Supplemental section of the file (for printing purposes, starts at p. 102)

There is no current detection program for smaller asteroids, of which there are perhaps half a million down to about 50 meters in diameter, the smallest size capable of penetrating Earth's atmosphere (and roughly the size of one that exploded over the Tunguska River in Siberia in 1908, destroying forests for hundreds of square miles). And there is no systematic survey for potentially hazardous comets, which come out of the astronomical equivalent of left field. "So we would either very likely have a lot of warning or none at all," said Dr. Clark Chapman of the Southwest Research Institute in Boulder.

Infrared Venus orbit telescope key to detection

Chandler ‘7 (David, New Scientist, “Could Venus Watch for Earth-Bound Asteroids,” http://www.newscientist.com/article/dn11356-could-venus-watch-for-earthbound-asteroids.html)

A dedicated space-based telescope is needed to achieve a congressionally mandated goal of discovering 90% of all near-Earth asteroids down to a size of 140 metres by the year 2020, says a report NASA sent to the US Congress on Thursday. Asteroids of that size are large enough to destroy a major city or region if they strike the planet - but NASA says it does not have the money to pay for the project. The study says Venus is the best place for the telescope. That is because space rocks within Earth's orbit - where Venus lies - are most likely to be lost in the Sun's glare, potentially catching astronomers off guard. The telescope could be placed either behind or ahead of Venus in its orbit by about 60° - the stable Lagrange points, known as L4 or L5, where the gravity of the Sun and Venus are in balance. "There are quite a few [objects] that are interior to Earth's orbit," NASA's Lindley Johnson told New Scientist. "Those are really hard to detect [from Earth]; the opportunities to see them are very limited." From the orbit of Venus, however, "you're always looking away from the Sun, always looking out", he says. "And, of course, you can observe 24 hours a day - you don't have to worry about night and day." Even from Earth orbit, a telescope's view of any given part of the sky is blocked about half the time by the Earth itself. In addition, because Venus orbits the Sun in about two-thirds the time the Earth does, a telescope in that orbit would catch up with any near-Earth asteroids in their orbits more frequently than Earth does, offering more opportunities for discovery. "You're able to sample that population more rapidly in the same amount of time," Johnson says. Missed deadline An infrared telescope would be more effective than one that studies visible light, because asteroids reflect sunlight more strongly at infrared wavelengths. The background sky is also much less bright in the infrared, providing better contrast for discovering even small, faint asteroids. With the Venus-orbit IR telescope, NASA could exceed its goal by three years, finding 90% of the most dangerous space rocks by 2017. But the space telescope is estimated to cost $1.1 billion for 15 years of operation, and NASA says there is currently no money in its budget to pursue any of the search proposals it studied.

But there are no current plans for the Venus telescope

Easterbrook ‘8 (Gregg, Editor of The Atlantic and The New Republic and Sr. Fellow at Brookings, “The Sky is Falling,” June, http://www.theatlantic.com/doc/200806/asteroids)

Current telescopes cannot track asteroids or comets accurately enough for researchers to be sure of their courses. When 99942 Apophis was spotted, for example, some calculations suggested it would strike Earth in April 2029, but further study indicates it won’t—instead, Apophis should pass between Earth and the moon, during which time it may be visible to the naked eye. The Pan-STARRS telescope complex will greatly improve astronomers’ ability to find and track space rocks, and it may be joined by the Large Synoptic Survey Telescope, which would similarly scan the entire sky. Earlier this year, the software billionaires Bill Gates and Charles Simonyi pledged $30 million for work on the LSST, which proponents hope to erect in the mountains of Chile. If it is built, it will be the first major telescope to broadcast its data live over the Web, allowing countless professional and amateur astronomers to look for undiscovered asteroids. Schweickart thinks, however, that even these instruments will not be able to plot the courses of space rocks with absolute precision. NASA has said that an infrared telescope launched into an orbit near Venus could provide detailed information on the exact courses of space rocks. Such a telescope would look outward from the inner solar system toward Earth, detect the slight warmth of asteroids and comets against the cold background of the cosmos, and track their movements with precision. Congress would need to fund a near-Venus telescope, though, and NASA would need to build it—neither of which is happening.

NASA wants a venus orbit infrared telescope

Bucknam & Gold ‘8 (Mark, Deputy Dir for Plans in the Policy Planning Office of the Office of the US Secretary of Defense, Colonel USAF, PhD in War Studies from U of London, BS in physics, MS in materials science and engineering from Virginia Tech & Robert, Chief Technologist for the Space Department at the Applied Physics Laboratory of Johns Hopkins “Asteroid Threat? The Problem of Planetary Defence,” Survival vol. 50 no. 5 | 2008 | pp. 141–156)

NASA analysed options for better detecting PHOs, ranging from continuing the current terrestrial-based Spaceguard Survey to putting visual or infrared sensors on satellites in space. The existing Spaceguard techniques have little to contribute to the expanded goal of detecting objects on the scale of 140m, and NASA estimates Spaceguard could only detect approximately 14% of the 140m-or-larger PHOs by 2020,10 well short of Congress’ goal of 90%. The addition of a ground-based telescope, such as the University of Hawaii’s planned Panoramic Survey Telescope and Rapid Response System (PanSTARRS 4)11 or the proposed Large Synoptic Survey Telescope (LSST),12 would boost the results to 75–85%, depending on whether NASA shared the telescope with another agency or supported building an additional copy of its own. The most efficient means of finding PHOs would be to place an infrared sensor in a Venus-like orbit – that is, 0.7 astronomical units from the sun. By itself such a sensor system could find 90% of PHOs larger than 140m by 2020. Furthermore, a space-based infrared telescope would allow scientists to reduce the uncertainties in determining the size of PHOs to 20% from over 200% for optical telescopes.13 A factor-of-two uncertainty – the limit of accuracy with optical telescopes – equates to a factor-of-eight uncertainty in mass. Because the size and mass of a PHO are important characteristics for assessing the danger it could pose, the added performance of a space-based infrared telescope warrants serious consideration. Moreover, an infrared telescope in a Venus-like orbit could efficiently detect PHOs that primarily orbit between the Earth and the Sun; these are difficult to detect from Earth and, according to NASA, have a chance of being perturbed by gravity and becoming a threat. The cost of such a system is on the order of $1bn, and the harsh space environment would likely limit its useful life to around seven to ten years.14 Though radar telescopes, such as the giant 305m dish at Arecibo, Puerto Rico, enable rapid and accurate assessments of PHO size and orbit, they are only useful when the objects pass within a few million kilometres of Earth. NASA recommended against developing a radar specifically for finding and tracking PHOs, stating that ‘orbits determined from optical data alone will nearly match the accuracy of radar-improved orbits after one to two decades of observation’.15 Existing radar telescopes should be used as far as possible to refine predictions of Apophis’s trajectory – either confirming or ruling out the potential for an impact in 2036. In addition to fielding new Earth- and space-based sensors as suggested by NASA, former astronaut Rusty Schweickert called for placing a transponder on Apophis during a close approach in 2013 to help determine whether a 2036 collision is likely.16 This could save years of worrying, or give us extra years to prepare and act. Such a mission would cost on the order of a few hundred million dollars. In addition to new sensors, NASA will need new data-processing capabilities for the expanded effort to find, track, characterise, catalogue and then store and distribute the data for the estimated 18,000 PHOs larger than 140m that the space agency will be expected to monitor. Today, NASA’s Jet Propulsion Laboratory uses a system called Sentry to turn known PHO data into predictions of PHO orbits projected 100 years into the future. Though NASA’s March 2007 report briefly described four possible alternatives for managing data, it left out details on the costs of going from tracking nearly 800 PHOs today to a system that could handle 18,000 PHOs.

NASA favors using an infrared Venus orbit telescope

NASA ‘6 (“2006 Near-Earth Object Survey and Deflection Study” http://www.b612foundation.org/papers/NASA-finalrpt.pdf)

Detection and tracking alternatives identified by the study team included optical systems located on the ground and optical and infrared assets located in space. For ground-based alternatives, the study team considered sharing planned observatories such as PanSTARRS 4 (PS4), funded by the U.S. Air Force, and the Large Synoptic Survey Telescope (LSST), partially funded by the National Science Foundation. The team also considered new NASA-funded facilities that would be dedicated to the search for hazardous objects and would be based on these planned observatories. Although cost margin was applied to alternatives that leveraged planned assets, programs that rely on these projects may carry additional cost and schedule risk. Specific results include: • An architecture, which combines the sharing of the planned PS4 and LSST systems with a second, dedicated NASA-funded LSST, was the only groundbased alternative able to meet the congressional goal of identifying 90% of the hazardous objects by 2020. This combination is estimated to have a life-cycle cost of $820M ($FY06). • A shared PS4, a shared LSST, and a dedicated NASA-funded PS8 were able to catalog 90% of hazardous objects by 2024, with a life-cycle cost of $560M. • A dedicated, NASA-funded observatory based on LSST’s design was also able to catalog 90% of potentially hazardous objects in 2024 without the contributions of other programs. Its estimated life-cycle cost is $870M. Space-based search alternatives were located in low-Earth orbit, at Sun-Earth Lagrange points, and in heliocentric Venus-like orbits. Only an infrared system operating in a Venus-like orbit was able meet the congressional goals without the contribution of shared ground-based assets. All space-based alternatives were able to meet the goals when combined with a ground-based baseline of a shared PS4 and a shared LSST. A space mission failure could delay achieving the 90% goal by up to 5 years, after which the catalog could be completed with shared ground-based assets. Infrared systems operating in space could provide more accurate size estimates of up to 80% of objects in the catalog. Observatories located in a Venus-like orbit are the most efficient at finding objects inside Earth’s orbit, a potentially underestimated population. Additionally, by the end of 2020, infrared systems in Venus-like orbits can find 90% of the objects measuring over about 80 meters, exceeding the 140-meter requirement. Finally, space-based systems have much less uncertainty in the date of reaching 90% due to their superior sensitivity. Selected space-based alternatives include: • A 0.5-meter infrared system operating in a Venus-like heliocentric orbit completes 89% of the survey by 2020 which is within the uncertainty of the analysis. This system has a life-cycle cost of $840M ($FY06). • A similar 0.5-meter infrared system operating in a Venus-like orbit and working in concert with a shared PS4 and a shared LSST completes 90% of the survey in 2018, with a life-cycle cost of $1B through 2018. • A 0.5-meter infrared system operating at Sun-Earth L1 in conjunction with the baseline finishes 90% of the survey in 2020. Its life-cycle cost is $1.1B. Infrared systems with a 1.0-meter aperture complete the survey about 1 year earlier than the 0.5-meter alternatives described above, and have life-cycle costs about $300M higher. Optical systems with 1.0-meter and 2.0-meter apertures in Venus-like orbits, combined with the baseline ground-based systems, completed the survey by 2017 and 2019 respectively, with life-cycle costs in excess of $1.7B. The visible system with a 2.0-meter aperture progressed more slowly than the 1.0-meter system due to differences in development time. Acquisition of new systems was assumed to start October 1, 2007, and delays in funding will affect the ability of some alternatives to meet the 90% completeness goal by the end of 2020. Congress provided two objectives for characterizing potentially hazardous objects. The first objective, to “assess the threat,” requires analysts to determine the orbit and approximate the mass of each hazard. Detection and tracking systems with judicious follow-up are all able to provide warning, and some are able to provide very good size and mass estimates. Systems operating in the visible spectrum are limited by a factor of two for size estimates, resulting in a factor-of-eight uncertainty in mass. Infrared systems provide data for much more accurate size estimates. If detection systems must characterize the catalog, the time to complete the survey to a 90% completion level will be extended. Furthermore, the costs of these systems may increase $100M-$400M to accommodate filters and additional data processing. In addition, the smallest and faintest objects may remain visible to sensors only for a few days or weeks. Therefore, if characterization is required and it is not performed by detection systems, either formal relationships with extant observatories for “on demand” access must be negotiated or new dedicated characterization facilities will be needed. Radar may quickly and precisely characterize and determine the orbit of about 10-25% of the objects of interest within 5 years of their detection. While the number of objects observed by radar increases with time, the relative value of radar to precisely determine the orbits of the full catalog declines over the same period. Orbits determined from optical data alone will nearly match the accuracy of radar-improved orbits after decades of observation. Therefore, the utility of radar is limited to a relatively few “short warning” cases that may be of very high interest during the survey. Up to $100M in funding (not included in detection and tracking life-cycle costs) may be required to maintain radar capability through 2020, as NASA and National Science Foundation funding for existing radars is currently in flux. The second objective of characterization is to “inform mitigation.” Depending on the mitigation strategy selected, this objective may require information beyond the size and orbit of potential threats. This information may include the structure, porosity, rotation rate, material composition, and surface features of the threats. The deflection alternatives considered are sensitive to the maximum mass that needs to be deflected, but some alternatives are orders of magnitude less sensitive than others. Characterization by remote sensing provides some information about the diversity of objects in the population. From this information, analysts build models that can be used to infer a limited number of characteristics of a particular object. Only in-situ encounters can provide the definitive observations necessary to calibrate the remote observations. More importantly, only in-situ visits can obtain the information needed by some of the deflection alternatives to mitigate a specific threat. For credible threats with sufficient warning, it is expected that in-situ characterization will always be performed to both confirm the probability of impact (with a transponder, for example) and to characterize the potential threat if deflection is necessary. This study has determined that it is premature to set specific characterization requirements to enable mitigation until a mitigation strategy has been determined; therefore, the study has developed characterization options that provide a range of capabilities. These options included the use of detection and tracking assets, dedicated ground and space systems for remote observation, and in-situ missions to inform mitigation of threats with sufficiently high impact probabilities. These options have lifecycle costs ranging from $50M-$8B ($FY06) over several decades. It is expected that during the 5-10 years of a survey, a total of 500,000 objects will be discovered by more than 2 million individual observations. About 21,000 of these objects will measure 140 meters or larger and be tracked as potentially hazardous. Although this study uses an estimate of the population of potentially hazardous objects based on statistical projections, the actual number of objects will not affect the date of reaching the 90% goal as long as the objects are approximately distributed in orbits as predicted. This volume of observations will require a data-processing capability that is 100 times more capable than current cataloguing systems. After objects are detected, the system must be able to obtain follow-up observations, store and distribute collected data, and analyze these data for observed but previously undetected objects. Currently, uncompensated or under-funded analysts perform many of these functions. Such an approach likely will not remain viable. Finally, either the NASA Survey or otherwise funded activities, such as PS4 and LSST, are expected to produce impact warnings at a rate that is 40 times greater than what is experienced today. This much higher rate of warnings will start as early as 2010.

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: