|
Responding to the Potential
Threat of a Near-Earth-Object Impact
Evidence that the Earth may be impacted by an
asteroid or comet large enough to cause global devastation
is increasing rapidly. As recommended by AIAA's 1990 position
paper, Congressional directed workshops on Near-Earth-Object
(NEO) detection and intercept were conducted and interagency
and international collaborations began. This position paper
recommends continuing the NEO activities by:
a)accelerating the search for asteroids and
short period comets,
b)developing concepts and plans for following
detection and intercept systems, and c) establishing a central
program office in the U.S. to provide a focal point for systems
engineering, technology integration and international cooperation.
In April 1990, AIAA's Space Systems Technical
Committee, chaired by E. Tagliaferri, published the position
paper, Dealing With the Threat of an Asteroid Striking the
Earth. This paper, precipitated by the close passage of asteroid
1989FC - with zero warning time - helped stimulate broad interest
and concern in this potential threat to civilization and even
to the survival of humanity. Soon afterwards, the U.S. House
of Representatives Committee on Science, Space and Technology
directed NASA to conduct two workshops related to the asteroid
threat as recommended in the position paper, one for the detection
and characterization of the threat, including determining
the orbits with precision which would allow the accurate prediction
of an impact, and another which dealt with issues related
to mitigating the threat. On March 24, 1993, the results of
these workshops were summarized and discussed in a formal
hearing before this same Congressional Committee. The class
of potentially threatening objects was enlarged to include
long period comets as well as earth-orbit crossing asteroids;
together they were defined as near earth objects (NEOs).
World-wide attention, based on recognition of
the reality of the NEO threat has increased enormously over
the past decade. Scientific consensus that a NEO impact was
the primary cause of the Cretaceous/Tertiary (KT) boundary
and the sharp end of the age of the dinosaurs was further
consolidated with the identification of the probable impact
crater on the Yucatan Peninsula. As requested by Congress,
the participation by the U.S. Department of Defense and the
developed nations worldwide has begun. Public attention has
been captured by the prediction of on earth by comet Swift-Tuttle
(later retracted ) and then by the actual impact on Jupiter
by comet Shoemaker-Levy 9, which not only proved to be the
most violent event in the solar system during recorded history,
but was also an excellent example of rapid and accurate orbit
determination.
The Space Systems Technical Committee of the
AIAA believes it has a responsibility to continue the work
begun by Mr. Tagliaferri five years ago by helping to focus
national and international attention on the issues raised
by the NASA workshops. By providing a forum open to a diversity
of views and competencies, we can perhaps help illuminate
and resolve issues with broad system and technical implications.
In this activity, we are joined by other capable organizations
with an interest on converging to the best possible decisions
regarding these issues: AIAA's Systems Engineering Technical
Committee, the National Council on Systems Engineering (NCOSE),
the Institute of Electrical and Electronic Engineers' (IEEE)
Aerospace and Electronic Systems Society (AESS), and the Space
Studies Institute (SSI).
It is the consensus of these organizations that,
although the likelihood of an NEO impact is extremely low,
the consequence can rage from the devastation typical of a
nuclear warhead for small objects to billions of fatalities,
the end of civilization and even the extinction of mankind
for large objects. This combination of likelihood and consequence
is significant enough to demand a response and, fortunately,
humanity's resources and technology can probably provide cost
effective answers to this potential threat.
- Immediate approval of a program to accelerate the discovery
of NEOs. Extrapolating the present rate of discovery of
kilometer-size NEOs by a small and dedicated team of astronomers,
it would take hundreds of years to discover the approximately
2000 objects of this size. The investment in a system to
accelerate the discovery schedule to about 20 years seems
to have an extremely attractive cost benefit ratio, reducing
the risk of global catastrophe by about a factor of four.
This first phase postpones the investment of a mitigation
system since it is estimated that 75% of the objects discovered
will be asteroids or short period comets where the impending
impacts will have ample warning times for the development
of mitigation systems.
- Immediate institution of a plan to conduct operations
and mission analysis, systems concepts and technology studies
to implement followon phases of the eventual planetary defense
system. These studies would be devoted to a broad perspective
examination of the systems engineering, risk management
and cost effectiveness aspects of extending the total system
capability in at least these directions:
- Improving the accuracy and speed of orbit determination,
- Improving the detection capability and warning time
against large, long period comets capable of global devastation,
- Improving the capability against smaller NEOs capable
of major mortality and destruction
- Determining the feasibility of NEO rendezvous for characterization
regarding potential intercept concepts as well as for
scientific and potential exploitation purposes,
- Developing mitigation system concepts,
- Establishing a test plan to reduce technical uncertainties,
- Constructing the architecture of a command, control
and communication system
- Laying out a total program development plan whose schedule
is phased in response to available resources and the criticality
of the risk assessment as a function of time.
- Implement hardware and test programs on the phased schedule
developed in item 2) Once the primary sensor system described
in 1) has been deployed, opportunities for increasing its
capability or critical tests, can be undertaken in accordance
with the development plan.
- Establish an Office of Primary Responsibility in the United
States and Encourage the Establishment of Similar Offices
in the Developed Nations. The objective of this office is
to provide the focal point for overall program management,
planning and systems engineering, as well as coordinate
delegated responsibilities regarding NEO detection, intercept,
rendezvous, command and control systems and activities with
our international partners.
In his opening statement to the Congressional
hearings on the NEO threat on March 24, 1993, George E. Brown,
Jr. stated:
"If some day in the future we discover
well in advance that an asteroid that is big enough to cause
a mass extinction is going to hit the Earth, and then we alter
the course of that asteroid so that it does not hit us, it
will be one of the most important accomplishments in all of
human history."
AIAA and its cooperating organizations strongly
believe Congressman Brown's statement is true, as well as
its reverse:
If some day an asteroid does strike the Earth,
killing not only the human race but millions of other species
as well, and we could have prevented it but did not because
of indecision, unbalanced priorities, imprecise risk definition
and incomplete planning, then it will be the greatest abdication
in all of human history not to use our gift of rational intellect
and conscience to shepherd our own survival, and that of all
life on Earth."
George Friedman, Chairman, NEO Subcommittee,
Space System Technical Committee, AIAA
Ed Tagliaferri, Special Advisor to the NEO Subcommittee, AIAA
Robert Jones, Secretary, Space Systems Technical Committee,
AIAA
Rosario Nici, Space System Technical Committee, AIAA
Mike Simon, Space Systems Technical committee, AIAA
Bruce Pittman, Chairman, Systems Engineering Technical Committee,
AIAA
Al Myer, Systems Engineering Technical Committee, AIAA
Myron Kayton, President, Aerospace and Electronics Systems
Society (AESS), IEEE
John Morris, Chairman, Space and Environmental Systems Panel,
AESS, IEEE
Eric Honour, Chairman, Technical Board, National Council on
Systems Engineering (SSI)
Roger O"Neill, Chairman, Space Studies Institute
Our Thanks to the Following Who Provided Additional
Comments Which Constructively Changed the Position Paper:
David Morrison, NASA Ames
Clark Chapman, Planetary Science Institute
Louis Friedman, The Planetary Society
John Darrah, U.S. Air Force Space Command
Terry Dawson, U.S. Congressional Staff
Draft of January 9, 1995
|
