COMMENTS BY CLARK CHAPMAN, 7 MARCH 2004
White Paper
Summarizing Findings and Recommendations
from the
2004 Planetary defense Conference: Protecting Earth From Asteroids
Overview
The Planetary defense Conference: Protecting Earth from Asteroids was held on February
23-26, 2004 at the Hyatt Regency Orange County, California. The meeting was
sponsored by the American Institute of Aeronautics and Astronautics (AIAA) and The
Aerospace Corporation, and was attended by over 130 participants, listed in the
Attachment.
The conference brought together experts in detection of Near Earth Objects (NEOs), in
possible methods of deflecting a threatening NEO, in mission design, and in [IS
POLITICAL DIFFERENT FROM POLICY; ANYWAY, MISSPELLED], policy, and
disaster preparedness areas. One purpose of the conference was to assess the current
state of knowledge of NEO threats. Another purpose was to accumulate a body of
information that might be useful should a real NEO threat be detected in the short and
long terms. Finally, the conference looked at whether and how we should move ahead to
improve our ability to mitigate a NEO threat. Findings and recommendations resulting
from the conference are provided here.
Threat Detection and Characterization
Current efforts to track and understand the nature of asteroids and comets were discussed
at the beginning of the conference. Information on Near Earth Object orbits, size,
composition, and dynamics is critical to initially assessing and finally mitigating threats
posed by these types of objects. The process for verifying observations and for providing
notifications of potential close approaches requires formalization.
Findings:

The threat of impacts upon the Earth, chiefly by Earth-crossing asteroids is very
real. The potential damage from an impact depends on characteristics of the
specific impactor: size, type/composition, impact speed relative to the Earth and
the location [LOCATION OF IMPACT IS NOT A CHARACTERISTICS OF
THE IMPACTOR] of the impact point (e.g., inhabited land, uninhabited land or
the oceans).

Asteroids or comets sufficiently large [THE SIZES THAT CAUSE PROPERTY
DAMAGE DIFFER GREATLY FROM THE SIZE THAT CAUSES
EXTINCTION] to cause extensive damage to property and potentially extinction
of some life forms will impact Earth again. Probability of these events is very
small, but their occurrence is a certainty.

The probability of a civilization-ending impact, or an even greater extinction
event, is very small. However, dice have no memory, and we need only lose in
this lottery once, therefore we cannot afford to ignore this menace.

Current estimates of the probability of an intermediate-level [IS THAT THE
RIGHT TERM?]impact (large enough to destroy a city—100 meters and larger)
are based in turn on estimates, not an actual census, of the real number, types or
orbits of the vast host of as-yet-undiscovered asteroids whose orbits cross that of
the Earth. We urgently need more information about these bodies.

Current search programs are designed to scan only for Earth-crossing asteroids
that are greater than one kilometer in diameter – e.g., those whose impacts could
destroy civilization. We urgently need to improve this search program, to locate
all Earth-crossing asteroids greater in size than 100 meters, to fully evaluate the
threat of an impact that could destroy any one city, killing millions of people.

U.S. Government commited to an effort to detect and catalog 90% of Near Earth
Objects 1 km and larger in size by 2008.

Objects as small as 50 m in diameter can have serious consequences should they
impact in populated areas (the object that caused the Tunguska explosion was
estimated to be 60 m in diameter).[REDUNDANT WITH AN EARLIER
FINDING]

The economic and social costs of an impact are difficult to measure but are
important considerations in assessing the overall threat and justifying the cost
ofmitigation measures.

Once the goal of finding >90% of >1 km bodies has been met, the predominant
threat will be from much smaller objects 50 to 400 m in size.

There is large uncertainty in the composition and structure of asteroids and
comets. Lack of good information increases uncertainty in effectiveness of
mitigation approaches.

Comets will be much harder to deflect due to short warning times, high velocities,
and non-gravitational forces on the comet, as well as uncertainties in the nature of
comets. Fortunately, hazard from comets is a very small fraction of overall risk.

An adequate warning time is essential to enable designing and implementing a
mission to deflect a threatening object. The sooner a threatening object is
detected, the more likely a successful mitigation effort. [NOT A POWERFUL
POINT]

Accurate tracking is key to predicting threat to Earth. Uncertainty in the position
and orbit of the threatening object leads to uncertainty in the possibility of Earth
impact and decreases the likelihood that a mitigation mission could be proposed,
funded and completed [THIS POINT COULD BE IMPROVED]

NASA has responsibility to find and track Near Earth Objects. No formal process
in place for forwarding notice of a high priority threat to agencies responsible for
civil defense, nor do such agencies have any formal plans for responding to such
notice

ADDITIONAL FINDINGS COULD ADDRESS LACK OF OPENNESS TO
ALL RELEVANT DATA, LACK OF INTERNATIONAL COORDINATION,
MORE SPECIFICS ON SDT RECOMMENDATIONS FOR GROUND- OR
SPACE-BASED SYSTEMS FOR DISCOVERING SMALLER NEAS, LACK
OF FUNDED FOLLOW-ON OBSERVATIONS EVEN IN PRESENT MODE.
Recommendations:
1. Improve coordination of current activities to detect NEOs. We have many
different telescopes using similar techniques trying to accomplish similar
objectives, but they are poorly coordinated at present.
2. Build and operate systems to efficiently survey for NEOs down to 50-100
meters in size. [MUST BE CONSISTENT: IS IT 50, 100, 140, …?] The central
conclusion of the NASA SDT report on Near-Earth Objects is that the global
residual hazard is substantial, but reducible by relatively inexpensive telescopic
and/or spacecraft systems. Such systems can rapidly retire most of the residual
hazard for a fraction of the hazard’s fiscal value.
3. Seek an increased funding base for the new NEO surveys and associated
projects. The current funding level (~$3.7 million) for this work within NASA is
inadequate even to carry out appropriate follow-up astronometry and to meet the
2008 goal. The effort proposed by the SDT probably requires a steady funding
base of $20-30 million a year for about a decade and a half.
4. Develop and fund missions to several asteroids to determine physical
characteristics, consistency, etc., and to install transponders to improve
tracking. Accurate tracking is key to assessing the real risks of impact. Placing
transponders or other enhancement devises on potentially threatening asteroids
can help assure that a deflection mission is not initiate d prematurely.
[MUDDLED RECOMMENDATION. LAST PHRASE IS NOT THE CHIEF
MOTIVATION. DETERMINING PHYSICAL CHARACTERISTICS SHOULD
BE A MATTER RELEVANT TO THE NEXT SECTION ON MITIGATION. IF
THIS RECOMMENDATION IS TO FOCUS ON TRACKING, IT SHOULD
ALSO MENTION RADAR.
5. Establish a firm and clearly understood protocol for the flow of information
regarding new discoveries and for NEO approaches where probability of
impacting Earth exceeds specified threshold. The astronomers and researchers
need a clear and unambiguous answer to the question: “Who do we call?” [SO
AS TO AVOID LINDLEY’S OBJECTION TO THIS PHRASE, IT SHOULD BE
AMPLIFIED TO REFLECT THE ASSIGNMENT OF RESPONSIBILITY
ABOVE NASA AS WELL AS AN INTERNATIONAL COMMUNICATIONS
ROUTE]
6. Enhance our scans for long-period comets to extend the possible warning
prior to an impact. Comets have the potential for even greater harm than do the
near-Earth asteroids, because: (1), they are likely to impact the Earth at ahigher
velocity, delivering more energy per ton of mass, and (2) we are far less likely to
have sufficient time to investigate a comet, and to mobilize a successful response,
compared to the possible decades of warning of an asteroidal impact. [THIS
RECOMMENDATION NEEDS TO BE THOUGHT OUT MORE.
STATEMENTS ABOUT THE SERIOUSNESS OF COMETS ARE CORRECT,
AS I HAVE EDITED THEM ABOVE, AS FAR AS THEY GO. BUT IT
SHOULD ALSO BE ACKNOWLEDGED THAT THEY CONSTITUTE A
VERY TINY PART OF THE HAZARD. AND THE COST OF
MEANINGFULLY ENHANCING SCANS FOR COMETS IS VERY HIGH. I
WOULD SUGGEST DELETING THIS RECOMMENDATION.]
Mitigation Options
Several options for deflecting a threatening NEO were presented at the conference.
These options are in various states of availability--some might be available within a few
years, others would require years [DECADES?] of development and testing before being
used to move an approaching object. In some cases, technology developed for other
missions might be applied to moving an asteroid or comet. A specific example includes
the attachment of a high-efficiency electric propulsion system, whose development would
be beneficial for many space missions, to an asteroid. In other cases, such as the use of
nuclear weapons, technology might have to be maintained or customized for this
application. Participants generally agreed that we need a test program to confirm our
ability to move asteroids and comets in a controlled fashion.
Findings:

Given sufficient warning, on the order of twenty years or more, there are a variety
of methods that could be used to shift the orbit of an asteroid, to prevent its
predicted impact upon the Earth. If, however, we have only a few years warning,
then our options are greatly reduced – and may be limited to nuclear weapons.
[SHOULD STATE THAT YEARS OF WARNING IS MUCH LESS LIKELY
THAN DECADES OF WARNING]

There are several candidate methods for moving asteroids, including nuclear
explosions, using a propulsion device to nudge the object, using mirrors to ablate
small amounts of material from the asteroid’s surface, etc.

Use of nuclear weapons may be the only option available for deflecting NEOs
with short warning times. Current international agreements forbid testing or use
of nuclear weapons in space.

The method applicable to a particular case depends on the size of the body, its
makeup (e.g., solid body, loose aggregation of smaller bodies), and the time
available to affect a change in the object’s orbit. [OTHER ISSUES AS WELL:
NATURE OF IMMEDIATE SURFACE THAT WOULD HAVE TO BE
INTERACTED WITH, SPIN STATE, PRESENCE OF SATELLITE…]

Our technology is advancing with great speed, and it is likely that humanity’s
ability to affect the course of an asteroid will develop more rapidly than we will
encounter specific impact threats. Development and deployment of an actual
system to deflect a possible future asteroid prior to discovery of such an object is,
therefore, likely to prove a waste of resources at this stage.

There have been no tests of possible mitigation methods
Recommendations:
7. Fund research on options for moving a Near Earth Object. Research should
include assessing the effectiveness of deflection techniques for different NEO
sizes, dynamics, porosities, and lead times.
8. Match deflection technology and availability to probable warning times,
object sizes, and other mission characteristics and use this information to
affect funding and research levels.
9. Conduct tests of mitigation techniques—demonstrate ability to move an
asteroid. [MY BIAS IS TO CONDUCT A TEST OF A LOW-THRUST,
CONTROLLED OPTION, IN ASSOCIATION WITH LEARNING ABOUT
PHYSICAL CHARACTERISTICS, AND NOT TO TEST
CONTROVERSIAL NUCLEAR OPTIONS, WHICH ADDRESSES
SCENARIOS THAT ARE MUCH LESS PROBABLE]
10. [NEED SEPARATE RECOMMENDATION ON STUDYING PHYSICAL
PROPERTIES OF DIVERSE NEOS, WITH RECONNAISSANCE
MISSIONS SUPPLEMENTED BY GROUNDBASED RESEARCH.
Mission Design
This session considered the design of missions to deliver a mitigation method (explosive,
impactor, propulsion system, etc.) to the vicinity of an asteroid or comet.
Findings:

The options available for deflection depend on the warning time. For short
warning times (<15 [WHERE DOES THIS NUMBER COME FROM? WE GOT
TO THE MOON WITHIN 8 YEARS OF JFK’S SPEECH; SURELY, WITH A
DANGEROUS NEO BEARING DOWN ON US, LOW-THRUST,
CONTROLLED OPTIONS COULD BE DEVELOPED AND IMPLEMENTED
WITHIN 5 – 8 YEARS]years to impact), the nuclear or kinetic impact options
may fit within current launch vehicle, sensor, weapon, and manufacturing
capabilities. Options increase for longer warning times.

Overall reliability and trustworthiness of the deflection effort must be included in
the mission design.
Recommendations:
11. Conduct mission design studies to characterize mission requirements for
short, medium, and long-range missions. These types of studies will help
isolate and define areas where various deflection scenarios are most promising
and point out experiments that might be included in upcoming asteroid and comet
missions. These exercises would also compare current capabilities and directions
to mission requirements and highlight possible incompatibilities. For example,
we may be able to lift a heavy load to space for some deflection missions. Will
we have appropriate launch capabilities?
12. Establish a reliability goal for a NEO deflection mission. The objective of a
NEO deflection mission will be to lower the probability of the object impacting
Earth to less than some defined number (e.g., less than 1 in a million). This
probability must include the overall reliability that the deflection mission will be
successful, given failure experience with launch vehicles, new missions, new
sensors, etc., and uncertainties in NEO characteristics.
13. Develop decision and funding timeline for deflection mission. The overall
mission design should include a timeline for critical political, funding, and
mission decisions.
14. Fly a mission(s) to demonstrate basic NEO orbit tracking and modification.
Although we don’t currently possess the technology to deal with every NEO
impact scenario, we can demonstrate some basic mitigation missions. The two
missions that seem simplest to demonstrate are: 1) A mission to send a simple
tracking spacecraft to follow an NEO, and very accurately report its orbit, and 2)
A mission to demonstrate NEO orbit modification, using large kinetic impactors.
Both missions are within the realm of current technology, and are of reasonable
cost. Since a mitigation effort is likely to involve imparting very small velocity
increments, a mission that first places a transponder on an asteroid and a
subsequent mission to impart a velocity change to that same asteroid might be a
consideration. [I DISAGREE WITH THIS RECOMMENDATION. THE FIRST
MISSION HAS TOO LIMITED A CHARTER. PLACING A TRANSPONDER
ON AN ASTEROID SHOULD BE INCLUDED AS PART OF A MISSION
THAT DETERMINES THE ASTEROID’S PHYSICAL PROPERTIES.
PERHAPS BOTH OF THOSE GOALS COULD BE INCLUDED WITHIN A
B612-TYPE MISSION THAT ADDITIONALLY TRIES TO MOVE THE
ASTEROID IN A CONTROLLED, MEASURABLE WAY. I DO NOT
BELIEVE THAT A NUCLEAR OR KINETIC TEST SHOULD BE HIGHEST
PRIORITY; LITTLE WOULD BE LEARNED FROM IT OTHER THAN THAT
THE LAWS OF PHYSICS ARE OBEYED. THE IDIOSYNCRACIES OF THE
INDIVIDUAL ASTEROID, AND LOCATION OF IMPACT ON THE
ASTEROID, COULD DRAMATICALLY AFFECT THE OBSERVABLE
OUTCOME AND WOULD NOT BE RELEVANT TO THE MORE GENERAL
CASE. I BELIEVE THAT ROBUSTNESS AGAINST UNKNOWN
PROPERTIES OF THE TARGET, AS IN THE “LU TRACTOR BEAM”
APPROACH, SHOULD BE A PRIME FEATURE OF THE TECHNIQUE
TESTED. I ALSO BELIEVE THAT IT IS MORE IMPORTANT TO ADDRESS
THE MUCH MORE LIKELY DECADES-OF-WARNING RATHER THAN
YEARS-OF-WARNING CASE.]
Public Information and Communications
There is real empirical science in the social sciences that can be brought to bear on this
problem, but it needs to be synchronized with the science and engineering communities.
Much is known about how the public responds to disasters and to warnings of disaster
that can be helpful in developing an overall notification, warning, and response plan.
Findings:

People usually remain calm and perform rationally when confronted with a
disaster.

People are tolerant of false alarms as long as they are presented the facts

Potential impact of an asteroid or comet is an international issue

People will seek multiple sources of reliable information should a warning go out.

Need to erase the “giggle factor” associated with planetary defense

Utilize visuals and the media to show what can happen and develop increased
awareness of the problem and potential for deflection

Communications by trusted institutions is key
Recommendations:
15. The current use of the Torino Scale as a way of portraying the threat to the
public should be reviewed by social scientists to assure its effectiveness.[I
WOULD PREFER TO PHRASE THIS IN THE SENSE THAT THERE
SHOULD BE FURTHER DEVELOPMENT OF THE TORINO SCALE
AND ITS USE, IN THE CONTEXT OF SOCIAL SCIENCE RESEARCH IN
DISASTER WARNINGS, TO ENSURE ITS EFFECTIVENESS. AS
PRESENTLY WRITTEN, IT SUGGESTS INCORRECTLY THAT
SOCIAL SCIENTISTS HAVE NOT LOOKED AT THE MATTER AT
ALL.]
16. Bring evidence of previous NEO impacts to the attention of the public to
increase public awareness that impacts do happen and the possibility can’t
be ignored.
17. Develop communications protocols and contact lists for information
18. Include international entities in communication protocols
19. Develop format for warnings that presents information using specific,
relevant, and consistent terms. It may not be effective from the public
information perspective to define the threat in probabilistic terms. We need to
look for a better way to make this issue understood by and relevant to the public.
20. Demonstrate to the public that something can be done about the NEO
hazard. Placing a transponder on an asteroid, for example, is a small but helpful
first step to demonstrating control. Actually moving an asteroid measurably and
in a controlled manner would be even more convincing.
21. Develop information release protocols that maintains the public’s trust. The
public should be apprised of possible threats and potential actions that might be
taken in an accurate and authoritative way. The entity releasing this type of
information must be viewed by the public as accurate and objective, and the
information released should be supported by other experts in relevant fields.
Social scientists should assist in the development of these protocols.
Political and Policy Considerations
A deflection mission is not possible without political and policy level support. A
deflection mission with a short time frame would require substantial investment and
might require nuclear weapons, whose use currently is forbidden in space. Clearly, some
entity would need to be in charge of the effort to mount the defense, and preparations
would need to be made for mitigating the disaster if the deflection effort is unsuccessful
or only partially successful. In addition, there are substantial issues related to
international participation in the deflection effort and possible disaster mitigation.
Findings:

At present, there is no entity in charge of “planetary defense.” This fact leads to
many complexities and ambiguities on the NEO issue. Possible linkages of
existing and new projects to possible planetary defense applications are not
currently explored or encouraged.

There are no established guidelines or protocol as to when it is appropriate to send
out a notice of a specific future impact possibility and to whom the notice should
go.

Unnecessary “parasites” may be attached to possible deflection missions,
increasing cost and lowering probability of mission success.

There have been no detailed looks at potential disaster scenarios related to a NEO
impact.

International coordination and involvement must be assumed in dealing with any
serious NEO threat.

[PROBABLY THERE SHOULD BE FINDINGS RELEVANT TO VARIOUS
FORMS OF THE ‘DEFLECTION DILEMMA’]
Recommendations:
22. Relate deflection mission decision and funding timeline requirements to
warning thresholds and decision process. Of critical importance to a successful
deflection mission will be the resolution of issues and evolution of a decision
leading to funding of the mission. The decision timeline must be included in
mission planning so that all parties know the criticality of timely decisions.
23. Find or create an organizational/governmental home for the NEO issue. A
number of complexities and ambiguities on the NEO issue persist because there is
no one agency or group within the U.S. government that is responsible for it.
NASA, DoD, DoE, FEMA, and DHS have all been suggested as possible lead
agencies for the NEO issue. Alternatively, a new organization could be created,
although its relationship to these other Executive agencies could be complicated.
One suggestion to consider would be the establishment of an Army Corps of
Engineers-like entity, a Space Corps of Engineers, that would focus on major
projects of this kind.
24. Means for international participation should be included in planning NEOrelated missions, organizations, and policies.
25. Produce the political plans and processes for NEO mitigation before they’re
needed. If a specific, future impact event becomes probable and publicly known,
there are a significant number of major issues that would have to be resolved.
The intensity of the media scrutiny and the political uproar would make the
resolution of those issues much more difficult. The way around this is to
understand and solve as many of the big policy issues as possible before they need
to be invoked.
26. Look at how other major disasters involving large numbers of people are
handled and assess what levels of NEO impacts are or should be within the
disaster relief framework.
27. Make policy makers aware that use of nuclear weapons for NEO deflection
might be a possibility under certain circumstances. Provide information on the
set of missions where this might be a possibility.
Summary:
The first of a planned series of comprehensive conferences on the threat posed by Near
Earth Objects, possible techniques and mission for deflecting an oncoming object, and
political, policy, and disaster preparedness issues associated with NEO deflection was
held in February 2004. The conference produced [SOME NUMBER] recommended
actions.
Foremost among these is the recognition, even though the probability of a disastrous
impact is small, that we need to improve the public’s perception and appreciation of the
threat, to increase our efforts to detect threatening objects, and to move forward on
research of possible means to deflect a NEO.
A key recommendation is that the entity responsible for dealing with NEO threats and for
coordinating activities related to mitigating those threats be identified. Considerable work
needs to be done to assure that we are able to detect threats early and that the means
available for deflection are known to be effective.
The fact of past impacts of comets and asteroids is known, and without mitigation, future
impacts by comets and asteroids are a certainty. Such impacts can have severe
consequences—even ending civilization and humanity’s existence. Life on our planet
has evolved to the point where we can now control our destiny. We need to take this
threat seriously and to enhance our readiness to counter the next major threat from a Near
Earth Object.