Testimony of Subcommittee Chairman Mark Udall Good morning. I'd like to extend a welcome to our witnesses and in particular recognize Congressman Luis Fortuno's presence here with us today. As many of you may recall, today's hearing on Near-Earth Objects was originally scheduled for October 11th, but we postponed it in the wake of Rep. Jo Ann Davis's untimely death. Thus, before we proceed any further, I'd like to express my appreciation to each of the witnesses for your willingness to accommodate that postponement and appear before us today. Your testimony will be invaluable to us as we consider how best to proceed in getting a better understanding of the potential threats posed by Near-Earth ObjectsNEOs, as well as options for dealing with them. Today's hearing is the latest in a series that stretches back to the early 1990s. We have come along way since the late George Brown--former Chairman of the Science and Technology Committee--led the first efforts to focus congressional attention on the potential threat posed by Near Earth asteroids and comets. It has been a bipartisan effort over the intervening years, and a lot has been accomplished. In that regard, I in particular want to salute the dedication of Mr. Rohrabacher in pushing for continued federal initiatives to detect, track, and catalog NEOs, as well as to examine ways to deflect them if necessary. He has been an effective catalyst for action, and I look forward to continuing to work with him on this issue. As we will hear from our witnesses, much progress has been made in detecting and cataloging the largest NEOs over the last decade. However--as we will also hear--much more remains to be done. In particular, we need to survey potentially hazardous asteroids that are smaller than the ones cataloged to date, but which could do significant damage if they impact or explode above the Earth's surface near populated areas. That is why Congress directed NASA to "plan, develop, and implement" a NEO survey program for objects as small as 140 meters in size in the NASA Authorization Act of 2005. As a result, I'm disappointed and concerned that NASA's report to Congress failed to provide a recommended option and budget plan for such a survey, as directed by the Act. In fact, the report says NASA has no plans to do anything beyond the current Spaceguard program at this time. Equally troubling, one of the NASA witnesses will testify that "NASA would be pleased to implement a more aggressive NEO program if so directed by the President and Congress,"--with the implication that Congress has not yet done so. I think Sec. 321 of the NASA Authorization Act, which I quoted earlier, is unambiguous--Congress has in fact directed NASA to "plan, develop, and implement" such a program. And we would hope that the President would send over a NASA budget request that reflects that congressional direction. Today, I want to focus on where we go from here. Given the lack of a clear plan in NASA's report to Congress, I hope that our witnesses today will be able provide some guidance to this Committee on the best and most cost-effective path forward for meeting the goal of surveying NEOs down to 140 meters in size. In that regard, there are a number of related questions that need to be addressed. First, I'd like to hear from each of the witnesses about the planetary radar capabilities at Arecibo and Goldstone. How important are they to addressing the NEO task? Second, how can we make the most effective use of capabilities being planned or developed by other federal agencies, such as LSST and Pan-STARRS, and what role should NASA play in supporting them? NASA's testimony indicates that it has begun providing funds to the Air Force's Pan-STARRS project "so that it will be capable of providing data on NEO detections..." That's an interesting development, and it raises the question of whether NASA should also be providing funds to other facilities such as Arecibo and the proposed LSST project if doing so will materially contribute to meeting the NEO survey objectives in a responsible, cost-effective manner. Third, I'd like to know if there are adjustments to either the timetable or scope of the NEO survey called out in the NASA Authorization Act of 2005 that would make sense--either by allowing more cost-effective approaches on a slightly longer timetable or by focusing on just potentially hazardous objects rather than on all NEOs. Fourth, surveying NEOs is just part of the task. If we find one that it is headed towards Earth, we will need to have good options for deflecting it. What priority should be given to developing deflection technologies versus NEO survey systems in the coming years? Finally, the potential threat posed by Near-earth objects is not isolated to the United States. What contributions are other national and international bodies making to the effort? Should more be done? Well, as you can see, we have a lot to consider today. Fortunately, we have a very distinguished set of witnesses to assist us in our oversight task. I again want to welcome all of you, and I look forward to your testimony. Testimony of Rep. Luis G. Fortuņo, Congressman from Puerto Rico Every day an enormous quantity of cosmic material falls to the Earth. Most burns up on reentry in a harmless way, however NASA predicts that more than 20,000 large, potentially dangerous objects pass by the Earth in close proximity and, given the proper circumstance could threaten or severely impact our existence. Although the chances of a major impact are slim, the consequences are too great to disregard. I believe we should continue to advance our knowledge of Near Earth Objects and the potential consequences for our life on Earth. I commend Congressman Rohrabacher on his efforts to continue funding for Near Earth Objects surveillance programs. Since 1992, the Spaceguard program's goal was to discover 90% of the NEOs with one kilometer diameter potential by 2008. Although the success of this program will be substantial, there will still be thousands of objects--ranging from 200 to 500 meters in diameter--that will be overlooked. We must enhance our understanding of this phenomenon by studying and assessing the threats posed to our environment and to our national security. According to Director Michael Griffin, NASA does not have the funds to carry out a more extensive program. There have been suggestions that NASA and the National Science Foundation should cooperate to fund the construction of a new ground-based telescope to perform tracking functions of Near Earth Objects and other astronomy surveys. I do not think we need to take on such a burden, as there is still a great deal of information to be gained by utilizing the unique capabilities of the Arecibo Observatory in Puerto Rico. As the world's largest and most powerful radio telescope, the Arecibo Observatory is essential to monitoring and surveying Near Earth Objects. However, the National Science Foundation has threatened to close the Observatory in 2011 and NASA has so far been unwilling to assume funding of the radar required for tracking NEOs. Closing the Observatory will severely limit our ability to quickly and accurately refine the orbits of newly emerging threats, and reduce our monitoring capabilities. This is why I have introduced HR 3737, which directs the National Science Foundation and NASA to work together to ensure continued full funding of the Arecibo Observatory and in particular, the radar. It is my recommendation that these agencies start working collaboratively and reconsider how they allocate their funding. Mr. Chairman and Ranking Member Feeney, the Arecibo Observatory's radar is the world's most powerful instrument for post-discovery characterization and orbital refinement of near Earth asteroids. The observations performed with the radar are critical for identifying asteroids that might be on a collision course with Earth. I respectfully urge the committee to consider continuing the important work performed by the Arecibo Observatory and consider, as well, HR 3737 as one potential solution to this challenge. The unique capabilities of radar are critically important as we work towards fulfilling the 2005 congressional mandate of detecting and characterizing 90% of near Earth Objects down to 140 meters in diameter. A potentially dangerous collision of an asteroid or comet is a very real threat. We must take action now to enhance our awareness to prevent a catastrophe. A better understanding of our skies will not only help us to comprehend the wonders of the Earth's environment, but is essential to assessing the dangers that may threaten our society. The world's most sensitive radio/radar telescope at Arecibo Observatory must not be closed. Testimony of James Green, Science Mission Directorate, NASA HQ Mr. Chairman and Members of the Subcommittee, thank you for the opportunity to appear today to discuss the goals and accomplishments of NASA's Near Earth Objects (NEOs) Observation Program. The Subcommittee's invitation to testify identified a series of six questions, and I have structured my testimony around your specific concerns. Question 1: Please describe NASA's NEO Program and the infrastructure and operations in place to support the ongoing Survey (e.g., use of observatories, survey processing and NEO databases, analysis of identified objects, research, and sensor development)? To achieve NASA's stated goal of finding over 90% of the NEOs greater than one kilometer in diameter, the Agency's NEO Observation Program currently funds four survey teams that operate eight ground- based telescopes of mostly one meter class apertures essentially dedicated to the NEO search effort. Two of the teams are sponsored by the University of Arizona Lunar and Planetary Laboratory, Tucson, Arizona, one by Lowell Observatory in Flagstaff, Arizona, and one by the Massachusetts Institute of Technology Lincoln Laboratory. Each team conducts independent operations for 14 to 20 nights per month, as weather permits, avoiding approximately a week on either side of the full moon when the sky is too bright to detect these extremely dim objects from the ground. All collected observations believed to be of known or previously unknown NEOs are sent to the international "clearinghouse" for small body observation data, the Minor Planet Center (MPC). The MPC maintains the database of observations and orbits on all known small bodies (asteroids, comets, dwarf planets, Kuiper Belt Objects (KBO), etc) in the Solar System under the sanction of the International Astronomical Union. It is hosted by the Smithsonian Astrophysical Observatory's Center for Astrophysics in Cambridge, Massachusetts, but is largely funded by NASA. The MPC verifies and validates the observations by determining if they are of an already known object (by comparing them to the known orbits), or are indeed a new discovery. The MPC then determines and publishes an initial orbit for the new discovery so that observatories world-wide may look for the object and confirm its existence. Sometimes it takes a few nights of additional observations to adequately determine, or "secure", the orbit of a new object so that it may be regularly observed. Once a new object's orbit is secured, its potential for impacting the Earth is assessed. Well over 99% of all objects discovered (which also include Main Belt Asteroids, comets, Trojans, Centaurs and KBOs) have no potential for Earth impact even over many millennia, but the small fraction which do are tagged as Potentially Hazardous Objects (PHOs). More detailed and refined analysis of a PHO's orbit is conducted by NASA's NEO Program Office at the Jet Propulsion Laboratory in Pasadena, California, which also aids in coordinating the activities and operations of NASA's NEO projects. Observations on PHOs are automatically forwarded to JPL and their orbits updated with high precision analysis to determine a level of probability of the object impacting the Earth in the next 100 to 200 years. The results of this analysis is constantly updated and published on the NEO Program website at http://neo.jpl.nasa.gov . Since the program's inception in 1998, NASA has funded over $30M in NEO search efforts using funds from the Science Mission Directorate's Research and Analysis program. To date, these efforts have found the vast majority of the 724 one-kilometer Near Earth Asteroids and 64 Earth approaching comets now known, as well as the 4,128 known smaller NEOs. At the current discovery rate, we will have found about 50 more NEOs larger than one kilometer by the end of 2008, bringing us very close to achieving our 90% goal, measured against the current estimate of about 940 total one-kilometer objects. This work has retired the majority of the risk that Earth could be struck by a large asteroid in the foreseeable future. Question 2: What roles do other U.S. government institutions, universities, private and not-for-profit organizations, and international entities play in contributing to the NEO Survey and how is NASA coordinating with these institutions? As discussed above, NASA does not directly own or operate any of the NEO Survey assets, but fully or partially funds several universities and private institutions to conduct the necessary elements of the survey using existing ground-based astronomical facilities. The University of Arizona (UofA) operates most of the search telescopes, either directly or in partnership with others. Two telescopes are operated at Kitt Peak by the UofA Spacewatch project, while the UofA Catalina Sky Survey operates two telescopes at Mt Lemmon Observatory and one in partnership with the Australian National Observatory at Siding Spring Observatory in New South Wales, Australia, which is currently our only southern hemisphere survey site. Lowell Observatory, a private institution, operates a smaller search telescope outside Flagstaff, Arizona. The remaining search team, funded by NASA at MIT/Lincoln Laboratory, operates on two US Air Force- owned one-meter class telescopes at the Stallion Air Force Station on White Sands Missile Range near Socorro, New Mexico. The Minor Planet Center is operated by the Smithsonian Astrophysical Observatory using mostly NASA funding, and the NEO Program Office is at the Jet Propulsion Laboratory, managed by the California Institute of Technology. No significant NEO detection efforts are currently conducted by the international community. Less than 2% of NEOs detected in the last ten years were found by systems other than those funded by NASA. Currently, the only organized work in the international community that is significant to the NEO Survey is the NEO Dynamics Site (NEODyS), operated by the University of Pisa in Italy. NEODys conducts independent analysis on NEO orbits similar to that performed by NASA's NEO Program Office at JPL. JPL and NEODyS constantly compare results they obtain for PHO orbits and predicted impact probabilities. If the results from one vary significantly from the other, they redo their analyses until they can resolve the discrepancy. This work offers a completely independent check of impact prediction results prior to an announcement of any significant threat. Also worth noting is the current significant role for new discovery follow-up observations conducted world-wide by a dedicated amateur astronomer community. Through its website, the MPC supplies position information on newly discovered objects and solicits observations needed to improve the orbit from anyone who may want to attempt the work. Much of these follow-up observations are obtained by amateur astronomer individuals or clubs with relatively sophisticated but smaller telescope systems. However, once NASA moves the search to objects much smaller than one kilometer, this work quickly becomes beyond the capabilities of these amateur systems. Coordination of efforts is largely voluntary through the use of information published on the MPC and NEO Program Office websites. The competitive nature of the grant program used to finance the search teams has encouraged them to make improvements in their systems and data processing to maintain their detection rates. This community meets either in the US or internationally annually, on average, to discuss progress and improvements to the survey effort. In addition, last year the United Nations Committee on the Peaceful uses of Outer Space (COPUOS) established an Action Team on NEOs within its Scientific and Technical Subcommittee to encourage more international work on this issue. The Action Team is focused on identifying gaps in efforts and coordination within the international community, as well as recommending improvements. NASA is charter member of this new group. Question 3: How do spacecraft missions to comets and asteroids, as well as other scientific spacecraft, contribute to the NEO program? Currently, spacecraft missions do not contribute to the detection of NEOs. However, space missions do provide the most significant and detailed information on what we know about the character and composition of them. NASA Discovery missions such as the Near Earth Asteroid Rendezvous (NEAR), Stardust, Deep Impact, and the Japanese Hyabusa mission have contributed important information to our understanding of the origin of comets and asteroids, providing insight on their evolution into the inner Solar System near the Earth, their structure and physical properties, and their composition. The recently launched Dawn mission will travel to the two largest objects in the Main Belt of Asteroids - Vesta and the dwarf planet Ceres. This area of the Solar System has been shown to be the region of origin for most of the objects that now are near Earth, and the Dawn mission will tell us many things about their nature. Other significant contributions by spacecraft include studies by the Hubble Space Telescope, Spitzer, Galileo, and other asteroid and comet flybys performed by several Solar System exploration missions. Not only are these data important to the development of concepts to deal with any impact threat an NEO may pose, but they are also critical to an understanding of the nature NEOs for possible destinations and resources in our future exploration of the Solar System. While NASA does not have any formal responsibility for the task of mitigation, scientific missions such as Deep Impact and the current Dawn mission to Vesta and Ceres provide information that may be critical to planning an asteroid deflection. Likewise, many of the systems and technologies that are being developed for exploration missions are directly applicable to mitigation missions. These capabilities are the hallmarks of a robust, space-faring nation. Question 4: What is the Arecibo facility's role in the detection, tracking, and characterization of Near Earth Objects, and what alternatives, if any, exist to carry out its role if the facility is shut down? How do the capabilities of those alternatives compare to those of the Arecibo facility? The National Science Foundation's Arecibo Radio Telescope facility has had no useful role in the detection of NEOs - its technical characteristics make it incapable of conducting searches for these relatively small and distant objects. However, once we know the position of an object is accessible by a focused radar beam, Arecibo plays an important role in the quick refinement of the orbit to a precision not obtainable by other means, and for understanding the object's size, shape and spin rate. Arecibo also aids in the detection of possible binary objects, (~15% of NEOs), which in turn provides data that can be used to determine their mass. When an object passes close enough to the Earth to achieve a measurable radar return (about 20 million miles depending on the size), the use of radar is one of several valuable tools for obtaining additional information about these objects. The only other facility currently being used by NASA for routine planetary radar is NASA's own Goldstone facility, part of our Deep Space Network (DSN) for communication with spacecraft on missions beyond Earth's orbit. No international facility is capable of performing this feat on a regular basis. There are significant differences with the planetary radar capability at Arecibo compared to Goldstone. The Goldstone radar is a 70-meter steerable dish, allowing it to access objects significantly lower to the horizon than the more limited sky area accessible to the limited pointing capability of the Arecibo radar. However, Arecibo is twice as powerful as Goldstone and has a much larger (304 meter) collection dish, which allows it to observe objects significantly farther away than Goldstone. Question 5: Will NASA's current NEO program satisfy the requirement established in Sec. 321(d)(1) of the NASA Authorization Act of 2005, and if not, what is NASA's plan for satisfying that requirement? Although the current systems funded by NASA are capable of detecting objects smaller than one kilometer in size, the objects must come significantly closer to the Earth than a one kilometer object needs to in order to be detected. It would take timescales much longer than 15 years to observe 90% of these objects with the systems we currently use. As outlined in the report NASA submitted to Congress on March 7, 2007, pursuant to direction in section 321 of the NASA Authorization Act of 2005 (P.L. 109-155), the Agency recommended that the current survey program, funded at approximately $4M annually, be continued. In addition, NASA indicated that the Agency would look for opportunities using potential dual-use telescopes and spacecraft--and to partner with other agencies as feasible--to attempt to achieve the legislated goal within 15 years. Several alternatives as to how this might be accomplished were presented and analyzed in the March 7 report. However, due to current budget constraints, it is not possible for NASA to initiate a new program. The costs for the alternative programs ranged from $470M to in excess of $1.0B over 10 to 19 years, depending on how aggressive of a timeline would be pursued. The current NEO program is fully funded through 2012. In addition, NASA is initiating plans to use other survey systems to increase the survey's detection sensitivity and rates. For example, NASA has begun providing funds to the Air Force Panoramic Survey Telescope and Rapid Response System (Pan- STARRS) project so that it will be capable of providing data on NEO detections after it starts operations on its first telescope in the next year. If the Air Force continues to fund this project to its intended four telescope configuration by 2010, this system alone could discover over 70% of the potentially hazardous objects larger than 140 meters by 2020. NASA is also assessing the upgrades that must be instituted at the Minor Planet Center to absorb the substantial increase in new detection data that this system will provide. Finally, NASA is also assessing what already planned spacecraft might contribute to the detection effort. A leading example for possible dual-use is the Wide-field Infrared Survey Explorer (WISE). Currently being developed for a late 2009 launch for a six month astrophysics mission to map the infrared sky, the WISE instrument is also capable of detecting many asteroids, of which a portion will be NEOs. We are investigating improvements to the timeliness of the spacecraft's data downlink and archival plans to increase its utility for NEO detections, as well as a possible extended mission to double the time available to detect these objects. The science community may propose a NEO survey mission under the competitively-selected Discovery program. Question 6: What plans, policies, or protocols does NASA have in place in the event that a previously unknown object on a near term impact trajectory is detected? NASA has an NEO contingency notification plan to be utilized in the very unlikely event an object is detected with significant probability of impacting the Earth. The plan establishes procedures between the detection sites, the Minor Planet Center, the NASA NEO Program Office at JPL, and NASA Headquarters to first quickly verify and validate the data and orbit on the object of interest, and then up- channel confirmed information in a timely manner to the NASA Administrator. These procedures were first exercised with the discovery of the object now known as Apophis, which was found in December 2004 in a hazardous orbit but determined to not have a significant probability of impacting the Earth in the near-term. NASA will continue to refine this internal contingency plan, and begin work with other US government agencies and institutions when directed. Testimony of Scott Pace, Office of Program Analysis and Evaluation, NASA HQ Mr. Chairman and Members of the Subcommittee, thank you for the opportunity to appear today to review the findings and recommendations of NASA's report to Congress in response to the NASA Authorization Act of 2005 (P.L. 109-155). Below, I have addressed the questions posed by this Subcommittee in your invitation to testify. Question #1: What were the principal findings and recommendations of NASA's Near-Earth Object Survey and Deflection Analysis of Alternatives: Report to Congress, March 2007, and what was the basis for those findings and recommendations? The principal findings were the result of a study team, led by NASA's Office of Program Analysis and Evaluation (PA&E) that conducted an analysis of alternatives with inputs from several other U.S. government agencies, international organizations, and representatives of private organizations. The team developed a range of possible options from public and private sources and then analyzed their capabilities and levels of performance including costs, development schedules, and technical risks. In order to meet the congressional goal of completing the survey by 2020, the study team assumed primary project elements would have started their development by October 1, 2007. NASA recommended that the existing "Spaceguard Survey" program continue as currently planned, and that NASA would also take advantage of opportunities using potential dual-use telescopes1 and spacecraft--and partner with other agencies as feasible--to make progress toward achieving the legislative goal of discovering 90 percent of all potentially hazardous objects 140 meters in mean diameter and greater. However, due to budget constraints, NASA cannot initiate a new program beyond the Spaceguard Survey program at this time. NASA would be pleased to implement a more aggressive NEO program if so directed by the President and Congress. However, given the constrained resources and strategic objectives the Agency has already been tasked with, NASA cannot place a new NEO program above current scientific and exploration missions. For ease of following the findings and recommendations, simplified definitions are as follows: * "Detection" is the act of finding the objects; * "Tracking" is the act of determining their orbits; * "Characterization" is the act of determining their physical properties; * "Cataloging" is the act of maintaining a data base of the orbits and physical properties of known objects and predicting potential impacts with the Earth; and * "Mitigation" is the act of deflecting, destroying, or reducing the impact consequences of a specific object that is predicted to strike the Earth. Key Findings for the Survey Program * The goal of the Survey Program should be modified to detect, track, catalogue, and characterize, by the end of 2020, 90 percent of all Potentially Hazardous Objects (PHOs) greater than 140 meters whose orbits pass within 0.05 AU (Astronomical Units) of the Earth's orbit (as opposed to surveying for all NEOs). * The Agency could achieve the specified goal of surveying for 90 percent of the potentially hazardous NEOs by the end of 2020 by partnering with other government agencies on potential future optical ground-based observatories and building a dedicated NE0 survey asset, assuming the partners' potential ground assets come online by 2010 and 2014, and a dedicated asset by 2015. * Together, the two observatories potentially to be developed by other government agencies could complete 83 percent of the survey by 2020 if observing time at these observatories is shared with NASA's NE0 Survey Program. * New space-based infrared systems, combined with shared ground-based assets, could reduce the overall time to reach the 90 percent goal by at least three years. Space systems have additional benefits as well as costs and risks compared to ground-based alternatives. * Radar systems cannot contribute to the search for potentially hazardous objects, but may be used to rapidly refine tracking and to determine object sizes for a few NEOs of potentially high interest. * Determining a NEO's mass and orbit is required to determine whether it represents a potential threat and to provide required information for most alternatives to mitigate such a threat. Beyond these parameters, characterization requirements and capabilities are tied directly to the mitigation strategy selected. Key Findings for Diverting a Potentially Hazardous Object (PHO) The study team assessed a series of approaches that could be used to divert a NEO potentially on a collision course with Earth. Nuclear explosives, as well as non-nuclear options, were assessed. * Nuclear standoff explosions are assessed to be 10-100 times more effective than the non-nuclear alternatives analyzed in this study. Other techniques involving the surface or subsurface use of nuclear explosives may be more efficient, but they run an increased risk of fracturing the target NEO. They also carry higher development and operations risks. * Non-nuclear kinetic impactors are the most mature approach and could be used in some deflection/mitigation scenarios, especially for NEOs that consist of a single small, solid body. * "Slow push" mitigation techniques are the most expensive, have the lowest level of technical readiness, and their ability to both travel to and divert a threatening NEO would be limited unless mission durations of many years to decades are possible. * 30-80 percent of potentially hazardous NEOs are in orbits that are beyond the capability of current or planned launch systems. Therefore, planetary gravity assist swingby trajectories or on-orbit assembly of modular propulsion systems may be needed to augment launch vehicle performance, if these objects need to be deflected. Question #2: How were the cost estimates and technical options contained in the report arrived at, and was any independent assessment of the cost estimates and technical options conducted? Technical Options The technical options contained in the report were developed through a systematic exploration of the trade space for feasible alternatives, followed by a conceptual design of selected options. Concepts were selected to represent the available range of cost, performance, and acceptable technical risk to complete the detection, tracking, cataloguing, and characterization missions. Concepts were based on historical and existing projects and on white papers presented at a NASA-sponsored workshop of national experts. Trade trees were developed to describe the technical options. The detection and tracking trade tree consisted of existing and new ground- and space-based observatories operating in the visible and infrared spectra; ground based radars were considered for tracking. The characterization trade tree contained existing, proposed, and new remote and in-situ observing assets. Cataloguing considered a range of operations and data management options based on historical, proposed, and new information systems. Cost Estimates Life cycle costs were calculated as the total architecture cost in fiscal year 2006 billions of dollars including development, production, deployment, and operation of the alternatives. Life cycle costs for the detection, tracking, and data management options were calculated both for a fixed period (through 2020) and until the objective of cataloguing 90 percent of specified threats was complete. For some options that rely on existing systems or available technology, operational costs were much higher than the development costs over the 15-20 year life cycle. In order to meet the Congressional goal of completing the survey by 2020, the study team assumed primary project elements would have started their development by October 1, 2007. For space-based systems, the total life cycle costs included estimated costs for program management, systems engineering, mission assurance, launch vehicle, spacecraft, scientific instruments, mission specific ground data systems, mission operations, and data analysis. Ground-based systems included the cost of development, production, and operations. Operations costs were calculated over either the survey period for detection, tracking, and cataloguing missions or the predicted duration of characterization missions. The cost estimates for the space vehicles relied on multiple methods including historical analogies and prior cost-estimating experience. Cost-risk analyses were performed using these data as inputs and assumed that every cost element could be represented by statistical characteristics such as mean, standard deviation, and mode. A cumulative probability distribution of total cost was generated for this analysis by combining cost distributions from the different cost elements, and costs were estimated at the 65 percent cost confidence level when applicable. Programmatic costs were based on historical actual costs and applied as a percentage of the space vehicle costs. Launch vehicle costs were based on recent, publicly released estimates for commercial launch vehicles. Ground-based observatory costs were based on reported expenses for currently operating systems or based on estimates for systems currently in development. For several ground based options, concepts of operations postulated utilizing (sharing) data that would be collected on existing or planned systems without materially affecting the primary mission of these systems. For these systems, it was assumed that the NEO program would fund only a small portion (or none) of the development costs, but that an equitable portion of the annual operations costs would be funded by NASA. In cases where the ground based systems were expected to be copies of systems that are currently in development, only the production and operation costs of the NASA-acquired systems were considered -- substantially reducing their development costs and cost-risk. Although multiple cost-estimating methodologies, databases, and organizations were used, truly independent cost estimates were not generated as these are typically not within the scope of a conceptual, architecture-level study. Likewise, assessments of the technical options were carried out using an experienced team of personnel from several organizations, but fully separate evaluations of the concepts were not performed. Question #3: What is the "recommended option and proposed budget to carry out the Survey program pursuant to the recommended option", as called for in Sec. 321(d)(2)? NASA recommended that the existing "Spaceguard Survey" program continue as currently planned, and that NASA would also take advantage of opportunities using potential dual-use telescopes2 and spacecraft--and partner with other agencies as feasible--to make progress toward achieving the legislative goal of discovering 90 percent of all potentially hazardous objects 140 meters and greater. The goal of finding 90 percent of potentially hazardous objects 140 meters and larger is 1-2 orders of magnitude more technically challenging than the Spaceguard mission. To reach this goal within 10-15 years requires at least one new dedicated ground or space observatory. Cataloging the number of total number of objects--approximately 100,000 --at the rate they would be discovered, which is between 30 and 50 per day, requires a new tracking and data management infrastructure whose ongoing operations may constitute a sizeable portion of total costs. A delay (e.g. 5-10 years) in achieving the legislative goal carries little additional risk when the impact interval for 140 m objects is about once every 5000 years. This rate of impacts also indicates that the system may need to operate (searching and tracking) for an extended period before identifying a credible threat. There are three epochs to the problem of detection and tracking: * Now: We know where few 140 m objects are and when/if they will impact. * Initial 10-20 years of the survey: Average warning time will rise, unwarned impact risk gradually decline. Decades of warning become likely. * Steady-state: After 10-20 years of the survey, unwarned impacts of 140 m objects would be highly unlikely. Centuries of warning become possible. Currently, NASA carries out the "Spaceguard Survey" to find NEOs greater than 1 kilometer in diameter, and this program is currently budgeted at $4.1 million per year for FY 2006 through FY 2012. We also have benefited from knowledge gained in our Discovery space mission series, such as the Near Earth Asteroid Rendezvous (NEAR), Deep Impact, and Stardust missions that have expanded our knowledge of near-Earth asteroids and comets. Participation by NASA in international collaborations such as Japan's Hayabusa mission to the NEO "Itokawa" also greatly benefited our understanding of these objects. NASA's Dawn mission, launched on September 27, 2007, will increase our understanding of the two largest known main belt asteroids, Ceres and Vesta, between the planets Mars and Jupiter. NASA conducts survey programs on many celestial objects -- the existing Spaceguard program for NEOs, surveys for Kuiper Belt Objects, the search for extra-solar planets, and other objects of interest such as black holes to understand the origins of our universe. The science community could propose such a NEO survey mission under the competitively-selected Discovery program. NASA also identified an exemplar NEO Survey Program and estimates for its architectural costs that, if funded, could have achieved the specified goal of surveying 90 percent of the PHOs by the end of 2020 by constructing or funding a dedicated survey asset combined with NASA partnerships with other government agencies on potential future optical ground-based observatories: the Panoramic Survey Telescope and Rapid Response System (PanSTARRS-4 or PS4) and the Large Synoptic Survey Telescope (LSST) . Details of the exemplar program were provided in NASA's report. Note that budget estimates in the report are rough "architecture costs" and would require more rigorous analysis before a program could be assessed for implementation. Question #4: Will NASA's current NEO program satisfy the requirement established in Sec. 321(d)(1) of the NASA Authorization Act of 2005, and if not, what is NASA's plan for satisfying that requirement? The current NASA NEO "Spaceguard Survey" program, without any augmentation, would not be able to satisfy the requirements outlined in section 321(d)(1) of the NASA Authorization Act for 2005. The requirements for the Spaceguard Survey program are to find only NEOs greater than 1 kilometer in diameter, and its funding is currently budgeted at $4.1 million per year. NASA estimates that the current program, if continued without major augmentation, would detect 14 percent of the 140 meters or larger potentially hazardous objects by the end of 2020. However, NASA is initiating plans to use other survey systems to increase the survey's detection sensitivity and rates. For example, NASA has begun providing funds to the Air Force Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) project so that it will be capable of providing data on NEO detections after it starts operations on its first telescope in the next year. If the Air Force continues to fund this project to its intended four telescope configuration by 2010, this system alone could discover over 70 percent of the potentially hazardous objects larger than 140 meters by 2020. NASA recommended that the existing "Spaceguard Survey" program continue as currently planned, and that NASA would also take advantage of opportunities using potential dual-use telescopes and spacecraft--and partner with other agencies as feasible--to make progress toward achieving the legislative goal of discovering 90 percent of all potentially hazardous objects 140 meters and greater. NASA would be pleased to implement a more aggressive NEO program, if so directed by the President and Congress. However, given the constrained resources and strategic objectives the Agency has already been tasked with, NASA cannot place a new NEO program above current scientific and exploration missions. Question #5: How is progress on meeting the requirements of Section 321 being measured and monitored? Survey performance is tracked continuously by the NEO Program Office at JPL, and reported monthly on NASA's NEO Program website at http://neo.jpl.nasa.gov/stats . This database shows the performance of each survey team and reports the number of NEOs, including Earth approaching comets, found each month by orbit and size (larger or smaller than one kilometer) class. It also breaks out the objects which are potentially hazardous by size class. Specific orbit and estimated size information for each discovered NEO can also been found on the website, as well as probability of impact statistics for Potentially Hazardous Objects. The discovery statistics information is rolled up each year and reported by the Science Mission Directorate as part of our Government Performance Reporting Act (GPRA) submittal. In closing, NASA recommends that the existing "Safeguard Survey" program continue, as planned, and that the Agency take advantage of opportunities using potential dual-use telescopes and spacecraft, as well as partner with other agencies, to make progress toward achieving the legislative goal. 1 The proposed Large Synoptic Survey Telescope (LSST) and Panoramic Survey Telescope And the Rapid Response System (Pan-STARRS) present possible future opportunities, if they are funded by other agencies. Another possible opportunity would be the Lowell Discovery Channel Telescope (DCT), but its contribution would be less than LSST or Pan-STARRS. 2 The proposed Large Synoptic Survey Telescope (LSST) and Panoramic Survey Telescope And the Rapid Response System (Pan-STARRS) represent possible future opportunities, if they are funded by other agencies. Another possible opportunity would be the Lowell Discovery Channel Telescope (DCT), but its contribution would be less than LSST or Pan-STARRS. Testimony of Donald Yeomans, NEO Program Office, Jet Propulsion Laboratory Mr. Chairman and members of the Subcommittee, thank you for the opportunity to appear today to discuss the potential threats of near-Earth objects (NEOs), our progress toward meeting the discovery goal articulated in the NASA Authorization Act of 2005, the role of the Arecibo planetary radar within the NEO program and the response options available if a NEO is found to be on an Earth impacting trajectory. The Near-Earth Object Population: When the Earth was young, frequent collisions of comets and asteroids likely delivered much of the water and carbon-based molecules that allowed life to form, and once life did form, subsequent collisions may have punctuated the evolutionary process and allowed only the most adaptable species to progress further. We may owe our very existence atop the world's food chain to these objects. As the Earth's closest neighbors (some pass within the moon's distance), these icy comets and rocky asteroids have been termed near-Earth objects. Their proximity to Earth presents an opportunity to utilize their vast metal, mineral and water ice resources for future space structures and habitats. Their water resources can be broken down into hydrogen and oxygen - the most efficient form of rocket fuel. These near-Earth objects may one day be the resources, fueling stations and watering holes for human interplanetary exploration. While these objects are of extraordinary scientific interest, likely enabled the origin of life itself, and may loom large for the future development of space exploration, their proximity to Earth also presents a potential horrific threat should a relatively large near-Earth object once again strike Earth without warning. Potentially Hazardous Asteroids: Near-Earth objects are comets and asteroids that can pass within 45 million kilometers of the Earth's orbit. While some showy, naked-eye comets may occasionally pass close to Earth, it is the difficult to find (but far more numerous asteroids) that are of most concern in near-Earth space today. About one fifth of the near-Earth asteroids can approach the Earth's orbit even closer (to within 7.5 million kilometers), and these so-called potentially hazardous asteroids (PHAs) are of most concern for near-term hazard avoidance. Celestial debris hits the Earth all the time, but the vast majority of it is so small that it does not survive passage through the Earth's atmosphere. The debris is created over millions of years, as asteroids inevitably run into each other, producing smaller fragments, which themselves collide yielding even more debris. Over time, the fragments and debris spread out, and some of it migrates into Earth approaching orbits. The Earth is pummeled with more than 100 tons of impacting material each day but almost all of it is far too small to cause anything other than a harmless meteor, or shooting star, or the occasional fireball event. Larger objects are less numerous than smaller objects and hit the Earth less often. While a basketball-sized object strikes the Earth's atmosphere daily, larger car-sized impactors hit only a few times each year, and even these generally break up into smaller pieces as they streak through the atmosphere. Occasionally a fragment of a larger impactor will reach the Earth's surface -- one such hit may have occurred less than two months ago when a reported asteroid fragment perhaps one meter in diameter struck in southern Peru creating a 13-meter crater near Lake Titicaca. Larger impactors with diameters in the 50 to 140 meter range, while they do not usually impact the ground, can result in damaging air blasts that cause significant destruction. For example, on June 30, 1908, an impactor with a diameter of about 50 meters detonated over the Tunguska region of Siberia and leveled trees for 2000 square kilometers. Its impact energy has been estimated at about 10 million tons of TNT explosives (10 megatons or 10 MT), comparable in energy with a modern nuclear weapon. Roughly speaking, PHAs that have diameters larger than 140 m can punch through the Earth's atmosphere and cause regional damage if they strike land or create a harmful tsunami should they impact into an ocean. There are thought to be about 20,000 PHAs in this size range, each with a potential impact energy of 100 MT or more. On average, one of these objects would be expected to strike Earth every 5000 years and therefore would have a 1% probability of impact in the next 50 years. Although their mean impact frequency would be about once every 500,000 years, PHAs larger than a kilometer in diameter could cause global consequences due to not only the extraordinary blast itself (50,000 MT) but also the dust and debris thrown into the air, and the subsequent firestorms and acid rain. The extinction of the dinosaurs and a sizable fraction of the Earth's other species some 65 million years ago is thought to be due to an impactor with a diameter of about 10 kilometers that created an impact energy of as much as 50 million MT. Over very long time intervals, PHAs with diameters greater than one kilometer are statistically the most dangerous objects because their impacts would cause global consequences. NASA Responses to the PHA Issues: In 1998, before the Subcommittee on Space and Aeronautics, a NASA representative outlined the goal to discover and catalog 90% of the NEOs larger than one kilometer by the end of 2008. There are currently thought to be over 900 of these objects, and about 80% of them have already been found and cataloged. Roughly the same percentage of PHAs in this size range has also been found. When this goal has been reached, 90% of the global risk from PHAs would be retired. Almost all of these discoveries have come by way of NASA supported search programs. As part of the NASA Authorization Act of 2005, NASA was asked to consider options for extending the search down to objects as small as 140 meters in diameter, and to find and catalog them within 15 years of the Act becoming law (i.e., by the end of 2020). By finding and cataloging 90% of this population of PHAs, the statistical or actuarial risk to Earth from PHAs of all sizes would be reduced by 99% from pre-survey levels. We can speak of risk reduction in this case because once an object is discovered and cataloged, its future motion can accurately be predicted and, in the unlikely case where it does threaten Earth, there would be sufficient time to deflect it, thus saving the enormous costs due to fatalities and/or infrastructure damage. According to a 2003 NASA NEO Science Definition Team study that undertook a cost/benefit analysis for the discovery of PHAs, the risk reduction accruing from this next generation PHA search would pay for itself in the first year of operations. While an impact by a 140 meter-sized object would not generate global physical consequences, its impact energy would still be about 100 MT, and the likelihood of one of these impacts is 100 times greater than an impact by one of the less numerous one kilometer-sized PHAs. With regard to the uncertainty associated with threats from PHAs, the largest factor, by far, is the large number of undiscovered objects in the size ranges that are small enough to be very numerous but large enough to easily penetrate the Earth's atmosphere. For example, we have discovered only about 4% of the 20,000 PHAs larger than 140 meters and less than 1% of the 200,000 objects larger than 50 meters. The solution to this uncertainty is to continue and hopefully accelerate the search for PHAs. Once we find the vast majority of them, they can be tracked, cataloged and then ruled out (or in) as threats during the next 100 years or so. This process can continue year after year so the window of safety is always at least 100 years. There are other, less significant, uncertainties dealing with the refinement of a particular object's size, mass and structure as well as the dynamical model that is used to accurately predict the object's motion over 100 year time scales. For example, over long time intervals, the minute pressure of sunlight and its thermal re-radiation can significantly affect a PHA's motion. For a select number of Earth approaching objects, we will need the use of the planetary radars, or possibly rendezvous spacecraft missions, to better understand their sizes, shapes, masses, surface properties, and possible binary natures. The Next Generation of Search: As noted, the current NASA NEO goal is focused upon the discovery and tracking of objects one kilometer in diameter and larger. It is not realistic to expect the current survey program, with its modestly sized telescopes, to efficiently find the 140 meter-sized objects that are nearly 50 times fainter compared to a one kilometer-sized object at the same distance and with the same reflectivity. Because all PHAs do eventually come very close to the Earth, the current ongoing surveys could complete the goal outlined in the 2005 NASA Authorization Act but it would likely take over a century to do so. We cannot afford to wait that long. In the report to Congress requested by the 2005 NASA Authorization Act, several options were outlined, both ground-based and space-based, that could meet the goal of finding 90% of the PHAs larger than 140 meters by the end of 2020. For example, a one-meter aperture infrared telescope in a heliocentric orbit near Venus could do the job three years early. Within this report, NASA noted that it did not have the resources to carry out a survey option that would meet the 2020 deadline set by the 2005 Act and that, in an attempt to achieve the legislative goal by the end of 2020, it would seek to continue the current survey programs and look for opportunities to use dual use telescope facilities and spacecraft along with partnering with other agencies as feasible. At least two next-generation, ground-based, wide-field search telescope surveys are in development. The Panoramic Survey Telescope and Rapid Response System (PanSTARRS), under development at the University of Hawaii with Air Force funding, will have one of its four 1.8 meter telescopes operational in Hawaii in early 2008. If the planned, four telescope version of PanSTARRS is completed by 2010, it could help reach the goal by about 2040. Likewise the 8.4 meter aperture Large Synoptic Survey Telescope (LSST) that is under development with funding from NSF, DoE and other partners, could help reach the goal by about 2034 if it began operation in 2014. If we assume that both the PanSTARRS four telescope system and the LSST operate in their planned shared modes, which includes many observations unrelated to PHAs, then the goal could be reached by about 2026. The PHA discovery rate could be increased beyond the results shown in the NASA response to the 2005 Act if the observing time and sequences of PanSTARRS and LSST were optimized for PHA observations. In terms of actual discoveries of new PHAs, there has been little success beyond the survey programs supported by NASA. However, the international community, including many sophisticated amateur astronomers, is very active in providing the follow-up observations necessary to secure an object's orbit once it has been found. The NEODyS program in Pisa Italy works closely with, but independent of, the NEO Program Office at JPL to compute impact probabilities for predicted Earth close approaches for at least 100 years into the future. It is also encouraging to note the activities of a NEO Action Team within the UN Committee on the Peaceful Uses of Outer Space (COPUOS) includes an effort to encourage more international efforts on the NEO issues. The importance of Radar Observations: There are only two planetary radars in existence (and no alternatives) that can routinely observe close Earth approaching asteroids, and both of them are critically important for investigating the nature of these objects and for rapidly refining their trajectories. The 70-meter Goldstone antenna in California's Mojave desert is fully steerable, can track an asteroid and can cover large regions of sky while the larger 305-meter Arecibo antenna in Puerto Rico has twice the range but only observes within a 40-degree zone centered on the overhead position (20 degrees on either side of zenith). The capabilities of these two telescope complement one another and often a significantly better and longer set of observations can be achieved using both radars on a close approaching target asteroid. Most positional data for PHA orbit determination and trajectory predictions are based upon optical, plane-of-sky observations. Because the radars provide line-of-sight velocity and range information accurate to about the 1 mm/s and 10 meter levels, these data when used in conjunction with the optical data provide a secure orbit and trajectory far more rapidly than if only optical data are available. With only a limited amount of optical data to work with, the orbit of a newly discovered PHA is often not accurate enough to immediately rule out a future Earth impact. However, with radar data in hand, the orbit of a newly discovered PHA can be quickly and more precisely determined, its motion accurately projected far into the future and future impact possibilities can usually be quickly ruled out. Likewise, in the rare situation when an object is actually on an Earth threatening trajectory, radar observations will be critical in quickly identifying this case. Unfortunately the Arecibo radar program is not funded by the NSF beyond FY2007 and the planetary science community is in danger of losing one of its instrumental crown jewels. As a measure of this radar facility's importance, note that 65% of all radar experiments to characterize near-Earth asteroids were performed at Arecibo, 47% of all binary near-Earth asteroids were discovered at Arecibo and 85% of the near-Earth asteroids with the critical astrometric radar data for orbit improvement have data from Arecibo. All of this was accomplished with only 5% of this instrument's time. The superior sensitivity of the giant Arecibo radar can determine the sizes, shapes, rotation characteristics, surface characteristics and binary nature for many PHAs. All of these physical characteristics are important criteria to understand before a deflection mission is considered. Radar observations are responsible for the best physical characterization of any PHA as large as a kilometer (i.e., the binary asteroid 1999 KW4). Radar observations reduce a PHA's orbit uncertainties quickly and dramatically so that future impact possibilities can be quickly knocked down thus reducing the odds that we will need to invest in a spacecraft investigation to characterize the PHA's nature in preparation for a precautionary deflection mission. Thus the relatively modest costs of maintaining the Arecibo radar in a robust state could prevent the future need for 100's of millions of dollars per case for spacecraft reconnaissance of an object to determine whether or not it is an actual threat. What Should be Done in the Event of an identified NEO Threat? A number of existing technologies can deflect an Earth threatening asteroid - if there is time. The primary goal of the PHA survey programs is to discover them early and provide the necessary time. An asteroid that is predicted to hit Earth might require a change in its velocity of only 3 millimeters per second if this impulse were applied twenty years in advance of the impact. The key to a successful deflection is having sufficient time to carry it out, whether it is the slow, gentle drag of a gravity tractor or a more impulsive shove from an impacting spacecraft or explosive device. In either case, a verification process would be required to ensure the deflection maneuver was successful and to ensure the object's subsequent motion would not put it on yet another Earth impacting trajectory. While suitable deflection technologies exist, none of them can be effective if we are taken by surprise. It is the aggressive survey efforts and robust planetary radars that must ensure that the vast majority of potentially hazardous objects are discovered and tracked well in advance of any Earth threatening encounters. The first three steps in any asteroid mitigation process are: Find them early, find them early, and find them early! Testimony of Donald Campbell, Arecibo Observatory, Cornell University Mr Chairman and Members of the Committee, thank you for this opportunity to address you on the important issue of near-Earth objects and their potential threat to Earth. I have been asked to address issues related to the use of radar systems to track and characterize near-Earth objects (NEOs) and, specifically, to address the role of the radar system on the giant Arecibo telescope in Puerto Rico in this activity and the current state of funding for this National Science Foundation facility. I will address these questions in turn. * What role do Earth based radars play in the tracking and characterization of Near Earth Objects (NEOs)? What role, if any, do they play in providing information about specific hazardous objects? Radar plays an important role in predicting the future orbits of NEOs and measuring many of their physical characteristics such as size, shape, rotation state and, in the case of binary objects, their mass and density. Radar can measure distances to NEOs to an accuracy of about 10 m (30 ft) and their line-of-sight velocity to an accuracy of about 1 mm per second (12 ft per hour), orders of magnitude better than the equivalent optical measurements. For potentially hazardous objects (PHOs), optical observations based on measuring their changing position on the sky over days or weeks in many instances cannot rule out a possible future impact with the Earth. To do so can require optical positional measurements spanning years or decades. For future searches, radar astrometry, the measurement of distance and line-of-sight velocity, can be used to help cull the number of PHOs - not all the newly detected NEOs will be observable with radar - so that we can concentrate on the few that really are potentially hazardous. For these objects, additional precision radar measurements are extremely important to assess the impact probability and the need to take action to mitigate the threat. The more we know about NEOs in general and about specific ones that pose a threat to Earth, the easier it will be to design effective mitigation strategies. "Know your enemy" would seem to be good advice in this instance. NEOs form a very diverse population encompassing a large range of sizes, shapes, rotation states, densities, internal structure and binary nature. While a very small number of NEOs have been visited by spacecraft, radar provides by far the best means to survey these characteristics for a large number of objects. Knowing the range of characteristics facilitates the design of effective mitigation techniques that can be applied to an object with any of these characteristics. For an object that we know poses a direct threat to Earth, radar can provide vital input to mitigation planning including planning for any precursor space mission. Over the past few years, the accuracy of the Earth impact prediction based on precision radar astrometry for a few PHOs has been limited not by the accuracy of the radar measurements but by the inability to accurately model all of the very small forces on these objects in addition to that due to the Sun's gravity. One of these forces, the Yarkovsky effect, is related to sunlight absorbed by the body and its re-emission as heat. Precision radar astrometry over several years of a small asteroid, Golevka, demonstrated in 2003 that this effect can modify the orbits of small asteroids over very long periods of time. This h |
