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- A2: Ground-based CP
- Space-based observation is critical to ascertaining orbits of NEOs.
- Space-based detection is key to seeing small asteroids – impacts economy and nuclear war.
- Doesn’t solve – atmosphere and sunlight block the scopes
- Doesn’t solve – inner-earth objects
A2: CP use other SatsOnly the Venus-orbit solves by providing a comprehensive NEO survey – earth-orbiting telescopes can’t solve.Dunham & Genoca 2010 Using Venus for Locating Space Observatories to Discover Potentially Hazardous Asteroids D. W. Dunham1 and A. L. Genova2 1 Kinet X, Inc., 7913 Kara Ct., Greenbelt, Maryland 207703016, USA 2 NASA Ames Research Center, Moffett Field, California 94035, USA Cosmic Research, 2010, Vol. 48, No. 5 pp. 424–429 CONCLUSIONS The IRAS, and now WISE spacecraft, have proven that NEA’s can be discovered by space missions. NEOSSat and AsteroidFinder promise to accelerate NEA discoveries, and especially those of the possibly hazardous IEO’s, from the Sun-synchronous low- Earth orbit. But being near the Earth, these spacecraft never will be able to perform complete surveys; there will remain objects that are still too close to the Sun or staying too far from the Earth during the limited durations of the missions to be observed. Only the missions which enter heliocentric orbits well within the Earth’s one and “look out” towards it can hope to make comprehensive searches for potentially hazardous NEA’s in relatively few years of operations. It might seem that the complexity of maneuvers to achieve the halo orbit would better be avoided to just use a distant Venus flyby for entering the Venus-like heliocentric orbit like Shield’s Sentries or the NEO Survey mission. Certainly, less propellant would be needed for those missions, only what is enough to correct injection launch errors and to target the Venus B-plane to achieve the desired orbit. But the Venus halo orbit could be used for long-term near-Venus scientific observations, as well as for NEA surveying, because, unlike the other orbits, the Venus halo orbit would provide a nearly constant distance from the spacecraft to the Earth’s orbit, which would simplify coverage strategies and, possibly, thermal control at the more constant distance from the Sun due to Venus’ nearly circular orbit. These operations should not be too intensive, since the small maneuvers needed to maintain the halo would be needed only about every two months, which ensures a small cost relative to the operations that would be needed to acquire and analyze the large body of images for the NEA searches. A2: Ground-based CPSpace-based observation of NEOs are vastly more effective – That’s just science.Galvez et al 2003 THE ROLE OF SPACE MISSIONS IN THE ASSESSMENT OF THE NEO IMPACT HAZARD Andrés Gálvez1, Marcello Coradini2, Franco Ongaro2 1 ESA – ESTEC, Advanced Concepts Team Keplerlaan 1, 2200 AZ, Noordwijk ZH, The Netherlands http://www.esa.int/gsp/ACT/doc/MAD/pub/ACT-RPR-MAD-2003-THE%20ROLE%20OF%20SPACE%20MISSIONS%20IN%20THE%20ASSESSMENT%20OF%20THE%20NEO%20IMPACT.pdf Space missions dedicated to the detection, tracking (i.e. orbit determination) and remote characterisation (e.g. determination of taxonomic type and surface albedo) would be significantly more capable than most ground-based surveys. The objective of this type of missions would be to improve and expand our catalogue of dangerous objects. Though space borne telescopes cannot be made as large and powerful as their terrestrial counterparts, for these tasks and as a consequence of improved viewing geometry (especially as the observing point moves closer to the Sun) and better observation conditions the space option enables an improved access to certain types of objects: these include Inner to Earth Objects (IEOs) and Atens, that due to their proximity to the Sun in the sky are often difficult to observe. These favourable conditions can also result in efficient and extensive surveys in which smaller objects down to a few hundred meters in size may also be detected. Observation strategies can also be devised to ensure that newly discovered objects are re-detected again after they have moved to a new orbital location, thus providing a set of data that can enable the determination of accurate orbits. This in turn allows their future trajectories (and Earth encounters, if any) to be predicted. Finally, a space observatory can also have an unobstructed access to a broader range of wavelengths (e.g. in the IR) and to achieve a more efficient duty cycle than from below the Earth’s atmosphere, as in the case of ground-based telescopes. Space-based observation is critical to ascertaining orbits of NEOs.Galvez et al 2003 THE ROLE OF SPACE MISSIONS IN THE ASSESSMENT OF THE NEO IMPACT HAZARD Andrés Gálvez1, Marcello Coradini2, Franco Ongaro2 1 ESA – ESTEC, Advanced Concepts Team Keplerlaan 1, 2200 AZ, Noordwijk ZH, The Netherlands http://www.esa.int/gsp/ACT/doc/MAD/pub/ACT-RPR-MAD-2003-THE%20ROLE%20OF%20SPACE%20MISSIONS%20IN%20THE%20ASSESSMENT%20OF%20THE%20NEO%20IMPACT.pdf The ultimate goal of the NEO surveys is not simply to detect new objects, but to perform an accurate calculation of their orbits. Only this way can their trajectories be determined in order to ascertain whether they represent a serious threat to the Earth. In order to attain this goal it must be ensured that enough observations of an object are available (at least three), and that their spacing in time is long enough so that the ̈arc length ̈ on the sky has a significant angular size. Therefore an observatory must not only be capable of detecting a faint object and identifying it as a NEO, based on its rate of motion against the stars on the sky background. The survey strategy should be such that the same regions of the sky are periodically revisited in order to systematically re-detect, albeit in different positions, the newly discovered -or as it often happens, re-discovered- object. In space sequential observations cannot be hindered by adverse atmospheric weather conditions. Also, favourable NEO visibility conditions are not only limited to a region of the sky close to the opposition point, especially if the telescope is located within the Earth’s orbit. It is therefore much easier to devise a survey strategy that enables successive and repeated observation of sky regions even if the angular separation is important. Space-based detection is key to seeing small asteroids – impacts economy and nuclear war.Arentza et al 2010 NEO Survey: An Efficient Search for Near-Earth Objects by an IR Observatory in a Venus-like Orbit Robert Arentza, Harold Reitsemaa, Jeffrey Van Cleveb and Roger Linfielda a Ball Aerospace & Technologies Corp. 1600 Commerce St. Boulder, CO 80301 303-939-6140; rarentz@ball.com; hreitsema@aol.com; rlinfiel@ball.com b SETI Institute NASA Ames Research Center NS 244-30, Room 107G Moffett Field, CA 94035 650-604-1370 Space, Propulsion & Energy Sciences International Forum As reviewed in the Introduction, recent work by Boslough (2009) shows that the impact-physics of NEOs having diameters in the 30-100 meter range has been seriously misunderstood due to a process he named a Low-Altitude Airburst (LAA). In an LAA event, the main body of the NEO physically comes apart at high altitudes (~10 to ~80- km), but the object’s mass and kinetic energy are conserved as a fast moving, loosely aggregated, collection of particles that entrain a column of air which reaches the ground as “air hammer.” Boslough’s work shows that the air hammer from NEOs as small as 30 meters will inflict significant damage on the ground, as was seen in the 30- meter-class Tunguska event. Boslough has also shown that an LAA from a ~100 meter diameter NEO melted sand into glass across a region about 10-km in diameter during Libyan Desert Glass impact ~35 million years ago. During this event the LAA-induced fireball settled onto parts of modern Egypt and Libya for about a minute with temperatures approaching 5,000K—hotter than the Sun’s surface. Additionally, the hypersonic blast wave from this event perhaps extended eighty kilometers from the melt zone. Boslough has also shown that the interaction of an LAA with the ocean’s surface is much different from that of a large object striking offshore, therefore the tsunami risk from an LAA event is not well understood, either, but is different than previously thought. Therefore any survey instrument capable of searching well below the GEB limit of 140 meters is quite valuable. The NEO Survey concept 422 shown here captures about half of the >50 meter-class NEOs in its 7-year mission, and the completion rate increases rapidly with increasing diameter up to the design goal of 90% for all 140 meters, and larger, objects. Derating the Tunguska object from ~80 meters to today’s ~30 meters greatly decreases the mean impact interval from ~1,000 years to ~150 years. Given that Tunguska happened 101 years ago, the next impact is arguably 50 to 100 years away, so why the urgency? From contract start, it would take an experienced aerospace contractor about 3 years to build and launch NEO Survey, and then 7 more years (worst case) to complete the catalogue, or 10 years to completion. Assume for the moment that near the end of this period of 10 years, a 50-meter diameter NEO is discovered having an impact date in 50 years. What does this mean? Groundbased systems could easily miss such an object for an apparition or two, resulting in perhaps a few years, or perhaps a few months of warning time before impact. If, by remote chance, it was determined that the strike location was close to a high-density human population, it would force the evacuation of millions of people from a large geographic area and would produce a long-lasting, global sociological disruption that would eventually outweigh the immediate harm resulting from a large-scale loss of human life and damage to a distributed infrastructure. And since there is no predicting the reaction of populations or their governments to such a trauma, such an incident could possibly trigger a chain of events resulting in military action of unforeseeable severity. Clearly, the effect of such an event on the global economy could also be large compared to the cost of flying a sensitive and efficient NEO cataloguing mission. Consider also the value of finally having a deterministic answer to the question: “Are we safe for the next few hundred years?” as opposed to the present case of arguing from statistics. If NEO Survey found an incoming NEO with a warning time of only 50 years, what would it take to execute a successful mitigation effort, and how long would that effort last? To begin with, it would take a year or two for groundbased assets to do detailed follow-up orbital refinements. Then, a space mission to the object would be required for in-situ characterization because all conceivable mitigation techniques require detailed knowledge of the object’s composition, mechanical properties, spin state, whether it has a moonlet, and so on. Only then could the appropriate mitigation solution be chosen and negotiated in a global political setting. It would then take an additional 10 years, approximately, to design, build, fly, and complete the mitigation task. Additionally, the results of any mitigation action would have to be closely monitored, and perhaps a second mitigation mission would be required to produce the desired final result. These timelines are in series and mean that 50 years of lead-time is almost tomorrow. Reliance on groundbased assets to find these smaller NEOs over a period of decades ignores the threats LAAs represent to the modern world. Additionally, the longer the warning time becomes, the less delta-vee is needed to move an impact off the Earth, simplifying the mitigation effort. For example, the difference between 10 years and 20 years of warning time could enable a passive mitigation option compared to a nuclear option. Doesn’t solve – atmosphere and sunlight block the scopesNational Academies, 10 [ Over many decades, the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council have earned a solid reputation as the nation's premier source of independent, expert advice on scientific, engineering, and medical issues, “Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies” http://books.nap.edu/openbook.php?record_id=12842&page=41] The 2003 NASA NEO Science Definition Team Study concluded that an infrared space telescope is a powerful and efficient means of obtaining valuable and unique detection and characterization data on NEOs (Stokes et al., 2003). The thermal infrared, which denotes wavelengths of light from about 5 to 10 microns, is the most efficient color regime for an NEO search. An orbiting infrared telescope that detects these wavelengths and has a mirror between 0.5 and 1 meter in diameter is sufficient to satisfy the goal of detecting 90 percent of potentially hazardous NEOs 140 meters in diameter or greater. Also, locating an NEO-finding observatory internal to Earth’s orbit is preferable for identifying NEOs with orbits mostly or entirely inside Earth’s orbit. Specific advantages to space-based observations include the following: A space-based telescope can search for NEOs whose orbits are largely inside Earth’s orbit. These objects are difficult to find using a ground-based telescope, as observations risk interference from the Sun when pointing to the areas of the sky being searched; Thermal-infrared observations are immune to the bias affecting the detection of low-albedo objects in visible or near-infrared light, by observing the thermal signal from the full image of the NEO, providing more accurate albedo measurements (see the discussion above); Space-based searches can be conducted above Earth’s atmosphere, eliminating the need to calibrate the effects introduced by the atmosphere on the light from an NEO; and Observations can be made 24 hours a day. Doesn’t solve – inner-earth objectsESA, 3 [European Space Agency, Jan 2003, “ EARTHGUARD-I A Space-Based NEO Detection System,” http://www.esa.int/gsp/completed/neo/earthguard1_execsum.pdf] There is good theoretical evidence, however, to suggest there may be a population of asteroids in orbits that lie entirely within the Earth’s orbit, the so-called “inner-Earth objects” (IEOs) or Apohele asteroids. As a result of perturbation of their orbits by the inner planets they may become Earth crossers but remain virtually undetectable from the Earth. Only with the help of a space-based search telescope observing at small angular distances from the Sun can we hope to close the gap left by the groundbased surveys and facilitate a complete and reliable assessment of the terrestrial impact hazard Directory: files files -> Answer True False 2 points Question 2 files -> Integer programming and game theory files -> 4 Integer Programming files -> Bpa vehicle Window Repair Scenario #1 task: Procure vehicle window relacement. Objective files -> Pop Warner History files -> North Carolina Inclusion Initiative Mapping Where Children with ieps are Being Served Purpose files -> Fall 2013 Spring 2014 Program Data: Standard 1 Exhibit 4d files -> Hanban – asia society confucius classrooms network 2010 request for proposal files -> Northern England’s set-jetting locations Download 1.03 Mb. Share with your friends:
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