[FPSPACE] FW: NEO News (03/09/07) Planetary Defense Conference Pt 2

[LARRY KLAES]

>From: David Morrison <dmorrison at arc.nasa.gov>
>To: David Morrison <dmorrison at arc.nasa.gov>
>Subject: NEO News (03/09/07) Planetary Defense Conference Pt 2
>Date: Fri, 9 Mar 2007 16:20:41 -0800
>
>
>NEO News (03/09/07) Planetary Defense Conference Pt 2
>
>Below is a report on the second half of the Planetary Defense Conference 
>held this week in Washington DC. These sessions dealt with a range of 
>societal and strategy issues, and in this summary I am reporting on only a 
>few of the papers. At the end of this edition of NEO News are more press 
>comments from the meeting.
>
>I am happy to note that the NASA Study Report to Congress, submitted in 
>response to the mandate to present a program plan to find 90% of NEAs down 
>to 140m, was submitted late this week. This 27-page report is titled "Near 
>Earth Object Survey and Deflection Analysis of Alternatives". We will 
>comment on this report in a later edition of NEO News.
>
>David Morrison
>
>================================
>
>Impacts and Effects
>
>Several papers were presented on the effects of impacts of various sizes. 
>These included talks by both Galen Gisler (U Oslo) and Steven Ward (UC 
>Santa Cruz) on the effects of tsunamis. Both emphasized the uncertainty 
>that is caused by the fact that the wavelength and frequency of impact 
>tsunamis is intermediate between that of ordinary storm waves and seismic 
>tsunamis. Gisler presented detailed computer simulations of impacts, 
>creating extremely high waves that also have high turbulent dissipation. 
>However, his computer runs trace the waves only to 100 km from the point of 
>impact, so they do not address the important question of how far these 
>waves propagate. Ward's presentation noted one new effect, the build-up of 
>water when a series of short-wavelength waves hit the shore. If the waves 
>are coming in once every few minutes, they do not have time to retreat 
>before the next in the series hits, so that the run-up and run-in of the 
>impact tsunamis is greater than had been assumed previously.
>
>Mark Boslough (Sandia) discussed interesting simulations of atmospheric 
>explosions such as Tunguska. Noting that the fireball from a meteor 
>explosion has considerably downward momentum (unlike the classic mushroom 
>cloud from a nuclear explosion), he concludes that the Tunguska impactor 
>exploded higher and was smaller (energy of order 5 megatons) than usually 
>inferred.
>
>Preparing the Public
>
>Richard Davies (Western Disaster Center) challenged us to consider the 
>political ramifications if a small (few megaton) impact took place without 
>warning. Comparing with the government investigation following Katrina, he 
>noted that difficult questions would be raised concerning lack of 
>preparation. This scenario highlights the absence of communication today 
>between the NEO community and the Department of Homeland Defense, let alone 
>the many state and local disaster agencies.
>
>Several other speakers made similar points -- we are not connecting with 
>the communities that exist to deal with natural hazards. They have an 
>infrastructure that could include planning for a Tunguska-class impact, but 
>they don't know we exist. We have thought about response to an impact 
>warning, but not much to the consequences of an impact without warning, 
>which remains the most likely (at least until completion of the next 
>generation survey).
>
>Policy and Political Issues
>
>Several distinguished speakers from outside the normal NEO community spoke 
>to the conference about these questions. One major issue was the role of 
>international activities. Rusty Schweickart (Association of Space 
>Explorers) made a strong case that this is a global problem, and it is 
>likely that nearly every nation will at some point in the next few years 
>have to think about its own vulnerability to an impact. Other speakers 
>agreed that this is a topic that needs to be on the agenda of the UN and 
>other international agencies, and that decisions to intercept a threatening 
>NEA must be made internationally. Yet the fact is that there is very little 
>international contribution today to NEA studies. Japan and the European 
>Space Agency have scientific missions planned to NEAs, but the United 
>States is the only country contributing to the Spaceguard Survey or the 
>Arecibo Radar, two key elements in planetary protection that are happening 
>now.
>
>Geoff Sommer (Homeland Security Institute) noted that increasing 
>quantification of the impact risk as a result of NEA surveys might work to 
>our disadvantage in seeking resources, relative to other societal risks 
>that are not quantifiable. People are generally more concerned about 
>unknown risks than those that are well understood (e.g., terrorism or 
>pandemics rather than auto accidents or malaria).
>
>Chris Chyba (Princeton U.) also addressed the impact hazard in the context 
>of global threats, comparing it to issues such as global warming, nuclear 
>proliferation, pandemics, and terrorism. He concluded that dealing with 
>most global issues requires a response involving several nations, whereas 
>the U.S. alone can mitigate the impact risk. He noted that the impact risk 
>is static, while most other global threats are increasing -- which may 
>decrease the motivation to allocate resources to protecting against 
>impacts. Chyba also emphasized how strongly most of the international 
>community mistrusts any mitigation strategy that involves nuclear 
>explosions, and he recommended that we pursue non-nuclear options to the 
>extent possible. (This opinion is in contrast to the current NASA study, 
>which gives considerable attention to nuclear options for asteroid threat 
>mitigation.)
>
>Preparing a White Paper
>
>The final discussions at the meeting dealt with input to an AIAA White 
>Paper. The strongest consensus concerned the critical importance of 
>maintaining the Arecibo Planetary Radar; support for Arecibo was proposed 
>as the first resolution in the White Paper. Other ideas included expansion 
>of  current surveys (taking advantage of the opportunities to include NEAs 
>within the mission of the Pan-STARRS and LSST telescopes) and expanding the 
>capability to process these data and generate NEA orbits and impact 
>predictions. On the question of how to protect against an identified 
>threat, the opinions seemed to fall toward using the gravity tractor or the 
>ballistic impact in preference to nuclear explosives.
>
>All three of these deflection technologies need to be developed, however, 
>since they have very different capabilities, and we are dealing here with a 
>huge range of NEA sizes and orbits. One of the complications is just 
>getting to the asteroid, which is much harder when it chooses us, as 
>opposed to us choosing it. The gravity tractor must match orbits 
>(rendezvous) with the target. In contrast, the kinetic impactor does not 
>need to slow down near the asteroid, but it does have to hit a small target 
>at high speed. Nuclear charges would normally be used from a rendezvous 
>spacecraft, but in extreme cases might be deployed like kinetic impact, 
>with a high-speed intercept. There is no "one size fits all" solution.
>
>Below are specific comments on these deflection strategies from Rusty 
>Schweickart, as well as several press responses.
>
>=================
>
>Comments from Rusty Schweickart on asteroid defense strategy:
>
>In the last day of the conference it all came together nicely, integrating 
>much of what we had heard both re deflection options, characterization and 
>the anticipated discovery "demographics". My take on it is that we're now 
>very close to the following:
>
>There will be some cases where impact-threatening NEAs will experience 
>close gravitational encounters (usually with Earth) prior to impact.  In 
>most of these cases, due to the multiplication effect of the associated 
>keyhole, the gravity tractor (GT) will be adequate to the job.
>
>If not (e.g. large object and/or "weak" keyhole) then a kinetic impactor 
>(KI) will certainly be adequate.  However, since the keyhole makes the 
>uncertainty large, a transponder should be sent ahead to both collapse the 
>line of variations on arrival and also be there for surveying the detailed 
>results of the kinetic impact.  Since a gravity tractor also has a 
>transponder aboard, the transponder mission itself should be a GT, which 
>also then has the advantage of not only surveying the final result of the 
>KI but also "trimming" up the deflection with precision to assure (the 
>world) that the deflection did not put the NEO into another keyhole.
>
>Finally, when all else is inadequate, the world will have to make the tough 
>decision of whether to take the chance of a hit or use a nuke. This should 
>be an extremely small component of the overall threat, and a diminishing 
>one over time since the major need for a nuke is the possibility of finding 
>a NEA headed for a near-term impact during the next 15 years of the survey. 
>  After that it's only the small remaining component of the residual very 
>large NEAs.
>
>The GT is a bit wimpy, but precise and great for when the ball is on the 
>green. KI is far more capable but more imprecise and should not be launched 
>without a GT/transponder.
>
>===============
>
>Funds Keeping NASA From Finding Killer Asteroids
>Scientists Have The Skill, But Don't Have The Money
>
>Mar 6, 2007
>
>(CBS4) WASHINGTON If there is a hidden killer asteroid or comet out in 
>space with Earth's name on it, NASA has the technology to find it. What it 
>doesn't have is the money to pay for the search, so NASA officials say it 
>likely won't get done.
>
>NASA officials say the space agency is capable of finding nearly all the 
>asteroids that might pose a devastating hit to Earth, but there isn't 
>enough money to pay for the task.
>
>The cost to find at least 90 percent of the 20,000 potentially hazardous 
>asteroids and comets by 2020 would be about $1 billion, or about the cost 
>of supporting two weeks of the War in Iraq, according to a report NASA will 
>release later this week. The report was previewed Monday at a Planetary 
>Defense Conference in Washington.
>
>Earth got a scare in 2004, when initial readings suggested an 885-foot 
>asteroid called 99942 Apophis seemed to have a chance of hitting Earth in 
>2029. But more observations showed that wouldn't happen. Scientists say 
>there is a 1-in-45,000 chance that it could hit in 2036. They think it 
>would mostly likely strike the Pacific Ocean, which would cause a tsunami 
>on the U.S. West Coast the size of the devastating 2004 Indian Ocean wave.
>
>John Logsdon, space policy director at George Washington University, said a 
>stepped-up search for such asteroids is needed. "You can't deflect them if 
>you can't find them," Logsdon said. "And we can't find things that can 
>cause massive damage."
>
>Congress in 2005 asked NASA to come up with a plan to track most killer 
>asteroids and propose how to deflect the potentially catastrophic ones. "We 
>know what to do, we just don't have the money," said Simon "Pete" Worden, 
>director of NASA's Ames Research Center.
>
>==================
>
>Big blasts or tiny tugs: How to stop an asteroid catastrophe
>Collision with Earth is seen as inevitable, but scientists are meeting to 
>find solution
>
>Alok Jha, science correspondent
>The Guardian, March 7, 2007
>
>A huge asteroid hurtles in from outer space to devastate the Earth, an 
>unstoppable force of nature from which there is no escape. Just such a 
>catastrophe is thought to have killed off the dinosaurs, and, according to 
>most experts, it is only a matter of time before a similar fate befalls the 
>human race.
>
>But perhaps not all hope is lost. Hundreds of scientists, from nuclear 
>weapons engineers to planetary experts, are gathering in Washington this 
>week to try to develop a master plan to protect the Earth from such an 
>asteroid.
>
>The Planetary Defence Conference, organised by the US Aerospace 
>Corporation, will bring together scores of ideas on how to develop 
>technology to track and deflect objects heading towards the Earth. The 
>gathering will also consider the sticky problem of public relations - is it 
>best to warn people if the worst comes to the worst?
>
>"The collision of a moderately large asteroid or comet, also referred to as 
>a near-Earth object (NEO), with Earth would have catastrophic 
>consequences," writes Brent William Barbee of Emergent Space Technologies 
>Inc in a discussion paper to be presented at the meeting. "Such events have 
>occurred in the past and will occur again in the future. However, for the 
>first time in known history, humanity may have the technology required to 
>counter this threat."
>
>Many smaller objects around the Earth's orbit break up when they reach the 
>atmosphere, with no impact beyond a short fireworks display. An NEO wider 
>than 1km, however, collides with Earth every few hundred thousand years and 
>an NEO larger than 6km, which could cause mass extinction, will collide 
>with Earth every 100m years. Experts agree that we are overdue for a big 
>one.
>
>All eyes for the moment are on Apophis, a 390-metre wide asteroid 
>discovered in 2004, which has an outside chance of hitting the Earth in 
>2036. If it struck, Apophis would release more than 100,000 times the 
>energy released in the nuclear blast over Hiroshima. Thousands of square 
>kilometres would be directly affected by the blast but the whole planet 
>would see the effects of the dust released into the atmosphere. There could 
>be dark skies for a year or more and crops worldwide would be destroyed.
>
>====================
>
>Scientists consider asteroid defense
>'Gravity tug' possible solution to danger of close flybys
>
>By Robert S. Boyd, March 9, 2007
>
>NASA and the Air Force are studying ways to ward off a medium-sized 
>asteroid that will streak within 18,000 miles of Earth in 2029 and has an 
>extremely slight chance of crashing into our planet in 2036. Ideas 
>discussed this week at a Planetary Defense Conference in Washington include 
>a "gravity tug" or "space tractor" that would hover near the space rock and 
>tow it into a safe orbit. Other possibilities include a head-on collision 
>with an unmanned spaceship or a nuclear explosion.
>
>In the past eight years, 754 asteroids bigger than 1 kilometer (about 
>six-tenths of a mile, or 3,280 feet) across have been detected orbiting 
>near Earth. But none is expected to come as close as a smaller one called 
>Apophis, which was discovered just before Christmas in 2004.
>
>Named after an ancient Egyptian god of evil, Apophis is about 900 feet long 
>- three times the length of a football field - and is traveling at a speed 
>of 12,000 mph. If an object that size hit Earth, it would "destroy England 
>or Northern California," said Steven Chesley, an asteroid expert at NASA's 
>Jet Propulsion Laboratory in Pasadena, Calif.
>
>Even if it landed in the Pacific Ocean, it would cause a tsunami as big as 
>the one that devastated Indonesia and neighboring countries in 2004, 
>according to Clark Chapman, a planetary scientist at the Southwest Research 
>Institute in Boulder, Colo.
>
>Simon "Pete" Worden, the director of NASA's Ames Research Center in 
>Mountain View, Calif., told the conference that the United States has the 
>technology needed to send a mission to deflect an asteroid such as Apophis, 
>but the Bush administration hasn't requested money to pay for it. "We don't 
>yet have the resources to do much about this," Worden said. NASA's budget 
>includes $4 million a year to study the asteroid threat.
>
>Edward Lu, [an] astronaut at the Johnson Space Center in Houston, estimated 
>that the cost of a gravity tug would be about $300 million. He said the 
>gravitational force of a 1-ton robotic spacecraft orbiting just ahead of 
>the asteroid would gradually pull the space rock out of Earth's way. Other 
>methods, such as bombing the asteroid, might break it into smaller pieces 
>that could be even more dangerous to our planet, Lu said.
>
>Apophis gave NASA a brief scare at first, when astronomers thought it had a 
>3 percent chance of hitting Earth. Additional evidence, however, soon 
>eliminated any danger of a collision in 2029 and reduced the odds of an 
>impact in 2036 to 1 in 45,000.
>
>"Apophis is not really a threat," said Don Yeomans, the manager of NASA's 
>NEO (Near Earth Object) office in Pasadena, Calif. However, he said, the 
>passage of the big rock across the sky will be visible to the naked eye in 
>Europe and North Africa. "It's going to be quite a sight," Yeomans said.
>
>About 70 percent of the estimated 1,090 asteroids bigger than 1 kilometer 
>across have been detected and their orbits identified. Now NASA is under 
>congressional orders to find 90 percent of the much more numerous small 
>asteroids - those at least 140 meters (459 feet) across - by 2020.
>
>"They run the gamut from wimpy ex-comets to slabs of solid iron," Yeomans 
>said. "Our goal is to eliminate 90 percent of the risk from these smaller 
>objects."
>
>"We can't prevent hurricanes or tornadoes," said Russell "Rusty" 
>Schweikert, another former astronaut, "but we can prevent this asteroid 
>impact."
>
>To accomplish the goal, the Air Force is financing a system of ground-based 
>telescopes in Hawaii called Pan-Starrs that will start searching in 2010 
>for asteroids or comets that are on a collision course with Earth. The 
>National Science Foundation is building a Large Synoptic Survey Telescope 
>in Chile that will scan the sky every three days for faint objects - 
>including asteroids - starting in 2014.
>
>Although almost all possibly dangerous asteroids can be detected, the risk 
>can't be reduced to zero. "There's always a tiny chance that something is 
>hiding behind the sun," said Alan Harris, a member of the Space Science 
>Institute in Boulder, Colo.
>
>===================
>
>Astronomers hash out defense against asteroids
>A billion dollars needed to spot potential killer impacts.
>
>Jeff Kanipe: 9 March 2007
>
>Astronomers trying to save the world from Earth-threatening asteroids have 
>this week composed a white paper outlining the threat and what needs to be 
>done about it.
>
>Although it isn't their first white paper on the subject - that was 
>released in 2004 - it is the first mandated by Congress. This, scientists 
>hope, may mean that their conclusions will be taken more seriously by 
>decision-makers in Washington.
>
>In 2005, Congress passed a bill authorizing NASA to search for asteroids as 
>small as 140 metres that could possibly strike the Earth. The bill, 
>however, provided no money for the search.
>
>On Monday, Simon 'Pete' Worden, director of NASA's Ames Research Center, 
>said that the cost of finding at least 90% of the 20,000 estimated 
>potential Earth-killers by 2020 would cost about $1 billion. US government 
>employees, including NASA scientists, don't usually make public requests 
>for more cash, but Worden was clear: "We know what to do, we just don't 
>have the money."
>
>If Worden and his colleagues had their way, they would catalogue and track 
>all objects of 140 metres or larger. This would require a dedicated 
>space-based telescope and more time on the two ground-based radar 
>facilities currently used to spot incoming asteroids, scientists suggested 
>at the meeting. This would hopefully provide enough time to deflect a big, 
>bad rock.
>
>Scientist at the conference were keen to focus on how to do this. One idea 
>would be to use a robotic spacecraft as a 'tugboat' that would physically 
>attach itself to the asteroid and push it into a new orbit. The problem is 
>that the surface of an asteroid would probably be rough and unconsolidated. 
>An alternative would be to have a spacecraft hover above the asteroid 
>surface, using gravity as a towline (see 'Gravity tractors beat bombs').
>
>Other proposals call for nuclear detonations to push the asteroid off 
>target, anchoring a tether onto a rock so that a spacecraft can sling it 
>athwart, or attaching solar sails to blow it off course.
>
>In the meantime, astronomers acknowledge that they still have a lot to 
>learn about the nature of asteroids in order to better assess our 
>vulnerability. William Ailor of the Aerospace Corporation and general chair 
>of the conference, says [the white paper] will be posted on the conference 
>web page when finalised. But he hopes it won't stop there.
>
>"I know Congress is getting interested in this and I think that's very 
>encouraging," Ailor says.
>
>
>--
>+++++++++++++++++++++++++++++++++++++++++++
>
>NEO News (now in its thirteenth 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, the International 
>Astronomical Union, or any other organization. To subscribe (or 
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>please include this disclaimer.