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Congress Hearing: Asteroids: Perils and Opportunities (Long)


NASA MEMORANDUM FOR THE RECORD, by Barbara Cherry, Legislative Affairs Office

SUBJECT:	"Asteroids: Perils and Opportunities" hearing before the
Subcommittee on Space and Aeronautics, Committee on Science, May 21, 1998.

MEMBERS	Rohrabacher , Chairman, (R-CA), Brown (D-CA),  Cook (R-UT), Gordon
(D-TN),

PRESENT:	Bartlett (R-MD), Hall (D-TX), Roemer (D-IN), Weldon (D-FL),
Luther (D-MN)

WITNESSES:	Dr. Clark Chapman, Southwest Research Institute; Dr.
William Ailor, The AerospaceCorporation; Dr. Gregory Canavan, Los Alamos
National Laboratory; Dr. John Lewis, University of Arizona; Dr. Carl
Pilcher, NASA.

OPENING STATEMENTS:  Chairman Rohrabacher opened the hearing by commending
Congressman Brown for his leadership and long track record of pushing the
Executive Branch to deal with the issue of cataloging and characterizing
asteroids.   He stated that the potential impact of these hazardous objects
is one of national security, economic as well as scientific interest.
Congressman Rohrabacher noted that the potential to mine asteroids for
metals, minerals and other resources that can be used to build large
structures in space was an important aspect of the hearing.   Mr.
Rohrabacher chided NASA for not "walking the talk" by funding the Near
Earth Object (NEO) search program at the levels suggested in the Shoemaker
Report.  He noted that NASA has no trouble finding $50 million for a
program pushed by the Vice President to transmit pictures of Earth into
everyone's living room and cannot find a few million dollars to increase
the likelihood of cataloguing all of the potentially hazardous NEOs l km or
larger.

Congressman Brown echoed his long-standing interest in this subject and the
importance of addressing the issue of cataloging and characterizing NEOs
even though the risk of impact is small because of the enormous potential
catastrophic consequences.

Dr. Chapman discussed the "possibility that an asteroid or comet might
strike Earth in our lifetime, perhaps destroying civilization as we know
it."   He presented a chart which illustrated the chances of dying from an
asteroid impact against selected other causes (USA).  Congressman Cook
noted that the chances of dying from an airplane crash and from an asteroid
impact were both l in 20,000.

Dr. Chapman noted that if a mile-wide asteroid hit earth, it would create a
hole larger than Washington DC, it would be deeper that 20 Washington
monuments stacked on top of each other, ruin agriculture production, and
hundreds of millions to billions of people would die.  He noted that the
consequences were devastating and, therefore, it was prudent to implement
the recommendations contained in the Shoemaker Report of cataloging 90% of
all of the NEOs with diameters of 1 km or larger within a decade.  This
would reduce by a factor ten the uncertainty of knowing if an asteroid were
headed toward Earth and would likely provide sufficient time to try and
deal with the situation.

Dr. Pilcher testified that NASA is committed to the goal of cataloging 90%
of all of the NEOs with diameters larger than 1 km within a decade and that
we are on track to do so.  He stated that NASA has a rich program of
research on asteroids and comets which will provide essential information
if the Nation were ever to divert an asteroid.  Dr. Pilcher stated that the
Space Science Strategic Plan includes as a objective, to catalog 90% of the
NEOs with diameters larger than 1 km within 5-6 years and NASA has put into
place a program to do this.  Dr. Pilcher stated that the budget has been
doubled to $3 million and NASA will maintain at least this level of funding
in the future.  Dr. Pilcher outlined all of the elements of the NEO Search
program and where increases in the budget have enabled NASA to support new
activities.  He discussed the Partnership Council, a Council chaired by the
Administrator and General Estes of the Air Force to discuss issues of
mutual concern to both agencies - NEO detection is one issue which the
Partnership Council is addressing.  Dr. Pilcher stated that the only
recommendation that NASA is not implementing from the Shoemaker Report was
the recommendation to build a dedicated 2 meter telescope - -because
planned upgrades to existing telescopes can do the job.  Dr. Pilcher told
the Committee that NASA would do what it takes to do the job right.

Dr. Canavan's testimony addressed several issues.  He stated that new
technology developed since the Shoemaker Report was issued has increased
the detection rate.  He emphasized that one area that has not been
addressed is long period comets whose orbits intersect the Earth.  He said
there is no clear concept how to do this and it may constitute as high as
50% of the threat.  Dr. Canavan also stated that characterization of
asteroids is important if one were to try and alter the course of an
asteroid or comet.   He discussed the Clementine II mission, which he said
represented excellent collaboration between NASA and DOD before it was
canceled.   Dr. Canavan closed by saying that the current level of funding
for NEO searches is 1/3 to _ too low to adequately do the job.

Dr. Ailor discussed the risk the Leonid meteor shower will pose this
November.  He stated that in a normal year one see 10-15 meteors per hour
and this November there will be as many as 200-5,000 meteors per hour
traveling at a speed of approximately 155,000 miles per hour.  He discussed
the recommendations from a recent Conference that was held to address this
issue:  1) During the period, satellite controllers should be on duty and
check the health of the satellites frequently, 2) orient satellites so that
sensitive components are shielded from the oncoming stream of particles and
3) recovery plans should be in place in the event of a system failure.

Dr. Lewis discussed the economic value of asteroids as a source to mine
minerals and materials for earth or to produce materials in space for
future space transportation.  He noted  the very low departure speed
required to lift off from an asteroid for a return trip to Earth.  Dr.
Lewis stated that the keys to successful importation of materials from
space are lower launch costs and careful choice of exploitation targets to
favor those that are most accessible and have the richest resource
concentrations.

QUESTIONS:  Chairman Rohrabacher stated that NASA has not been spending
adequate funding to search for NEOs as recommended in the Shoemaker Report.
Dr. Pilcher noted that, the Office of Space Science has issued their
Strategic Plan which includes a goal of cataloging 90% of the 1 km
asteroids, that NASA funding wasn't adequate to accomplish this goal, and
NASA had doubled the funding of the NEO program.

Mr. Rohrabacher asked Dr. Pilcher how many of the asteroid missions he
discussed were actually in the budget.  Dr. Pilcher replied that  DS-1,
DS-4, Contour, STARDUST, Comet Nucleus Sample Return, and Pluto Kuiper
Express were all assumed in NASA's budget.

Congressman Gordon asked if NASA was the only Agency working on the
problem.  Dr. Pilcher responded that NASA supports researchers at
Universities to address this issue and works closely with the Air Force.
He stated that NASA is developing collaborations with the international
community as well.  Mr. Gordon asked if the Federal Government was
coordinating adequately.  Dr. Chapman responded that FEMA has little
appreciation for the hazard of such an event.  Dr. Canavan stated that
interagency cooperation between NASA and the Air Force hasn't percolated
down to the troops beyond the Administrator and General Estes.

Congressman Hall asked if we have to have a calamity before anyone takes
something seriously and noted that it is an international problem and
should have international participation.  He asked how much NASA is
spending on search activities.  Dr. Pilcher responded that NASA is spending
$3 million per year and approximately $1 billion over the next decade in
asteroid/comet missions.  Mr. Hall questioned if NASA is actually spending
all of the money allocated for the purposes which the Congress appropriated
the funds, indicating that Life and Microgravity funding was being spent
for hardware and not research.

Mr. Roemer noted that Dr. Chapman had provided the sound bite for the
evening news - that "a mile wide asteroid could hit the Earth tomorrow and
we wouldn't know anything about it."  He asked if the Federal Agencies had
held discussions among themselves on what you would need to do to
coordinate a response if an impact were imminent.  The witnesses indicated
that not much had been done.

Mr. Rohrabacher stated that one needs to put things in perspective and
perhaps we aren't spending money wisely.  He noted that Mission to Planet
Earth is budgeted at $1.4 billion and perhaps it makes more sense to spend
additional money on looking for NEOs  and improving interagency
coordination instead of spending money on Mission to Planet Earth.  He
stated that he hoped the Congress would move forward and lay the ground
work for the Clementine II mission.

 Congressman Hall said he thought the hearing was a waste of time unless
"we arrive at some actions - if it is money we need to know how much."
Both he and Congressman Rohrabacher charged each of the witnesses to draft
a two page action plan on what is needed to address the NEO issue and what
policies need to be developed to meet the challenges that a NEO impact
threat poses.

--------------------------------------------------------------------------------

Statement on The Threat of Impact by Near-Earth Asteroids by Dr. Clark R.
Chapman, Southwest Research Institute (for a version of these remarks that
includes the figures, see www.boulder.swri.edu/clark/hr.html)

Mr. Chairman and Members of the Subcommittee:

I am pleased to discuss with you the threat to our civilization from
impacting asteroids. The threat is something I think we should all think
about, but I am happy to report that I feel that we can still sleep well at
night. I am from the Southwest Research Institute, of San Antonio, Texas, a
large, diversified, non-profit research institute in its 52nd year of
serving this nation. As a research scientist in the Boulder, Colorado,
Space Studies Department, I am expert on asteroids and on studies of impact
craters on planetary surfaces. I participate on the imaging team of NASA's
Galileo mission that is currently orbiting Jupiter and studying its moon,
Europa, which may have an ocean beneath its icy crust. Earlier this decade,
Galileo made historic, first-ever observations of two asteroids, Gaspra and
Ida, which orbit the Sun within the main asteroid belt, between the orbits
of Mars and Jupiter.

I am also on the science team of the Near Earth Asteroid Rendezvous
mission; that spacecraft, developed at Johns Hopkins Applied Physics
Laboratory, will enter orbit around the asteroid Eros eight months from
now. Nearly 25 miles long, Eros is one of the largest of the so-called
Earth-approaching asteroids; it has a 5% to 10% chance of ending its
existence, several million years from now, by crashing into the Earth. NEAR
is studying Eros not because of its danger but for clues it may hold about
the origin of the solar system. If Eros does crash into Earth, it will be
even more devastating than the impact 65 million years ago that
extinguished the dinosaurs, and made it possible for mammals and,
eventually, homo sapiens to thrive on planet Earth.

The Impact Hazard

I wish to talk with you not about the probability of impacts millions of
years from now, but about the slight possibility that an asteroid or comet
might strike Earth in our lifetimes, perhaps destroying civilization as we
know it. It takes a truly huge object like Eros, or like the comet in the
movie "Deep Impact," to threaten mass extinctions of species. Fortunately,
Eros cannot strike Earth in the near future. And impacts of such magnitude
occur extremely rarely, once in perhaps 100 million years. That's only one
chance in a million of happening during the 21st century: really unlikely!
It is an appropriate topic for science fiction, but nothing to worry about.
Such a body is so large, there's little we could do about an Extinction
Level Event, anyway ("Deep Impact" notwithstanding).

A more serious problem, and one that we can do something about, is the
chance that a smaller asteroid or comet, about a mile wide, might hit. The
best calculations are that such an impact could threaten the future of
modern civilization. It could literally kill billions and send us back into
the Dark Ages. Such an impact would make a crater twenty times the size of
Meteor Crater in Arizona. The gaping hole in the ground would be bigger
than all of Washington, D.C., and deeper than 20 Washington Monuments
stacked on top of each other. It would loft so much debris into the
stratosphere, which would spread worldwide, that agricultural production
around our globe would come to a virtual halt: the dust would dim the
sunlight for months, perhaps a year. Especially if the asteroid struck
without warning, there would be mass starvation. No nation would be
unscathed, so no nation could assist others, unlike the aftermath of World
War II.

Such civilization-threatening impacts happen hundreds of times more often
than Extinction Level Events, perhaps once every few hundred thousand
years...or one chance in a few hundred thousand that one will impact next
year...or one chance in a few thousand during the next century -- during
the lives of our grandchildren. Those chances are so small that they are
difficult to comprehend. But it is more likely to happen than that the next
poker hand you are dealt will be a Royal Flush. The chances are much
greater than the chance that you will be the big winner in a state lottery,
yet people buy lottery tickets all the time. Few people would board an
airplane if they thought its chances of crashing were a chance in a few
thousand. Indeed, the chance that your tombstone will read that you died
from an asteroid impact holocaust is about the same as that of your
tombstone saying that you died in an airliner crash. The Table shows some
other comparative odds of death, to put the impact hazard into perspective.
Should we do nothing in the face of the slight possibility that everything
our forebears have created since the Renaissance might be undone?

Table. Chances of dying from selected causes (USA)

               Cause of death
Chances

Motor vehicle accident                                                   1
in 100
Homicide
1 in 300
Fire
1 in 800
Firearms accident
1 in 2,500
Electrocution
1 in 5,000
Asteroid/comet impact                                                   1
in 20,000
Passenger aircraft crash                                               1 in
20,000
Flood
1 in 30,000
Tornado
1 in 60,000
Venomous bite or sting                                                  1
in 100,000
Fireworks accident
1 in 1 million
Food poisoning by botulism                                          1 in 3
million
Drinking water with EPA limit of tricholoethylene  1 in 10 million

(From C.R. Chapman & D. Morrison, 1994, Nature 367, 33-40.)

Fortunately, unlike many disasters that threaten us about which we can do
little, there are things we can do about the impact hazard. First, and most
important, we can find out whether or not a mile-wide asteroid is actually
headed toward us. By sampling the heavens, we can tell that there are at
least 2,000 asteroids of the class that could strike the Earth which are
more than a kilometer across; that's nearly 2/3rds of a mile across, and
well within our uncertainties of what's big enough to cripple civilization.
Of the 2,000, however, we have discovered and charted the paths of only
about 245, or 12%. None of them, we have learned, are targeted towards
Earth within the foreseeable future. But any one of the other 88% -- 1,755
potential killer rocks out there -- could strike at any time, even this
afternoon, without warning. We simply haven't been looking hard enough.

Nothing is perfectly safe in this world. But if, ten years from now, we
could say that we have reduced our worries by a factor of ten -- that the
chances of an asteroid striking are ten times less, because we have
discovered and certified 1800 of the 2000 potentially dangerous asteroids
as safe, then we could sleep a little easier at night. Moreover, if -- by
bad luck -- there really is an asteroid headed our way, there might, after
ten years searching, be an excellent chance that we would have found it.
And then, we could probably save ourselves. At the very least, we could
evacuate ground-zero, and we could save up food supplies and try to weather
the global environmental catastrophe. We even have the military technology,
provided we have a decade's warning time or more (which is likely), to
study the threatening object, to launch a rocket with powerful bombs, and
explode a bomb in just the right place to give the object a little kick,
causing its path to change ever-so-slightly so that, years hence, it misses
the Earth instead of bringing catastrophe to our planet.

But we will not sleep easier, and we probably will not soon find the
threatening object if it is there, if we keep doing just the meager,
ineffective searches that we have been doing during the last few years.
David Morrison, of NASA's Ames Research Center, and I published our book,
"Cosmic Catastrophes" nine years ago, first calling to public attention the
work of Gene Shoemaker's 1981 Spacewatch workshop. Dr. Morrison addressed
the Congressional Space Caucus in 1989, telling them about the problem, and
about the prospects. The Congress responded by calling on NASA to study the
impact threat, which it has now done twice. There has been a lot of
subsequent talk, but very little if anything has actually been done in
response to the study's recommendations. One of the chief projects
searching the heavens, the Spacewatch program in Arizona, receives only
about a quarter of its funding from NASA -- most of the rest is from
private donations. Much of the NEO search effort has been assisted by
volunteers.

Gene Shoemaker, who died tragically last year in Australia while studying
impact craters in the remote Outback down under, worked tirelessly to help
our nation, and the world, understand that the impact threat is real. He
even co-discovered the comet, Shoemaker-Levy 9, that crashed onto Jupiter
in 1994 creating zones of firestorm and devastation as large as the entire
planet Earth. But despite Shoemaker's work, mine, and that of a few dozen
other scientists around the world -- including today's witnesses John Lewis
and Greg Canavan -- very little has been done to actually address the
hazard that could end our civilization, or even our species.

At the current rate of discovery, it will take nearly a century to
inventory 90% of the threatening asteroids. If an asteroid strikes during
the next few decades, we will have failed our responsibilities "on our
watch" to protect civilization, especially since we are the first
generation with tools adequate for the job. To be sure, a century from now,
technology will have inevitably advanced so that our great-grandchildren
will be effectively searching the skies for threats. Unless, that is,
civilization has been dealt a deadly blow before then, say in the next
thirty years, in which case it will be our fault that we did
next-to-nothing.

Now, I don't think the chances are great that this disaster will happen.
The chances are, in fact, very small. But the consequences are so great
that the simple probabilistic calculation of deaths per year is similar to
that of many natural disasters, like earthquakes, hurricanes, or floods.
Many more people die of war and disease than from natural disasters. But if
you think earthquakes are a matter of concern, you might well think of
impacts as of concern. As shown in the Figure 1, all natural hazards
combined kill only about ten times as many people as would die, on average,
from impacts. Of course, few people, if any at all, have died from impacts
in recorded history. But we're playing the odds: just as we sometimes make
a small investment in a high-risk chance of winning big in the stock
market, we can make a comparatively small national investment in protecting
civilization from the small chance of a global catastrophe.

The Spaceguard Survey

The visionary science fiction writer Arthur C. Clarke is widely credited
with foreseeing communications satellites half-a-century ago. In the 1970's
he wrote a novel that introduced the "Spaceguard Survey," a project that
would search the heavens for threatening asteroids. (A more recent Clarke
novel is the basis for the current movie, "Deep Impact.") Astronomers
trying to scan the skies for dangerous near-Earth objects (NEO's) have
adopted the name "Spaceguard Survey" to describe the proposed international
array of telescopes that could find most of the celestial bodies that
threaten us.

In 1992, the first Congressionally mandated Spaceguard Survey report was
written by a NASA committee chaired by David Morrison, outlining the
survey. The report was filed, but little was done. Following the
spectacular portent of the Shoemaker-Levy 9 comet crashes in 1994, NASA
formed another committee at Congress' behest, chaired by the late Gene
Shoemaker. I was a consultant to, and participant in the deliberations of,
this "Near-Earth Object Survey Working Group." Its updated plan and budget
for the Spaceguard Survey was published in June 1995. In response to one of
the questions of the Space and Aeronautics Subcommittee, I want to describe
its recommendations.

The goal adopted by the Committee was to find 90% of the near-Earth
asteroids and short-period comets larger than 1 km diameter within 15
years, or within 10 years if the recommended efforts by NASA could be
augmented significantly by the Air Force and by other nations. Figure 2
shows the fraction of completeness (1.0 = 100%) that can be achieved for
objects of different sizes (the x-axis is a logarithmic scale from 100
meters to 10 km diameter) for five different survey systems studied,
ranging from the Palomar telescope once used by Eleanor Helin and the
Shoemakers through an enhanced Spaceguard system.

The recommended approach was to build two 2-meter aperture (diameter of the
primary mirror) telescopes, designed and dedicated for NEO discovery.
These, and additional, existing 1-meter telescopes would be equipped with
state-of-the-art detectors and electronics to search for NEO's and to make
the crucial follow-up observations of initial discoveries. Additional funds
were proposed for coordinating the program and handling the massive load of
data, and for half-time use of an existing larger telescope to study the
physical properties of a representative sample of threatening objects.

The start-up costs were estimated to total $24 million for the first 5
years, followed by annual operations costs of about $3.5 million for a
15-year total of about $60 million, not including funding for the augmented
Air Force or international facilities.

There are other desirable features of the Spaceguard Survey, discussed in
the Shoemaker report. For example, radar observations of NEO's have
unprecedented capabilities to pinpoint their orbits, as well as to assess
their generic composition (metal, rock, ice). Scientific studies, which
would inevitably result from the Survey, would shed light on the origin of
planets as well as characterize NEO's for possible utilization of their
materials for space-construction, fuel, or life-support. Such an asteroid
may even serve as astronauts' "stepping stones" to exploration of Mars. I
am sure that Prof. Lewis will amplify on these possibilities.

An integral part of the Spaceguard Survey is its international character.
All nations are threatened by a globally destructive impact. So, naturally,
there has been international interest in addressing the threat. Interest
has been especially high in Russia, which -- due both to its vast area and
to bad luck -- has been the target of two of the worst impacts of the
twentieth century. In 1908, a 15-megaton TNT-equivalent blast occurred over
a remote portion of Siberia, flattening the forests for tens of miles in
every direction. This was due to the impact of a stony asteroid, which
exploded less than 10 km up in the atmosphere over the Tunguska river
valley. In 1947, another cosmic impact in the Sikhote-Alin region of
Siberia formed more than 90 craters between 1 and 27 meters in diameter
across the landscape. Not surprisingly, there has been interest among
Russian astronomers and military technologists alike to respond to the
cosmic threat. However, economic circumstances in the former Soviet Union
make it unlikely that an initiative to start the Spaceguard Survey will
begin in Russia. Another country, Australia, has actually backed away from
its fledgling telescopic program, which -- until the past couple of years
-- played a fundamental role by following-up on NEO's discovered elsewhere
from its special location in the southern hemisphere. International
attempts to encourage the Australian government to bring the telescopic
program back into operation have been to no avail.

Clearly, other nations are awaiting America's leadership to jump-start the
Spaceguard Survey. There are promising signs that the work is about to
begin. NASA recently adopted as an as-yet-unfunded element of its
scientific strategic plan the goal of finding 90% of the globally
threatening asteroids in the next 10 years. I am sure that NASA's Dr.
Pilcher will elaborate.

Three years after publication of the Shoemaker Committee report, its basic
conclusions remain sound, yet there are some new insights about how the
Spaceguard Survey should be conducted. Furthermore, technological advances
envisioned by the Shoemaker Committee have now been implemented, in several
test cases: the Spacewatch Program in Arizona; the Near Earth Asteroid
Tracking (NEAT) program -- a joint venture of the Jet Propulsion Laboratory
(JPL) and the Air Force in Maui; the Lowell Observatory Near-Earth Object
Survey (LONEOS); and the Lincoln Laboratory LINEAR program operating for
the last few months in New Mexico have all helped to demonstrate that the
Shoemaker Committee recommendations are robust. LINEAR, for example, with
advanced electronics controlling its large charge-coupled device (CCD)
array, is already discovering nearly twice as many potentially hazardous
asteroids as the other programs combined. But the programs are not all
fully operational. NEAT, for example, is allocated only 6 nights a month on
its telescope on the rim of Haleakala Crater in Maui.

Let me turn to how the goals of the Spaceguard Survey are being addressed
right now, in May 1998, and what the prospects are for the future.

How Are We Doing?

The bald truth is that we are not conducting the Spaceguard Survey...not
yet, anyway. At the present rate of discovery, it would take nearly a
century to meet the goal of finding 90% of NEO's larger than 1 kilometer
across. If, indeed, a kilometer-wide asteroid were actually going to hit us
in the year 2028 (not the false report headlined around the world in March,
to which I will return), the current search effort might well miss it
before it suddenly struck "out-of-the-blue".

Figure 3 shows how current efforts are slowly pushing up the numbers of
discovered NEO's. The straight, slanting line shows the estimated
population of Earth-orbit-crossing asteroids. Today, the survey is complete
only for objects brighter than absolute magnitude (H) of 15. We need to
survey to at least H = 18, for which it is estimated that there are 2,000
asteroids. The two curves, plotted for all discoveries through the end of
1995, and for discoveries through last month, show that we are inching up
very slowly. (Note that the vertical scale is in equal powers of ten.)

The backbone of implementing Spaceguard would be to place more telescopes
into operation. We cannot requisition existing telescopes for the task.
Nearly all telescopes at major observatories are designed to peer, at high
magnification, at extremely distant stars and galaxies in a tiny portion of
the sky. Neither they, nor orbiting telescopes like the Hubble, are
designed to survey asteroids. Spaceguard requires only modest-sized
telescopes, but with a special design that can cover broad regions of the
sky for objects down to about 20th magnitude (about a million times fainter
than the faintest stars you can see on a clear, moonless night from
metropolitan D.C.) According to an analysis by Dr. Alan Harris, of the Jet
Propulsion Laboratory, about half the improvement in the current effort
will be achieved by searching broader areas of the sky each month. The
remainder will come from upgrading the telescopes so that they detect
asteroids about a magnitude fainter than is currently achieved.

The Shoemaker Committee recommended achieving these goals by building and
putting on-line a couple new, larger telescopes about 2 meters in aperture.
But there is an alternative, or at least complementary, approach. That is
to take existing mothballed Air Force telescopes, part of the so-called
GEODSS program (Ground-based Electro-Optical Deep Space Surveillance),
installing them, equipping them with the finest detectors and electronics
(perhaps modelled on the LINEAR system), and operating them in conjunction
with the other search efforts currently underway. Perhaps four to six of
the one-meter GEODSS telescopes, appropriately deployed around the Earth,
would suffice. However, while there have been discussions over recent years
about cooperation between NASA and the Air Force on the impact hazard,
nothing has yet materialized, so far as I am aware.

There have been recent press reports of NASA augmenting its funding of
search efforts to several million dollars a year. Such funding should bring
the existing projects up to speed, but will be inadequate for meeting
Spaceguard goals. It will be necessary either to build more, larger
telescopes, or to bring quite a few GEODSS telescopes out of their crates
in order for the survey to approach Spaceguard goals. These major efforts
must also be factored into the cost estimates.

And that is not all, not by a long shot. Finding new Earth-approaching
asteroids is just the beginning, not the end, of a responsible program for
understanding the implications of the new discoveries, for properly
alerting government officials and the public, and for establishing a
framework in which mitigation -- should it prove necessary -- can proceed
responsibly. Let me remind you of the sobering case of ten weeks ago.
Headlines around the world screamed that a 1-mile-wide asteroid might
strike the Earth in the year 2028. The next day, astronomers claimed that
newly found data showed that the disaster wouldn't happen after all.

That's what was reported in the press, but it is not exactly what happened.
We now realize that data were already collected two-and-a-half months
before March 11th, and published on the Internet, which were sufficient to
demonstrate that the asteroid called 1997 XF11 was certifiably safe: it
simply could not, realistically, impact the Earth. But months went by and
the few astronomers who are funded, part-time if at all, to study all the
new asteroid discoveries never had a chance to examine the data in detail.
When one underfunded astronomer suddenly noticed quirky data about 1997
XF11 in early March, his hasty response was to announce a possible impact.
Within hours, his colleagues finally looked at the data and concluded -- as
they just as well could have done months earlier -- that the object could
not possibly strike Earth in 2028.

There are several lessons to be drawn from this example. First, the
Spaceguard Survey needs more than telescopes and observers. It needs to
support enough people to keep track of the factor of ten higher discovery
rate, to make carefully researched orbital calculations, and to report
scrupulously doublechecked findings to the public in ways that place
discoveries in a rational, unhyped framework. I look forward, for example,
to the further development of an Impact Hazard Scale, somewhat analogous to
categories of hurricanes or to the Richter scale of earthquakes, so that
the scientific community, policy makers, and the public will have a common
language for discussing new discoveries. A preliminary scale has already
been devised by Dr. Richard Binzel of M.I.T.

An element of a discovery program is follow-up. Once an object is
discovered, it must be observed from time to time, so that it isn't lost
and so that its future orbit may be charted accurately. Currently, much of
the follow-up work is done by amateur astronomers or by professional
astronomers at small observatories. Little of this work is supported by
NASA; indeed popular groups like The Planetary Society have invested their
members' dues and contributions for such efforts. A serious program,
however, must seriously address follow-up; it must also use non-search
telescopes to measure the physical properties of potentially threatening
objects. Are they made of iron? Are they dead comets, perhaps with the
consistency of snowballs? Do they have swarms of moonlets circling around
them? If we are ever going to have to divert a threatening asteroid, we
will need a better understanding of what Earth-approaching asteroids are
really like.

I want to comment on asteroids smaller than the 1-kilometer or 1-mile wide
bodies with which we are mostly concerned (because of their potential to
destroy civilization). For every kilometer-sized body there are a thousand
others capable of 15-megaton impacts like the one that formed Meteor Crater
50,000 years ago or the 15-megaton blast over Tunguska in 1908. Dozens of
those are larger than average -- large enough to cause a devastating
tsunami, or tidal wave, capable of destroying cities around the entire
coastline of an ocean or, if one was to hit land, capable of destroying a
small state or nation. On the one hand, I worry less about these smaller
cosmic projectiles. Whereas one just might, disastrously, kill hundreds of
thousands of people, other kinds of natural disasters like great floods or
magnitude 8 earthquakes are 100 times more likely to kill such multitudes
than is an asteroid impact.

On the other hand, even while the Spaceguard Survey is targeting asteroids
larger than 1 km in diameter, it will be finding perhaps ten thousand
smaller Earth-crossing asteroids. We won't know immediately just how big
they are. There's an excellent chance that objects capable of causing a
Tunguska-like explosion will, a couple times a decade, pass within the
30,000-mile distance from the Earth that 1997 XF11 was originally predicted
to pass. One of them might well hit during the next century. And even
smaller objects can cause frightening blasts in the atmosphere, which might
even be falsely mistaken (e.g. in a location like the Indian subcontinent)
for a nuclear attack. The White House was reportedly alerted on Feb. 1,
1994, following impact of an object only the size of a small house (tens of
kilotons TNT equivalent energy), observed by a couple of fishermen in the
South Pacific but also recorded by downward-looking surveillance
satellites.

As the rates of discovery, of objects both large and small, goes up and the
public becomes more aware of the danger from the skies, it will be
essential that planetary protection be elevated from a sideline activity of
a few astronomers, and some passionate amateurs, and be put on a sound,
appropriately funded footing. The cost is not large. I believe that "Deep
Impact" has already taken in more money at the box office than the cost of
the entire Spaceguard Survey, from beginning to end. Astronomical programs
are comparatively cheap. The really large expenses involve implementing
mitigation hardware -- rockets and bombs. Fortunately that won't be
necessary until a threatening, mile-wide object is found to be headed
toward Earth... and then, surely, there will be no debate about using
nuclear weapons in space -- just once -- to save civilization from
catastrophe. The chances, however, are truly excellent that Spaceguard will
find no threatening asteroid headed our way, and we can all feel a little
more secure about our lives on what Carl Sagan called this "pale blue dot"
-- planet Earth.

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Statement of Dr. Carl Pilcher, Science Director, Solar System Exploration,
Office of Space Science, National Aeronautics and Space Administration

Mr. Chairman and Members of the Subcommittee:

I am pleased to have this opportunity to appear before the Subcommittee
today to discuss NASA's current efforts and future plans to inventory and
characterize the population of Near Earth Objects (NEOs).

BACKGROUND

This Committee has been a leader in focusing attention on the importance of
cataloging and characterizing Earth-approaching asteroids and comets. In
1992, the Committee on Science directed that NASA sponsor two workshop
studies, the NEO Detection Workshop, which was chaired by NASA, and the NEO
Interception Workshop, which was chaired by the Department of Energy. In
March 1993, the Science Committee held a hearing to review the results of
these two workshops. In 1995, at the Committee's request, NASA conducted a
follow-up study which was chaired by the late Dr. Gene Shoemaker. Each of
these studies stressed the importance of characterizing and cataloging NEOs
with diameters larger than 1 km within the next decade. We have taken steps
to put us on a path to achieving this goal. I am here today to tell you
about those steps, as well as to bring you up to date on the rich program
of space missions to NEOs and related objects.

The NEO population is derived from a variety of scientifically interesting
sources including planetessimal fragments and some Kuiper belt objects.
Indeed, the Office of Space Science Strategic Plan includes as a specific
goal " . . . to complete the inventory and characterize a sample of Near
Earth Objects down to 1 km diameter."  While the threat of a catastrophic
collision is statistically small, NASA has a vigorous program of
exploration of NEOs planned, including both asteroids and comets.

There has been much recent discussion about the potential threat posed by
NEOs, but NASA has long been interested in them from a scientific
standpoint. NEO investigations have had to compete for support against a
number of other compelling science programs; funding selection criteria
were based principally on scientific merit. This approach has led to the
detection of over 400 NEOs, including more than 100 objects larger than 1
km and to a rapid advancement of the technologies necessary for NEO
detection. In fact, this research effort has demonstrated that we can
inventory the NEO population in a reasonable time, about a decade, with an
achievable increase in funding from recent levels.

A little less than a year ago, NASA initiated a study of its existing NEO
research to determine how well we were doing in terms of reaching our goal
of inventorying the population of NEOs larger than 1 km and characterizing
a sample of them. While we have made some impressive strides, it became
apparent that the funding levels resulting from scientific competitive
review ($1-1.5 M per year) was not sufficient to accomplish our goal. The
detection of new NEOs in 1997, the last year for which we have statistics,
is barely 10% of the rate needed to achieve the goal suggested in the
Shoemaker report (detection of 90% of the NEO population larger than 1 km
within a decade). In simple terms, we need to survey about 20,000 square
degrees of sky a month for NEOs to a limiting brightness of approximately
20th magnitude to accomplish the inventory. To understand what this means,
note that 20,000 square degrees is about half the sky and that magnitudes
are a measure of apparent brightness-a 6th magnitude object is at the limit
of detection for the human eye and 20th magnitude is almost 100,000 times
fainter.

I would now like to describe briefly the existing search programs, NASA's
plans to improve them, and some promising new research programs which we
are considering. I will also comment on our joint activities with the Air
Force Space Command. All of these efforts are directed toward increasing
the rate of discovery of NEOs in order to reach our goal.

STATUS OF ONGOING SEARCH PROGRAMS

NASA's ground-based NEO program comprises three parts: Spacewatch, the
Near-Earth Asteroid Tracking (NEAT) program, and the Lowell Near Earth
Asteroid Survey (LONEOS).

Spacewatch

Spacewatch is a program at the University of Arizona, led by Dr. Tom
Gehrels, which has done much of the pioneering work in the field of NEO
detection. This group is responsible for more NEO discoveries than any
other. The current Spacewatch Program searches 200 square degrees of sky
per month to a depth of 21st magnitude. This year NASA is funding a new
state-of-the-art focal plane camera for Spacewatch, which will lead to an
8-fold increase in the area of sky that they search each month (to 1600
square degrees per month). We hope in the future to assist them in their
efforts to bring their new 1.8 m telescope on line. This telescope will
enable them to detect even fainter NEOs.

NEAT

NEAT is a program headed by Dr. Eleanor Helin at the Jet Propulsion
Laboratory. NEAT uses a specialized camera, which is based on a 4096x4096
CCD array for use on the 1 m GEODSS (Ground-based Electro-Optical Deep
Space Surveillance) telescope, operated by United States Air Force Space
Command (USAFSC) on Haleakala, Maui, Hawaii. This group is currently
limited by the number of nights per month on which they can observe the sky
using the GEODSS system. They are presently observing six nights per month
on one of the seven GEODSS telescopes. With recent improvements they are
now able to search 800 square degrees per night (4800 square degrees per
month) to about 20th magnitude. We have funded the construction of 2 more
cameras, which we hope to install on two other GEODSS telescopes. This
increase in the level of effort for NEO detection is being discussed in the
NASA-USAFSC Partnership Council co-chaired by NASA Administrator Daniel
Goldin and AFSC Commander Gen. Howell Estes. It is in principle possible to
scan 21,000 square degrees a month with three cameras and full access to
three of the GEODSS telescopes. It is important to note that the GEODSS
system includes one southern hemisphere site.

While we certainly hope to increase our surveying ability using the GEODSS
system, we are aware that it has other vital missions. NASA's FY 1999
budget request includes sufficient funding for the construction of four
more NEAT cameras, which will enable us to equip all seven GEODSS
telescopes. The final application of the funds will depend on the
demonstration that the NEAT camera can support the existing mission of the
GEODSS system as well as the search for NEOs. This matter is currently
being reviewed by the Partnership Council on NEOs.

LONEOS

LONEOS is led by Dr. Ted Bowell at Lowell Observatory in Flagstaff,
Arizona. This group has great potential (capability to observe 4,300 square
degrees a month down to 20th magnitude); however, they have not yet reached
this level of performance. We are funding an augmentation to buy a second
focal plane CCD and to support additional software development in order to
allow them to reach their performance objective.

NEW SEARCH PROGRAMS

The increased interest in the search for NEOs has led to several recent
proposals from new groups:

Catalina NEO Survey

We are supporting a new search program at the University of Arizona, which
is headed by Mr. Steven Larson, to refurbish an existing telescope on Mount
Lemon. When fully operational, this system will survey 8,000 square degrees
of sky per month to a depth of 19th magnitude. This program will be fully
operational within a year.

LINEAR

NASA is evaluating a proposal for support of a very promising search
program from the MIT Lincoln Labs. This effort called LINEAR (Lincoln Near
Earth Asteroid Research program) uses a state-of-the-art camera which was
developed as a possible prototype for the next generation GEODSS detector.
They are proposing to use a 1 m telescope at their Experimental Test Site
near Socorro, New Mexico, to survey 10,000 square degrees down to 21st
magnitude each month.

With coordination of these different observational programs, NASA believes
it is possible to obtain the level of sky coverage to the appropriate
limiting magnitude required to complete the survey. NASA has already
committed over $3M this year, much of it to fund improvements to focal
plane detectors, software, and electronics. NASA is committed to funding
both existing and new search programs at, at least, the FY1998 level. We
believe this is close to the level required to achieve our objective.

SPACE-BASED MISSIONS RELEVANT TO OUR UNDERSTANDING OF NEOs

The study of the physical characteristics of NEOs is a major focus of both
ground-based research and space missions. The ground-based work includes
NASA-supported radar imaging of NEOs utilizing the Arecibo Radio Telescope
and spectroscopy of NEOs from optical/IR telescopes to determine their
composition.

Several NASA missions will travel to asteroids and/or comets to provide us
with exciting new scientific insights about these objects at the same time
this information is valuable for any future effort to respond to an impact
threat. Over the next decade NASA will invest approximately $1B in these
missions. Missions in flight or in development are:

        NEAR, which will reach the near-Earth object Eros in January, 1999,
orbit for one year to measure its surface and interior properties, and then
land on Eros.

        CONTOUR, which will fly by a set of three short-period comets and
make the first detailed comparative study of cometary nuclei.

         STARDUST, which will return a sample from the coma of short-period
comet in 2006.

          ROSETTA, is a European Space Agency (ESA) mission to comet
P/Wirtanen. NASA is providing three ROSETTA orbiter instruments and support
to eight U.S. co-investigators on other orbiter instruments.

Missions soon to enter development are:

          MUSES-C/N with Japan to deploy a US-provided micro-rover on the
surface of an NEO and to return a sample of the asteroid to Earth in 2006.

           DS-4/Champollion to land on a comet, measure its composition,
test sampling and sample-return technologies for small bodies, and perhaps
even return a sample.

           Pluto/Kuiper Belt Express to survey one or more Kuiper belt
objects before deflection into the inner solar system.

CONCLUDING REMARKS

The issues and challenges posed by NEOs are inherently international, and
any comprehensive approach to addressing them must be international as
well. Central areas of concern include coordination among NEO observers and
orbit calculators around the globe and public notification should an object
posing a significant hazard to Earth be discovered. NASA has begun
discussing, with the international community, convening an international
workshop to address these issues. The workshop will likely be held during
the first half of 1999. The goal of this workshop will be to develop
international procedures and lines of communication to ensure that the best
available accurate information about any potentially hazardous object is
assembled and disseminated to the public in the shortest possible time.

To facilitate coordination among NASA-supported researchers, other agencies
and scientists, and the international community, NASA is establishing an
NEO Program Office. This Office will coordinate ground-based observations,
ensure that calculated orbital elements for NEOs are based on the best
available data and support NASA Headquarters in the continuing development
of strategies for the exploration and characterization of NEOs. In the
unlikely event that a potentially hazardous object is detected, the Office
would coordinate the notification of both the observing community and the
public of any potentially hazardous objects discovered.

NASA is committed to achieving the goal of detecting and cataloging 90% of
NEOs larger than 1 km in diameter within 10 years, and to characterizing a
sample of these objects. We are developing and building instruments, and
developing partnerships -- particularly with the Air Force -- which should
lead to the necessary detection and cataloging capability being in place in
1-2 years. This capability will also allow us to detect and characterize
many NEOs smaller than 1 km.

In summary, NASA's obligation and commitment is to ensure that we have the
information necessary to understand the hazards posed by NEOs.