21 December 2008
Several more fragments have been found from the 10-ton asteroid that exploded over western Canada on November 20, including a head-sized piece weighing 13-kilograms (28 lbs). Imagine that landing on your house or car (or head!). University of Calgary professor Alan Hildebrand, who is leading the search estimates there could be 2,000 fragments per hectare (about 2.5 acres) in the area near where fragments were initially found. The asteroid is becoming known as the Buzzard Coulee fireball, named after the picturesque, but luckily uninhabited valley where the first pieces were located. Check out the website of Bruce McCurdy of Edmonton Space & Science Foundation and the Royal Astronomical Society of Canada, who has joined in the search for more meteorite images.
More than two dozen pieces of the asteroid have been found by researchers or members of the public. The search is focused on a 24-square-kilometer section of agricultural land along the Battle River where the scientists calculated the debris would be located.
25 November 2008
The camera will offer sharper, broader views of the sky.
By Robert Lemos
The project, known as the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), aims to scan the entire sky visible from the summit of Mount Haleakala in Maui Island, Hawaii, three times a month, searching for asteroids and near-Earth objects (NEOs) as small as 300 meters in diameter. At the heart of each telescope is a 1.4-billion-pixel digital camera that can photograph broad swaths of the night sky in sharp detail.
The first prototype telescope using the camera will go online in December. This telescope will scan the night sky, searching for asteroids and comets that could pose a threat to Earth. Pan-STARRS is designed to have at least three times the collecting power of current NEO telescopes.
The Pan-STARRS's cameras, each consisting of a 40-centimeter-square array of charge-coupled devices (CCDs), bring new technology to the optics used in astronomy. Perhaps the most innovative aspect is the ability of each CCD cell to electronically shift an image to counteract atmospheric blur and deliver clearer astrophotography, says Barry Burke, a senior staff member at MIT's Lincoln Laboratory, which makes the cameras.
"The atmosphere is the limit to the quality of the image, but there is a special feature of these chips that allows them to remove some of the blur due to atmospheric effects," Burke says. "It allows the image to be shifted in any direction in the chip in a way that matches the motion of the stars and that takes out a significant part of the blur."
Known as orthogonal transfer CCD (OTCCD), the technology uses electronics to adjust the image rather than mechanically tilting a camera's lens or mirror, a more common technique used in consumer cameras that have optical image stabilization. Because the process is electronic, the technology can be distributed to each cell of the CCD array, allowing for much more granular adjustments to localized atmospheric turbulence. The result is an image that is sharper than what a ground-based observatory could produce.
The mosaic structure of the CCD camera also leads to a more reliable system and less expensive manufacturing costs, Burke says. "The chip could not possibly be made to that size, so we are forced to break the camera down into tiles," he says.
Each Pan-STARRS camera consists of an eight-by-eight array of devices, each containing an eight-by-eight array of CCD cells. The size of each cell--about six millimeters on a side--is determined by a sweet spot...
Space experts call for asteroid action plan
Time needed to deflect asteroids, evacuate people living in impact zone
updated 11:55 a.m. ET, Tues., Nov. 25, 2008
VIENNA, Austria - Space experts are urging the United Nations to devise a plan that allows for quick action against asteroids. Rusty Schweickart, a former U.S. astronaut, says such a plan would save the time needed to deflect asteroids or evacuate people living in a possible impact zone. He says researchers will increasingly be able to predict collisions and that, for the first time in history, technical capabilities exist to prevent them. Schweickart and other experts spoke to reporters Tuesday after presenting a report on the matter to U.N. officials in Vienna.
24 November 2008
It was 2,300 years ago. The Palisades that frame the Hudson River were whisper-quiet, the sandy beaches of Long Island and New Jersey empty, and Manhattan was still just an unbroken sylvan carpet.
Then came the mammoth wave, roaring into the serenity. No one knows for sure what caused it, but new clues found in the Hudson's silt suggest an asteroid 100 meters (330 feet) in diameter slammed into the Atlantic Ocean nearby.
The team found grains of several shocked minerals in the sediments as well, but the discovery remains controversial.
"To get a wave 2.5 meters high that far up the Hudson, you need a wave 20 meters high at Manhattan," said Steven Ward of the University of California, Santa Cruz. "It would've gone several hundred meters inland on Long Island; you should see evidence of this thing all over the place."
"If you hear that, then you're probably within 30 kilometres of it."
22 November 2008
About 1730 yesterday, in Edmonton, Canada:
"I just happened to look outside facing east," he said. "All of a sudden I saw this big flash coming down and I thought somebody was playing tricks on me, like fireworks behind the house or something.
"Just before that I heard a boom. I didn't know if it was a tree against the house. It was green and blue and it was coming down pretty fast."
Gobeil said the light display eventually turned orange, yellow and red and lasted 10 seconds.
"I was waiting for it to explode," he said. "It looked similar to when we watch (news reports) in Afghanistan. When I didn't see that, I said, 'well, that's something from outer space.' I'm sure it landed way out in Winnipeg or something."
"It's exciting - both scary and really nice."
10 November 2008
To consider the space solar power concept requires an understanding of science, technology, engineering, math, energy, policy, environmental factors, and more. Space solar power is an engineering project on a scale that rivals the greatest in history. Students need to be informed and able to participate in the conversation.
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…
27 October 2008
26 October 2008
The United States and the rest of the world need to find alternative sources of energy besides fossil fuels. The National Space Society believes that one of the most important long-term solutions for meeting those energy needs is Space Solar Power (SSP), which gathers energy from sunlight in space and sends it to Earth. We believe that SSP can solve our energy and greenhouse gas emissions problems. Not just help, not just take a step in the right direction; solve. SSP can provide large quantities of energy to each and every person on Earth with very little environmental impact. The NSS recommends that SSP be considered along with ground-based solar collectors and wind turbines as a safe, renewable, and clean energy option.
Solar energy is routinely used on spacecraft today, and the solar energy available in space is literally billions of times greater than we use today. The lifetime of the sun is an estimated 4 to 5 billion years, making SSP a truly long-term energy solution. Space solar power can have an extremely small environmental footprint, perhaps competitive with ground-solar and wind, because with sufficient investments in space infrastructure, the SSP can be built from materials from space with zero terrestrial environmental impact. Only energy receivers need be built on Earth. As Earth receives only one part in 2.3 billion of the sun's output, SSP is by far the largest
potential energy source available, dwarfing all others combined. Development cost and time, of course, are considerable. This makes SSP a long-term solution rather than a short-term stop-gap, although there are some intriguing near-term possibilities.... While all viable energy options should be pursued with vigor, SSP has a number of substantial advantages over other energy sources...
All of these technologies are consistent with the laws of physics, are reasonably nearterm, and have multiple attractive approaches. However, a great deal of work is needed to develop economically competitive space solar power. The NSS encourages both the private sector and governments to devote substantial resources toward SSP research and development.
SSP deserves a place alongside ground-based solar collectors, nuclear power plants, and
wind turbines as potential solutions to energy dependence and global greenhouse-gasinduced
warming. If SSP is given serious consideration, NSS expects it will play a growing, and perhaps dominant, role in providing safe, clean, renewable energy for our planet for the foreseeable future and beyond.
The Vision of NSS is people living and working in thriving communities beyond the Earth, and the use of the vast resources of space for the dramatic betterment of humanity.
The Mission of NSS is to promote social, economic, technological, and political change in order to expand civilization beyond Earth, to settle space and to use the resulting resources to build a hopeful and prosperous future for humanity. Accordingly, we support steps toward this goal, including human spaceflight, commercial space development, space exploration, space applications, space resource utilization, robotic precursors, defense against asteroids, relevant science, and space settlement oriented education.
Space Solar Library:http://www.nss.org/settlement/ssp/library/index.htm
The Space Enterprise Council of the U.S. Chamber of Commerce supports the National Security Space Office recommendation of a research program addressing space-based solar power, to explore whether or not this potential energy source could enhance commerce and security. The importance of alternative energy research is becoming increasingly clear, given the urgency of the national and global need for energy that is inexhaustible, affordable, and environmentally clean. Assuring access to energy is particularly relevant to U.S. national security, not only for supply of reliable power to deployed forces but also for avoiding international conflicts that might arise because of energy shortages.
SBSP is unusual among renewable energy options because it might satisfy all four of the following criteria critical to investment decisions: environmental cleanliness, sustainability of supply, flexibility of location, and capacity to generate continuous rather than intermittent power. The cost of SBSP-generated electricity would initially be greater than that provided by fossil fuel or nuclear power but could be comparable to other alternative energy sources, particularly for baseload power. In addition, SBSP might offer an attractive approach, not only for satisfying today's needs but also for meeting tomorrow’s much greater requirements. We cannot accurately predict environmental and other consequences of harvesting energy from natural Earthbound sources (e.g., wind, ocean current, geothermal, biofuels), when these methods are scaled up to considerably higher levels. By providing an additional source of renewable energy, SBSP might help avoid potentially negative consequences if limits to the cost-effective expansion of other renewable sources become evident. Beyond enhancement of energy production per se, SBSP might help create new economic opportunities through resultant technology advances in space launch, space utilization, and technological spin-offs applicable to a host of materials and processes. For example, SBSP research might lead to improvements in the efficiency of solar cells that power communications satellites, as well as power management systems for terrestrial solar power systems. Also, to the extent that SBSP is integrated into terrestrial solar power production, development of SBSP ground infrastructure might generate revenue even before deployment of systems in space. In this and related applications, SBSP could emerge as an enhancement for, rather than a competitor with, terrestrial solar power generation.
"Later, during a question-answer session, the External Affairs Minister said that despite having vast deposits of thorium, India could not pursue production of nuclear energy as access to critical nuclear technology was denied to it over the last 30 years. He said India was now collaborating closely with the US to tap space solar power."
Biden (D-DE) called U.S. ties with India the “single most important relationship that we have to get right for our own safety's sake” (Rediff.com).
And for the United States, no relationship is more important than the one we are building with India.” — Senator Joseph Biden, November 16, 2006
25 October 2008
SEC. 801. REAFFIRMATION OF POLICY.
(a) Reaffirmation of Policy on Surveying Near-Earth Asteroids and Comets- Congress reaffirms the policy (g)) (relating to surveying42 U.S.C. 2451set forth in section 102(g) of the National Aeronautics and Space Act of 1958 (near-Earth42 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.
(a) In General- Prizes can play a useful role in encouraging innovation in the development of technologies and products that can assist NASA in its aeronautics and space activities, and the use of such prizes by NASA should be encouraged.
(b) Amendments- Section 314 of the National Aeronautics and Space Act of 1958 is amended--
(1) by amending subsection (b) to read as follows:
‘(b) Topics- In selecting topics for prize competitions, the Administrator shall consult widely both within and outside the Federal Government, and may empanel advisory committees. The Administrator shall give consideration to prize goals such as the demonstration of the ability to provide energy to the lunar surface from space-based solar power systems, demonstration of innovative near-Earth object survey and deflection strategies, and innovative approaches to improving the safety and efficiency of aviation systems.’; and
(2) in subsection (i)(4) by striking ‘$10,000,000’ and inserting ‘$50,000,000’.
They join a long-line of organizations which have called for action:
Space Frontier Foundation: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://www.space-frontier.org/Projects/TheWatch/
Association of Space Explorers: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://www.space-explorers.org/
Planetary Society: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://www.planetary.org/programs/projects/apophis_competition/
AIAA: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://www.aero.org/conferences/planetarydefense/ & position paper: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://www.planetarydefense.info/resources/pdf/Asteroids-Final.pdf
Gaia Shield Group: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://gaiashield.com/two.html
Lifeboat Foundation: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://www.lifeboat.com/ex/asteroid.shield
Secure World: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://22.214.171.124/~admin23/index.php?id=16%26page=Near_Earth_Objects
National Space Society: https://webmail.hq.af.mil/exchweb/bin/redir.asp?URL=http://www.nss.org/settlement/asteroids/
Which reminds me, the Canadians have a project called NEOSat, which will spend half its time doing Space Situational Awarness, and the other half doing search for Asteroids. It will use a 15cm diameter telescope. It is about the size of suitcase, and weighs 65kg. They hope to launch it in 2010. Unfortunately, it still apparently needs to find an opportune ride to orbit...perhaps on a polar weather satellite.
The Europeans are also doing interesting work. They are pushing the asteroids onto the agenda for SSA. Currently they still have Don Quiote mission on the books, and one can hope against their troubles that they will not completely abandon it. Particularly in Britain, leading Study Group 14 for the UN COPUOS, and Dr. M. Vasile who is comparing a number of different methods continues to turn out useful work comparing various options.
Another interesting site that will get quite a bit more press early next year is the international Association of Space Explorers (ASE), theinternational organization of astronauts and cosmonauts from 33 countries:
Not in particular this paper, which says:
- Within 10-15 will be tracking~300,000 NEOS =>45m (Tunguska Size) due to projected upgrades, of which 10,000 will have non-zero probability of earth impact in next 100 years and 50-100(.5-1%) are likely to appear threatening enough to warrant active monitoring or deflection!
Back in the US, the official site for the Iowa State Asteroid Deflection Center (ADRC), where eventually the presentations will be posted.
In fact, here is the layout for near term events:
- Dec 2008 - Dedicated National Space Society (NSS) Ad Astra magazine
- Spring 2009, Association of Space Explorers (ASE) issues its report, "Asteroid Threats: A Call for Global Response" to the United Nation's Committee on the Peaceful Uses of Outer Space
- March 23-27 Lunar & Planetary Science Conference
- April 23-24 Space Law Conference: Near Earth Objects (NEOs): Risks and Opportunities, Lincoln, Nebraska
- April 27-30 International Planetary Defense Conference, Grenada, Spain
- October 2010 National Research deadline of review of NASA NEO report to congress
- October 2010 The deadline for the Office of Science and Technology Policy (OSTP) to recommend a lead agency to Congress
24 October 2008
The conference included participants from NASA, DTRA, USAF, AFRL, DHS, DIA, LLNL, Sandia, and NSF as well as the National Academies National Research Council which is now conducting a review of NEO discovery and deflection for the Congress. It also included represenatives from several corporations such as Lockheed, Orbital Sciences, Emergent Space, as well as a number of representatives from SIGMA, a unique think tank (http://www.sigmaforum.org/) which provides pro-bono services to government agencies. Correspondents from the Discovery Channel and National Geographic were also present.
Lindley Johnson provided an excellent overview of history and current NASA efforts, and details of 2008 TC3 incident.
Mark Boslough of Sandia provided compelling computer simulations of Low Altitude Airbursts that he asserted dominated the near threat, and he also made the case that deflection of asteroids for Geoengineering (to Earth-Sun L1 then create dust to create shadow) to avert rapid climate change was even more compelling for him in the near term. He discussed some fascinating and counterintuitive physics of Airburst phenomena that require much lower mass to cause equivalent damage, can create cratering, peristent vortices at temperatures above the melting temperature of rock, and a sort of massive plume where the colder, thicker atmosphere acts as a kind of rocket nozzle for the heated air.
Topics discussed ranged from solar sails, to kinetic impactors, to gravity tugs, to antimatter, fission, and fusion devices, and both deflection and disruption was discussed. The group seemed to think that there was no one best way, but that it would be useful to have a number of tools in the tool kit, but that there was much work to be done to create the underlying tools and common scenarios to allow decisionmakers to make proper selection.
While the conference was mainly technical, a significant theme, perhaps best articlated by Dr. Pete Worden, NASA Ames director, is the near term problem is not so much technology as Command and Control (C2)...who identifies the threat, who validates/believes it, who builds it, who decides, who tests, who tells whom, etc. Links to in-situ resource utilization, space industrialization, prizes and private sector participation (Tom Matula's asteroid bounty idea, Public-Private protected IP/limited liability) were discussed. International aspects were discussed.
Near-term missions for survey (such as NASA Ames MAAT) were discussed, but it was apparent that the existing vehicles for funding such missions currently have criteria to select for the best science or exploration technology, and that critical planetary technology missions are unfortunately not compelling under these criteria.
A spirited discussion took place around the topic of whether or not the discovery program had actually reduced risk, and the role of fear and rationality in decisionmaking. For an excellent discussion of these issues, see the following essay:
18 October 2008
A formal announcement of the ADRS 2008 can be found at
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.”
See Brochure at: http://www.adrc.iastate.edu/fileadmin/www.aere.iastate.edu/ADRC/ADRS_2008.pdf
See Orbit at: http://www.youtube.com/watch?v=DEMXqN3Zze8
See Flash Explosion: http://www.youtube.com/watch?v=WPWqB5Zo53M&NR=1
Video of TC3 a few hours before Impact:
Fly with TC3 Animation:
See TC3 to Ground: http://www.youtube.com/watch?v=4FW3oaZgCz0&NR=1
A recently discovered Apollo Asteroid, 2008 TC3, exploded over Sudan at about 1046 EDT on October 7, 2008. 2008 TC3 was discovered on Monday by an observer at the Mt Lemmon Observatory near Tucson, Arizona. 2008 TC3 is notable in that it is the first Asteroid of its size that was identified before impact and tracking it put the entire Spaceguard tracking system to an extreme test. TC3 is estimated to be only two to five meters in diameter but exploded with the force of a one kiloton nuclear device. Asteroids of this size hit the Earth every few months according JPL scientists. No deaths have been reported yet. The important lesson here is that Spaceguard is able to identify and track these smaller objects as well as the larger ones. A 20 to 50 meter asteroid exploding over a major city could result in a significant loss of property and life. The most imagined dire consequences of AGW could never stack up to the actual consequences of a larger asteroid actually impacting nearly anywhere on the Earth. If for this reason alone, funding for space exploration needs to be continued.
Meteosat 8 / EUMETSAT IR image of the 2008 TC3 explosion. Copyright 2008 EUMETSAT
It exploded tens of kilometers above the ground with the energy of around one kiloton of TNT, causing a large fireball in the early morning sky. Very few people inhabit the remote area of the Nubian Desert where the explosion took place; The Times, however, reported that the meteoroid's "light was so intense that it lit up the sky like a full moon and an airliner 1,400 km (870 miles) away reported seeing the bright flash." A low-resolution image of the explosion was captured by the weather satellite Meteosat 8. The Meteosat images place the fireball at 21°00′N 32°09′E / 21.00, 32.15. Infrasound detector arrays in Kenya also detected a sound wave from the direction of the expected impact corresponding to energy of 1.1 to 2.1 kilotons of TNT. Meteoroids of this size hit Earth about two or three times a year.
The trajectory showed intersection with Earth's surface at roughly 20°18′N 33°30′E / 20.3, 33.5 though the object was expected to break up perhaps 100–200 kilometers west as it descended, somewhat east of the Nile River, and about 100 kilometers south of the Egypt–Sudan border.
According to U.S. government sources U.S. satellites detected the impact at 02:45:40 UT, with the initial detection at 20°54′N 31°24′E / 20.9, 31.4 at 65.4 km altitude and final explosion at 20°48′N 32°12′E / 20.8, 32.2 at 37 km altitude.
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.
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.
Sounds a bit anticlimactic-and that’s not the half of it. It’s not even a rare event! Objects of this size are believed (and sometimes observed) to enter Earth’s atmosphere a few times each year. So what’s the blog deal? Observers on the ground reported the fireball lit up the skies with the intensity of the Full Moon. A nearby airliner (not in danger, as the fireball exploded tens of kilometers above the ground, well above the airliner’s flight path) reported seeing a bright flash.
In a sense, this event was kind of a dress rehearsal for the international system of predicting, and possibly defending against, impacts on Earth by much larger asteroids and comets. We already know of thousands of Near Earth Objects (NEOs-asteroids and comets that cross Earth’s orbit and are large enough to cause a catastrophe should they strike the Earth). It is also expected that there are many thousands more that we haven’t yet detected, being small enough to “fly under the radar” of our NEO detecting network.
Early detection and sustained tracking of NEOs is key to the protection plan against impact disaster. If we can accurately predict an impact far enough in advance, we could potentially send a spacecraft to it and gently “nudge” it off course and deflect the eventual impact.
So ends the existence of another chunk of rock that had, up to that point, been serenely orbiting the Sun for billions of years…
More information is available at the CBAT site.
UPDATE: the body was 5 meters in diameter. It was a carbonaceous chondrite, and its darkness explains why the diameter had been underestimated by luminosity measurements before the impact. It is quite likely that many small bodies will be found in northern Sudan, which is above the impact point of the asteroid. Also worth noting is that dr. Peter Brown, from West Ontario University, detected a sound wave from the impact with detectors located in Kenya.
The fireball made by the body at 4.46AM yesterday has been spotted by a airplane pilot from Air France-KLM, according to Jacob Kuiper, a meteorologist from the Netherlands who had informed the pilots of the possibility before the impact. The fall has freed an energy of about two kilotons of TNT, about a tenth of the energy of the first atomic bomb over Hiroshima.
UPDATE: thanks to the Meteosat, we now have a picture of the event. It is a temperature scan, which shows the impact of the object with the atmosphere. It is the first time that the impact of a body with the Earth is predicted and then observed. Near-Earth object surveys are getting better and better…
The Planetary Society Blog
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.
20 August 2008
MOSCOW, July 1 (RIA Novosti) - Nuclear explosive devices are the most effective means of protecting Earth from possible collisions with space bodies, including comets and asteroids, a Russian nuclear physicist told RIA Novosti on Tuesday.
Scientists around the world have long been seeking means of protecting the Earth from the threat of dangerous Near Earth Objects (NEOs). Scientists say such collisions pose a threat on average once every 200-1,000 years.
Vadim Simonenko, deputy head of the Russian Federal Nuclear Center, believes that nuclear explosive devices are more energy efficient, compact and less heavy than lasers or the so-called "gravitational tractors" in terms of their practical application as "weapons against NEOs."
"We in Russia have a wealth of experience in the controlled use of nuclear explosions for peaceful purposes," Simonenko said. "A nuclear device in skillful hands is like a scalpel in the hands of a surgeon."
The scientist said special nuclear devices must be created for effective use against NEOs. In order to disperse an asteroid with diameter of up to 100 meters, these devices must have a yield of about one megaton of TNT equivalent, and weigh several hundred kilograms.
"It is a difficult technical task but it can be accomplished. Besides, there is no need for actual testing [of these devices] because it may be done through computer modeling," he said.
Existing nuclear devices, both military and civilian, were created for specific purposes and do not meet the requirements for "precision strikes" against NEOs, especially comets, which are less predictable than asteroids, Simonenko said.
An earlier report at a Moscow scientific conference said 99942 Apophis, or Asteroid 2004 MN4, with a diameter of 350 meters, currently poses biggest space threat to Earth.
In 2029, this NEO will be at a distance of only 36,000 km (22,400 miles) - closer than satellites in geostationary orbit. Earth's gravity could alter the path of Apophis in such a way that it would collide with Earth on its next approach in 2036.
The explosion could surpass the famous Tunguska explosion of June 30, 1908, which affected a 2,150 square kilometer (830 sq miles) area of Russia felling over 80 million trees in the Krasnoyarsk Territory in Siberia.
Some researchers believe, however, that blowing up NEOs in space poses could result in large fragments surviving the fiery passage through the atmosphere and still hitting the planet.
They propose a more cautionary approach toward dealing with NEOs, by deflecting them from their collision path toward the Earth.
"Deflection is the most favorable strategy, but it requires a considerable early warning period - up to a few years," Simonenko said. "We may not have such a luxury because small asteroids [100-150 m in diameter] are hard to detect."