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.
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
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
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
Articles: Explosing Asteroid over Canada
From the Astrobiology article...
Geological evidence found in Ohio and Indiana in recent weeks is strengthening the case to attribute what happened 12,900 years ago in North America -- when the end of the last Ice Age unexpectedly turned into a phase of extinction for animals and humans – to a cataclysmic comet or asteroid explosion over top of Canada. The study could yield clues about how objects from space could affect the future of life on our planet.
A comet/asteroid theory advanced by Arizona-based geophysicist Allen West in the past two years says that an object from space exploded just above the earth’s surface at that time over modern-day Canada, sparking a massive shock wave and heat-generating event that set large parts of the northern hemisphere ablaze, setting the stage for the extinctions.
Now University of Cincinnati Assistant Professor of Anthropology Ken Tankersley, working in conjunction with Allen West and Indiana Geological Society Research Scientist Nelson R. Schaffer, has verified evidence from sites in Ohio and Indiana – including, locally, Hamilton and Clermont counties in Ohio and Brown County in Indiana – that offers the strongest support yet for the exploding comet/asteroid theory.
Samples of diamonds, gold and silver that have been found in the region have been conclusively sourced through X-ray diffractometry in the lab of UC Professor of Geology Warren Huff back to the diamond fields region of Canada.
The only plausible scenario available now for explaining their presence this far south is the kind of cataclysmic explosive event described by West’s theory. "We believe this is the strongest evidence yet indicating a comet impact in that time period," says Tankersley.
During the period known as the Younger Dryas, large mammals like wooly mammoths became extinct.
Credit: USGS
Ironically, Tankersley had gone into the field with West believing he might be able to disprove West’s theory.
Tankersley was familiar through years of work in this area with the diamonds, gold and silver deposits, which at one point could be found in such abundance in this region that the Hopewell Indians who lived here about 2,000 years ago engaged in trade in these items.
Prevailing thought said that these deposits, which are found at a soil depth consistent with the time frame of the comet/asteroid event, had been brought south from the Great Lakes region by glaciers.
"My smoking gun to disprove (West) was going to be the gold, silver and diamonds," Tankersley says. "But what I didn’t know at that point was a conclusion he had reached that he had not yet made public – that the likely point of impact for the comet wasn’t just anywhere over Canada, but located over Canada’s diamond-bearing fields. Instead of becoming the basis for rejecting his hypothesis, these items became the very best evidence to support it."
Additional sourcing work is being done at the sites looking for iridium, micro-meteorites and nano-diamonds that bear the markers of the diamond-field region, which also should have been blasted by the impact into this region.
Much of the work is being done in Sheriden Cave in north-central Ohio’s Wyandot County, a rich repository of material dating back to the Ice Age.
Tankersley first came into contact with West and Schaffer when they were invited guests for interdisciplinary colloquia presented by UC’s Department of Geology this spring.
West presented on his theory that a large comet or asteroid, believed to be more than a mile in diameter, exploded just above the earth at a time when the last Ice Age appeared to be drawing to a close.
Many scientists hypothesize that mass extinctions our planet’s history may well have been due to comet and asteroid impacts.
Credit: NASA ARC
The timing attached to this theory of about 12,900 years ago is consistent with the known disappearances in North America of the wooly mammoth population and the first distinct human society to inhabit the continent, known as the Clovis civilization. At that time, climatic history suggests the Ice Age should have been drawing to a close, but a rapid change known as the Younger Dryas event, instead ushered in another 1,300 years of glacial conditions. A cataclysmic explosion consistent with West’s theory would have the potential to create the kind of atmospheric turmoil necessary to produce such conditions.
"The kind of evidence we are finding does suggest that climate change at the end of the last Ice Age was the result of a catastrophic event," Tankersley says.
Currently, Tankersley can be seen in a new documentary airing on the National Geographic channel. The film "Asteroids" is part of that network’s "Naked Science" series.
The new discoveries made working with West and Schaffer will be incorporated into two more specials that Tankersley is currently involved with – one for the PBS series "Nova" and a second for the History Channel that will be filming Tankersley and his UC students in the field this summer. Another documentary, this one being produced by the Discovery Channel and the British public television network Channel 4, will also be following Tankersley and his students later this summer.
As more data continues to be compiled, Tankersley, West and Schaffer will be publishing about this newest twist in the search to explain the history of our planet and its climate.
Climate change is a favorite topic for Tankersley. "The ultimate importance of this kind of work is showing that we can’t control everything," he says. "Our planet has been hit by asteroids many times throughout its history, and when that happens, it does produce climate change."
Link: Astrobiology Press Release
Link: UPI Article
Link: Montreal Gazette Article
Geological evidence found in Ohio and Indiana in recent weeks is strengthening the case to attribute what happened 12,900 years ago in North America -- when the end of the last Ice Age unexpectedly turned into a phase of extinction for animals and humans – to a cataclysmic comet or asteroid explosion over top of Canada. The study could yield clues about how objects from space could affect the future of life on our planet.
A comet/asteroid theory advanced by Arizona-based geophysicist Allen West in the past two years says that an object from space exploded just above the earth’s surface at that time over modern-day Canada, sparking a massive shock wave and heat-generating event that set large parts of the northern hemisphere ablaze, setting the stage for the extinctions.
Now University of Cincinnati Assistant Professor of Anthropology Ken Tankersley, working in conjunction with Allen West and Indiana Geological Society Research Scientist Nelson R. Schaffer, has verified evidence from sites in Ohio and Indiana – including, locally, Hamilton and Clermont counties in Ohio and Brown County in Indiana – that offers the strongest support yet for the exploding comet/asteroid theory.
Samples of diamonds, gold and silver that have been found in the region have been conclusively sourced through X-ray diffractometry in the lab of UC Professor of Geology Warren Huff back to the diamond fields region of Canada.
The only plausible scenario available now for explaining their presence this far south is the kind of cataclysmic explosive event described by West’s theory. "We believe this is the strongest evidence yet indicating a comet impact in that time period," says Tankersley.
During the period known as the Younger Dryas, large mammals like wooly mammoths became extinct.
Credit: USGS
Ironically, Tankersley had gone into the field with West believing he might be able to disprove West’s theory.
Tankersley was familiar through years of work in this area with the diamonds, gold and silver deposits, which at one point could be found in such abundance in this region that the Hopewell Indians who lived here about 2,000 years ago engaged in trade in these items.
Prevailing thought said that these deposits, which are found at a soil depth consistent with the time frame of the comet/asteroid event, had been brought south from the Great Lakes region by glaciers.
"My smoking gun to disprove (West) was going to be the gold, silver and diamonds," Tankersley says. "But what I didn’t know at that point was a conclusion he had reached that he had not yet made public – that the likely point of impact for the comet wasn’t just anywhere over Canada, but located over Canada’s diamond-bearing fields. Instead of becoming the basis for rejecting his hypothesis, these items became the very best evidence to support it."
Additional sourcing work is being done at the sites looking for iridium, micro-meteorites and nano-diamonds that bear the markers of the diamond-field region, which also should have been blasted by the impact into this region.
Much of the work is being done in Sheriden Cave in north-central Ohio’s Wyandot County, a rich repository of material dating back to the Ice Age.
Tankersley first came into contact with West and Schaffer when they were invited guests for interdisciplinary colloquia presented by UC’s Department of Geology this spring.
West presented on his theory that a large comet or asteroid, believed to be more than a mile in diameter, exploded just above the earth at a time when the last Ice Age appeared to be drawing to a close.
Many scientists hypothesize that mass extinctions our planet’s history may well have been due to comet and asteroid impacts.
Credit: NASA ARC
The timing attached to this theory of about 12,900 years ago is consistent with the known disappearances in North America of the wooly mammoth population and the first distinct human society to inhabit the continent, known as the Clovis civilization. At that time, climatic history suggests the Ice Age should have been drawing to a close, but a rapid change known as the Younger Dryas event, instead ushered in another 1,300 years of glacial conditions. A cataclysmic explosion consistent with West’s theory would have the potential to create the kind of atmospheric turmoil necessary to produce such conditions.
"The kind of evidence we are finding does suggest that climate change at the end of the last Ice Age was the result of a catastrophic event," Tankersley says.
Currently, Tankersley can be seen in a new documentary airing on the National Geographic channel. The film "Asteroids" is part of that network’s "Naked Science" series.
The new discoveries made working with West and Schaffer will be incorporated into two more specials that Tankersley is currently involved with – one for the PBS series "Nova" and a second for the History Channel that will be filming Tankersley and his UC students in the field this summer. Another documentary, this one being produced by the Discovery Channel and the British public television network Channel 4, will also be following Tankersley and his students later this summer.
As more data continues to be compiled, Tankersley, West and Schaffer will be publishing about this newest twist in the search to explain the history of our planet and its climate.
Climate change is a favorite topic for Tankersley. "The ultimate importance of this kind of work is showing that we can’t control everything," he says. "Our planet has been hit by asteroids many times throughout its history, and when that happens, it does produce climate change."
Link: Astrobiology Press Release
Link: UPI Article
Link: Montreal Gazette Article
06 July 2008
ESA ROSETTA Mission and Flyby of Asteroid Steins
From the article about the ROSETTA mission and its flyby of asteroid Steins...
European Space Agency mission managers woke the Rosetta probe from hibernation to prepare for its encounter with asteroid Steins on Sept. 5, according to a statement this week. The robot's ultimate destination is comet 67/P Churyumov-Gerasimenko.
Launched in March 2004, Rosetta will reach its final destination only in 2014, after traveling a total of about 4 billion miles (6.5 billion kilometers).
Rosetta has swung by Earth twice and Mars once, to get gravitational boosts. The third and last Earth swing-by is scheduled for November 2009. The spacecraft will also fly by asteroid Lutetia in June 2010.
When it reaches asteroid Steins this year, Rosetta will be about twice as far from the sun as is Earth. The encounter will occur in the asteroid belt between Mars and Jupiter. The probe will come within 500 miles (800 kilometers) of the asteroid.
"Spacecraft Woken for Asteroid Encounter"
SPACE.com Staff
05 July 2008
From Paolo and IM4 on the Unmannedspaceflight.com forums (UnmannedSpaceflight.com/ Other Missions/ Cometary and Asteroid Missions/ Rosetta flyby of Asteroid Steins, 5th September 2008)...
Steins is a small body less than 10 km across, discovered on 4 November 1969 by Soviet astronomer N. Chernykh at the Nauchnyj Observatory in Crimea and named after Karlis Steins, former director of the Latvian University Astronomical Observatory. While the properties of Lutetia, the second asteroid target are relatively well known, being a largish and bright object discovered more than a century ago, almost nothing was known about Steins, and observational campaigns were started in 2004 to characterize it. Steins was observed by the largest astronomical observatory on Earth, including the European Very Large Telescope (VLT) in Chile, JPL's Table Mountain Observatory, the Spitzer infrared astronomy satellite and Rosetta itself.
The Rosetta orbiter observed continuously Steins (1.06 AU away) for 24 hours with its science camera on 11 March 2006 in order to collect a “light curve” at phase angles larger than ever achievable from Earth, due to observational geometry constrains and for a longer time span, uninterrupted by day and night cycles. A total of 238 images were taken, covering four rotations.
Although researchers initially catalogued Steins in the S class (like most previously-visited bodies), the observational campaigns found that its spectral and polarimetric properties placed it in the E taxonomic class of reddish bodies with high albedo believed to be thermally evolved and of igneous origin, which underwent at least a partial melting and differentiation early in their history. E asteroid spectra probably makes them related to some rare enstatite chondrite or aubrite meteorites and therefore these bodies are believed to have a surface consisting of iron-free or iron-poor silicates. Observations pinpointed Steins' rotation period at about 6.05 hours, while the measured diameter could vary between 2 and 5 km, depending on its albedo. Asymmetries in the light curve confirmed that the small body has an irregular shape, with a ratio between the main axes of about 1.3. Other researchers pointed out that some of the characteristics of Steins could hint at a young and very rough surface at most a few million years old.
While fewer than 30 members of the E class of asteroids were known, including (44) Nysa, the largest, and two near-Earth objects, (3103) Eger and (4660) Nereus (a recurrent space mission target), little is known about the evolutionary history of the type. Steins was initially placed in the same family as (64) Angelina, but other studies showed that it shared most of the same spectral characteristics as Eger, both bodies being believed to be members of an old eroded family which formed in the inner asteroid belt close to the present position of Steins, which appears to be the largest member of the family. The presence of Eger in an Earth-intersecting orbit of course provides a path for enstatite and aubrite meteorites to hit our planet.
The encounter on 5 September 2008 will be at a distance of 1745 km and a relative speed of 8.6 km/
Flyby in a nutshell:
1. Closest approach on 5 Sept. 2008 18:33:57 ± 30 sec
2. Heliocentric distance 2.14 AU, geocentric distance 2.41 AU
3. Low phase angle during approach, high phase angle after closest approach, coverage 0-140°
4. Minimum flyby distance of 800 km
5. Zero phase angle will be reached at a distance of 1280 km
6. One way light travel time will be 20 min
Flyby strategy
1. Default pointing
2. Spacecraft flip (T-40 min -> T-20 min)
3. Inverted pointing (> T-20 min)
4. +Z axis points at Steins at all times
Flyby Science:
1. Alice: point at Steins to obtain FUV spectra search for exosphere/coma around Steins
2. COSIMA: execute normal dust collection cycle
3. GIADA: Impact sensor operational, but cover closed
4. MIRO: Steins observations during approach and recession. Special asteroid mode sequence at closest approach (CA)
5. ROSINA: Pressure monitoring, single mass measurement sequence
6. RPC: Measurements of plasma environment
7. RSI: Attempt for mass determination (probably not feasible)
8. OSIRIS: Light curve for 2 weeks before CA for shape reconstruction. At CA: spectrophotometry, mapping and surface properties, satellite/dust search
9. VIRTIS: Steins light curve determination starting 7 hours before CA. At CA: mineralogy mapping
Expected data volume:
1. 600 MiB before closest approach
2. 2400 MiB after closest approach
Link: Space.com article
Link: LPSI Abstract on Asteroid Steins (PDF)
Link: Unmannedspaceflight.com Forums
Link: Wikipedia Entry for Asteroid Steins
European Space Agency mission managers woke the Rosetta probe from hibernation to prepare for its encounter with asteroid Steins on Sept. 5, according to a statement this week. The robot's ultimate destination is comet 67/P Churyumov-Gerasimenko.
Launched in March 2004, Rosetta will reach its final destination only in 2014, after traveling a total of about 4 billion miles (6.5 billion kilometers).
Rosetta has swung by Earth twice and Mars once, to get gravitational boosts. The third and last Earth swing-by is scheduled for November 2009. The spacecraft will also fly by asteroid Lutetia in June 2010.
When it reaches asteroid Steins this year, Rosetta will be about twice as far from the sun as is Earth. The encounter will occur in the asteroid belt between Mars and Jupiter. The probe will come within 500 miles (800 kilometers) of the asteroid.
"Spacecraft Woken for Asteroid Encounter"
SPACE.com Staff
05 July 2008
From Paolo and IM4 on the Unmannedspaceflight.com forums (UnmannedSpaceflight.com/ Other Missions/ Cometary and Asteroid Missions/ Rosetta flyby of Asteroid Steins, 5th September 2008)...
Steins is a small body less than 10 km across, discovered on 4 November 1969 by Soviet astronomer N. Chernykh at the Nauchnyj Observatory in Crimea and named after Karlis Steins, former director of the Latvian University Astronomical Observatory. While the properties of Lutetia, the second asteroid target are relatively well known, being a largish and bright object discovered more than a century ago, almost nothing was known about Steins, and observational campaigns were started in 2004 to characterize it. Steins was observed by the largest astronomical observatory on Earth, including the European Very Large Telescope (VLT) in Chile, JPL's Table Mountain Observatory, the Spitzer infrared astronomy satellite and Rosetta itself.
The Rosetta orbiter observed continuously Steins (1.06 AU away) for 24 hours with its science camera on 11 March 2006 in order to collect a “light curve” at phase angles larger than ever achievable from Earth, due to observational geometry constrains and for a longer time span, uninterrupted by day and night cycles. A total of 238 images were taken, covering four rotations.
Although researchers initially catalogued Steins in the S class (like most previously-visited bodies), the observational campaigns found that its spectral and polarimetric properties placed it in the E taxonomic class of reddish bodies with high albedo believed to be thermally evolved and of igneous origin, which underwent at least a partial melting and differentiation early in their history. E asteroid spectra probably makes them related to some rare enstatite chondrite or aubrite meteorites and therefore these bodies are believed to have a surface consisting of iron-free or iron-poor silicates. Observations pinpointed Steins' rotation period at about 6.05 hours, while the measured diameter could vary between 2 and 5 km, depending on its albedo. Asymmetries in the light curve confirmed that the small body has an irregular shape, with a ratio between the main axes of about 1.3. Other researchers pointed out that some of the characteristics of Steins could hint at a young and very rough surface at most a few million years old.
While fewer than 30 members of the E class of asteroids were known, including (44) Nysa, the largest, and two near-Earth objects, (3103) Eger and (4660) Nereus (a recurrent space mission target), little is known about the evolutionary history of the type. Steins was initially placed in the same family as (64) Angelina, but other studies showed that it shared most of the same spectral characteristics as Eger, both bodies being believed to be members of an old eroded family which formed in the inner asteroid belt close to the present position of Steins, which appears to be the largest member of the family. The presence of Eger in an Earth-intersecting orbit of course provides a path for enstatite and aubrite meteorites to hit our planet.
The encounter on 5 September 2008 will be at a distance of 1745 km and a relative speed of 8.6 km/
Flyby in a nutshell:
1. Closest approach on 5 Sept. 2008 18:33:57 ± 30 sec
2. Heliocentric distance 2.14 AU, geocentric distance 2.41 AU
3. Low phase angle during approach, high phase angle after closest approach, coverage 0-140°
4. Minimum flyby distance of 800 km
5. Zero phase angle will be reached at a distance of 1280 km
6. One way light travel time will be 20 min
Flyby strategy
1. Default pointing
2. Spacecraft flip (T-40 min -> T-20 min)
3. Inverted pointing (> T-20 min)
4. +Z axis points at Steins at all times
Flyby Science:
1. Alice: point at Steins to obtain FUV spectra search for exosphere/coma around Steins
2. COSIMA: execute normal dust collection cycle
3. GIADA: Impact sensor operational, but cover closed
4. MIRO: Steins observations during approach and recession. Special asteroid mode sequence at closest approach (CA)
5. ROSINA: Pressure monitoring, single mass measurement sequence
6. RPC: Measurements of plasma environment
7. RSI: Attempt for mass determination (probably not feasible)
8. OSIRIS: Light curve for 2 weeks before CA for shape reconstruction. At CA: spectrophotometry, mapping and surface properties, satellite/dust search
9. VIRTIS: Steins light curve determination starting 7 hours before CA. At CA: mineralogy mapping
Expected data volume:
1. 600 MiB before closest approach
2. 2400 MiB after closest approach
Link: Space.com article
Link: LPSI Abstract on Asteroid Steins (PDF)
Link: Unmannedspaceflight.com Forums
Link: Wikipedia Entry for Asteroid Steins
NYTimes DotEarth Blog Picks Up on Planetary Defense
The New York Times DotEarth Blog picks up on the planetary defense story. They include both the SGAC Move An Asteroid 2008 competition and The Planetary Society's Apophis Mission Design Competition (both of which I was involved with).
"Solar System Roulette"
Andrew C. Revkin
06 July 2008
Link: NYTimes DotEarth Blog
"Solar System Roulette"
Andrew C. Revkin
06 July 2008
Link: NYTimes DotEarth Blog
04 July 2008
Article: Strange Asteroid Shapes Explained
Selections from the article...
Researchers have been using a vast database to study a staggering 11,735 asteroids. They have discovered that asteroids change shape over time, and they think they know the reason why.
Gyula Szabó from the University of Szeged [Hungary] is the lead author of the study, which was published in the July edition of Icarus. He explains, "There are several hundred thousand asteroids in our solar system. They orbit the sun, but because they are small their surface gravity is low. This means that many have strange, irregular shapes."
Scientists like Gyula think that about one third of known asteroids belong to groups called "families." These clusters probably formed from piles of debris after larger objects collided.
But what changes the asteroids' shape? Gyula and his team have shown that asteroids change shape from elongated to roughly spherical due to being impacted during their lifetimes. They are like pebbles on the beach that become worn smooth over many years -- only in space, erosion is caused by small impacts as rocks knock into each other and chip pieces off.
"Strange Asteroid Shapes Explained"
Lee Pullen
Astrobiology Magazine
03 July 2008
Link: Space.com article
---- ICARUS ABSTRACT
"The shape distribution of asteroid families: Evidence for evolution driven by small impacts"
Gyula M. Szabóa, b, Corresponding Author Contact Information, E-mail The Corresponding Author and László L. Kissc
aMagyary Fellow, School of Physics A28, University of Sydney, NSW 2006, Australia
bDepartment of Experimental Physics, University of Szeged, 6720 Szeged, Hungary
cSchool of Physics A28, University of Sydney, NSW 2006, Australia
Received 17 July 2007;
revised 22 November 2007.
Available online 29 February 2008.
Abstract
A statistical analysis of brightness variability of asteroids reveals how their shapes evolve from elongated to rough spheroidal forms, presumably driven by impact-related phenomena. Based on the Sloan Digital Sky Survey Moving Object Catalog, we determined the shape distribution of 11,735 asteroids, with special emphasis on eight prominent asteroid families. In young families, asteroids have a wide range of shape elongations, implying fragmentation–formation. In older families we see an increasing number of rough spheroids, in agreement with the predictions of an impact-driven evolution. Old families also contain a group of moderately elongated members, which we suggest correspond to higher-density, more impact-resistant cores of former fragmented asteroids that have undergone slow shape erosion. A few percent of asteroids have very elongated shapes, and can either be young fragments or tidally reshaped bodies. Our results confirm that the majority of asteroids are gravitationally bound “rubble piles.”
Link: ICARUS Abstract
Researchers have been using a vast database to study a staggering 11,735 asteroids. They have discovered that asteroids change shape over time, and they think they know the reason why.
Gyula Szabó from the University of Szeged [Hungary] is the lead author of the study, which was published in the July edition of Icarus. He explains, "There are several hundred thousand asteroids in our solar system. They orbit the sun, but because they are small their surface gravity is low. This means that many have strange, irregular shapes."
Scientists like Gyula think that about one third of known asteroids belong to groups called "families." These clusters probably formed from piles of debris after larger objects collided.
But what changes the asteroids' shape? Gyula and his team have shown that asteroids change shape from elongated to roughly spherical due to being impacted during their lifetimes. They are like pebbles on the beach that become worn smooth over many years -- only in space, erosion is caused by small impacts as rocks knock into each other and chip pieces off.
"Strange Asteroid Shapes Explained"
Lee Pullen
Astrobiology Magazine
03 July 2008
Link: Space.com article
---- ICARUS ABSTRACT
"The shape distribution of asteroid families: Evidence for evolution driven by small impacts"
Gyula M. Szabóa, b, Corresponding Author Contact Information, E-mail The Corresponding Author and László L. Kissc
aMagyary Fellow, School of Physics A28, University of Sydney, NSW 2006, Australia
bDepartment of Experimental Physics, University of Szeged, 6720 Szeged, Hungary
cSchool of Physics A28, University of Sydney, NSW 2006, Australia
Received 17 July 2007;
revised 22 November 2007.
Available online 29 February 2008.
Abstract
A statistical analysis of brightness variability of asteroids reveals how their shapes evolve from elongated to rough spheroidal forms, presumably driven by impact-related phenomena. Based on the Sloan Digital Sky Survey Moving Object Catalog, we determined the shape distribution of 11,735 asteroids, with special emphasis on eight prominent asteroid families. In young families, asteroids have a wide range of shape elongations, implying fragmentation–formation. In older families we see an increasing number of rough spheroids, in agreement with the predictions of an impact-driven evolution. Old families also contain a group of moderately elongated members, which we suggest correspond to higher-density, more impact-resistant cores of former fragmented asteroids that have undergone slow shape erosion. A few percent of asteroids have very elongated shapes, and can either be young fragments or tidally reshaped bodies. Our results confirm that the majority of asteroids are gravitationally bound “rubble piles.”
Link: ICARUS Abstract
Secure World Foundation and NEOs
The Secure World Foundation has some activities on NEOs. Selection from an article on their activities...
Speaking recently at a Secure World Foundation luncheon at the University of Colorado - Boulder, Schweickart [Apollo astronaut, Russell L. (Rusty) Schweickart] emphasized that what is needed is an international protocol – “mission rules” -- that deal with asteroids that are menacing to Earth. Such a plan could calls upon nations around the globe to consider and embrace steps that can help mitigate the destructive nature stemming from an asteroid striking our planet.
Working with the Association of Space Explorers and the talents of the B612 Foundation – and supported in part by the Secure World Foundation -- the former astronaut has organized a series of workshops on the NEO threat, geared to creating a protocol for submission to the United Nations for its deliberation. These are to be spelled out in a mission rules document for protecting the Earth from asteroid impacts.
Moreover, the document is to be briefed to stakeholders around the globe – from spacefaring nations and agencies, as well as to key decision-makers in leadership positions.
Link: ScienceDaily Article
Link: Secure World Foundation - NEO Page
Link: Secure World Foundation - Press Release on NEO Talk
Speaking recently at a Secure World Foundation luncheon at the University of Colorado - Boulder, Schweickart [Apollo astronaut, Russell L. (Rusty) Schweickart] emphasized that what is needed is an international protocol – “mission rules” -- that deal with asteroids that are menacing to Earth. Such a plan could calls upon nations around the globe to consider and embrace steps that can help mitigate the destructive nature stemming from an asteroid striking our planet.
Working with the Association of Space Explorers and the talents of the B612 Foundation – and supported in part by the Secure World Foundation -- the former astronaut has organized a series of workshops on the NEO threat, geared to creating a protocol for submission to the United Nations for its deliberation. These are to be spelled out in a mission rules document for protecting the Earth from asteroid impacts.
Moreover, the document is to be briefed to stakeholders around the globe – from spacefaring nations and agencies, as well as to key decision-makers in leadership positions.
Link: ScienceDaily Article
Link: Secure World Foundation - NEO Page
Link: Secure World Foundation - Press Release on NEO Talk
02 July 2008
Article: Tunguska at 100
"Tunguska meteoroid turns 100 years old: KP journalist visits the region where the 20th Century's most mysterious cosmic visitor exploded"
Andrey Moiseenko
02 July 2008
Link: Part 1 of Article
Link: Part 2 of Article
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