Article: "Cameras capture 'fireball' in the sky"

"At 05:28 am on Wednesday morning, October 15, all seven cameras of Western's Southern Ontario Meteor Network (SOMN) recorded a bright, slow fireball in the predawn sky. In the all-sky view from Orangeville (below) the fireball passes from upper left (North) to right (West) ending near the setting moon (the brightest object at upper right)."

From the article...

For the second time this year, The University of Western Ontario Meteor Group has captured rare video footage of a meteor falling to Earth.

The team of astronomers suspects the fireball dropped meteorites in a region north of Guelph, Ont. that may total as much as a few hundred grams in mass. For high-resolution images, videos and maps, click here.

The Physics and Astronomy Department at Western has a network of all-sky cameras in southern Ontario that scan the sky monitoring for meteors.

On Wednesday, Oct. 15 at 5:28 a.m., all seven cameras of Western’s Southern Ontario Meteor Network recorded a bright, slow fireball in the predawn sky.

Associate Professor Peter Brown and Phil McCausland, a postdoctoral researcher in Planetary Science, are hoping to enlist the help of local residents in recovering one or more possible meteorites that may have crashed.

“This event was a relatively slow fireball that made it far into the Earth’s atmosphere. Most meteoroids burn up by the time they hit an altitude of 60 or 70 kilometres from the ground,” says McCausland, who is heading to the region next week to investigate.

“This one was tracked by our all-sky camera network to have penetrated to an altitude of about 37 kilometres and it slowed down considerably, so there is a possibility that at least one and possibly several small meteorites made it to the ground.”

By knowing the trajectory from the camera observations, the researchers can also track backwards to get the orbit of the object before it hit the Earth.

“The meteorite was on a typical Earth-crossing asteroid-type orbit, so we also expect that it is a stony-type meteorite,” says McCausland.

In March, the network of all-sky cameras captured video of a meteor falling to Earth that may have crashed in the Parry Sound area.

Cameras capture 'fireball' in the sky

Communications Staff
The University of Western Ontario
24 October 2008

Link: Article

Link: SOMN fireball event: 15 October 2008

2008 TC3 impact flash observations: Webcam?

From mpml....

Apparently, this Webcam about 725 km north of the impact site of 2008 TC3, in Egypt on the Red Sea, was looking the wrong way to see the actual impact flash. However, it does show foreground objects illuminated by the flash. There's a full-moon image provided for comparison, in which nothing is visible. The implication is that the meteor flash was probably much brighter than full moon intensity, even at a distance of 725 km.

The page also claims that the angle of illumination suggests that the meteor exploded about 33 km above the ground, after allowing for refraction and the earth's curvature. (Based solely on the distance between the Meteosat-8 image of the flash and where it was projected to hit the earth, I'd have thought a little lower than that, but could believe 33 km.)

I do wonder how a flash this bright could have gone unobserved elsewhere, but the images don't seem completely unreasonable.

- Bill J Gray (from online posting)

Link: MPML: 2008 TC3 impact flash observations

Link: Original Link (in German)

Link: Translation of above German article

Official Annoucement: on Asteroid Deflection Research Symposium from Iowa State's Asteroid Deflection Research Center (ADRC)

Here is the official announcement from Iowa State about the Iowa State University Asteroid Deflection Research Center (ADRC) and its first symposium entitled: "Asteroid Deflection Research Symposium"

"Iowa State research center sponsoring asteroid deflection symposium"
October 17, 2008

Ames, Iowa—The Iowa State University Asteroid Deflection Research Center (ADRC) is sponsoring an Asteroid Deflection Research Symposium on October 23–24, 2008, at Doubletree Hotel Crystal City-National Airport, Arlington, Virginia.

The purpose of this symposium is to exchange technical information and to develop an integrated multidisciplinary R&D program for asteroid deflection/fragmentation using high-energy as well as low-energy options, according to Bong Wie, the Vance D. Coffman Chair Professor in Aerospace Engineering at Iowa State and ADRC director.

Planetary defense researchers from such agencies as NASA, the U.S. Air Force, the Air Force Research Laboratory, the Defense Threat Reduction Agency, Sandia National Laboratories, Lawrence Livermore National Laboratory, and the National Research Council as well as industry and academia, plan to participate in the symposium. These are researchers who are currently involved in exploring and/or developing various options for asteroid deflection/fragmentation.

The ADRC was established at Iowa State last spring to coordinate and lead a research effort to address the complex engineering and science issues of asteroid deflection.

The collision of a moderately large asteroid or comet (also referred to as a near-Earth object) with Earth would have catastrophic consequences. Such events, Wie points out, have occurred in the past and will likely occur again in the future.

“For the first time in history,” he adds, “we have practically viable options to counter this threat, but there is no consensus on how to reliably deflect asteroids in a timely manner. This research symposium is a first step in bringing researchers together to discuss options and develop a roadmap for determining the best solution.”

The complete agenda is available at Asteroid Deflection Research Symposium. Please contact Dr. Bong Wie at bongwie@iastate.edu for further information.

Link: Iowa State Press Release

Link: Agenda: Asteroid Deflection Research Symposium

Paper on conventional explosive deflection of NEOs

Paper on conventional explosive mitigation of NEOs. This paper reflects some elements that were incorporated into a recent NASA NEO Analysis of Alternatives (AoA) report.

"Near-Earth object deflection using conventional explosives"
J.D. Walker and S. Chocron
International Journal of Impact Engineering (Article in Press)
Available online 5 August 2008

Abstract:
Due to the large number and distribution of asteroids and comets in the solar system, there is the distinct possibility of one of them striking Earth just as comet Shoemaker-Levy 9 struck Jupiter. A debate is ongoing in the scientific community as to how best to divert such a threat. In 2005 NASA was directed by Congress to provide a report on the detection of near-Earth objects (NEOs) and their mitigation if determined to be a threat. The report was delivered in March 2007; as input to that report, the work reported here provided information on conventional methods to divert a potentially hazardous object (PHO) including conventional explosives and direct impact with a rocket. Other slow push conventional approaches include propulsion systems attached to the asteroid or comet and the recently proposed gravitational tractor. Advantages of conventional explosives are that they can be delivered in small packages so that the asteroid or comet is in no danger of being broken up and it is possible to accurately compute the momentum transferred to the asteroid or comet through modern validated numerical techniques. This work demonstrates that conventional explosives can be an efficient conventional method to divert an asteroid or comet and computes the amounts of explosives needed.

Link: ScienceDirect Paper

Elements on NASA Authorization Act of 2008 Related to NEOs

As President Bush in the United States has just signed the NASA Authorization Act of 2008, let me quote the elements of the legislation dealing with NEOs:

Link: National Aeronautics and Space Administration Authorization Act of 2008 (Enrolled as Agreed to or Passed by Both House and Senate

H.R.6063
National Aeronautics and Space Administration Authorization Act of 2008 (Enrolled as Agreed to or Passed by Both House and Senate)

TITLE VIII--NEAR-EARTH OBJECTS

SEC. 801. REAFFIRMATION OF POLICY.

(a) Reaffirmation of Policy on Surveying Near-Earth Asteroids and Comets- Congress reaffirms the policy set forth in section 102(g) of the National Aeronautics and Space Act of 1958 (42 U.S.C. 2451(g)) (relating to surveying near-Earth asteroids and comets).

(b) Sense of Congress on Benefits of Near-Earth Object Program Activities- It is the sense of Congress that the near-Earth object program activities of NASA will provide benefits to the scientific and exploration activities of NASA.

SEC. 802. FINDINGS.

Congress makes the following findings:

(1) Near-Earth objects pose a serious and credible threat to humankind, as many scientists believe that a major asteroid or comet was responsible for the mass extinction of the majority of the Earth's species, including the dinosaurs, nearly 65,000,000 years ago.

(2) Several such near-Earth objects have only been discovered within days of the objects' closest approach to Earth and recent discoveries of such large objects indicate that many large near-Earth objects remain undiscovered.

(3) Asteroid and comet collisions rank as one of the most costly natural disasters that can occur.

(4) The time needed to eliminate or mitigate the threat of a collision of a potentially hazardous near-Earth object with Earth is measured in decades.

(5) Unlike earthquakes and hurricanes, asteroids and comets can provide adequate collision information, enabling the United States to include both asteroid-collision and comet-collision disaster recovery and disaster avoidance in its public-safety structure.

(6) Basic information is needed for technical and policy decisionmaking for the United States to create a comprehensive program in order to be ready to eliminate and mitigate the serious and credible threats to humankind posed by potentially hazardous near-Earth asteroids and comets.

(7) As a first step to eliminate and to mitigate the risk of such collisions, situation and decision analysis processes, as well as procedures and system resources, must be in place well before a collision threat becomes known.

SEC. 803. REQUESTS FOR INFORMATION.

The Administrator shall issue requests for information on--

(1) a low-cost space mission with the purpose of rendezvousing with, attaching a tracking device, and characterizing the Apophis asteroid; and

(2) a medium-sized space mission with the purpose of detecting near-Earth objects equal to or greater than 140 meters in diameter.

SEC. 804. ESTABLISHMENT OF POLICY WITH RESPECT TO THREATS POSED BY NEAR-EARTH OBJECTS.

Within 2 years after the date of enactment of this Act, the Director of the OSTP shall--

(1) develop a policy for notifying Federal agencies and relevant emergency response institutions of an impending near-Earth object threat, if near-term public safety is at risk; and

(2) recommend a Federal agency or agencies to be responsible for--

(A) protecting the United States from a near-Earth object that is expected to collide with Earth; and

(B) implementing a deflection campaign, in consultation with international bodies, should one be necessary.

SEC. 805. PLANETARY RADAR CAPABILITY.

The Administrator shall maintain a planetary radar that is comparable to the capability provided through the Deep Space Network Goldstone facility of NASA.

SEC. 806. ARECIBO OBSERVATORY.

Congress reiterates its support for the use of the Arecibo Observatory for NASA-funded near-Earth object-related activities. The Administrator, using funds authorized in section 101(a)(1)(B), shall ensure the availability of the Arecibo Observatory's planetary radar to support these activities until the National Academies' review of NASA's approach for the survey and deflection of near-Earth objects, including a determination of the role of Arecibo, that was directed to be undertaken by the Fiscal Year 2008 Omnibus Appropriations Act, is completed.

SEC. 807. INTERNATIONAL RESOURCES.

It is the sense of Congress that, since an estimated 25,000 asteroids of concern have yet to be discovered and monitored, the United States should seek to obtain commitments for cooperation from other nations with significant resources for contributing to a thorough and timely search for such objects and an identification of their characteristics.

NASA's Spitzer Space Telescope Views Comet Holmes

From JPL news...


NASA's Spitzer Space Telescope captured the picture on the left of comet Holmes in February 2008, four months after the comet suddenly erupted and brightened a millionfold overnight. The contrast of the picture has been enhanced on the right to show the anatomy of the comet.

Every six years, comet 17P/Holmes speeds away from Jupiter and heads inward toward the sun, traveling the same route typically without incident. However, twice in the last 116 years, in November 1892 and October 2007, comet Holmes mysteriously exploded as it approached the asteroid belt. Astronomers still do not know the cause of these eruptions.

Spitzer's infrared picture at left reveals fine dust particles that make up the outer shell, or coma, of the comet. The nucleus of the comet is within the bright whitish spot in the center, while the yellow area shows solid particles that were blown from the comet in the explosion. The comet is headed away from the sun, which lies beyond the right-hand side of the picture.

The contrast-enhanced picture on the right shows the comet's outer shell, and strange filaments, or streamers, of dust. The streamers and shell are a yet another mystery surrounding comet Holmes. Scientists had initially suspected that the streamers were small dust particles ejected from fragments of the nucleus, or from hyerpactive jets on the nucleus, during the October 2007 explosion. If so, both the streamers and the shell should have shifted their orientation as the comet followed its orbit around the sun. Radiation pressure from the sun should have swept the material back and away from it. But pictures of comet Holmes taken by Spitzer over time show the streamers and shell in the same configuration, and not pointing away from the sun. The observations have left astronomers stumped.

The horizontal line seen in the contrast-enhanced picture is a trail of debris that travels along with the comet in its orbit.

The Spitzer picture was taken with the spacecraft's multiband imaging photometer at an infrared wavelength of 24 microns.

Image credit: NASA/JPL-Caltech

Link: NASA JPL Article

Updated Impact Information for 2008 TC3

Ground path of the meteoroid over Sudan. The red line is the object's path, terminating where it would have hit the ground. The green line is the infrasound detection of the object's explosion. METEOSAT IR fireball location indicated by orange crosshairs. Predicted altitude as the object crossed the Nile River and several other points are listed. Exact path and fireball altitude have not been confirmed. (Source: http://en.wikipedia.org/wiki/2008_TC3)


Meteosat 8 / EUMETSAT IR image of the 2008 TC3 explosion. Copyright 2008 EUMETSAT. (Source: http://en.wikipedia.org/wiki/2008_TC3)

Link: Meteosat-8 Rapid Scan captures asteroid impact (09 October 2008)

JPL Gravity Tractor Analysis For B612

From JPL NEO...

Near-Earth Object (NEO) Analysis of Transponder Tracking and Gravity Tractor Performance.
October 2008

A study, requested and funded by the B612 Foundation, was carried out by JPL scientists to determine the feasibility of using a gravity tractor concept for use in NEO impact mitigation and to build credibility for the concept. Using a hypothetical Earth impacting asteroid, simulations and analyses were carried out; this report presents the analysis results arising from an investigation into the:

* facility with which a spacecraft can be safely maintained in close proximity to an irregularly shaped, rotating asteroid (even a very simple control law allows proximity spacecraft operations).

* rapidity with which optical navigation and ground-based spacecraft radio tracking can be used to precisely determine the asteroid's current and future trajectories (only a few days/weeks of tracking are necessary).

* viability of using an impacting spacecraft to provide enough of a velocity change (deflection) to avert an Earth collision several years in the future (this is a viable primary deflection concept for the most common hazardous asteroids).

* density and sizes of so-called "keyholes" near the Earth. At an Earth close approach, a keyhole passage by an asteroid would ensure a subsequent Earth collision (a few % of deflected impactors may also require trajectory trimming to avoid a keyhole).

* utility of a gravity tractor in preventing the asteroid from entering one of these keyholes should the primary deflection attempt inadvertently push the NEO into it (a gravity tractor is a viable concept for trajectory trimming to avoid most keyholes).

This work, requested and funded by the B612 Foundation, was carried out by JPL scientists and engineers in the Guidance, Navigation and Control Section (343): D.K. Yeomans, S. Bhaskaran, S.B. Broshart, S.R. Chesley, P.W. Chodas, M.A. Jones, and T.H. Sweetser.

The complete report is available here (Word Document - 4.4 MB)

Link: JPL NEO News Article

Minor Planet Mailing List (MPML) Has Multiple 2008 TC3 Items

There are multiple posts on the Minor Planet Mailing List about 2008 TC3.

Some sample information includes the following:

We have received a set of photometric data taken by Marek Kozubal and Ronald Dantowitz at the Clay Center Observatory, Dexter School, MA, spanning about 2 hours. In addition to a dramatic trend of about 2.5 magnitudes brightening, the data show a very clear periodicity of about 0.9 magnitude amplitude and a simple period of 49 seconds, or a double period of 98 seconds. Thus Richard's analysis is just about right, within his stated error estimate. After de-trending the data and examining a longer time series, it appears that the variation is not simply periodic, but instead the object appears to be in a non-principal axis spin state, or "tumbling". There are a few other tumbling super-fast rotators, so this is not a unique case. It will take a bit more time for a careful analysis, since aspect is changing as fast as the brightness, so there may need to be a "de-trending" of the time series applied as well.

Alan Harris (Senior Research Scientist, Space Science Institute) and Brian Warner

Link: Minor Planet Mailing List (MPML)

Link: Post

Summary from the Planetary Society on 2008 TC3

Good summary from the Planetary Society on 2008 TC3.

To briefly review: the night before last (my time), or at 06:38 UTC on October 6, astronomers at the University of Arizona discovered an object provisionally called 8TA9D69 that appeared to be on a collision course with Earth. Three other observatories reported sightings within the next few hours -- Sabino Canyon and Siding Spring in Arizona and a Royal Astronomical Society site in Moorook, Australia. Together these four observers provided enough data on the object so that a Minor Planet Electronic Circular was issued at 14:59 UTC the same day, giving 8TA9D69 the more formal name 2008 TC3, and advising the astronomical community that "The nominal orbit given above has 2008 TC3 coming to within one earth radius around Oct. 7.1. The absolute magnitude indicates that the object will not survive passage through the atmosphere. Steve Chesley (JPL) reports that atmospheric entry will occur on 2008 Oct 07 0246 UTC over northern Sudan."

Link: The Planetary Society

2008 TC3 (Additional Updates)

From SpaceWeather.com

(Updated Oct. 8th) On Oct. 7th, asteroid 2008 TC3 hit Earth and exploded in the atmosphere over northern Sudan. An infrasound array in Kenya recorded the impact: map. Dr. Peter Brown of the University of Western Ontario has inspected the data and he estimates that the asteroid hit at 0243 UTC with an energy between 1.1 and 2.1 kilotons of TNT. The explosion was imaged by the weather satellite Meteosat 8:

"The explosion was visible in all 12 of the satellite's spectral channels, covering wavelengths from 0.5 to 14 microns," says Jiri Borovicka
of the Czech Academy of Sciences, who is analyzing the data. "The satellite takes pictures every five minutes; the fireball appeared at 0245 UTC and had faded away by 0250 UTC."

So far, no ground pictures of the fireball have been submitted; the impact occurred in a remote area with few and possibly no onlookers capable of recording the event. The only report of a visual sighting comes from Jacob Kuiper, General Aviation meteorologist at the National Weather Service in the Netherlands:

"Half an hour before the predicted impact of asteroid 2008 TC3, I informed an official of Air-France-KLM at Amsterdam airport about the possibility that crews of their airliners in the vicinity of impact would have a chance to see a fireball. And it was a success! I have received confirmation that a KLM airliner, roughly 750 nautical miles southwest of the predicted atmospheric impact position, has observed a short flash just before the expected impact time 0246 UTC. Because of the distance it was not a very large phenomenon, but still a confirmation that some bright meteor has been seen in the predicted direction. Projected on an infrared satellite image from Meteosat 7, I have indicated the position of the plane (+) and the predicted impact area in Sudan (0)."

2008 TC3 was discovered on Oct. 6th by astronomers using the Mt. Lemmon telescope in Arizona as part of the NASA-funded Catalina Sky Survey for near-Earth objects. Asteroids the size of 2008 TC3 hit Earth 5 to 10 times a year, but this is the first time one has been discovered before it hit.

BONUS: 2008 TC3 was so close to Earth, different observers around the globe saw the asteroid trace different paths among the stars. This effect, called parallax, is beautifully illustrated in a compilation of 566 published observations prepared by Matthias Busch: image.

Link: SpaceWeather.com

JPL: "Impact of Asteroid 2008 TC3 Confirmed"

Impact of Asteroid 2008 TC3 Confirmed
Don Yeomans
NASA/JPL Near-Earth Object Program Office
October 7, 2008

Confirmation has been received that the asteroid impact fireball occurred at the predicted time and place. The energy recorded was estimated to be 0.9 to 1.0 kT of TNT and the time of detection was 02:45:45 on October 7 (Greenwich Standard Time). More details on this detection will be forthcoming. An additional confirmation was apparently reported by a KLM airliner (see: http://www.spaceweather.com/). As reported by Peter Brown (University of Western Ontario, Canada), a preliminary examination of infrasound stations nearest to the predicted impact point shows that at least one station recorded the event. These measurements are consistent with the predicted time and place of the atmospheric impact and indicate an estimated energy of 1.1 - 2.1 kT of TNT.

The follow-up astrometric observations from professional and sophisticated amateur astronomers alike were rather extraordinary, with 570 observations from 26 observatories being reported between the time of discovery by the Catalina Sky Survey to just before the object entered Earth's shadow (57 minutes prior to impact). All this happened in less than 19 hours!

Link: JPL NEO Site Press Release: Impact of Asteroid 2008 TC3 Confirmed

Update on 2008 TC3 Impact

From SpaceWeather.com...


Projected on an infrared satellite-image of Meteosat-7 of 0300 UTC, indicated the position of the plane (+) and the predicted impact area in Sudan (0)."


Image credit: Peter Brown, University of Western Ontario

ASTEROID IMPACT--UPDATE: Asteroid 2008 TC3 hit Earth this morning, Oct. 7th, and exploded in the atmosphere over northern Sudan. An infrasound array in Kenya recorded the impact. Dr. Peter Brown of the University of Western Ontario has inspected the data and he estimates that the asteroid hit at 0243 UTC with an energy between 1.1 and 2.1 kilotons of TNT. Most of the 3-meter-wide space rock should have been vaporized in the atmosphere with only small pieces reaching the ground as meteorites.

No pictures of the fireball have been submitted; the impact occurred in a remote area with few and possibly no onlookers capable of recording the event. So far, the only report of a visual sighting comes from Jacob Kuiper, General Aviation meteorologist at the National Weather Service in the Netherlands:

"Half an hour before the predicted impact of asteroid 2008 TC3, I informed an official of Air-France-KLM at Amsterdam airport about the possibility that crews of their airliners in the vicinity of impact would have a chance to see a fireball. And it was a success! I have received confirmation that a KLM airliner, roughly 750 nautical miles southwest of the predicted atmospheric impact position, has observed a short flash just before the expected impact time 0246 UTC. Because of the distance it was not a very large phenomenon, but still a confirmation that some bright meteor has been seen in the predicted direction. Projected on an infrared satellite-image of Meteosat-7 of 0300 UTC, I have indicated the position of the plane (+) and the predicted impact area in Sudan (0)."

2008 TC3 was discovered on Oct. 6th by astronomers using the Mt. Lemmon telescope in Arizona as part of the NASA-funded Catalina Sky Survey for near-Earth objects. Asteroids the size of 2008 TC3 hit Earth 5 to 10 times a year, but this is the first time one has been discovered before it hit.

pre-impact images: from Paolo Beltrame of CAST Astronomical Observatory, Talmassons, Italy; from Eric Allen of Observatoire du Cegep de Trois-Rivieres, Champlain, Québec; from Ernesto Guido et al. of Remanzacco Observatory, Italy; from S.Korotkiy and T.Kryachko of Kazan State University Astrotel observatory, Russia;

Link: SpaceWeather.com

NEO News (10/07/08) First reports on Sudan bolide

From Dave Morrison...

NEO News (10/07/08) First reports on Sudan bolide

While I have not yet seen any eyewitness accounts from ground observers in Africa, here are two early reports that the bolide (now designated as asteroid 2008 TC3, surely the shortest-lived asteroid name, since it was destroyed a few hours after the name was given) did explode in the atmosphere above Sudan early this morning.

David Morrison

==============================

From Peter Brown (pbrown@uwo.ca): A very preliminary examination of several infrasound stations proximal to the predicted impact point for the NEO 2008 TC3 has yielded one definite airwave detection from the impact. The airwave was detected at the Kenyian Infrasonic Array, (IMS station IS32), beginning near 05:10 UT on Oct 7, 2008 and lasting for several minutes. The signal correlation was highest at very low frequencies - the dominant period of the waveform was 5-6 seconds. The backazimuth of the signal over the entire 7 element array is shown in the attached map - it clearly points to within a few degrees of the expected arrival direction. Moreover, assuming a stratospheric mean signal speed of 0.28 km/s, the arrival time corresponds to an origin time near 02:43 UT, which is consistent with the expected impact time near 02:45:40 UT given expected variations in stratospheric arrival speeds. The dominant period of 5-6 seconds corresponds to an estimated energy (using the AFTAC period at maximum amplitude relationship from ReVelle, 1997) of 1.1 - 2.1 kilotons of TNT. The five other closest infrasound stations were briefly examined for obvious signals and showed none - more detailed signal processing of these additional data are ongoing in the search for additional signals.

Peter Brown
Canada Research Chair in Meteor Science
University of Western Ontario, London, ON

=============================

From Spaceweather.com: ASTEROID IMPACT--UPDATE: Asteroid 2008 TC3 hit Earth this morning, Oct. 7th, and exploded in the atmosphere over northern Sudan. An infrasound array in Kenya recorded the impact. Dr. Peter Brown of the University of Western Ontario has inspected the data and he estimates that the asteroid hit at 0243 UTC with an energy between 1.1 and 2.1 kilotons of TNT. Most of the 3-meter-wide space rock should have been vaporized in the atmosphere with only small pieces reaching the ground as meteorites.

No pictures of the fireball have been submitted; the impact occurred in a remote area with few and possibly no onlookers capable of recording the event. So far, the only report of a visual sighting comes from Jacob Kuiper, General Aviation meteorologist at the National Weather Service in the Netherlands:

"Half an hour before the predicted impact of asteroid 2008 TC3, I informed an official of Air-France-KLM at Amsterdam airport about the possibility that crews of their airliners in the vicinity of impact would have a chance to see a fireball. And it was a success! I have received confirmation that a KLM airliner, roughly 750 nautical miles southwest of the predicted atmospheric impact position, has observed a short flash just before the expected impact time 0246 UTC. Because of the distance it was not a very large phenomenon, but still a confirmation that some bright meteor has been seen in the predicted direction.

=============================

Erik Asphaug of University of California, Santa Cruz, asks rhetorically: How would the US respond if the identical impact was forecast over, say, Bozeman? On the one hand we expect that the public would behave themselves, but some in the discussion felt that the public would freak out entirely out of proportion.

David Morrison comments: This issue of public response to a very small impact has been discussed previously, including mention in three of my papers (see below), but in fact no one knows the answer. The issue is important because impacts this small are relatively common:

Morrison, D., R. Binzel, C.R. Chapman, and D. Steel, "Impacts and the Public: Communicating the Nature of the Impact Hazard." In Mitigation of Hazardous Comets and Asteroids (M. Belton, T. Morgan, N. Samarasinha & D. Yeomans, eds.). Cambridge University Press, Cambridge (2004).

Morrison, D. "Defending the Earth against Asteroids: The Case for a Global Response," Science and Global Security 13:105-116 (2005).

Morrison, D. "The Impact Hazard: Advanced NEO Surveys and Societal responses," In Comet/Asteroid Impacts and Human Society (P. Bobrowsky & H. Rickman, eds.) Springer, New York (2007)

--
+++++++++++++++++++++++++++++++++++++++++++

NEO News (now in its fourteenth year of distribution) is an informal compilation of news and opinion dealing with Near Earth Objects (NEOs) and their impacts. These opinions are the responsibility of the individual authors and do not represent the positions of NASA, Ames Research Center, the International Astronomical Union, or any other organization. To subscribe (or unsubscribe) contact dmorrison@arc.nasa.gov. For additional information, please see the website http://impact.arc.nasa.gov. If anyone wishes to copy or redistribute original material from these notes, fully or in part, please include this disclaimer.

Animation of impact from the asteroid's point of view

From the website:

We [Pasquale Tricarico of the Planetary Science Institute] has prepared a short animation, showing the Earth as viewed by the asteroid 2008 TC3. The asteroid is reaching Earth from the night side, and enters the Earth's shadow cone around 1:50 UTC.

Link: Animation of impact from the asteroid's point of view (Pasquale Tricarico of the Planetary Science Institute)

2008 TC3 (Images and Video)

From Astronomy.com blog:
First images of asteroid 2008 TC3
Posted 10-07-2008 by Matt Quandt

This morning, the husband and wife observing team of Imelda Joson and Edwin Aguirre forwarded to Astronomy an image and an animation of the asteroid 2008 TC3 they received from amateur astronomer friends in Italy. Imelda runs an image service company and is a contributor to Astronomy magazine.

"Here's a sequence of photos and animation of 2008 TC3 taken by our astronomer friends in Italy," Imelda writes. "They're among the first (if not the first) amateur images of the object."

Link: Video of October 6 asteroid 2008 TC3 (Astronomy.com)

Link: First images of asteroid 2008 TC3 (Astronomy.com blog)

Video Reports on 2008 TC3

From JPl News:



An asteroid measuring several feet in diameter is expected to enter the atmosphere over northern Sudan before dawn Tuesday, setting off a potentially brilliant natural fireworks display. (Oct. 6)
Link: YouTube Video

From KTVUTV (California):



MOUNTAIN VIEW: Lloyd LaCuesta Reports On First Successful Asteroid Impact Forecast
Link: YouTube Video

From CelestiaDev (YouTube):



Final few minutes of asteroid 2008 TC3 before it burns up in Earth's atmosphere. Trajectory of 2008 TC3 from HORIZONS. Green circle indicates area of Earth's surface where the asteroid appears above the horizon.
Link: YouTube Video



The view from asteroid 2008 TC3 in the minutes before it enters Earth's atmosphere. The point of entry is on the night side of Earth, so the brightness of Earth has been enhanced for the visualization. We don't know what the shape of 2008 TC3, so I've substituted a model of the asteroid Itokawa. The time rate is 20x normal.
Link: YouTube Video

From walcom77 (YouTube):



Animation showing the motion of small asteroid 2008 TC3 few hours before to enter Earth atmosphere. Images obtained at Remanzacco Observatory by G. Sostero, E. Guido & V. Gonano
Link: YouTube Video

From observatorij (YouTube):



A tiny asteroid 2008 TC3 was discovered by astronomers a day before it entered the atmosphere in Northern Sudan and exploded. The video shows animated motion between the stars few hours before the impact. Images taken from the Črni Vrh Observatory in Slovenia with a 60 cm telescope and a CCD camera. http://www.observatorij.org
Link: YouTube Video


From gusmul1 (YouTube):



imagenes en video de la noche del 6-10-2008 del asteroide con menor vida conocida en el mundo de la astrometria. colisionó con la atmósfera terrestre sobre sudan. g
Link: YouTube Video

2008 TC3 Update

Overhead view showing 2008 TC3's trajectory to Earth. Tick marks are in 15 minute increments.


Movie showing the discovery images of 2008 TC. Images taken at around 06:30 UTC on October 6, 2008. The asteroid was at 19th magnitude and moving at 2.5 degrees per day. Image Credit: Richard Kowalski and Ed Beshore, Catalina Sky Survey

Small Asteroid Predicted to Cause Brilliant Fireball over Northern Sudan
Don Yeomans
NASA/JPL Near-Earth Object Program Office
October 6, 2008

A very small, few-meter sized asteroid, designated 2008 TC3, was found Monday morning by the Catalina Sky Survey from their observatory near Tucson Arizona. Preliminary orbital computations by the Minor Planet Center suggested an atmospheric entry of this object within a day of discovery. JPL confirmed that an atmospheric impact will very likely occur during early morning twilight over northern Sudan, north-eastern Africa, at 2:46 UT Tuesday morning. The fireball, which could be brilliant, will travel west to east (from azimuth = 281 degrees) at a relative atmospheric impact velocity of 12.8 km/s and arrive at a very low angle (19 degrees) to the local horizon. It is very unlikely that any sizable fragments will survive passage through the Earth's atmosphere.

Objects of this size would be expected to enter the Earth's atmosphere every few months on average but this is the first time such an event has been predicted ahead of time.

Update - 6:45 PM PDT (1 hour prior to atmospheric entry)

Since its discovery barely a day ago, 2008 TC3 has been observed extensively by astronomers around the world, and as a result, our orbit predictions have become very precise. We estimate that this object will enter the Earth's atmosphere at around 2:45:28 UTC and reach maximum deceleration at around 2:45:54 UTC. These times are uncertain by +/- 15 seconds or so. The time at which any fragments might reach the ground depends a great deal on the physical properties of the object, but should be around 2:46:20 UTC +/- 40 seconds.

Link: Press release from the Near-Earth Object Project Office at NASA JPL

Link: Minor Planet Center

NEO News (10/06/08): Bolide impact predicted

From Dave Morrison's NEO news

NEO News (10/06/08) Bolide impact predicted tonight!

This is a first: a very small asteroid (or rock) has been discovered that is on course for an impact tonight in Sudan. This information is from various reports to posted to MPML (the Minor Planet Mailing List at groups.yahoo.com/group/mpml/). The impactor is only about 2 m across and will break up in the atmosphere, with no risk to those on the ground. (If something this size hit in the daytime, it would probably not be noticed, but at night it should put on quite show).

Alan Harris writes that this object, with the survey-assigned designation 8TA9D69, was discovered by the University of Arizona Mt. Lemmon survey and will almost certainly, tonight, become the first impacting bolide discovered before entry into the Earth's atmosphere. Steve Chesley (JPL) reports that atmospheric entry will occur on 2008 Oct 07 0246 UTC over northern Sudan.

Andrea Milani of the University of Pisa wrote the following: Today the object with the provisional designation 8TA9D69 was submitted to impact monitoring by using the normal software of the NEODyS system, by using the observations as reported by the MPC on the NEO Confirmation Page. Based on 26 optical observations from 2008/10/06.278 to 2008/10/06, the probability of impact is between 99.8% and 100%; in practice the impact can be considered sure and is for tonight. Our computation has already been confirmed independently by others, including the JPL NEO Program Office (with which we consult in all relevant cases of possible impact). The effect of this atmospheric impact will be the release, in either a single shot or maybe a sequence of explosions, of about 1 kiloton of energy. This means that the damage on the ground is expected to be zero. The location of these explosions is not easy to predict due to the atmospheric braking effects. The only concern is that they might be interpreted as something else, that is man-made explosions. Thus in this case, the earlier the public worldwide is aware that this is a natural phenomenon, which involves no risk, the better.

This is the first time an asteroid impact has been predicted, and it reflects the increasing capability of the Spaceguard Survey. There was one previous false alarm when, for a few hours around Christmas 2004, it appeared that an impact by a 30-m asteroid was possible, but this was ruled out by additional observations. The current case, however, seems much more solid.

David Morrison

Moonshield: Game Trailer

Moonshield is a management/strategy game which projects the player into the near future, where he or she will have to use signature Thales technologies to defend the Earth from a deadly meteor shower that could destroy all civilization.

Link: YouTube Video