Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
1,525
result(s) for
"Near-Earth Objects"
Sort by:
Chasing comets, asteroids, and mysterious space objects
\"Oumuamua is a space rock that formed around another star. Of the 10,000 space objects that have hurled past our Sun, this rock provides some proof that there are planets similar to Earth outside our solar system. This intriguing book reveals to young space explorers the secrets contained in the rocks that fly around in space\"-- Provided by publisher.
Book
Exclusive Seismoacoustic Detection and Characterization of an Unseen and Unheard Fireball Over the North Atlantic
Small meteoroids that enter Earth's atmosphere often go unnoticed because their detection and characterization rely on human observations, introducing observational biases in space and time. Acoustic shockwaves from meteoroid ablation convert to infrasound and seismic energy, enabling fireball detection using seismoacoustic methods. We analyzed an unreported fireball in 2022 near the Azores, recorded by 26 seismometers and two infrasound arrays. Through polarization analyses, array methods, and 3‐D ray‐tracing, we determined that the terminal blast occurred at 40 km altitude, ∼60 km NE of São Miguel Island. This location matches an unidentified flash captured by a lightning detector aboard the GOES‐16 satellite. The estimated kinetic energy is ∼10−3 kT TNT equivalent, suggesting a 10−1 m object diameter, thousands of which enter the atmosphere annually. Our results demonstrate how geophysical methods, in tandem with satellite data, can significantly improve the observational completeness of meteoroids, advancing our understanding of their sources and entry processes. Plain Language Summary Every year, hundreds to thousands of small near‐Earth objects, known as meteoroids, enter Earth's atmosphere. Their hypersonic entry speed and break‐up can generate flashes known as fireballs and associated shockwaves that can reach the ground. However, it is only the largest objects breaking up above populated areas that we typically see or hear, or that are captured by dedicated camera systems. Many of the smaller meteoroids go unnoticed. This observational bias limits our understanding of these objects and how they enter Earth's atmosphere. Here, we report on a fireball that broke up over the Northern Atlantic Ocean in June 2022 and was recorded on a network of seismometers that record sensitive ground motion and infrasound sensors that “hear” low‐frequency sound waves. Our analyses of these data show a small (40 cm diameter) meteoroid exploded at around 40 km altitude and 60 km northeast of São Miguel Island. Crucially, a flash recorded by a lightning mapper aboard a weather satellite provides us with the exact time of the explosion. To the best of our knowledge, this event is one of few documented cases of a fireball detected solely by geophysical means without relying on initial reports from human observers or photographic/video evidence. Key Points We use seismic and infrasound data to characterize a previously unreported fireball over the North Atlantic Ocean in June 2022 The fireball was detected by the Geostationary Lightning Mapper onboard the GOES‐16 satellite, giving a precise constraint on blast time Seismoacoustic data, in tandem with satellite observations, can help to improve our observational completeness of near‐Earth objects
Journal Article
Asteroids : how love, fear, and greed will determine our future in space
Human travel into space is an enormously expensive and unforgiving endeavor. So why go? In this accessible and authoritative book, astrophysicist Martin Elvis argues that the answer is the asteroid exploration, for motives of love, fear, and greed. Elvis's personal motivation is one of scientific love - asteroid investigations may teach us about the composition of the solar system and the origins of life. A more compelling reason may be fear - of a large asteroid hitting our planet. Finally, Elvis maintains, we should consider greed: asteroids likely hold vast riches, such as large platinum deposits, and mining them could provide both a new industry and a funding source for bolder space exploration. Elvis explains how each motive can be satisfied, and how they help one another. From the origins of life, to \"space billiards\" and space sports, Elvis looks at how asteroids may be used in the not-so-distant future.
Book
Asteroids
A unique, wide-ranging examination of asteroid exploration
and our future in space Human travel into space is an
enormously expensive and unforgiving endeavor. So why go? In this
accessible and authoritative book, astrophysicist Martin Elvis
argues that the answer is asteroid exploration, for the strong
motives of love, fear, and greed. Elvis's personal motivation is
one of scientific love-asteroid investigations may teach us about
the composition of the solar system and the origins of life. A more
compelling reason may be fear-of a dinosaur killer-sized asteroid
hitting our planet. Finally, Elvis maintains, we should consider
greed: asteroids likely hold vast riches, such as large platinum
deposits, and mining them could provide both a new industry and a
funding source for bolder space exploration. Elvis explains how
each motive can be satisfied, and how they help one another. From
the origins of life, to \"space billiards,\" and space sports, Elvis
looks at how asteroids may be used in the not-so-distant future.
eBook
On the predictability horizon in Impact Monitoring of Near Earth Objects
The Impact Monitoring (IM) of Near Earth Objects (NEOs) is a fundamental part of the planetary defense strategy. Current NEO IM systems (Aegis, NEODyS and Sentry) scan the Confidence Region (CR) of each observed object looking for Virtual Impactors (VIs) with a time horizon of about 100 years. This procedure is performed regardless of the uncertainty with which the orbit of the object is known, and without considering whether a scattering encounter is present in the propagation time span. In view of the likely future increase of the IM workload due to higher future NEO discovery rates, it might be more reasonable to adapt the predictability horizon of the impacts to each object, taking into account the orbit uncertainty and the close encounters experienced. In this paper we discuss the problem of estimating a reasonable predictability horizon when multiple close encounters are present and start to address the problem proposing a formal mathematical definition of scattering encounter.
Journal Article
Fire in the sky : cosmic collisions, killer astroids, and the race to defend Earth
A \"historical survey about asteroid hits sustained by Earth and the defenses being prepared against future asteroid-caused catastrophe\"-- Provided by publisher.
Book
Proper elements for resonant planet-crossing asteroids
Proper elements are quasi-integrals of motion of a dynamical system, meaning that they can be considered constant over a certain timespan, and they permit to describe the long-term evolution of the system with a few parameters. Near-Earth objects (NEOs) generally have a large eccentricity, and therefore they can cross the orbits of the planets. Moreover, some of them are known to be currently in a mean-motion resonance with a planet. Thus, the methods previously used for the computation of main-belt asteroid proper elements are not appropriate for such objects. In this paper, we introduce a technique for the computation of proper elements of planet-crossing asteroids that are in a mean-motion resonance with a planet. First, we numerically average the Hamiltonian over the fast angles while keeping all the resonant terms, and we describe how to continue a solution beyond orbit-crossing singularities. Proper elements are then extracted by a frequency analysis of the averaged orbit-crossing solutions. We give proper elements of some known resonant NEOs and provide comparisons with non-resonant models. These examples show that it is necessary to take into account the effect of the resonance for the computation of accurate proper elements.
Journal Article
Feed-Forward Neural Network Denoising Applied to Goldstone Solar System Radar Images
The study of Near-Earth Asteroids (NEA) is crucial for human safety. Small hazardous asteroids with small radar cross sections are not easy to detect, track, and characterize due to the small signal-to-noise ratio (SNR) of the radar echo. This manuscript describes the results obtained for the application of a feed-forward neural network (FFNN) denoising methodology to NEA data obtained from the Goldstone Solar System Radar (GSSR). We demonstrate an increase in the signal level of up to ×4 the original value—in terms of sigma above the mean noise—when applying the FFNN denoising technique to radar Z-score normalized Binary Phase Code (BPC) images. This improvement benefits better radar detection of NEAs in general. Reducing the noise background level for antennas that have lower aperture, e.g., 34 m dishes, enables the use of FFNN denoising to improve visual detections on those noisier conditions. In addition, reducing noise level benefits shorter integration times of the data to obtain adequate signal levels. When talking about detection of small bodies crossing the antenna beam, since the asteroids or debris can move across the beam quite fast, it is relevant to reduce the integration time to allow for an increased number of independent pieces of information crossing the target through the antenna beam. The increased distance between the signal level and the noise level enables a better detection of the small-bodies at shorter integration times and therefore would be very useful for the detection of objects in the cis-lunar space.
Journal Article
Legal Aspects of Planetary Defence
Impacts by asteroids or comets on Earth may lead to natural disasters of catastrophic dimensions. This book addresses legal and policy aspects of 'planetary defence' activities by space agencies and other actors aiming at the prediction and mitigation of Near-Earth Objects (NEOs).
eBook