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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Multi‐Sensor Trajectory Reconstruction of the 24 April 2025 Alaska Fireball and Implications for Planetary Defense

On 24 April 2025 at 18:30:57 UTC, a bright daytime fireball over Southcentral Alaska was detected by 37 seismic stations, 16 single infrasound sensors, and four infrasound arrays, yielding 30 ballistic and multiple fragmentation arrivals. Here, the unprecedented density of seismoacoustic coverage enabled detailed reconstruction of the event using acoustic signals, with fragmentation source locations further guiding the identification of Doppler weather radar signatures of a meteorite fall. Incorporation of a radar-derived terminal point yielded a final trajectory solution, which agreed closely with an independent optical trajectory solution from video analysis. The reconstructed entry parameters from seismoacoustic analysis indicate a velocity of 25.3 km/s, an entry angle of 19°, and an energy release of ∼38 t TNT equivalent. Assuming a chondritic composition, the pre-entry object diameter was ∼0.7 m. Using orbital parameters from the optical solution, we estimate meteoroid composition as most likely an L-type ordinary chondrite. The event occurred in the sub-Arctic, where space-based optical systems face challenges in detection, demonstrating the critical role of dense ground-based seismoacoustic networks in characterizing high-latitude atmospheric entries. This uniquely well-recorded event demonstrates the capability of dense seismoacoustic networks to constrain bolide trajectories, energetics, and fragmentation, with radar and optical data providing critical confirmation and complementary perspectives. These results bridge the methodological gap between planetary-defense monitoring of natural impactors and space-traffic analyses of artificial reentries, illustrating how multi-sensor integration can deliver calibration-grade trajectories even for unpredicted events.

Fireball↗
NASA NTRS2011

A Space-Based Near-Earth Object Survey Telescope in Support of Human Exploration, Solar System Science, and Planetary Defense

Human exploration of near-Earth objects (NEOs) beginning in 2025 is one of the stated objectives of U.S. National Space Policy. Piloted missions to these bodies would further development of deep space mission systems and technologies, obtain better understanding of the origin and evolution of our Solar System, and support research for asteroid deflection and hazard mitigation strategies. As such, mission concepts have received much interest from the exploration, science, and planetary defense communities. One particular system that has been suggested by all three of these communities is a space-based NEO survey telescope. Such an asset is crucial for enabling affordable human missions to NEOs circa 2025 and learning about the primordial population of objects that could present a hazard to the Earth in the future.

Abell, Paul A.↗
NASA NTRS2011

Near-Earth Objects: Targets for Future Human Exploration, Solar System Science, Resource Utilization, and Planetary Defense

U.S. President Obama stated on April 15, 2010 that the next goal for human spaceflight will be to send human beings to a near-Earth asteroid by 2025. Given this direction from the White House, NASA has been involved in studying various strategies for near-Earth object (NEO) exploration in order to follow U.S. Space Exploration Policy. This mission would be the first human expedition to an interplanetary body beyond the Earth-Moon system and would prove useful for testing technologies required for human missions to Mars and other Solar System destinations. Missions to NEOs would undoubtedly provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while conducting in-depth scientific investigations of these primitive objects. In addition, the resulting scientific investigations would refine designs for future extraterrestrial resource extraction and utilization, and assist in the development of hazard mitigation techniques for planetary defense. This presentation will discuss some of the physical characteristics of NEOs and review some of the current plans for NEO research and exploration from both a human and robotic mission perspective.

Abell, Paul A.↗
NASA NTRS2016

Planetary Defense Architecture for Mitigating Short-Term Warning Cosmic Threats: READI Project

Earth is being constantly bombarded by a large variety of celestial bodies and has been since its formation 4.5 billion years ago. Among those bodies, mainly asteroids and comets, there are those that have the potential to create large scale destruction upon impact. The only extinction-level impact recorded to date was 65 million years ago, during the era of dinosaurs. The probability of another extinction-level, or even city-killer, impact may be negligible, but the consequences can be severe for the biosphere and for our species. Therefore it is highly imperative for us to be prepared for such a devastating impact in the near future, especially since humanity is at the threshold of wielding technologies that allow us to do so. Majority of scientists, engineers, and policymakers have focused on long-term strategies and warning periods for Earth orbit crossing Near-Earth Objects (NEOs), and have suggested methods and policies to tackle such problems. However, less attention has been paid to short warning period NEO threats. Such NEOs test current technological and international cooperation capabilities in protecting ourselves, and can create unpredictable devastation ranging from local to global scale. The most recent example is the Chelyabinsk incident in Russia. This event has provided a wakeup call for space agencies and governments around the world towards establishing a Planetary Defense Program. The Roadmap for EArth Defense Initiative (READI) is a project by a team of international, intercultural, and interdisciplinary participants of the International Space University's Space Studies Program 2015 hosted by Ohio University, Athens, OH proposing a roadmap for space agencies, governments, and the general public to tackle NEOs with a short warning before impact. Taking READI as a baseline, this paper presents a technical description of methodologies proposed for detection and impact mitigation of a medium-sized comet (up to 800m across) with a short-warning period of two years on a collision course with Earth. The hypothetical comet is on a highly-inclined orbit having a high probability for Earth impact after its perihelion. For detection, we propose a space-based infrared detection system consisting of two satellites located at the Earth-Moon Lagrange points L1 and L2 coupled with space observatories, like the James Webb telescope and the Centennial telescope. These telescopes are supported by ground-based telescopes, like the Arecibo and Green Bank telescope, in the search for NEOs. Upon detection, the comet is tracked constantly using space- and ground-based telescopes. The deflection system is two-pronged, firstly involving the use of a high energy Directed Energy Laser Terminals (DELT) placed at Sun-Earth Lagrange points L4 and L5 so as to initiate and increase the ablation rate of the comet and deviate it from its collision trajectory, and secondly by the Hypervelocity Comet Intercept Vehicle (HCIV), a space-borne system combining a kinetic impactor with a thermonuclear device. The policy and international collaboration aspects to implement these methods are also outlined in the paper. The techniques mentioned could also be applied to mitigate medium-to-large sized asteroids (up to 2km across).

Laser Applications↗
NASA NTRS2015

Advanced Solar Electric Propulsion for Planetary Defense

Once the current survey to identify all near-Earth objects larger than 140-m diameter is complete, the major hazard from asteroid impacts may be from asteroids in the 50- to 100-m diameter size range. High-power solar electric propulsion systems employed in “slow-push” techniques may be the best way to deflect asteroids in this size range if deflection is warranted. The relative performance of three slow-push techniques—gravity tractor (GT), enhanced gravity tractor (EGT), and ion beam deflection (IBD)—are compared, assuming solar electric propulsion vehicles derived from NASA’s Asteroid Redirect Robotic Mission concept vehicle. Both the enhanced gravity tractor and ion beam deflection concepts are shown to be significantly better than the standard gravity tractor concept. The Hall-thruster based enhanced gravity tractor systems and ion beam deflection systems (based on the use of high-power gridded ion thrusters) are shown to provide comparable performance, i.e., similar deflection times and propellant required. Enhanced gravity tractor systems require the acquisition of material from the surface of the hazardous object in order to achieve the required “enhancement” of the gravitational coupling force. This makes EGT systems sensitive to the rotational state and surface properties of the unknown object, and potentially severely limits its applicability. Ion beam deflection is completely independent of the characteristics of the threat object. In fact, it is the only asteroid deflection technique, slow-push or otherwise, that can make this claim, thus potentially greatly increasing its applicability relative to other deflection techniques. Finally, high-power IBD systems are shown to be capable of deflecting the fictitious asteroid 2015 PDC used in the hypothetical asteroid impact exercise conducted at the 2015 Planetary Defense Conference.

Brophy, John↗
NASA NTRS2012

Missions to Near-Earth Asteroids: Implications for Exploration, Science, Resource Utilization, and Planetary Defense

Introduction: In 2009 the Augustine Commission identified near-Earth asteroids (NEAs) as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. More recently the U.S. presidential administration directed NASA to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010. NEA Space-Based Survey and Robotic Precursor Missions: The most suitable targets for human missions are NEAs in Earth-like orbits with long synodic periods. However, these mission candidates are often not observable from Earth until the timeframe of their most favorable human mission opportunities, which does not provide an appropriate amount of time for mission development. A space-based survey telescope could more efficiently find these targets in a timely, affordable manner. Such a system is not only able to discover new objects, but also track and characterize objects of interest for human space flight consideration. Those objects with characteristic signatures representative of volatile-rich or metallic materials will be considered as top candidates for further investigation due to their potential for resource utilization and scientific discovery. Once suitable candidates have been identified, precursor spacecraft are required to perform basic reconnaissance of a few NEAs under consideration for the human-led mission. Robotic spacecraft will assess targets for potential hazards that may pose a risk to the deep space transportation vehicle, its deployable assets, and the crew. Additionally, the information obtained about the NEA's basic physical characteristics will be crucial for planning operational activities, designing in-depth scientific/engineering investigations, and identifying sites on the NEA for sample collection. Human Exploration Considerations: These missions would be the first human expeditions to interplanetary bodies beyond the Earth-Moon system and would prove useful for testing technologies required for human missions to Mars, Phobos and Deimos, and other Solar System destinations. Current analyses of operational concepts suggest that stay times of 15 to 30 days may be possible at a NEA with total mission duration limits of 180 days or less. Hence, these missions would undoubtedly provide a great deal of technical and engineering data on spacecraft operations for future human space exploration while simultaneously conducting detailed investigations of these primitive objects with instruments and equipment that exceed the mass and power capabilities delivered by robotic spacecraft. All of these activities will be vital for refinement of resource characterization/identification and development of extraction/utilization technologies to be used on airless bodies under low- or micro-gravity conditions. In addition, gaining enhanced understanding of a NEA s geotechnical properties and its gross internal structure will assist the development of hazard mitigation techniques for planetary defense. Conclusions: The scientific, resource utilization, and hazard mitigation benefits, along with the programmatic and operational benefits of a human venture beyond the Earth-Moon system, make a piloted sample return mission to a NEA using NASA s proposed human exploration systems a compelling endeavor.

Abell, P. A.↗
NASA NTRS2017

Multi-Organization Multi-Discipline Effort Developing a Mitigation Concept for Planetary Defense

There have been significant recent efforts in addressing mitigation approaches to neutralize Potentially Hazardous Asteroids (PHA). One such research effort was performed in 2015 by an integrated, inter-disciplinary team of asteroid scientists, energy deposition modeling scientists, payload engineers, orbital dynamist engineers, spacecraft discipline engineers, and systems architecture engineer from NASAs Goddard Space Flight Center (GSFC) and the Department of Energy (DoE) National Nuclear Security Administration (NNSA) laboratories (Los Alamos National Laboratory (LANL), Lawrence Livermore National Laboratories (LLNL) and Sandia National Laboratories). The study team collaborated with GSFCs Integrated Design Centers Mission Design Lab (MDL) which engaged a team of GSFC flight hardware discipline engineers to work with GSFC, LANL, and LLNL NEA-related subject matter experts during a one-week intensive concept formulation study in an integrated concurrent engineering environment. This team has analyzed the first of several distinct study cases for a multi-year NASA research grant. This Case 1 study references the Near-Earth Asteroid (NEA) named Bennu as the notional target due to the availability of a very detailed Design Reference Asteroid (DRA) model for its orbit and physical characteristics (courtesy of the Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission team). The research involved the formulation and optimization of spacecraft trajectories to intercept Bennu, overall mission and architecture concepts, and high-fidelity modeling of both kinetic impact (spacecraft collision to change a NEAs momentum and orbit) and nuclear detonation effects on Bennu, for purposes of deflecting Bennu.

Planetary Defense↗
NASA NTRS2013

Human Expeditions to Near-Earth Asteroids: Implications for Exploration, Resource Utilization, Science, and Planetary Defense

Over the past several years, much attention has been focused on human exploration of near-Earth asteroids (NEAs) and planetary defence. Two independent NASA studies examined the feasibility of sending piloted missions to NEAs, and in 2009, the Augustine Commission identified NEAs as high profile destinations for human exploration missions beyond the Earth-Moon system as part of the Flexible Path. More recently the current U.S. presidential administration directed NASA to include NEAs as destinations for future human exploration with the goal of sending astronauts to a NEA in the mid to late 2020s. This directive became part of the official National Space Policy of the United States of America as of June 28, 2010. With respect to planetary defence, in 2005 the U.S. Congress directed NASA to implement a survey program to detect, track, and characterize NEAs equal or greater than 140 m in diameter in order to access the threat from such objects to the Earth. The current goal of this survey is to achieve 90% completion of objects equal or greater than 140 m in diameter by 2020.

Abell, Paul↗
DOE OSTI2025

Multiparameter Constraints on Empirical Infrasound Period-Yield Relations for Bolides and Implications for Planetary Defense

How effective are methods for estimating bolide energies from infrasound signal period-yield relationships? A single global period–energy relation can obscure significant variability introduced by parameters such as the atmospheric Doppler wind profile and the bolide’s energy deposition profile as a function of altitude. Bolide speed, entry angle, burst altitude, and multiepisode fragmentation may all play a role in defining the detected period of the shockwave. By leveraging bolide light-curve data from the Center for Near Earth Object Studies, we re-examined the period–energy relation as a function of these parameters. Through a bootstrap approach, we show that various event subsets can deviate from widely cited period–energy models and we identify which specific conditions most strongly reshape the period–energy scaling. The results define both the fidelity and reliability of period–energy relations when no additional data beyond the infrasound record is available and improve the outcome when supporting data from bolide trajectories and light curves are included. Ultimately, these findings expand the scope of earlier models, providing a nuanced and robust framework for infrasound-only yield estimation under a range of bolide scenarios.

Planetary science↗