An International Workshop on Collaboration and Coordination Among NEO Observers and Orbital Computers
Kurashiki City Art Museum, Kurashiki, Okayama, Japan
October 23 to 26, 2001
A PROGRESS REPORT ON SPACEWATCH
University of Arizona
The purpose of the Spacewatch program is to explore the statistics of
asteroids and comets as a continuation with CCDs of the
photographic Yerkes-McDonald and Palomar-Leiden surveys.
The 0.9-meter f/5 Newtonian telescope currently surveys 3000 square
degrees per year to a V magnitude limit of 21.7. The 0.9-meter is
about to be reconfigured with wider field (f/3) prime-focus optics and
an array of four 2048x4608 CCDs. It will continue the limit of V =
21.7 for the surveying, but in stare mode with six times higher rate of
sky coverage, probably yielding 300 detections of Earth-approachers,
old and new, per year.
Astrometry with the 1.8-m telescope began in April of 2001 with a
field of view 0.8 degrees (diagonal of the CCD). The 1.8-meter will
continue to be dedicated to surveying and follow-up of NEOs that are
in urgent need.
SPACEWATCH WEBSITE AND RECENT PUBLICATIONS
Bottke, W. F., R. Jedicke, A. Morbidelli, J. Petit, and B. Gladman,
2000. "Understanding the Distribution of Near-Earth
Asteroids." Science, 288: 2190-2194.
Bottke, W.F., A. Morbidelli, R. Jedicke, J-M. Petit, H. Levison, P.
Michel, and T.S. Metcalfe, 2001. "Debiased orbital and size
distributions of the near-Earth objects. Icurus, in press.
Durda, D. D., R. Greenberg, and R. Jedicke, 1998. "Collisional
Models and Scaling Laws: A New Interpretation of the Shape
of the Main-belt Asteroid Size Distribution" Icarus 135:
Gehrels, T. 1998. "Detecting Asteroids" Meteorite 2: 18-20 and 3:
Gehrels, T. 1999. "A review of comet and asteroid statistics." Earth,
Planets, Space 51: 1155-1161
Gehrels, T. 2001 "Collisions with Comets and Asteroids." Sc.
American, Decade Choice, in press.
Gehrels, T. 2002. "The Attraction of Asteroids." In Asteroids III, eds.
W. Bottke, A. Cellino, P. Paolicchi, and R. P. Binzel, 2002.
(Univ. Ariz. Press), in press.
Gehrels, T. and L. Ksanfomality. 2000. "The Search for
Earth-Approaching Comets and Asteroids". Solar System Res.
Jedicke, R. and T. S. Metcalfe. 1998. "The Orbital and Absolute
Magnitude Distributions of Main Belt Asteroids." Icarus 131:
Jedicke, R., J. Larsen, and T. Spahr. 2002. "Observational Selection
Effects in Asteroid Surveys and Estimates of Asteroid
Population Sizes" In Asteroids III, eds. W. Bottke, A. Cellino,
P. Paolicchi, and R. P. Binzel (Univ. Ariz. Press), in press.
Larsen, J., A. E. Gleason, N. M. Danzl, A. S. Descour, R. S.
McMillan, T. Gehrels, R. Jedicke, J. L. Montani, and J. V.
Scotti. 2001. "The Spacewatch Wide Area Survey for Bright
Centaurs and Transneptunian Objects." Astron. J. 121,
McMillan, R. S. 1999. "The Spacewatch Search for Material
Resources Near Earth." Space Manufacturing 12: Challenges
and Opportunities in Space: ProC. Fourteenth Space Studies
Inst. Princeton Conference on Space Manufacturing, ed. B.
Greber (SSI Publ. Princeton, NJ), 72-75.
Ostro, S. J., P. Pravec, L. A. M. Benner, R. S. Hudson, L. Sarounova,
M. D. Hicks, D. L. Rabinowitz, J. V. Scotti, D. J. Tholen, M.
Wolf, R. F. Jurgens, M. L. Thomas, J. D. Giorgini, P. W.
Chodas, D. K. Yeomans, R. Rose, R. Frye, K. D. Rosema, R.
Winkler, and M. A. Slade. 1999. "Radar and Optical
Observations of Asteroid 1998 KY26." Science 285: 557-559.
Perry, M. L., T. H. Bressi, R. S. McMillan, A. F. Tubbiolo, and L. D.
Barr 1998. "The 1.8m Spacewatch Telescope Motion Control
System." Proc. SPIE 3351, Telescope Control Systems III,
Scotti, J. V. 1998. "Fleeting Expectations: The Tale of an Asteroid."
Sky and Tel. 96, 1: 30-34.
THE LOWELL OBSERVATORY
Lowell Observatory, Flagstaff, Arizona, U.S.A.
The Lowell Observatory Near-Earth-Object Search (LONEOS)
currently uses a 59-cm Schmidt telescope to discover asteroids and
comets that can approach the Earth.
In terms of discovery of larger (> 1 km diameter) NEOs, our search
effort has, over the past two years, been the second most effective
program worldwide (after LINEAR). As of the end of April 2001, we
have discovered 6 Atens, 35 Apollos, 36 Atens, and 13 comets. In
three years, we have submitted some 920,000 astrometric
observations to the Minor Planet Center. About a year ago, we
installed a new Lowell-built camera containing two 2048 x 4096
thinned, back-illuminated chips. Compared to the old camera, the
new camera has a shorter read time (12 s vs. 45 s), a higher peak
DQE (85%), lower read noise, and far fewer defects. A larger field
size (of 8.1 deg2), adoption of new observing techniques, and the
application of a better source-detection algorithm have together led to
a 7-fold increase in NEO detection rate compared to that at the
beginning of 2000.
The LONEOS Schmidt and its operation are now almost fully mature.
During the coming year we will implement an image-subtraction
method of moving-object detection, which will allow us to work at
smaller galactic latitudes; and we will work on exploiting archived
images for moving-object data mining. In October 2001, we expect to
begin a collaboration with scientists at the U.S. Naval Observatory
Flagstaff Station, using a new mosaic camera on their 1.3-m
telescope. If we use 45-s integrations, we should cover 60 deg2/hr to
V_lim = 21.0 mag. Rough modeling indicates that we should detect
between 2 and 3 times more NEAs per unit time compared to the
current LONEOS Schmidt's performance. Depending on the time
available on the 1.3-m, we should, at the beginning of 2002, double
or triple our current discovery rate. In 2005, we expect the Next
Generation Lowell Telescope to come online. Planned as a 4-m, f/2.4
reflector having a 3.2 deg2 fov, we should attain hourly coverage of
about 50 deg2 to V_lim = 22.3 mag, yielding an NEA detection rate
100 times greater than that of the LONEOS Schmidt.
Grant H. Stokes and Jenifer B. Evans
The Lincoln Near Earth Asteroid Research (LINEAR) program has
applied electro-optical technology developed for Air Force Space
Surveillance applications to the problem of discovering Near Earth
Asteroids (NEAs) and comets. LINEAR, which started full
operations in March of 1998, has discovered through August of 2001,
682 NEAs, 36 unusual objects, and 65 comets. Over the past 3 years,
LINEAR is contributing ~70% of the world-wide NEA discovery
This talk reviews the performance statistics of the LINEAR system
addressing the system's sky coverage, detection statistics, and
contribution to NASA's congressionally mandated goal of
discovering 90% of all large NEAs by 2008.
This work is sponsored by the Dept. of the Air Force and NASA
under Air Force Contract No. F19628-00-C-0002. Opinions,
interpretations, conclusions and recommendations are those of the
authors and are not necessarily endorsed by the United States Air
STATUS OF THE CATALINA SKY SURVEY AND
S. Larson, C. Hergenrother, R. Whiteley, T. Kelly, R. Hill, and Rob
Lunar and Planetary Laboratory, University of Arizona
*Siding Spring Observatory, Australian National University
The Catalina Sky Survey, down for over a year for upgrades, is now
coming back on-line. Upgrades to the Mt. Lemmon 1.5-m telescope
are also underway to provide more routine astrometric follow-up and
physical observations of the fainter NEOs. During our surveying
haitus, we have been obtaining lightcurve and colors of NEOs, and
several monolithic very fast rotators have been identified among the
The Uppsala Schmidt at Siding Spring Observatory (SSO), Australia
is undergoing modifications to provide a similar survey capability at
high southern declinations not covered by the northern hemisphere
surveys. Critical astrometric observations of PHAs observable from
the southern hemisphere are being made with the SSO 1-m telescope.
We will describe the current status of the upgrades and anticipated
improvements in coverage and depth of surveying. This work is
supported by NASA's Near Earth Object Observation program.
ASTEROID OBSERVATIONS IN BISEI SPACEGUARD
Makoto Yoshikawa and BATTeRS
Bisei Spaceguard Center (BSGC) is a facility to observe near earth
asteroids and space debris. It was built by Japan Space Forum (JSF)
in 1999, and since the beginning of the year of 2000, observations
have been carried out by Japan Spaceguard Association (JSGA) with
the financial support from National Space Development Agency of
Japan (NASDA). At present (July 2001), two small telescopes (25 cm
and 50 cm) are working for test observations. Up to now, we found
one Apollo type asteroid (20826) 2000 UV13, which is the second
brightest one in the Apollo type asteroids. In addition to this we
found more than 100 new asteroids. They are main belt asteroids,
because the limiting magnitude of the system in the test phase is
about 18.5. However, in the summer of 2001, the 1.0 m telescope will
be installed in BSGC. Then we will start full observations.
THE ONDREJOV NEO FOLLOW-UP PROGRAMME:
LIGHTCURVE AND ASTROMETRIC OBSERVATIONS OF
I will review the NEO Follow-Up Programme conducted at the
Ondrejov Observatory of the Astronomical Institute of the Czech
Academy of Sciences since 1993. The observations are made with the
0.65-m telescope equipped with inexpensive, small-field CCD
cameras, currently a thinned CCD with a FOV of 18'x18' and the
limiting effective V magnitude of 20.5 for a 3-min integration time
with no filter. The observational program consists of two main parts:
(1) lightcurve observations of NEAs in favorable conditions (often
shortly ---days and weeks--- after their discoveries); (2) astrometric
observations of newly discovered NEOs, mostly NEO candidates
from the MPC's NEO Confirmation Page. Lightcurve observations
are aimed to derive rotational properties of NEAs and to reveal their
possible binary nature. We have derived rotation periods for nearly
100 NEAs during the past seven years, that is more than half of all
known NEA rotation periods. We have detected two-period
lightcurves that reveal their binary nature for several NEAs. We also
provide a support to radar and IR observations of NEAs --- lightcurve
data are often an important addition to their data allowing their better
interpretation and derivation of better models. As more and more
NEAs are to be discovered, the importance of their physical
follow-up is expected to further increase, and we plan to continue our
lightcurve observations at a rate only limited by a number of
available targets and a number of observing nights available to us. A
collaboration with other stations doing similar observations has been
quite fruitful in past and it is expected to further increase.
Astrometric observations of NEOs are an important complementary
program --- since they can often be completed rapidly (normally in
several minutes), we can utilize short breaks in photometric series to
switch to astrometric observations of NEOCP and other objects in a
need of follow-up. The astrometry is also a useful program for (parts
of) nights when there is no suitable photometric target on our list. We
pay attention to estimating reliable magnitudes of the astrometric
targets from the unfiltered images.
Observations within the Ondrejov NEO Programme are done on
every (at least partly) clear night throughout each lunation except
+/-3 days around full moon when moonlight is too strong. We attempt
to maximize our time availability for the NEO follow-up, and we also
coordinate our observations with several other European stations
through a special NEO Coordination Page that allows us to better
allocate observational resources when there occurs too many targets
to follow-up on the NEOCP than we can observe at a given time.
With a suitable coordination of the follow-up observations with other
stations, I believe that we shall be able to comply with a several-fold
increase of the demand of follow-up of NEA discoveries up to V=20
to 20.5 (depending mainly on an apparent motion of the objects) in
near future. We would appreciate keeping and amending a standard
way of exchange of the information on NEO discoveries, best
through the MPC's NEOCP to which we have optimized our software.
Whenever a new discovery of a potential NEO appears on the
NEOCP before or during our observing night, we always put it
immediately on a top of our priority observing list and do it at the
earliest suitable moment.
The Ondrejov NEO Programme is done in close collaboration with
the Astronomical Institute of the Charles University in Prague,
co-investigator M. Wolf. The Ondrejov Observatory Asteroid Group
currently consists of four people that devote a full or part of their
worktime to the project (equivalent 2.8 people): P. Kusnirak and L.
Sarounova, observers who do most of the observations (and not only),
M. Velen, who develops some key parts of our software, and me as
the principal investigator. A couple more people are expected to join
us for a part of their worktime in near future. A future advance of our
programme is critically dependent on an availability of more
financial resources, mostly for people salaries. Among (nonfinancial)
rewards to our observers, there is, besides their satisfaction that they
contribute to the very interesting field of astronomy, a possibility to
propose names for their (accidentally) discovered new (main belt)
asteroids; a follow-up of them is therefore a third, supplementary part
of our programme being done at suitable moments as allowed by the
two main tasks described above.
KLET NEO FOLLOW-UP ASTROMETRIC PROGRAMME
J. Ticha, M. Tichy and M. Kocer
Zatkovo nabrezi 4
CZ-370 01 Ceske Budejovice
Near-Earth Objects (NEOs) belong to the most fascinating bodies in
the solar system. These small bodies have the capability of making
close approaches to or even collide with the Earth. The number of
known Near-Earth Objects has increased enormously in recent years
due to LINEAR and other large surveys (Spacewatch, LONEOS,
NEAT and CSS). This discovery process has to be followed by
follow-up observations to obtain a sufficient number of precise
astrometric data needed for an accurate orbit determination of newly
discovered bodies. About forty per cent of the known NEOs have
been observed for more than one opposition.
The Klet Observatory has pursued NEO follow-up CCD astrometry
since 1994. This follow-up programme covers confirmatory
observations of newly discovered NEO candidates, continues over a
sufficient observing arc of NEOs in the discovery apparition and also
considers testing of newly discovered NEOs for possible cometary
activity. A very important part of this programme are NEO recoveries
in the second convenient apparition. A special attention is given to
the Potentially Hazardous Asteroids (PHAs).
We discuss here methods, techniques and results of the Klet NEO
follow-up CCD astrometric programme using 0.57-m telescope. The
present magnitude limit of this programme is about V=20 mag. The
Klet Observatory is one of the most productive world sites in this
We also mention ways for selecting useful and important targets for
NEO follow-up astrometry.
Finally we present here a planned extension of Klet NEO programme
to fainter objects by means of larger, 1-m telescope, which is being
built at Klet now. An increasing magnitude limit of NEO surveys as
well as a need for astrometric data for fainter objects (observations in
a longer arc, recoveries, cases of "virtual impactors" etc.) shows that
NEO observations need more observing time on larger telescopes,
and we hope to help.
M. Tichy, J. Ticha and M. Kocer
Zatkovo nabrezi 4
CZ-370 01 Ceske Budejovice
Considering the critical points of NEO astrometry we have decided to
extend the Klet Observatory NEO follow-up programme to fainter
objects using a new 1.06-meter reflector equipped with a more
efficient CCD camera. This KLENOT Project started in 1997/1998.
The KLENOT project is a project of the KLEt observatory Near earth
and Other unusual objects observations Team (and Telescope),
concentrating particularly on fainter objects, up to a limiting
magnitude of V = 22.0.
The planned main goals of project KLENOT are confirmation and
follow-up astrometry of newly discovered NEOs, recoveries of NEOs
in the second opposition, and follow-up astrometry of poorly
observed NEOs and other unusual objects.
For the proposed project we are building the new 1.06-m KLENOT
telescope. We present here the current status of the KLENOT Project.
A NEO SURVEY IN THE SOUTHERN HEMISPHERE:
BUSCA - Busqueda Uruguaya de Satelites, Cometas y Asteroides
Tancredi G.(1), Sosa A.(1) (2), Acosta E.(2) & Ceretta A.(2)
(1)Depto. Astronomia, Fac. Ciencias, Montevideo, URUGUAY
(2)Observatorio Astronomico "Los Molinos", Ministerio de
Educacion y Cultura, URUGUAY
The surveys looking for Near-Earth Objects have been concentrated
up to the moment in the northern hemisphere. None of the existing
surveys reach declinations southern than 30deg, therefore more than
25% of the celestial sphere is not covered by any project.
Almost none of this programs include searches in the nearby region
to the Sun, instead they generally look at the opposition region. As an
important consequence, several NEOs, specially those which orbits
interior to the Earth (Atens), are lost; as well as an important portion
of the new comets, those coming from the Oort cloud with perihelion
distances of the order of 1AU. The only search programs in this
region are the amateurs visual searches, principally from Japan, USA
and Europe. These programs are dedicated to the search for comets
(not asteroids), and its efficiency has remained practically constant
since the last century (10 comets per year) since they have not
improved the method (visual telescopic search).
Recognizing this North-South asymmetry several groups have urged
to build new facilities in the southern hemisphere (e.g. the NASA -
NEO Survey Group, the UK Task Force on NEOs, the Spaceguard
Foundation, the IAU Working Group on NEOs, etc.).
The Dept. of Astronomy (University of Uruguay) and the
Observatorio Astronomico "Los Molinos" (Code 844) have got a
small research grant to install a new survey telescope in the
countryside of Uruguay (Latitude 34S). The installation of a search
program in our latitude will be an important contribution to the
discovery of new objects. It is also intended to cover especially the
deficiencies of the actual programs, i.e. the region close to the Sun
where Aten like objects and long period comets should be found.
We will start our survey with a telescope in the lower range of the
already existing surveys, i.e. diameter about 45cm. Software to
completely automatize the telescopes will be installed.
The telescope will be installed in a Touristic Ranch in the Province of
Maldonado at an altitude of 300m (Long. 55W Lat. 34S). It is a very
dark site without public electricity and no populated towns at distance
less than 40 km.
We plan to start the observations before the end of 2001.
With a 45cm telescope and a dark sky, we expect to reach a limiting
magnitude of ~19 in images without filter. During the main part of
the night we plan to cover the region of declinations between -30 and
60deg. Furthermore, in the summer, when we have the better weather,
the opposition region in ecliptic reaches -23deg increasing the
chances to detect low-inclination asteroids. In the twilight we plan to
search for Aten and long period comets. Since the visual amateurs
searchs do not reach magnitudes fainter than 12, with a CCD survey
we expect to find fainter objects.
Follow-up observations of the discovered objects will be done from
the 35cm telescope already installed at the OALM.
Due to the fact that it will be possible to detect objects fainter than in
the amateur searches and in consideration to the North-South
asymmetry, the installation of a searching program in South America
will be an important contribution in the number of discoveries as well
as it will succeed in mending in part the present selection effects.
NEO FOLLOW-UP AT MAUNA KEA OBSERVATORY
D. J. Tholen, University of Hawaii
The following facilities are available at Mauna Kea Observatory for
astrometric follow-up of NEOs. The University of Hawaii 2.24-m
telescope has two CCD cameras, a Tektronix 2048x2048 device
offering a 7.5 arcmin field of view at the f/10 Cassegrain focus of the
telescope, and a mosaic incorporating eight Loral 2048x4096 devices
(8192x8192 overall format) that covers about 19 arcmin. Single
exposure limiting magnitude for the former device is dependent on
the seeing, but has reached about V=24.5 under excellent conditions.
The mosaic camera currently has thick chips, therefore the quantum
efficiency isn't as high as for the Tektronix device, with a
correspondingly brighter limiting magnitude of about V=23 under
good conditions. The camera will be upgraded with thinned chips in
the coming months. We also have a proposal to the National Science
Foundation for a focal reducer, whose design would increase the field
of view of the mosaic camera to about 32 arcmin. The telescope itself
has excellent non-sidereal tracking capabilities and can theoretically
track on an object moving several hundred arcsec per sec. In practice,
the fastest object observed with the new control software was moving
a little over 1 arcsec per sec (2001 EC16 on 2001 March 24). An
autoguider is also available, though limits on the movement of the
pick-off mirror could restrict the length of an exposure on a
sufficiently fast moving object. However, unguided exposures of 300
sec duration have yielded excellent results. Recent follow-up
observations have pushed the telescope to its software zenith distance
limits of 75 deg (about 3.8 airmasses). Given adequate manpower,
this telescope could be used for NEO follow-up observations for at
least two nights a month.
The Canada-France-Hawaii Telescope has a mosaic camera with
twelve thinned Lincoln Labs 2048x4096 devices (12288x8192
overall format) that subtend 42x28 arcmin at the telescope's prime
focus. Readout time is 50 sec when using no binning and 20 sec when
binned 2x2 (producing an effective pixel size of 0.4 arcsec). The
single exposure limiting magnitude is about 26. Due to heavy
demand on this large-aperture telescope, opportunities to do
follow-up astrometry are limited.
The Subaru telescope is still in its commissioning phase. The primary
wide-field imaging device, SuPrime, is currently undergoing an
upgrade to its detectors. Ten thinned Lincoln Labs 2048x4096
devices (10240x8192 overall format) provide a 30x24 arcmin field of
view at the telescope's prime focus. The expected limiting magnitude
should be fainter than 27. It is unlikely that this system would be
allocated for routine follow-up work, but for special cases, such as
those involving objects with non-zero collision probabilities, one can
expect that a compelling scientific case could be made for sufficient
telescope time to perform the observation.
During my presentation, I will summarize recent follow-up activities
utilizing the facilities above. Since 2000 November, heavy use has
been made of the Spaceguard Central Node's "Menu of
Opportunities" to select objects that utilize these facilities to best
advantage. Through March, approximately 50 objects fainter than
magnitude 20 have been selected from this list and successfully
observed. The principal reason for a failed observation has been due
to crowded star fields at low galactic latitude.
STATUS OF NEO INITIATIVES AROUND THE WORLD
Andrea Carusi, President, The SPaceguard Foundation
The status of on-going or planned initiatives concerning NEOs is
reviewed in this presentation. Particular attention is given to
international initiatives involving major international organizations.
Both scientific and political initiatives are considered, including
approved and/or proposed space missions. The current and future
activities of The Spaceguard Foundation are also examined, and its
future role discussed.
NEO FOLLOW-UP COORDINATION ACTIVITIES OF THE
NODE: RESULTS AND GENERAL RECOMMENDATIONS
Andrea Boattini, Germano D'Abramo and Giovanni Valsecchi
I.A.S - Planetologia, Area di Ricerca CNR,
via Fosso del Cavaliere 100, I-00133 Roma, Italy.
In the past year and a half the Spaceguard Central Node (SCN) has
provided support for the astrometric follow-up activities of Near
Earth Objects (NEOs), in particular of newly-discovered objects.
Several services, updated on a daily basis, have been developed: the
most important is the Priority List, which classifies the need to
observe newly-discovered NEOs, into four categories. Following
these suggestions, the relative number of lost NEOs has been
significantly reduced. In order to address the impact hazard more
accurately, we have also organized several campaigns regarding
targets with non-zero collision probabilities, thanks to the feedback
supplied by the teams involved in collision predictions: this has also
included targeted observations of several virtual impactors for1998
OX4, currently the biggest such lost NEO. The recent case of 2000
SG344 has demonstrated the need of such targeted work, and, once
more, the need for all the programs to save their own archives: CCD
archival resources promise to offer the information that the
photographic ones cannot. A recent feature of the SCN is a general
monitoring of both search and follow-up activities: a monthly
summary report provides suggestions for improving current and
NASA'S NEAR-EARTH OBJECT PROGRAM OFFICE
Donald K. Yeomans, Ronald C. Baalke, Alan B. Chamberlin, Stephen
R. Chesley, Paul W. Chodas, Jon D. Giorgini, Michael S. Keesey
( JPL/Caltech, Pasadena, CA, USA) and Ravenel N. Wimberly (User
Technology Associates, Inc., Pasadena, CA, USA).
In early 1999, NASA established its Near-Earth Object Program
Office at the Jet Propulsion Laboratory, with the stated objectives to:
* Facilitate communications within the observing community and
between the community and the public with respect to any
potentially hazardous objects.
* Establish and maintain a catalog of Near-Earth Objects (NEOs) and
provide information on their future close Earth approaches and
Earth impact probabilities.
* Help coordinate ground-based observations in order to complete the
Spaceguard Goal of discovering 90% of the Near-Earth Asteroids
(NEAs) larger than one kilometer within a ten year period.
* Support NASA Headquarters in coordinating with other
government agencies and with foreign governments and
international organizations on NEO issues.
* Develop and support a strategy and plan for the scientific
exploration of NEOs including their discovery, recovery,
ephemerides, characterization, in-situ investigations, and resource
Significant progress has been made on all of these objectives. An
award winning interactive NEO web site has been established
(http://neo.jpl.nasa.gov/) to communicate information to the scientific
community and public. An automatic update process has been
established for all NEOs. As new astrometric data become available
for a particular NEO, its orbit is automatically updated and future
close Earth approach circumstances determined - including impact
probabilities when appropriate. At timely intervals, metrics are
generated and displayed on the web site to track the contributions of
each NASA supported search site toward meeting the Spaceguard
Goal. Significant efforts to coordinate the nightly search for NEAs
within the United States have been undertaken and efforts to further
coordinate these NEA search efforts are underway. In an effort to
facilitate the coordination of NEO activities on an international scale,
fruitful interactions have taken place with personnel of the British
Task Force, the Spaceguard Foundation, the Japanese Spaceguard
Foundation and the international Organization for Economic
Cooperation and Development (OECD).
NEO RESEARCH AND THE IAU
Hans Rickman, Uppsala Astronomical Observatory
(IAU General Secretary)
Since 1998 the IAU has taken a much more active role than
previously in supporting NEO research initiatives on the international
scale as well as facing its responsibility, as the world's leading
international organization of professional astronomers, to deal
properly with informing society and the public about the results -
including such that may cause concern. While I believe that
significant progress has been achieved, in part within the framework
of the Working Group on Near-Earth Objects that will not be covered
in detail in this talk, much surely remains to be done. I will present a
survey of ongoing initiatives where the IAU takes part, aiming to
emphasize a broadening perspective of its involvement.
MISSIONS TO NEO, THE MUSES-C AND INTERNATIONAL
The Institute of Space and Astronautical Science (ISAS),
3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan.
As the number of Near Earth Objects (NEO) has increased through
the recent intensive and extensive search efforts, while the potential
impact of them to the Earth has raised not only scientific but also
social and cultural concern, there are proposed direct missions
opportunities to those objects, which the specialists believe provides
the intimate and straight forward information on how those objects
has evolved and what material those are made of. As a concrete
incarnation of them, the Institute of Space and Astronautical Science
(ISAS) of Japan started its great challenge that the human has ever
embarked on, the MUSES-C, the world's first sample and return
mission from extra terrestrial objects. What made the MUSES-C
mission enabled derives from not only the innovative high efficiency
electric propulsion system aboard but also the recent discovery and
identification of the NEO objects.
The Earth history itself is that of the NEO objects impacts, and in
other words, the inspection, analysis and examination of those Near
Earth Asteroids and Comets are sure to disclose some key clues to the
questions of where the ocean comes from and where the life is
originated and the like. The only information available so far in
regard to those questions is the meteorites on the ground and the
telescopic and remote observation of those objects that are seen as
one point in the sky. Therefore, the direct visit to those objects does
connect the correlation between those two and will be extended to
understand about much more objects in the solar system.
However, in view of the technological aspects on the sample and
return have still a lot of difficulties which have prevented from
realization until today. Those are, as already mentioned, the
revolutionary electric propulsion, the highly autonomous guidance
and navigation function, the surface sample collection method and
the recovery method. As a result, the engineering demonstration of
those new technologies is essential and the MUSES-C is about to be
launched one year ahead of today. The author believes the mission
does open the new type of interplanetary exploration door and will
contribute to understanding even the social and cultural aspects of
having the NEO closely flying with our Earth.
The paper presents, first of all, the MUSES-C project time line and its
development and current status. The spacecraft is launched in
November to December of 2002 and accumulates the orbital energy
via what we call the Electric Delta-V Earth Gravity Assist technique
including the Earth swing by on May of 2004, making a rendezvous
with the asteroid in summer of 2005, leaving the asteroid for Earth in
the end of 2005, followed by the sample recovery on the Earth in
June of 2007. The round trip flight period is four and a half years.
Every flight hardware has been already fabricated and ready now and
the flight model integration starts from December of this year. The
mission, while it is an engineering demonstration mission, carries the
scientific instruments aboard, which are visible camera, near infra-red
spectrometer as well as X-ray fluorescent spectrometer in addition to
the laser altimeter and the sample collector. The spacecraft releases
its robotic lander on the surface.
The project has developed the tight collaboration with NASA of
United States from the moment the project started in 1996. From the
engineering point of view, ISAS had to develop the thermal
protection system for the reentry capsule and the ISAS deep space
antenna cannot have a long time tracking of the spacecraft due to the
geographical reason. Talking about the scientific aspects, ISAS thinks
that having the NASA scientists participate in the sample analysis is
the complementary benefit to ISAS, and NASA thinks participation
in the orbiter carried instruments has benefit to it. Currently, both
NASA and ISAS have established the collaboration frame and are
working together toward the joint effort. For this purpose, the joint
science working group was built two years before and has been held
annually or on request.
The science information that may be obtained through the mission is
very precious to the world. And as the story above indicates, this kind
of project consists of very sophisticated technologies. It should be
stressed that every mission like the MUSES-C had better look for the
international collaboration as much as possible to these aims. When
the spacecraft is sent to the comets that may preserve the original
intact material in its nuclei, the information provided will advance the
human being knowledge in a wide variety fields. The paper discusses
what kind of exploration scenarios may be found and will give the
perspectives on the international collaboration structure as for the
missions foreseen to the NEOs.
NEOs AND THE MINOR PLANET CENTER
Brian G. Marsden, Harvard-Smithsonian Center for Astrophysics,
Cambridge, Massachusetts, U.S.A.
Following the receipt of reports of candidate NEOs by the Minor
Planet Center, tentative ephemerides and their uncertainties are
placed in the internet on The NEO Confirmation Page (NEOCP).
These ephemerides are revised as follow-up observations are received,
and when an orbit computation is reasonably assured, and it is
tolerably clear whether the object is asteroidal or cometary, the MPC
designation, full complement of observations, credits to the observers
and orbital elements accompany an updated ephemeris on a Minor
Planet Electronic Circular (MPEC). The NEOCP also notes the
disposition of the NEO candidates, including those deemed lost or
not to exist, with in the cases of real and confirmed objects the
correspondence of the temporary and MPC designations and
reference to the MPEC number, if relevant. As yet more follow-up
observations are received these and further revisions to the orbital
elements are included in the Daily Orbit Update MPECs. Another
detailed MPEC is also issued when observations of a given NEO are
located at a second opposition, whether found by identification,
precovery or recovery. Definitive documentation of the information is
contained, as appropriate, in the monthly Minor Planet Circulars
(MPC), the (currently) twice-monthly Minor Planet Circulars
Supplement (MPS) and the monthly Minor Planet Circulars Orbit
Supplement (MPO), as well as in the Minor Planet Center's databases
of astrometric observations, orbital elements and identifications.
COLLISION PROBABILITY COMPUTATION USING
K. Muinonen (1,2), J. Virtanen (2), M. Kaasalainen (2),
and T. Laakso (2)
(1) Observatory of Turin, Pino Torinese, Italy
(2) Observatory, University of Helsinki, Finland
We compute collision probabilities based on the true six-dimensional
orbital-element probability density, that is, the full solution of the
statistical inverse problem of astrometric observations. The highlights
include the general nonlinear assessment of the 1997 XF11
Earth-collision probability in 2028: using maximum likelihood
collision orbits, that is, best-fit orbits that allow a collision, the
collision probability turned out to be negligible. Furthermore, we
succeeded in computing a fully six-dimensional collision probability
for asteroid 1998 OX4 with a strongly non-Gaussian orbital-element
probability density. Although 1998 OX4 is currently lost, the
collision solutions have been eliminated by negative observations
coordinated by the Spaceguard Central Node. Our orbit computation
techniques are under constant development: recently, we have put
forward a general computational technique entitled statistical orbital
ranging, have pointed out that without securing the invariance of the
non-Gaussian orbital analyses, the collision probability may be off by
a factor of several, have developed methods for the evaluation of the
so-called linear approximations, and are developing fast numerical
integrators particularly suitable for collision probability computation.
We review the various computational techniques, covering linear and
nonlinear approximations and the essentially rigorous statistical
AN ANALYTIC THEORY OF RESONANT RETURNS
IAS-CNR, Roma, Italy
An important aspect of NEO monitoring is the possibility to predict
the location, shape and size of impact keyholes. In Italy, over the last
two years, an extension of Opik's theory of close encounters has been
developed, by the explicit introduction of the nodal distance and of a
time coordinate. Assuming a keplerian unperturbed heliocentric
motion between consecutive close encounters it is possible to
compute the initial conditions for an encounter as functions of the
outcomes of a previous one; in this way a completely analytical
theory of resonant returns is obtained. It turns out that the initial
conditions of a close encounter that lead to a resonant return lie close
to easily computable circles on the b-plane of that encounter. With
the further assumption that the nodal distance varies uniformly with
time, due to secular perturbations, the location, shape and size of
impact keyholes can be computed.
THE ESA OPTICAL SURVEY FOR SPACE DEBRIS IN THE
T. Schildknecht(1), R. Musci(1), M. Ploner(1), S. Preisig(1),
J. de Leon Cruz(2)
(1) Astronomical Institute, University of Bern, Sidlerstrasse 5,
CH-3012 Bern, Switzerland
(2) Instituto de Astrofisica de Canarias, 38200 La Laguna,
It has been suspected since a long time that the geostationary ring
may contain a population of small debris objects. The current
catalogue population, e.g. from the US Space Command catalogue, is,
however, limited to objects larger than about 1 m2. In view of this
situation, several space agencies started to perform optical
observations of the GEO ring under the auspices of the Inter-Agency
Space Debris Coordination Committee (IADC). The European Space
Agency (ESA) initiated its own program for optical observations of
space debris using a 1 m Ritchey Chretien telescope on Tenerife
After a first test survey of 13 nights in 1999 the ESA telescope is
routinely used for GEO surveys since January 2001. We will present
the search strategies, the object detection and data reduction
procedures of the surveys. The results clearly confirm the substantial
population of small objects in the size range from 1 to 0.1 m which
was first detected in the 1999 test survey. Furthermore for the first
time a clear signature of 'clouds' of faint objects has been seen which
can be most easily explained by single sources or events.
OVERVIEW OF NASDA'S ORBIT ANALYSIS SYSTEM - FOR
A CASE OF SPACE DEBRIS
Kazuaki Nonaka, Mikio Sawabe(NASDA), Takao Yokota(JSF),
Syuzo Isobe(JSGA), Nariyasu Hashimoto(JSGA), and Masaya
NASDA requests the Bisei Spaceguard Center (BSGC) to observe
space debris for the purpose of an investigation of space debris
environment. BSGC is developed by Japan Space Forum, and
operated by Japan Spaceguard Association.
NASDA has acquired observation data of space debris obtained by
BSGC since February 2000, and has developed an orbit analysis
system for space debris for the debris observation and determination.
At present some geostationary objects are regularly observed and
some objects on transfer orbit and low earth orbit (LEO) are
experimentally observed. One of the experimentally observations,
MIR the Russian space station was carried out a controlled de-orbit
last March, was observed using simple observation system at BSGC.
As a result of the MIR's orbit determination using observation data
for three days, we ware confirmed that the determined orbit is useful
for an orbit prediction to track the MIR from BSGC.
On the other hand, NASDA will launch the Laser Ranging
Equipment (LRE) in this summer that has 50cm in diameter and will
be injected into a transfer orbit. So we will observe LRE at BSGC for
a study of small satellite visibility and the orbit determination.
In the near future, we will survey all the zone around GEO
observable from BSGC. Then we will be able to put about two
hundred geostationary objects in a catalog. On the other hand, we
have a plan to make coordinated observation programs using both of
BSGC and KSGC. KSGC is the Kamisaibara Spaceguard Center, a
radar observation facility at Kamisaibara, will be ready for operation
This paper shows an overview of NASDA's orbit analysis system,
some results of orbit determination for space debris and Ideas of
BSGC future observations.
RECENT STATUS AND EVALUATION OF NASDA ORBIT
- FOR A CASE OF SPACE DEBRIS
Masafumi Yoshimura, Masaya Kameyama, Shiro Ishibashi (Fujitsu Ltd.)
Kazuaki Nonaka, Mikio Sawabe (NASDA),
Syuzo Isobe, Nariyasu Hashimoto (JSGA)
and Takao Yokota(JSF)
Japan Space Forum (JSF) is now constructing two kinds of facilities
for observing Near Earth Objects (NEO) and space debris. Optical
observation using telescopes with diameter of 0.5m and 1m is
performed at Bisei Spaceguard Center (BSGC), and operation with
0.5m telescope has already started since 2000.
A phased array radar equipment of Kamisaibara Spaceguard Center
(KSGC) will be completed in 2003. By using these observation data,
National Space Development Agency of Japan (NASDA) has a plan
to determine the orbit of space debris.
Optical and radar observation data are transferred to the data
processing center at Tsukuba Space Center (TKSC). At TKSC these
data are used for orbit determination, and resultant orbital elements
are stored in a database.
From orbital data, observation planning and orbit prediction are
performed, and these results are used for the next observations at
BSGC and KSGC.
For this one and a half year, NASDA has evaluated orbit
determination results using optical data from BSGC. A few days
observation data give a sufficient orbit determination precision in
case of near-geostationary objects.
Residuals of observed angle data after estimation are consistent with
the seeing size of optical data. These results show the quality of
observed data from BSGC and the validity of the orbit determination
system at TKSC.
In this paper the outline of NASDA orbit determination system is
described, and typical results of orbit determination of
near-geostationary objects are presented.