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Permanent Monitoring Panel -
Defence Against Cosmic Objects


Members of the Panel:

Chairman:
Walter F. Huebner (SwRI, USA)

Members:
Alberto Cellino (INAF - Observatory Torino, Italy); Andres Galvez (ESA, France); Alan W. Harris (DLR, Germany); Hajime Yano (ISAS, Japan); Lindley Johnson (NASA, USA); Donald K. Yeomans (JPL, USA); Anatoly V. Zaitsev (Planetary Defense Center, Russia)

Associate Members:
William F. Boetke (USA); Clark R. Chapman (USA); Andrew F. Cheng (USA); Marco Delbó (Italy); Mario Di Martino (Italy); Raymond Goldstein (USA); Jack Hills (USA); Thomas G. Müller (Germany/Spain); Paolo Paolicchi (Italy); Catherine Plesko (USA); John Remo (USA); Ali Safaeinili (USA); Russell L. Schweickart (USA); Jondale Solem (USA); Roberto Somma (Italy); Edward F. Tedesco (USA); James Walker (USA); John Zinn (USA)


Summary of the Emergency

It has been recognized that the continuing impacts of cosmic objects (asteroids and comet nuclei) on Earth present a very low probability threat but with devastating consequences. Objects larger than about 140 meters in effective diameter will cause local, regional, or global catastrophes if they collide with Earth. Objects that come close to the Earth's orbit are also known as Near-Earth Objects (NEOs) or, if they pass the Earth within 0.05 astronomical units (1 AU = 150,000,000 km), as Potentially Hazardous Objects (PHOs). For the first time in man's history we have the potential to prevent such collision with Earth by deflecting or destroying threatening PHOs. Five main objectives are considered in this program:

  1. Find the objects (there are an estimated 1000 objects larger than 1 km and about 25,000 objects larger than about 140 m in effective diameter).
  2. Follow the objects in their orbits, determine their orbital parameters, and catalog them
  3. Determine their physical properties, such as their masses, material strengths, surface properties, and internal structures.
  4. Based on these properties, develop Earth collision mitigation technologies.
  5. Study, promote, and advise on scientific, technological, and related political and public relations issues.

The first step to survey and catalogue the approximately 1000 near-Earth asteroids (NEAs) larger than about 1 km and find 90% of them by 2008 has been accomplished. The next step is to survey and catalogue 90% of NEAs larger than 140 m by 2028. Since the number of NEAs of any size increases with decreasing diameter, many “city killers” with diameter larger than 100 m are not included in these surveys. The Tunguska object that leveled 2000 square kilometers of forest land on 30 June1908 is thought to have been 50 m and possibly only about 25 m in effective diameter. While objectives (1) and (2) are actively pursued, objectives (3) and (4) lag behind. The permanent monitoring panel will focus its attention on those objectives where progress is most constructive for reaching the final goal: Countermeasures to avoid collisions with Earth. One of the first intermediate goals is to acquire geological and geophysical data of NEOs in general. As the most dangerous known example of natural disasters, the PHO impact hazard calls for the most careful consideration and planning by the international community.


Priorities in dealing with the Emergency

The priorities of the NEO program are as follows:

  1. Find NEOs and follow up with observations to determine and catalog their orbits.
  2. Physically characterize them. This includes remote sensing to determine the effective size of the objects and their albedo independently.
  3. Determine their geophysical and geological properties such as mass and mass distribution, moments of inertia, material strengths, internal structure, bulk composition, and the relationship of their global properties to their surface properties.
  4. Develop techniques for Earth-collision avoidance based on geological and geophysical properties.
  5. Investigate and support geopolitical cooperation and international laws to support and develop countermeasures for collision avoidance.

Comments about the priorities:

  1. Significant progress has been made in discovering NEOs with effective diameters larger than 1 km. Many objects have been found that are in the range of 140 m to 1 km in effective diameter. However, this effort must be expanded. Telescopes are needed that can find the smaller but more numerous and much fainter objects.
  2. The rate of discovery of NEOs is so large that the rate of physical characterization by remote sensing cannot keep pace. More dedicated telescope time is needed to determine the size and albedo of NEOs as separate quantities, by means of thermal radiometry and polarimetric observations.
  3. Several fully instrumented missions are needed to globally measure geophysical properties including material strength macroporosity, and internal structure of NEOs.
  4. Collision avoidance must be worked out depending on the geological and geophysical properties of NEOs. This must take into account alternative procedures to select the most effective means for collision avoidance.

Workshop and Meeting Reports

  • Hazards from Cosmic Objects: International Seminars on Nuclear War and Planetary Emergencies, 23rd Session, p. 370-371, 1999.
  • Physical and Chemical Properties of Comet Nuclei: International Seminars on Nuclear War and Planetary Emergencies, 23rd Session, p. 169-179, 1999
  • The Physical Properties of Asteroids and the Effects of Shock Waves: International Seminars on Nuclear War and Planetary Emergencies, 23rd Session, p.180-191, 1999.
  • Asteroids as Rubble Piles: International Seminars on Nuclear War and Planetary Emergencies, 23rd Session, p.192-202, 1999
  • NEOs: Physical Properties: International Seminars on Nuclear War and Planetary Emergencies, 25th Session, p. 309-340 (2001).
  • Summary of the Workshop on Geophysical and Geological Properties of NEOs: "Know Your Enemy,": International Seminars on Nuclear War and Planetary Emergencies, 26th Session, p. 419-432 (2002).
  • Recent Perspectives on the Hazard of an Asteroid Impact: International Seminars on Nuclear War and Planetary Emergencies, 32nd Session, p. 155-161 (2005).
  • Recent Close Approaches of Asteroids to the Earth: International Seminars on Nuclear War and Planetary Emergencies, 32nd Session, p. 162-176 (2005).
  • Asteroid Deflection: Hopes and Fears: International Seminars on Nuclear War and Planetary Emergencies, 32nd Session, p. 177-184 (2005).
  • The Near-Earth Object Impact Hazard: Space Mission Priorities for Risk Assessment and Reduction: International Seminars on Nuclear War and Planetary Emergencies, 32nd Session, p. 185 (2005).
  • Hayabusa and its Follow-up Plans by JAXA: International Seminars on Nuclear War and Planetary Emergencies, 32nd Session, p. 186-212 (2005).
  • Cosmic Objects Permanent Monitoring Panel: International Seminars on Nuclear War and Planetary Emergencies, 32nd Session, p. 318-322 (2005).
  • Overview of Recent Research Activities on Cosmic Objects: International Seminars on Nuclear War and Planetary Emergencies, 36th Session, p. 321-324 (2007).
  • Meteor Impact Hazards and Some Meteor Phenomena: International Seminars on Nuclear War and Planetary Emergencies, 36th Session, p. 325-340 (2007).
  • Scientific Results from the Deep Impact Mission: International Seminars on Nuclear War and Planetary Emergencies, 36th Session, p. 341-350 (2007).
  • Countermeasures to Avoid Asteroid and Comet Nucleus Impacts on Earth: A Summary of Progress: International Seminars on Nuclear War and Planetary Emergencies, 43rd Session, p. 381-395 (2011).
  • Momentum Enhancement from Kinetic Impactors and Conventional Explosives: International Seminars on Nuclear War and Planetary Emergencies, 43rd Session, p. 397-412 (2011).
  • Looking before we Leap: An Ongoing, Quantitative Investigation of Asteroid and Comet Impact Hazard Mitigation: International Seminars on Nuclear War and Planetary Emergencies, 43rd Session, p. 413-428 (2011).
  • Defense Against Asteroid-Comet Nucleus Dangers – A Real Task of Today: International Seminars on Nuclear War and Planetary Emergencies, 43rd Session, p. 429-441 (2011).
  • PMP Report for Cosmic Objects: International Seminars on Nuclear War and Planetary Emergencies, 43rd Session, p. 583-588 (2011).

Some Publications Especially Relevant for our Goals

  • The Asteroid Tugboat, R. L. Schweickart, E. T. Lu, P. Hut, C. R. Chapman, Scientific American 289, 54 – 61 (2003).
  • Mitigation of Hazardous Comets and Asteroids, M. J. S. Belton, T. H. Morgan, N. Samarasinha, D. K. Yeomans, Cambridge University Press, Cambridge, UK, pp. 414 (2004).
  • Gravitational Tractor for Towing Asteroids, E. T. Lu, S. G. Love, Nature 438, 177-178 (2005).
  • A Comprehensive Program for Countermeasures against Potentially Hazardous Objects (PHOs), W. F. Huebner et al., Solar Syst. Res. 43, 348 -356 (2009).
  • Protecting the Earth against Collisions with Asteroids and Comet Nuclei, A. Finkelstein, W. Huebner, V. Shor (Eds.). Saint Petersburg “Nauka” (2010).

Special Recommendations

A database of geophysical and related properties has been established. The database consists of four parts: An observational database, a material properties database, a database for missions and instrument development, and a database for dissemination and public outreach. The database acts like a vector, defining direction and magnitude of efforts needed to accomplish the goals of geological and geophysical data on NEOs. It also serves as a metric to measure the progress and success of scientific research and technology developments to avert (destroy or divert) cosmic objects from colliding with Earth. The database can be accessed at: http://neodata.space.swri.edu.