, the diverse properties of a range of spectral and physical types of NEOs to be determined. Physical and compositional properties of NEOs are so varied between types that no single impact mitigation method will be applicable to all Earth-threatening objects. Instead, mitigation methods must be tailored to each type based on detailed data which can only be gathered by space missions conducting close reconnaissance of representative bodies of each type. The cost of mounting missions to rendezvous and survey multiple objects in the population would be very high using conventional spacecraft technology. However, in the paper we show how the latest technological advancements and innovations in propulsion and power systems, and instrument miniaturization, enable microsatellites to perform this essential task at a fraction of the normal cost. The five identical 120-kg spacecraft have been designed for low-cost piggyback launch on the Ariane-5 into GTO, from where each uses a high specific impulse gridded-ion engine to escape Earth gravity and ultimately to rendezvous with a different NEO target. The paper describes the mission objectives, measurement requirements and baseline payload instruments, the overall mission design including NEO target selection and optimized rendezvous trajectories, and the spacecraft design with its advanced technologies. The SIMONE mission as a means for close reconnaissance of the NEO population is now realizable at low cost and promises to provide a very significant precursor contribution to planning and implementing an effective NEO impact mitigation capability that is ready to counter any impactor.

  48. The B612 mission design

    Bobby G. Williams, D. D. Durda and D. J. Scheeres

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    This paper describes a mission proposed by the B612 Foundation to demonstrate the feasibility of docking a spacecraft with a small asteroid and applying a controlled, steady thrust to it in order to measurably alter the asteroids orbit and rotation pole by the year 2015. The target would be a rocky 200-m asteroid with a mass of about 10 billion kilograms that does not pose any impact threat to the Earth. The technology goal of the mission is to demonstrate a measurable change in the orbital velocity of the asteroid, say 0.2 cm/s, minimum. In addition, in situ science would also be performed to determine materials and structural properties of the surface. Secondary goals could include technology demonstrations for mining the natural resources found on the asteroid. The spacecraft would have liftoff mass of less than 20 metric tons, including fuel for the trip to the asteroid and fuel to push the asteroid once it has arrived, and it would be launched on a single heavy lift rocket such as the Proton, Ariane 5 or Titan 4. The spacecraft borrows heavily from NASAs Jupiter Icy Moons Orbiter (JIMO) concept vehicle in that it would rely on nuclear reactor power and ion-propulsion systems. A major departure, however, would be the use of a promising new propulsion engine known as the VASIMR (Variable Specific Impulse Magnetoplasma Rocket) which uses radio waves to excite fuel into a plasma and magnetic fields to direct the expanding stream of ions out of the engine at specific impulses between 10,000 and 30,000 s. With this configuration, the spacecraft would be able to apply a force of 2.5 Newtons to the asteroid over a period of about three months. The mission includes plans to reorient the spin axis of the asteroid to a preferred alignment with respect to its orbital velocity vector such that the spacecraft thrust is most effective in changing the orbital velocity. The continuous, controlled thrust will produce a change of about 0.2 cm/s in the asteroid orbital velocity. This change in velocity can easily be verified by processing Earth-based, radio metric tracking (range and/or Doppler) from NASAs Deep Space Network.

  49. The leverage of bimodal nuclear thermal rockets in planetary protection

    Alan J. Willoughby and Stanley K. Borowski

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    The methods for fragmenting and deflecting asteroids are broadly surveyed. Four criteria show even the best methods are too risky. The versatile bimodal nuclear thermal rocket (BNTR) could swiftly transport humans and deliver large payloads to potential threat asteroids. BNTR would greatly improve the success rate of the best collision mitigation methods. The Athos catastrophe is only marginally avoided without BNTR. With BNTR, we would be safe. Avoiding the global Aramis catastrophe is a slim chance without BNTR. With BNTR, protection is probable.

  50. Did Bielas Comet cause the Chicago and Midwest fires?

    Robert Wood

    2004 Planetary Defense Conference: Protecting Earth from Asteroids; Orange County, CA; Feb. 23-26, 2004

    On October 8, 1871, a fire started that burned much of Chicago, killing 300, and destroying $200,000,000 worth of property. Most people are unaware that within a few minutes, major fires started in upstate Wisconsin and Michigan, killing more than 2000 people in the farming country. Biela's Comet, with a solar orbital period of 6 years 9 months, had been disturbed by Jupiter on a previous passage and broke into two large comets. It has been hypothesized that one of them struck Earth and broke into several smaller pieces. These pieces, consisting of frozen comet gases would have likely included combustibles like methane CH4 and acetylene C2H2 that melted, vaporized and explosively ignited, causing impressive incendiary results upstate, consistent with surviving witness reports. A two dimensional evaluation by the author of the orbit of Bielas Comets two parts shows that it is reasonable to hypothesize that Jupiter may have disturbed either the primary or the secondary comet sufficiently to have speeded up its arrival at Earth by about a year earlier than expected. In the plane of the ecliptic, it has been determined that one post-Jupiter encounter comet solution is period of 3229 days and eccentricity of 0.801, thus resulting in Earth orbit arrival at the right time. It is suspected that a precision 3D calculation will show that the orbit parameters are within expected comet uncertainties. The credibility of this scenario has been evaluated to respond to skeptical concerns about: the lack of advance warning; feasibility of orbits; large fire routinely-reported phenomena; inaccurate reporting of observations; and the presence of some fires already burning upstate. This example suggests that witness testimony, even when inconsistent with the theories of the day or the favored media explanations, may be reevaluated later and support new theoretical interpretations, such as the idea that Earth has recently been struck by a comet, causing the widespread and ferocious destruction of October 8, 1871.