This area will cover relevant news of the threat to the planet from Near Earth Objects (NEOs) including concepts and designs for mitigation. All opinions are those of the author.

26 December 2008

Article: China starts building world's largest radio telescope

From the article...

GUIYANG, Dec. 26 (Xinhua) -- China officially started construction of a Five-hundred-meter Aperture Spherical Telescope (FAST), the largest in the world, in a remote southwest region on Friday.
Preparation and research for the project took some 14 years.

The dish-like telescope, as large as 30 football fields, will stand in a region of typical Karst depressions in Guizhou Province when it's done in 2013.

Karst depressions are usually located in regions plentiful in limestone and dolomite, where groundwater has enlarged openings to form a subsurface drainage system.

The facility will greatly improve China's capacity for astronomical observation, according to the National Astronomical Observatory (NAO), the major developer of the program.

FAST's main spherical reflector will be composed of 4,600 panels. Its observation sensitivity will be 10 times more powerful than the 100-m aperture steerable radio telescope in Germany. Its overall capacity will be 10 times larger than what is now the world's largest (300 m) Arecibo radio telescope developed by the United States, according to Nan Rendong, the chief scientist of the project and an NAO researcher.

The project, costing more than 700 million yuan (102.3 million U.S. dollars), will allow international astronomers and scientists to discover more of the secrets of the universe based on cutting-edge technologies, said Zhang Haiyan, an NAO official in charge of construction.

Scientists have so far observed only 1,760 pulsars, which are strongly magnetized spinning cores of dead stars. With the help of FAST, they could find as many as 7,000 to 10,000 within a year, Nan said.

Pulsars have allowed scientists to make several major discoveries, such as confirmation of the existence of gravitational radiation as predicted by the theory of general relativity.

FAST could also be a highly sensitive passive radar to monitor satellites and space debris, which would be greatly helpful for China's ambitious space program.

The telescope could also help to look for other civilizations by detecting and studying communication signals in the universe.

Chinese scientists and officials selected Dawodang, Pingtang County as the site, where a Karst valley will match the shape of the huge bowl-like astronomical instrument.

The sparsely populated, underdeveloped region will provide a quiet environment to ensure the electromagnetic waves, the crucial requirement of operation, are not interrupted by human activities.

Construction of a new residential area about 60 km away also began on Friday to relocate 12 households. By 2013, when the telescope is to be in operation, all 61 farmers will move to their new houses in Kedu town, with farmland allocated by the government.

"The project is beyond my imagination. I'm glad to see that an ordinary old guy like me could contribute to the country's science program," said Yang Chaoli, 68.

The project was approved by the National Development and Reform Commission, the country's top planning body, the Ministry of Science and Technology, the Chinese Academy of Sciences and its subordinating NAO, Guizhou Province and other departments.

Link: Article

19 December 2008

In Remembrance: Steven Ostro

In Remembrance: Steven J. Ostro, radar astronomer at the Jet Propulsion Laboratory.

Link: Article - Sky and Telescope

Link: Planetary Society

Link: Blog Entry from Steve's brother (Stu Ostro)

10 December 2008

New Report: "Meteorites Hitting Early Earth's Oceans May Have Helped Spawn Life"

From the articles...

Many theories about the origins of life on Earth posit that prebiotic compounds may have arrived from outer space on asteroids or comets. But a new study suggests that extreme chemical reactions fired up by meteorite impacts may have jump-started life in the early oceans, rather than delivering its building blocks preformed. Meteorites striking the primordial oceans, the paper's authors say, could have supplied significant amounts of carbon, critical to life, and created a sort of chemical pressure cooker by the force of their impacts to synthesize the foundations of biological molecules.

The researchers report in Nature Geoscience today that they replicated the impact of a chondrite, a common type of meteorite, striking the ocean at about 1.25 miles (two kilometers) per second. The team did this by subjecting chemical constituents of chondrites (iron, nickel and carbon), as well as water and nitrogen, believed to be plentiful in the early atmosphere, to shock compression. The resulting pressures and temperatures, which likely exceeded 5,000 degrees Fahrenheit (2,760 degrees Celsius), yielded a variety of organic (carbon-based) compounds, such as fatty acids and amines. And when ammonia, which a previous study showed impacts could produce, was added to the starting mix, the experiment also yielded glycine (a simple amino acid).

Study co-author Toshimori Sekine, a researcher at the National Institute for Materials Science in Tsukuba, Japan, says he was surprised by the output from the experiment, adding that "there are many additional molecules we found but didn't analyze yet." Lead author Yoshihiro Furukawa, a PhD candidate at Tohoku University in Sendai, Japan, says that in light of the results, "we can say those ocean impact events [were] very effective processes for the production of various biomolecules on the early Earth." He is quick to note, though, that it is unclear how much or how many of these biomolecules would be needed to initiate life.

Link: Article: "Meteorites laid groundwork for early life"

Link: Article: Rock and Roil: Meteorites Hitting Early Earth's Oceans May Have Helped Spawn Life

02 December 2008

NYTimes Article on Early Earth

An interesting New York Times article on new evidence for a more benign early Earth has some information on early Earth bombardment. I would recommend the entire article but here is a section on early impact events...

Earth, like the other planets, coalesced more than 4.5 billion years ago. It is commonly hypothesized that almost immediately, a Mars-size object about 4,000 miles wide hit it — a true cataclysm that vaporized much of the object and Earth. Some of the debris ejected into orbit became the Moon. The molten Earth cooled quickly, probably within a few million years, and nothing that large ever struck again.

Dr. Sleep [Norman H. Sleep, professor of geophysics at Stanford] said his calculations suggested that during the 700 million years of the Hadean period about 15 objects 100 miles wide or wider hit the Earth. About four of the objects were wider than 200 miles, and those collisions would have been violent enough to boil off most of the oceans. (By contrast, the more recent object that hit the Earth 65 million years ago and helped kill off the dinosaurs was about 6 miles wide.)

But in numerical simulations that will be presented this month at a meeting of the American Geophysical Union in San Francisco, Dr. Mojzsis and Oleg Abramov, a postdoctoral researcher at the University of Colorado, show that the Late Heavy Bombardment impacts were not quite as lethal as had been thought.

“Things are hurt really bad,” Dr. Mojzsis said. But the computer calculations indicated that even rocks up to 300 miles wide would not kill everything, that pockets would exist where organisms that thrive in high-temperature environments like hydrothermal vents could survive.

Genetic studies of current life support that notion, pointing to an organism that lived in a high-temperature environment as the last common ancestor. That does not mean that life started there, but that is almost certainly where survivors of the giant impacts would have huddled.

Link: NYTimes Article: A New Picture of the Early Earth

01 December 2008

Article on Asteroid Threat and Initiatives Through U.N.

Former NASA Apollo astronaut, Russell Schweickart, is leader of an international Panel on Asteroid Threat Mitigation. Their report -- Asteroid Threats: A Call for Global Response -- is being briefed to United Nations officials, as well as leaders of space agencies around the world.

From the article...

A milestone-making report on the need to develop an international decision-making program to respond to the threat of Near Earth Objects (NEOs) has been briefed to United Nations officials in Vienna, Austria.

The report -- Asteroid Threats: A Call for Global Response -- was compiled by the international Panel on Asteroid Threat Mitigation, a group comprised of members of the Association of Space Explorers (ASE), as well as other experts tackling the NEO threat and repercussions to the Earth.

Former NASA Apollo astronaut, Russell Schweickart, is chairman of the panel and led the November 25 consultation with UN officials.

The briefing on the ASE-NEO report, its findings and implications, was given to a group of national representatives from the Permanent Missions to the United Nations in Vienna, in cooperation with One Earth Future Foundation.

The session was opened by Austrian Ambassador Helmut Böck who, along with Ciro A. Arévalo Yepes, the Chairman of the UN Committee on the Peaceful Uses of Outer Space (COPUOS), and Mazlan Othman, Head of the United Nations Office for Outer Space Affairs (UN-OOSA) sponsored the briefing.

The report is being submitted for consideration and subsequent action by the United Nations, with the goal to assist the international community in preventing loss of life and property resulting from an asteroid impact on Earth.

As the report underscores, there is need for a world-wide response to NEOs and the implications for Earth.

“Faced with such a threat, we are far from helpless. Astronomers today can detect a high proportion of Near Earth Objects and predict potential collisions with the Earth. Evacuation and mitigation plans can be prepared to cope with an unavoidable impact,” the report explains.

“For the first time in our planet's 4.5-billion-year history, the technical capacities exist to prevent such cosmic collisions with Earth. The keys to a successful outcome in all cases are preparation, planning, and timely decision-making,” the report states.

The Secure World Foundation (SWF) has a working relationship with the Association of Space Explorers and the Schweickart-chaired ASE Panel on Asteroid Threat Mitigation.

“We share a common interest in NEO governance. We also want to promote the results of their two-year process that has led to the report being submitted for consideration and subsequent action by the United Nations,” explained Cynda Collins Arsenault, President of the Secure World Foundation.

“These briefings are very important in terms of the UN receiving our report. There is only one institution in the world that represents everybody,” Schweickart said. To prevent an actual impact, he added, an international decision-making program, including necessary institutional requirements, must be agreed upon and implemented within the framework of the United Nations.

Schweickart also noted that briefings on the ASE-NEO report have been given to officials of several space agencies: The Indian Space Research Organization, the Canadian Space Agency, as well as NASA. Future briefings are being negotiated with the European Space Agency, China, Japan and Russia, he said.

At the close of the UN briefing in Vienna, former Austrian Ambassador Walther Lichem -- a member of the ASE International Panel on Asteroid Threat Mitigation -- made closing comments on the need for the UN “system” to deal seriously with the need for building the institutional capability to support the decision-making process ultimately required.

Link: Article

Podcast: Radio Astrobiology: Marco Polo and Meteorites

From the article...

Astrobiology Magazine presents a new podcast with our host Simon Mitton. In this interview, Beda Hofmann, an astrobiologist at the Natural History Museum in Bern, Switzerland, explores the links between meteorites, asteroids, and astrobiology. Europe's proposed Marco Polo Mission would land on an asteroid, drill down for samples, and return them to Earth. As Hofmann explains, the samples will be older than any rocks on Earth, and may contain important clues on the formation of the solar system.

Link: Astrobiology Magazine Article

Link: Podcast (.mp3)

29 November 2008

Update: Evidence of Alberta, Canada Meteorite

University of Calgary graduate student Ellen Milley poses with a fragment of a meteorite in a small pond near Lloydminster, Sask., Canada Friday, Nov. 28, 2008. Scientists said Friday they had found remains of a meteor that illuminated the sky before falling to earth in western Canada earlier this month. University of Calgary scientist Alan Hildebrand and Milley found several meteor fragments near the Battle River along the rural Alberta-Saskatchewan border, near the city of Lloydminster late Thursday. (AP Photo/The Canadian Press, Geoff Howe)

A woman's hand, to show the scale, is seen by what scientists say is a fragment of a meteorite found in a small pond near Lloydminster, Sask., Canada Friday, Nov. 28, 2008. Scientists said Friday they had found remains of a meteor that illuminated the sky before falling to earth in western Canada earlier this month. University of Calgary scientist Alan Hildebrand and graduate student Ellen Milley found several meteor fragments near the Battle River along the rural Alberta-Saskatchewan border, near the city of Lloydminster late Thursday. (AP Photo/The Canadian Press, Geoff Howe)

From the article...

Scientists said Friday they had found remains of a meteor that illuminated the sky before falling to earth in western Canada earlier this month.

University of Calgary scientist Alan Hildebrand and graduate student Ellen Milley found several meteor fragments near the Battle River along the rural Alberta-Saskatchewan border, near the city of Lloydminster late Thursday.

They said there could be thousands of meteorite pieces strewn over a 7-square-mile area of mostly flat, barren land, with few inhabitants.

Link: Associated Press Article

28 November 2008

Using LIDAR to find meteor craters

From a recent paper on using LIDAR to find meteor impacts on the Earth...

Anatomy of a young impact event in central Alberta, Canada: Prospects for the missing Holocene impact record
Volume 36, Issue 12 (December 2008)
Article: pp. 955–958
C.D.K. Herd, D.G. Froese, E.L. Walton, R.S. Kofman, E.P.K. Herd, and M.J.M. Duke

Small impact events recorded on the surface of Earth are significantly underrepresented based on expected magnitude-frequency relations. We report the discovery of a 36-m-diameter late Holocene impact crater located in a forested area near the town of Whitecourt, Alberta, Canada. Although undetectable using visible imagery, the presence of the crater is revealed using a bare-Earth digital elevation model obtained through airborne light detection and ranging (LiDAR). The target material comprises deglacial Quaternary sediments, with impact ejecta burying a late Holocene soil dated to ca. 1100 14C yr B.P. Most of the 74 iron meteorites (0.1–1196 g) recovered have an angular exterior morphology. These meteorites were buried at depths <25 cm and are interpreted to result from fragmentation of the original projectile mass, either at low altitude or during the impact event. Impact of the main mass formed the simple bowl-shaped impact structure associated with an ejecta blanket and crater fill. The increasing availability of LiDAR data for many terrestrial surfaces will serve as a useful tool in the discovery of additional small impact features.

Link: Geology Reference

Link: ars technia Article

Article: "Searchers find remains of fireball meteor"

From the article...

VANCOUVER, British Columbia (Reuters) – Searchers have found the remains of a 10-ton meteor that produced a dramatic fireball in the skies over the Canadian Prairies this month, researchers said on Friday.

Thousands of meteorite fragments have been found densely strewn over a 20-square-kilometre (8 square mile) area south of the community of Lloydminster on the Alberta-Saskatchewan border, according to the University of Calgary.

Searchers have been scrambling to find the remains of the meteor since it streaked across the sky in the early evening of November 20, producing a fire ball that shone brightly enough to be seen over an area 700 km (435 miles) wide.

Link: Article

26 November 2008

Update on Alberta Canada Meteorite

View Larger Map

From the article...

Investigation of the fireball that lit up the skies of Alberta and Saskatchewan on November 20 has determined that an asteroid fragment weighing approximately 10 tonnes entered the Earth’s atmosphere over the prairie provinces last Thursday evening. And University of Calgary researcher Alan Hildebrand has outlined a region in western Saskatchewan where chunks of the desk-sized space rock are expected to be found.

The fireball first appeared approximately 80 kilometres above and just east of the border city of Lloydminster, Alberta/Saskatchewan, and traveled SSE towards the Battle River valley fragmenting spectacularly in a series of explosions. The fireball penetrated the atmosphere at a steep angle of approximately 60 degrees from the horizontal and lasted about five seconds from 17:26:40 to 17:26:45 MST with the largest explosion at 17:26:44. The fireball was recorded on all-sky and security cameras scattered across Saskatchewan and Alberta in addition to being witnessed by tens of thousands of people who saw it streak across the sky, saw its arc- welding blue flash, or heard the subsequent explosions.

Hildebrand estimates that hundreds of meteorites larger than 50 grams could have landed since the rock was large and its entry velocity was lower than average. The object’s speed is calculated to be only roughly 14 km/sec when it entered the atmosphere versus the average of around 20 km/sec.

Link: Article

Link: Google Map of Search Area

23 November 2008

Meteor in Alberta in western Canada on 20 November 2008

From Canadian Press article...

Scientist determines pieces of large meteor may have landed in central Sask.

2 days ago

SASKATOON — A leading researcher says one of the largest meteors to streak over Canada in the last decade broke up into pieces that may have landed in central Saskatchewan.

Planetary scientist Alan Hildebrand from the University of Calgary plans to spend the weekend in the Manitou Lake area near the town of Macklin, Sask., about 100 kilometres south of Lloydminster, near the Alberta boundary.

As co-ordinator of the Canadian Fireball Reporting Centre with the Canadian Space Agency, Hildebrand was busy Friday talking with some of the witnesses who sent him 300 e-mail reports about the fireball they saw light up the night sky Thursday.

With their descriptions of the meteor - its brightness, colour and sound - he pinpointed the most likely fall location to be near Manitou Lake.

"Right now, the important thing is not searching because we don't know which field to search in. It's a big world," Hildebrand said. "What's important now is finding proximal eyewitnesses, so you know where meteorites might have fallen."

Meteor sightings have been widely reported across the Prairies, from Edmonton to Regina to Swan River, Man. Witnesses heard sonic boom rumblings and reported it was as bright as the sun.

Cattle farmer Trevor Crisp had just finished hauling a load of animals when he arrived at his home near the village of Richard, about 200 kilometres west of Manitou Lake, for supper Thursday night. It was completely dark outside.

"All of a sudden everything lit up," said Crisp. "I thought it must have been a lightning strike.

"You could hear quite a rumble going through, and you could see a bit of vibration in the windows. It was pretty neat."

Tammy Evans was getting some sleep before her night shift as a nurse in North Battleford, Sask., when her worried 10-year-old daughter ran into the bedroom.

"She said there was a flash of light, and she said the house shook twice and it sounded like dinosaurs were walking."

Minutes later, Evans received a call from her brother-in-law who was driving to Edmonton.

"He said the whole sky lit up, and he had to squint because he couldn't see."

Hildebrand says the meteor could likely be seen up to 700 kilometres away, into the northern United States. It contained about a tenth of a kiloton of energy when it entered the earth's atmosphere, equal to 100 tons of the chemical explosive TNT.

"It would be something like a billion-watt light bulb."

Besides sonic boom sounds, he said witnesses also reported hearing hissing or crackling noises like frying bacon. Fireballs can act as radio transmitters, Hildebrand said, causing odd sounds.

He said other people saw the meteor break into pieces and turn red as it slowed down.

Because it came down over the bald prairie instead of ocean or forest, there's a good chance meteorites may be found, said Hildebrand. He just wants to get to them before they're covered or ruined by more snow.

Martin Beech, an associate professor of astronomy at the University of Regina, said meteorites are valuable to learning about the history of the solar system. The artifacts are 4.5 billion years old.

"Picking up a meteorite is almost equivalent to doing a space exploration mission between Mars and Jupiter," he said.

Richard Herd is curator of Canada's national meteorite collection in Ottawa, with samples from 1,100 different meteorites that have landed across the country.

He said the biggest meteorite fall occurred northeast of Edmonton near the town of Bruderheim in 1960. More than 700 fragments recovered totalled 300 kilograms.

About 75 fireball events are reported each year.

Rick Huziak, an amateur astronomer in Saskatoon, helps operate a fireball camera on top of the University of Saskatchewan physics building that captured video of the meteor.

Although the camera records one every two to three weeks, this meteor was among the brightest seen in Canada in the last dozen years, he said.

"It was quite spectacular. The ground lights up all over the place."

Huziak said only one in a thousand fireballs actually drop meteorites. Most meteors burn up completely.

Phil Langill, director of the Rothney Astrophysical Observatory at the University of Calgary, said he wasn't lucky enough to see the meteor.

But if someone is lucky enough to find one of its meteorites, they should be careful not to contaminate it.

"So if anybody finds it, they should pick it up carefully with a Ziploc bag or something like that and not touch it with their hands."

Link: Article

10 November 2008

JPL Update on 2008 TC3

Figure 1a. The terminal trajectory for Earth impacting asteroid 2008 TC3. The view is looking down on the ecliptic plane.

Figure 1b. The terminal trajectory for Earth impacting asteroid 2008 TC3. The view is from the sun. Note that the asteroid enters Earth shadow at about 1:49 UT so that the final portion of the trajectory is behind the Earth.

Figure 2. The predicted path of the asteroid is noted at 10 km intervals from 100 to 0 km altitude, neglecting atmospheric drag. The red dots indicate the reported instances of atmospheric entry at 65.4 km altitude and for the airburst at 37 km.

Figure 3,. Dispersion of 900 variant orbits, all of which could fit the existing observational data, at an altitude of 50 km. The nominal (most likely) position is denoted by the red dot in the center of the diagram. The results of this Monte Carlo simulation demonstrate that most possible orbits fell within 1 km from the mean, which is at (31.804°E, 20.858°N). The 1-, 2- and 3-sigma uncertainty ellipses are noted in red. Statistically and respectively, these ellipses capture 39%, 86% and 99% of the cases. The time of impact uncertainty at a given altitude is 0.16 seconds, 1-sigma.

Figure 4. Meteosat 8 / EUMETSAT infrared image of the 2008 TC3 explosion. The scale at the right gives the image intensity. Copyright 2008 EUMETSAT

From JPL, update on 2008 TC3:


A spectacular fireball lit up the predawn sky above Northern Sudan on October 7, 2008. This explosion was caused by the atmospheric entry of a small near-Earth asteroid, estimated to be no more than a few meters in diameter. The explosion likely scattered small meteorite fragments across the Nubian desert below. Although such small impact events occur several times per year around the globe, this case was unprecedented because the asteroid was actually discovered the day before it reached the Earth and the impact location and time were for the first time predicted in advance.

At 6:39 UT (UT = GMT) on the morning of October 6, 2008, Richard Kowalski, at the Catalina Sky Survey, discovered this small near-Earth asteroid using the Mt. Lemmon 1.5 meter aperture telescope near Tucson, Arizona. When the discovery observations were reported to the Minor Planet Center (MPC) in Cambridge Massachusetts, a preliminary orbit computation immediately indicated that the object was headed for an Earth impact within 21 hours. The MPC quickly made the discovery and subsequent "follow-up" observations available to the astronomical community and contacted the NASA/JPL Near-Earth Object Program Office. The MPC also notified NASA Headquarters of the impending impact so that subsequent US government interagency alerts and inter-governmental notifications could begin. By the time this object (now designated as 2008 TC3) entered the Earth's shadow 19 hours after discovery, some 570 astrometric (positional) measurements had been reported from 26 observatories around the world, both professional and amateur.

Within an hour of receiving the initial data set, JPL predicted that the object would enter the Earth's atmosphere above northern Sudan around 02:46 UT on October 7. As the day progressed and more and more data arrived from the MPC, JPL continued to improve the orbit for 2008 TC3 and forwarded updated predictions to NASA Headquarters. On the afternoon of Oct 6th, NASA Headquarters alerted officials at the National Security Council, the Office of Science and Technology Policy, the Department of State, and the Department of Defense Northern Command and Joint Space Operations Center. NASA also issued a press release at approximately 21:30 UT announcing the predicted impact later that night.

Detections of the actual atmospheric impact event suggested that it was an airburst explosion at an altitude of 37 km with an energy equivalent to about one kiloton of TNT explosives. The time and place of the predicted impact agree very well with a number of atmospheric entry observations including those from U.S. government satellites, infrasound signals from at least one ground station, images from the Meteosat 8 weather satellite and a sighting by a KLM airline pilot flying over Chad. The latest JPL trajectory estimate, which carefully considers all available data, including some measurements not available until after the event, is accurate to within a few kilometers at the time of atmospheric entry.

This dramatic prediction of an actual impact underscored the successful evolution of the Near-Earth Object (NEO) Program's discovery and orbit prediction process. The discovery was made, observations were provided by 26 international observatories, the orbit and impact computations were determined, verified and announced well before the impact, which took place only 20.5 hours after the discovery itself. While improvements to the impact prediction process still need to be made, the system worked well for the first predicted impact by a near-Earth object.

Asteroid 2008 TC3 Strikes Earth: Predictions and Observations Agree
Steve Chesley, Paul Chodas, and Don Yeomans
November 4, 2008

Link: JPL NEO News Release

First Images of Asteroid 2008 TC3 Impact Aftermath?

The long-lasting persistent train after the impact of 2008 TC3 over the Sudanese skies (NASA)

From Universe Today Post...

A month after asteroid 2008 TC3 hit the Earth's atmosphere, the first ground-based image of the event has surfaced on the Internet. Admittedly, it's not the fireball everyone has been waiting to see, but it is visual evidence that something hit us above Sudan on October 7th. The image above was taken from a frame of video that was being recorded by Mr. Mohamed Elhassan Abdelatif Mahir in the dawn following the asteroid impact with the atmosphere. The smoky feature is the remnant of the fireball as the 3 meter-wide asteroid blasted through the upper atmosphere, eventually exploding. The long-lasting persistent train is seen hanging in the air, high altitude winds causing it to twist in the morning sunlight.

We may not have a dazzling fireball re-entry video of 2008 TC3, but this striking image provides the first ground-based evidence of the direct hit, and may help refine the search for any meteorites from the disintegrated asteroid…

Although details are sketchy, it would appear that a person on the ground observed the skies of Sudan shortly after 2008 TC3 exploded in the upper atmosphere. It is unclear whether the observer was part of a meteorite-hunting team, or a Sudanese resident videoing the scene, but it is very fortunate he captured this footage. Dr. Muawia H. Shaddad of the University of Karthoum communicated this single frame, and the picture is being showcased as the November 8th NASA Astronomy Picture of the Day.

It is currently the only ground-based evidence that something hit the Earth at the right time and right location as predicted by scientists using the Mount Lemmon telescope in Arizona as part of the NASA-funded Catalina Sky Survey for near-Earth objects. However, as Nancy reported on October 13th, indirect support for an atmospheric fireball came from a webcam on a beach in Egypt. Also, at 02:43 UTC on that Tuesday morning, an infrasound array in Kenya detected an explosion in the atmosphere (with an energy equivalent of 1.1–2.1 kT of TNT). These observations were backed up by the European weather satellite METEOSAT-8, capturing the fireball from orbit. The pilot of a KLM airliner also witnessed a bright flash, 750 miles from the impact location.

This was the first time that an asteroid has been discovered before it hit the Earth, thereby proving an early-warning system for future asteroid impacts is possible. Although there are 5-10 space rock collision events per year, this is the first time we knew something about it before it happened. This is an amazing achievement as 2008 TC3 was only 3 meters in diameter.

Link: Universe Today Post on 2208 TC3 Impact

National Academies Study: "Review of Near-Earth Object Surveys and Hazard Mitigation Strategies

Information on National Academies study entitled: "Review of Near-Earth Object Surveys and Hazard Mitigation Strategies." They will be having a meeting from December 9-11, 2008 in Washington, D.C.

Here is more information on the project:

Project Scope

In response to long-standing interest in the hazards posed by Near-Earth Objects (NEOs), NASA was directed by Congress in 2005 to initiate a program to detect, track, catalogue, and characterize 90 percent of the objects in space larger than 140 meters in diameter, with a perihelion distance of less than 1.3 astronomical units. As the first step in the definition of this program, NASA was required to prepare and deliver to Congress a report containing an analysis of possible alternative approaches to conducting the requested survey, and an assessment of possible alternatives that could be employed to divert a NEO on a likely collision course with Earth. In response to these instructions, NASA undertook a series of activities culminating in the publication in March 2007 of Near-Earth Object Survey and Deflection Analysis of Alternatives: Report to Congress and 2006 Near-Earth Object Survey and Detection Study.

In response to these documents, Congress included language in the Joint Explanatory Statement attached to the Consolidated Appropriations Act 2008 calling on NASA to contract with the National Research Council to undertake a two-phase study to review those two NASA studies and other relevant literature, and to provide recommendations focusing on both the optimal approach to surveying the NEO population and the optimal approaches to developing a deflection capability.

Statement of Task
The National Research Council Space Studies Board, in cooperation with the Aeronautics and Space Engineering Board, shall conduct a two-part study to address issues in the detection of potentially hazardous NEOs and approaches to mitigating identified hazards. Both tasks should include an assessment of the costs of various alternatives, using independent cost estimating. Options that blend the use of different facilities (ground- or space-based), or involve international cooperation, may be considered. Each study phase will result in a report to be delivered on the schedule provided in the contract. Key questions to be addressed during each phase of the study are the following:

Task 1: NEO Surveys
What is the optimal approach to completing the NEO census called for in the George E. Brown, Jr. Near-Earth Object Survey section of the 2005 NASA Authorization Act to detect, track, catalogue and characterize the physical characteristics of at least 90% of potentially hazardous NEOs larger than 140 meters in diameter by the end of year 2020? Specific issues to be considered include, but are not limited to, the following:
--What observational, data-reduction, and data-analysis resources are necessary to achieve the Congressional mandate of detecting, tracking, and cataloguing the NEO population of interest?
--What physical characteristics of individual objects above and beyond the determination of accurate orbits should be obtained during the survey to support mitigation efforts?
--What role could be played by the National Science Foundation's Arecibo Observatory in characterizing these objects?
--What are possible roles of other ground- and space-based facilities in addressing survey goals, e.g., potential contributions of the Large Synoptic Survey Telescope (LSST) and the Panoramic Survey Telescope and Rapid Response System (Pan STARRS)?

Task 2: NEO Hazard Mitigation
What is the optimal approach to developing a deflection capability, including options with a significant international component? Issues to be considered include, but are not limited to, the following:
--What mitigation strategy should be followed if a potentially hazardous NEO is identified?
--What are the relative merits and costs of various deflection scenarios that have been proposed?

This project is sponsored by NASA.
The start date for this project is November 4, 2008.

Schedule: An interim report, based upon Task 1, shall be produced and delivered to NASA by September 30, 2009. A final report including both Tasks 1 and 2 will be delivered by December 31, 2009.

Project Duration: 21 months

Link: National Academies Project Information

Link: Meeting Information (December 9, 2008 - December 11, 2008)

Planetary Defense Student Competition (related to IAA Planetary Defense Conference)

From ESA, regarding student involvement in the upcoming IAA Planetary Defense Conference:

ESA is holding a competition for the upcoming Planetary Defense Conference in 2009, in order to stimulate some innovative research and encourage European research students to participate. The Advanced Concepts Team (ACT) has come up with a few concepts that young researchers from various fields may wish to research. The titles of the different concepts are:

* Deflecting Binary asteroid systems
* Graveyard orbit deflection
* Maximum charge of a satellite
* Deflection strategies using multiple spacecraft
* Avoiding reaggregation by electrostatic charge
* The Magnetostatic Tractor
* Lorentz Deflection during an Earth fly-by
* Observing Apophis with LISA
* Changing the internal structure of asteroids

To see details of these concepts, or for more information on how to take part, visit our webpage:

Abstracts must be submitted before _1 December 2008.

The Advanced Concepts Team

25 October 2008

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

20 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

17 October 2008

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 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

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

16 October 2008

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

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



(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.


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.


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.


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.


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


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.


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.

14 October 2008

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

11 October 2008

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:

Meteosat 8 / EUMETSAT IR image of the 2008 TC3 explosion. Copyright 2008 EUMETSAT. (Source:

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

09 October 2008

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)


(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.


07 October 2008

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: 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


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;


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 ( 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 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 For additional information, please see the website 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 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 (

Link: First images of asteroid 2008 TC3 ( 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.
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 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

06 October 2008

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

28 September 2008

NEO News (09/25/08) Managing the Impact Hazard

From Dave Morrison

NEO News (09/25/08) Managing the Impact Hazard

After a two-year study involving a cast of international experts in government and science, the Association of Space Explorers Committee on Near-Earth Objects has completed a proposal to encourage the international community to set up procedures to protect the Earth from future asteroid impacts. The Executive Summary of Asteroid Threats: A Call for Global Response was released today (September 25) at a press event in San Francisco. The press kit and a copy of the Executive Summary are enclosed as a pdf file.

The study recommends that a global, coordinated response by the United Nations to the NEO impact hazard should ensure that three logical, necessary functions are performed:

1. An Information, Analysis, and Warning Network should be established. This network would operate a global system of ground- and/or space-based telescopes to detect and track potentially hazardous NEOs. The Network, using existing or new research institutions, should analyze NEO orbits to identify potential impacts. The Network should establish criteria for issuing NEO impact warnings.

2. A Mission Planning and Operations Group, drawing on the expertise of the space-faring nations, should be established and mandated to outline the most likely options for NEO deflection missions. This group should assess the current, global capacity to deflect a hazardous NEO by gathering necessary NEO information, identifying required technologies, and surveying the NEO-related capabilities of interested space agencies. In response to a specific warning, the group should use these mission plans to prepare for a deflection campaign to prevent the threatened impact.

3. The United Nations should exercise oversight of the above functions through an intergovernmental NEO Threat Oversight Group. This group would develop the policies and guidelines that represent the international will to respond to the global impact hazard. The NEO Threat Oversight Group should establish impact risk thresholds and criteria to determine when to execute a NEO deflection campaign. The NEO Threat Oversight Group would submit recommendations to the Security Council for appropriate action.

At the press event, former astronauts Rusty Schweickart and Ed Lu noted that two of the three elements needed to respond responsibly to the impact hazard, involving surveys and development of deflection technologies, are already underway at some level. Their emphasis is thus on the third element, an international decision-making process to manage to complex political-technical issues of how to respond to impact threats of various levels. It is this third essential element of defending the Earth that this study hopes to initiate.

09 July 2008

Editorial on Apophis and Russian NEO Efforts

From the article...

Meanwhile, Russia is taking steps to improve its monitoring of the dangerous space intruder. The Russian Space Agency (Roscosmos), together with the Defense Ministry and Academy of Sciences, has launched an anti-asteroid program. The first step will see a special radar mounted on a 70-metre telescope in Ussuriisk. The radar will pick up signals reflected by natural space bodies.

The Lavochkin Research and Production Association (NPO Lavochkin) is working on a space program for 2012-2014 that will gather as much information about Apophis as possible. It is also planning a series of experiments to see if the asteroid's orbit could be changed by sustained energy impacts. An unmanned craft is being developed for the purpose, and different flight scenarios considered.

In mid-June, when examining the NASA budget for the next year, the House of Representatives told the Space Agency to cooperate with Russia in all matters concerning asteroids.

The Americans rightly believe that bodies like Apophis threaten all humanity. Republican Congressman Dan Rohrbacher, who pushed for the inclusion of international asteroid cooperation in NASA's budget, thinks the U.S. should share this responsibility with others.

Russia will not stand aloof. It is willing to contribute its RT-70 high-powered antenna system for deep space communications. Its facilities, located in the Far East and Crimea, will effectively complement American facilities in Puerto Rico and California.

How to deal with "asteroid terrorism"?
09 July 2008

Article: RIA Novosti

07 July 2008

NYTimes Article: "Maybe Chicken Little Wasn’t Paranoid After All"

Selections from the article...

NASA’s Jet Propulsion Laboratory in Pasadena, Calif., has estimated that a Tunguska-size asteroid will enter Earth’s atmosphere once every 300 years and says there may be 375,000 objects of such size out there.

NASA estimates that there are about 940 or so near-Earth space rocks a kilometer in diameter or larger. So far, according to Dr. Yeomans, NASA has identified 743. (Overall, NASA has pinpointed more than 5,500 near-Earth objects.)

Mr. Schweickart said progress so far had come through constant pushing against resistant bureaucracies and politicians focused on whatever is the issue of the moment. And he said there was still no significant effort to devise an international agreement, let alone a deflection technique, for dealing with the inevitable earthbound asteroid or comet, large or small, when it is identified.

“It may be subtle,” he said, “but failure of the international decision process is the most likely reason that we’ll take a hit in the future.”

"Maybe Chicken Little Wasn’t Paranoid After All"
Andrew C. Revkin
06 July 2008

Link: NYTimes Article
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