THE IMPACT IMPERATIVE: PROTECTING THE EARTH FROM HAZARDOUS ASTEROIDS, METEOROIDS, AND COMETS

1. THE IMPACT IMPERATIVE: PROTECTING THE EARTH FROM HAZARDOUS ASTEROIDS, METEOROIDS, AND COMETS Dr. Jonathan W. Campbell COL, USAF (ret) NASA Administrator’s Fellow NASA/MSFC 2008

3. The Comet Approaching Jupiter Note The Apparent Linear Alignment Of Multiple Objects

4. Linear Impact Sites on Jupiter

5. Comet Shoemaker-Levy 9 • First discovered March 24, 1993 • By May it was determined that it would impact Jupiter • Impacts occurred from July 16-22 1994

6. EARTH DEFENSE • We Can Do Something - Technology Now Coming Available To Enable Orbit Shaping In The Next Few Decades • We Need To Start Moving NOW In The Direction Of Building An Infrastructure For NEO Orbit Modification Both On The Ground And In Space • Will Require Both Robust Detection And Tracking And Mitigation Capabilities.

7. PHO Population • Estimated 200,000 100 m class objects in orbits crossing the Earth’s • Estimated 2000 1-10 km class objects • > 10 km TBD • numbers do not include comets • Many asteroids not yet detected and orbits not yet known • Long Period Comets Greatest Danger

8. The Asteroid Impact Site On The Yucatan Peninsula Ironically Is Only Visible Using Space-based Sensors The Earth Has Been Struck Many Times In The Past. This is a Crater Found in Australia.

9. Tunguska in Siberia, Russia1908 • About 100 m diameter • Asteroid exploded above ground • Energy release on the order of 10 MT • Destruction of nearly 500,000 acres of trees

10. Kinetic energy (MT) vs diameter of Earth-crossing asteroids (NEO's) with velocity 10 to 30km/s and density r = 1000-9000 kg/m3. Below the chart, total number of NEO's and probability of Earth impact are shown. A 100 m class object impacting the Earth releases on the order of 10 MT of energy.

11. Time Geological Period Mass Extinctions 438 million years ago Ordovician/Silurian boundary 360 million years ago Devonian/Carboniferous boundary 245 million years ago Permian/Triassic boundary 208 million years ago Triassic/Jurassic boundary 65 million years ago Cretaceous/Tertiary boundary (K/T) • 5 major mass extinctions • High probability impact event associated cause in 1st and last (dinosaurs) • Impact event strongly suspected in other three • Effects: volcanism, earthquakes, changes in ocean oxygen, sea level, and climate, mass extinction • 95% all species in 1st, 70% all species in last

12. IMPACT DAMAGE MECHANISMS SHORT TERM * Crater formation * Sun-obscuring dust and clouds (Similar to nuclear winter) * Blast overpressure (Destruction of manmade structures) * Thermal burn from ablation plume (40-m-dia. NEO entering at 30 km/s and 10 km altitude will ignite pine forest [Hills 1992]) * Earthquakes (A 30km/s, 80-m-dia. iron NEO will cause a Richter 7 quake [Hills 1992]) * Ram-up of deep water tsunami (Tsunami from a 30km/s, 80-m-dia. Iron NEO will cause a 40-m-high tidal wave onshore) • LONG TERM • Block out Sun’s rays • global cooling • Change precipitation patterns • Alter climate patterns • Massive loss of plant life due to rapidly changing environment • Disruption of natural order • Potential for mass extinction

13. Compares the magnitudes of asteroids • Provides communication for scientists and public • Scale ranges from 0 to 10 • Ranked based on impact probability, size, energy, and speed • Tunguska impact would have been an 8 • 2002 NT7 is a 1

14. Near-Earth Asteroids (NEO’s) • Some are Potentially Hazardous (PHA) • Have Earth-Crossing Orbits • Hypervelocities mean small size impacts cause great disasters • Over 200,000 Estimated 100 m class objects Asteroid 1950 DA Sun Earth Positions on April 5, 2002

15. Near-Miss Asteroids • Pass within 1 AU (1.5x108 km) • Over 1700 recorded • Normally not a factor unless perturbed • Results of summer study indicate that a smaller object impacting a larger rock may force it from its stable, “safe” orbit into an impact orbit with the Earth

16. APOPHIS The Kitt Peak National Observatory was where (99942) Apophis also known as 2004 MN4 was discovered June 19, 2004. Apophis is going to pass Earth with a potential impact in 2029 and 2036. It is projected that Apophis will approach a “keyhole” on April 13, 2029. A probe will be sent out to rendezvous with the asteroid in 2019. A collision with the Earth is presently projected as highly unlikely. However, an unlikely collision with Earth would be estimated at 880 Mt of TNT.

17. CLOSE APPROACH EXAMPLE I: 2002 EM7 March 8, 2002 • Was not noticed until 4 days outbound - illustrates current inadequate level of Earth’s early warning capability • No response time for intervention – an impact would have caught the Earth entirely by surprise without time for evacuation or other casualty/damage minimization • Only 1.2 times the distance to the moon (450,000 km)--a close call! • Between 50-100 meters across • Among the 10 closest known asteroids • Has potential to collide with Earth within the next century Meteor Crater in Arizona

18. CLOSE APPROACH EXAMPLE II: 2002 MN June 15, 2002 • Detected 2 days outbound from Earth • Point of closest approach was 0.3 lunar distances away (within the Moon’s orbit) • Diameter was between 50-120 meters • Nothing this close since December 1994 Crater found in Australia

19. CLOSE APPROACH Example III • Asteroid 2002 NT7 • Predicted closest approach to the Earth Feb. 1, 2019 • ~1.2 km in diameter (global disaster) • Possible impact risk

20. Recent Close Approaches

21. Closest Approach • asteroid 2004 FH • Discovered March 18, 2004 • Closest approach on March 18, 2004 • about 30 meters in diameter • passed approximately 43,000 kilometers above the Earth's surface (nearly ten times closer than the Moon

22. Kuiper Belt Objects • The Kuiper Belt is believed to be the source of comets with periods less than 200 years • There are a great number of undiscovered objects in our solar system • Over 70,000 objects with diameters over 100 km discovered so far • For reference, Pluto’s diameter is 2274 km • Sedna • Discovered November 2003 • Between 1180 and 1800 km diameter • Quaoar • Discovered June 2002 • 1250 km diameter • “Xena” 2003 UB313 • discovered January 2005 • 2400 km diameter

23. Asteroid Perturbing Factors • In Our Solar System There Are Billions Of Rocks With Sizes Ranging From Small To Large In “Safe” Orbits Around The Sun • ThereAre Several Physical Mechanisms That May Naturally Modify These Orbits To Become UnSafe. • Solar Wind • Radiation Pressure • Gravitational influence of large masses (i.e. planets, asteroids, comets, etc.) • Collisions with other asteroids • Yarkovsky Effect • Transfer of momentum due to uneven heating of asteroid surface • Thus, The NEO Population Is Dynamic!!! Bad Rocks Are Being Eaten And Created Continuously In Our Solar System.

24. Destabilizing Event Simulation • A small meteoroid may collide into large asteroid in a stable safe orbit • Causes orbit to become unstable • Simulation Sequence • House-size rock hits asteroid (¾- km diameter) • Transfers momentum • Alters orbit sufficiently to become potentially dangerous to Earth

25. Discovery of New NEO’s Despite years of looking, the number of newly discovered NEO’s continues to rise. The total number of known NEO’s is increasing steadily.

26. Potential Impacts…What Can We Do? • 1 in 250,000 chance in 2019 (~1.2 km) • 1 in 300 chance in 2880 (~1 km) • Alert The Science Community And The Decision Makers. Define The Threat. Increase Awareness. • Advocate This Area As A Worldwide Priority For International Space Funding • Immediately Begin An International Program To Build An Infrastructure Of Sensors, Lasers, And Other Mitigative Measures To Accomplish Orbit Shaping • Set Objectives: Conduct Orbit Shaping Tests - Move A 1 km Class NEO To A Safe Orbit In Less Than 10 Years

27. LINEAR Spacewatch JSGA Asiago in Italy ASTEROID SEARCH PROGRAMS Spacewatch

28. Current Asteroid Detection Hungarian Asteroid J95Y25R • Sky scanned nightly • Compare for changes • Track and check for danger • Illustrates the difficulty in searching the entire sky to find potentially dangerous asteroids

29. Asteroid Detection Requirements • Important Parameters: • Size • Brightness • Shape and internal structure • Surface geology • Chemical composition • Spin state • Pole Orientation • Knowing these parameter crucial to calculating orbits and then planning protective measures if necessary

30. Advanced Detection • National Optical Astronomy Observatories • 6.5-meter optical Large-Aperture Synoptic Survey (LSST) • Telescope • Goal: discover 90% of all 300-meter or bigger asteroids within 10 years • Weekly scanning • Detect lower light levels • $170 million • Multiple uses • Advanced technologies are coming to improve Earth’s detection/early warning capabilities LSST

31. INTERVENTION TECHNOLOGIES • Long time or short time • An interceptor may use a number of alternate strategies as well to include kinetic energy transfer, nuclear ablation (internal and/or external), electric propulsion, kinetic energy, laser ablation, gravitation attraction, and tugboat just to name a few . • Interceptor approaches require significant early warning • tumbling PHO’s offer complications

32. Constellation Architecture Enables Kinetic and Nuclear Intercept Options Ares I 12 Ares V 12

33. * Recent Missions have found water in deep craters at the lunar poles * Technology can be developed to reclaim this water for use in permanent facilities and to make rocket fuel

34. Laser Technology Has Turned The Corner And We Will See Its Increasing Use In The Next Millenium ABL

35. SBL Laser And Other Systems Are Being Planned/Developed To Be Deployed From The Ground And From Space To Defeat Missiles. Peacetime Missions Could Include Orbital Debris Removal And Comet, Asteroid, Meteoroid Deflection.

36. EARTH Defense The Next Stepping Stone For Laser Technology in Space May Be As Part Of An Infrastructure, One Element In A System of Systems, To Modify The Orbits of Asteroids, Meteoroids, and Comets

37. The Lack of an Atmosphere Makes the Moon an Excellent Location for Astronomical Observatories And/or Large Scale Laser Systems

38. Earth Defense Laser Scenario • Beam Hits Surface, Ablation Occurs • Sputters Material Off – Action/Reaction Occurs ∆V Plasma Object Beyond Martian Orbit LASER PULSES RADAR/LADARDETECT/TRACK SYSTEM MOON • Rocket Effect Causes Small Change In Orbit • Many Such Interactions Over A Sufficient Period Of Time Propel Object Clear Of Earth

39. Earth/LEO Option An Array of Multiple Laser Beam Directors Operating For ~1 Month Was Sufficient to Deflect a One Kilometer Iron Asteroid in this Orbital Mechanics Simulation.

40. Libration Point Option An Array of Multiple Laser Beam Directors Operating For ~1 Month Was Sufficient to Deflect a One Kilometer Iron Asteroid in this Orbital Mechanics Simulation. Dr. Jonathan W. Campbell

41. Lunar Option An Array of Multiple Laser Beam Directors Operating For ~1 Month Was Sufficient to Deflect a One Kilometer Iron Asteroid in this Orbital Mechanics Simulation.

42.  Lateral displacement and final velocity of asteroid from original orbit per 2-D orbital mechanics simulation using expected coupling coefficients and state of the art laser intensities. Time (in days) Displacement R Final lateral Velocity vf 1.0 d 4.9 km 0.11 m/s 10.0 485.0 km 1.08 m/s 36.0 1.00 RE 4.07 km/s 38.8 1.10 RE 4.19 km/s 44.0 1.45 RE 4.75 km/s 46.3 1.56 RE 5.00 km/s The threshold for success in this simulation is derived to be deflecting the asteroid just outside the atmosphere. Due to the hypervelocity approach, the Earth’s gravitational influence on the object is small. Hence, working on the object with the laser for 38.8 days is sufficient to guarantee the object does not impact the Earth.

43. Example Missions to Asteroids or Comets

44. DEEP IMPACT MISSION Comet Impact:July 4, 2005Impact Velocity:23,000 mphSpacecraft Size:Flyby spacecraft - nearly as large as a Volkswagen Beetle automobile.Impactor spacecraft - about the same dimensions as a typical living room coffee table.

45. This image shows the initial ejecta that resulted when NASA's Deep Impact probe collided with comet Tempel 1 at 10:52 p.m. Pacific time, July 3 (1:52 a.m. Eastern time, July 4) . It was taken by the spacecraft's medium-resolution camera 16 seconds after impact.

46. SUMMARY AND CONCLUSIONS I • Recent computational fluid dynamics (CFD) simulations have shown that relatively small objects (asteroids, meteoroids, comets) impacting the Earth at hypervelocities may cause large scale disasters. • Disasters similar to these have occurred multiple times in the past. • Orbiting the Sun, a substantive population of potential Earth impact objects presently exist in space. Many have not yet been found or their orbits calculated. • Detection capabilities are improving however we are still years away from finding and cataloging all potential Earth impactors. • Dynamic mechanisms in the asteroid belt, the Ort Cloud, and other locations in the solar system are adding to the population. For example, a meteoroids impacting an asteroid may force it into a potential impact orbit with the Earth. • Given sufficient early warning, technology should become available in the near future enabling orbit shaping of potential Earth impact objects allowing the avoidance of impact disasters. Moving the objects to convenient orbits around the Sun enables mining and in situ materials utilization. • Given the length of time necessary to develop capabilities in space, it is imperative that we begin immediately to build a multi-layered defense infrastructure to protect the Earth against impact.

47. SUMMARY AND CONCLUSIONS II • Clearly this plan should be a series of overlapping steps starting with a comprehensive study, road mapping, planning and demonstration phase that should be begun immediately. • Also, Infrastructure building should start on the Earth with the acceleration of existing detection and tracking programs and the construction and/or dedication of an array of sensors to push early warning to years in advance. • Next, sensors and laser facilities must go into orbit constantly expanding capability and early warning time. • The moon is the next step with multiple stations for accomplishing the Earth defense role as well as supporting other objectives such as space science. • The libration points offer advantages as well. • An interceptor program must be considered as well. Taking the laser to the asteroid may offer some advantages. In addition, an interceptor could have a repertoire of approaches in addition to the laser such as nuclear ablation devices, nuclear electric thrusters, etc. • This challenge to our civilization’s continued existence can only be addressed by doing everything we know how to do. Our protective shield must be 100% effective. • This is the IMPACT IMPERATIVE.