Clark R. Chapman

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NEO Mitigation and Coordination with the Disaster
Management Community

• Clark R. Chapman
• Rusty Schweickart
• B612 Foundation

1st IAA Planetary Defense Conference Granada,
Spain 1530 29 April 2009
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From Telescopic Discovery to Effective Emergency
Management

• Currently, if a threatening NEO is discovered,
  there is inadequate infrastructure to evaluate
  the threat and communicate it effectively to any
  relevant national or international emergency
  management agency.
• Pieces are in place (e.g. JPL Sentry, NEODys, IAU
  MPC, UK NEO Information Centre, etc.) but they
  have narrowly defined roles
• organizing NEO observers
• calculating orbits and predicting impacts
• maintaining NEO news websites
• NASA has a formal structure for observers to
  notify Lindley Johnson, Johnson to notify NASA,
  and NASA to notify US Executive Branch.
• But it is doubtful that FEMA/DHS in U.S. or any
  other national/international emergency management
  agency would know what to do in response to
  notification.
• We will show that the need to establish such
  linkages between astronomers and those who would
  respond to a threat is more urgent than had been
  thought.

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Understand the Power-LawSmall Ones Happen Much
More Often

• We think about the big ones, which might threaten
  civilizationand we should.
• But the most likely kind of event that
  politicians, officials, and the public will have
  to deal with are the smallest predicted impacts
  that might be dangerous (Spacelabs re-entry in
  1979 was an extreme example).
• Past PDCs have studied scenarios focused on
  Apophis and other templates for probable
  impacts, which are far larger NEAs and more
  unlikely than the overwhelmingly most likely
  event to confront officials.
• For every Apophis, there are more than 50
  Tunguskas, and 1000 impacts by 15 m NEOs that
  might compel officials to act.

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What is the Smallest NEO that is Dangerous?
Model of 30 m NEA 1998 KY26 (radar)
This will be a vital issue for decision-makers

• Metallic objects are not impeded much by the
  atmosphere, whatever their size they create most
  craters lt1 km diam. but are only 3 of NEOs.
• The 2003 SDT report considered 50 m diameter to
  be the smallest truly dangerous
  non-metallic NEO.
• Some analyses (e.g. Bosloughs study of Tunguska)
  suggest that the threshold for danger is near 30
  40 m.
• Should we then be unconcerned about deflection/
  evacuation for a 25 m body? They impact 10
  times as often as 50 m impactors.
• A nominal 25 m body may actually be 50 m in
  diameter (because of bimodal albedo
  distribution).
• What will public officials do about a predicted
  impact by a 15 m NEO? Be safe not sorry and
  evacuate! (They impact 30 times as often as 50
  m impactors, 20 chance this decade.)

? LSST 15 m NEO?
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Short-Term Warning the New Reality

• There is better than 1-chance-in-3 that the
  Spaceguard Survey will provide short-term warning
  (few weeks) for any potentially dangerous impact
  during the next decade!
• Previously it was said that the Survey would
  provide decades of warning for threatening NEOs
  found, but that the Survey would miss the vast
  majority of Tunguskas and we would first learn of
  such an impact by the flash and explosion.
• The recent case of NEA 2008 TC3 teaches us that
  we have a much better early-warning system than
  we thought.
• Since astronomers can provide early warning,
  communications channels with emergency managers
  must be established.

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2008 TC3 Some Background

• NEA discovered 7 Oct. 2008, predicted to impact
  Sudan 20 hours later.
• Before impact, other telescopes observed TC3s
  physical properties.
• Nearly 300 pieces of rare ureilite meteorites
  recovered.
• TC3 was 4 meters diameter, roughly an annual
  impact on Earth.
• Spaceguard Survey was expected to find only
  1-in-1 million TC3-sized NEOs.
• Was it a miracle that we found beforehand what
  was plausibly the largest NEA to impact Earth in
  2008?
• NO! Astronomers overlooked Spaceguards
  short-term warning capability.

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Short-Term Warning Capabilities of NEO Surveys

• Current Spaceguard Survey will find 35 of NEAs
  gt30 m diameter on final plunge could be
  improved to 50 or better.
• It is 100 times more likely that the Spaceguard
  Survey will find a gt30 m impactor on its final
  plunge than that it will find one long in advance
  that will eventually hit.
• Next generation survey (LSST, Pan-STARRS) will
  find 35 of impactors gt2 m diameter for gt30 m
  NEAs, there are similar chances for
• Short-term warning
• Long-term warning
• No warning at all
• Short-term warning was not studied for current
  Survey SDT (2003) did study short-term warning
  for next generation surveys.

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Public Officials Must Make Decisions Much More
Often than NEOs will Hit
Low Probability Impact What is the Threshold
for Action? 20? 5?

• Post-disaster rescue and recovery if NEO strikes
  undetected.
• Warnings for evacuation, disaster-preparedness if
  there is a short-term warning.
• Preparing for a low-probability chance that a
  virtual impactor proves to be about to strike.
• Preparing for Apophis-like scenarios decisions
  to launch a pre-deflection mission (e.g.
  transponder with Gravity Tractor capability) must
  be made long before keyhole passage, perhaps very
  long before the threatened impact.
• Evaluation of marginal impact scenarios
• Predicted impact by NEO 15 m diameter just
  watch the fireworks or be prudent?
• Immature or spurious impact warnings

See next chart
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Example Virtual Impactor Search
Palmer Divide Observatory

• At any time, there are numerous low-probability
  impacts listed on the JPL Sentry Risk website.
• In some cases, the NEA may not be observable
  again until its possible final plunge.
• The approach would be to search telescopically
  for the virtual impactors that would strike the
  Earth during the weeks prior to impact.
• If the NEA is coming from the general direction
  of the Sun, radar would be required to search for
  the possibly incoming NEA (warning might be only
  a couple of days).
• If the chance for impact were high enough (how
  high?) then public officials (responsible for
  localities in the risk corridor) should give
  forethought to emergency management preparations.
  Note the risk corridor of possible impact
  points will be well known.
• If the NEA is on an impacting course, then the
  preparations must be implemented quickly.

Arecibo
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Relative Frequency of NEO Event-Types and
Required Actions

• Hyped or unreliable media news stories.
  Officials irritated but must do nothing. Annual
  ? more often?
• Impact predictions for future decades requiring
  analysis, but leading to no action. 20/decade ?
  several per year.
• Short-term impact warning for 15 m NEA.
  Immediate evacuation would be prudent.
  7/decade ? 15/decade.
• Prediction of an impact during next 50 years
  eventually requiring launching of a transponder
  mission (for NEAs gt 100 m). 1 chance ? 15
  chance.
• Short-term impact warning for gt40 m NEA.
  Immediate evacuation required (by ships or from
  ground-zero). 0.3/decade ? 1/decade.
• Detection of NEA gt100 m that would ultimately
  impact during next 50 years if deflection isnt
  attempted or successful. 0.01 ? 0.2.
• Detection of civilization-threatening NEO that
  will strike in next 50 years. 0.001 ? 0.0003
  chance.

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Mitigation What does it mean?

• Mitigation means lessening unfavorable
  consequences (in engineering, economics,
  environmental impacts, medical field, and
  especially in emergency management)
• In Planetary Defense, mitigation has been
  distorted to mean only deflection
• NASA 2007 report notes broad meaning of
  mitigation but explicitly restricts meaning to
  deflection (not even fragmentation)
• US Congress has ordered NASA to evaluate NEOs in
  order to provide warning and mitigation for the
  potential NEO hazard.
• Any sensible mitigation plan must include all
  plausible emergency management methods, including
  warning and evacuation.

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What is the Primary Mitigation Approach
Evacuation or Deflection?
Both!

• Evacuation
• Why it is Important
• By far the most likely case we will face
• Attributes
• Inexpensive and familiar apply usual all
  hazards emergency procedures
• Requires rapid, reliable communications between
  astronomers and officials, and famililarity with
  the issues by emergency managers.

• Deflection
• Why it is Important
• Only responsible way to prevent global or
  regional-scale disaster from happening.
• Attributes
• Deflection implementation is much less likely
  than the need to evacuate.
• Advance decisions must be made when need to
  deflect is still not known.
• Expensive! Especially if need uncertain.

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Need to Establish Infrastructure for Evaluation,
Warning, Coordination of Emergency Managers

• Optical and radar observatories need to develop
  rapid communications to respond to NEOs before
  impact.
• NASA needs to develop understandings within
  agencies (those it would warn) about nature of
  NEA impact warnings so that emergency responses
  will be appropriate and effective. (Analogous
  links should be established in other countries.)
• Internationally, ASE has recommended establishing
  under the U.N. an Information Gathering,
  Analysis, and Warning Network (IAWN) to
  coordinate the integrated end-to-end process from
  telescopic searching for threatening NEOs through
  coordination with national and international
  disaster management agencies.
• These needs exist today, but will become crucial
  as the surveys are upgraded during the next
  decade.

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433 Eros
Comet McNaught
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