Optimal trajectories from the Earth-Moon L1 and L3 points to deflect hazardous asteroids and comets.
International Academy of Astronautics, Torino, Italy.
Software code named asteroff was recently created by the author to simulate the deflection of hazardous asteroids off of their collision course with the Earth. This code was both copyrighted and patented to avoid unauthorized use of ideas that could possibly be vital to construct a planetary defense system in the vicinity of the Earth. Having so said, the basic ideas and equations underlying the asteroff simulation code are openly described in this paper. A system of two space bases housing missiles is proposed to achieve the planetary defense of the Earth against dangerous asteroids and comets, collectively called impactors herein. We show that the layout of the Earth-Moon system with the five relevant Lagrangian (or libration) points in space leads naturally to only one, unmistakable location of these two space bases within the sphere of influence of the Earth. These locations are at the two Lagrangian points L(1)(between the Earth and the Moon) and L(3)(in the direction opposite to the Moon from the Earth). We show that placing missile bases at L(1) and L(3) would enable those missiles to deflect the trajectory of impactors by hitting them orthogonally to their impact trajectory toward the Earth, so as to maximize their deflection. We show that confocal conics are the best class of trajectories fulfilling this orthogonal deflection requirement. One additional remark is that the theory developed in this paper is just a beginning for a wider set of future research. In fact, we only develop the Keplerian analytical theory for the optimal planetary defense achievable from the Earth-Moon Lagrangian points L(1) and L(3). Much more sophisticated analytical refinements would be needed to:(1) take into account many perturbation forces of all kinds acting on both the impactors and missiles shot from L(1) and L(3);(2) add more (non-optimal) trajectories of missiles shot from either the Lagrangian points L(4) and L(5) of the Earth-Moon System or from the surface of the Moon itself; and (3) encompass the full range of missiles currently available to the US (and possibly other countries) so as to really see which impactors could be diverted by which missiles, even in the very simplified scheme outlined here. Published for the first time in February 2002, our Keplerian planetary defense theory has proved, in just one year, to be simple enough to catch the attention of scholars, in addition to popular writers, and even of someone from the US Military. These recent developments might possibly mark the beginning of an all embracing vision in planetary defense beyond all learned congressional activities, dramatic movies, and unknown military plans covered by secrecy.
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International Academy of Astronautics (IAA) and Co-Chair, SETI Permanent Study Group of the IAA, Via Martorelli, 43, Turin, 10155, Italy. email@example.com
Darwinian evolution theory may be regarded as a part of SETI theory in that the factor f(l) in the Drake equation represents the fraction of planets suitable for life on which life actually arose. In this paper we firstly provide a statistical generalization of the Drake equation where the factor f(l) is shown to follow the lognormal probability distribution. This lognormal distribution is a consequence of the Central Limit Theorem (CLT) of Statistics, stating that the product of a number of independent random variables whose probability densities are unknown and independent of each other approached the lognormal distribution when the number of factors increased to infinity. In addition we show that the exponential growth of the number of species typical of Darwinian Evolution may be regarded as the geometric locus of the peaks of a one-parameter family of lognormal distributions (b-lognormals) constrained between the time axis and the exponential growth curve. Finally, since each b-lognormal distribution in the family may in turn be regarded as the product of a large number (actually "an infinity") of independent lognormal probability distributions, the mathematical way is paved to further cast Darwinian Evolution into a mathematical theory in agreement with both its typical exponential growth in the number of living species and the Statistical Drake Equation.
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Richard P Binzel, Alessandro Morbidelli, Sihane Merouane, Francesca E Demeo, Mirel Birlan, Pierre Vernazza, Cristina A Thomas, Andrew S Rivkin, Schelte J Bus, Alan T Tokunaga
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. firstname.lastname@example.org
Telescopic measurements of asteroids' colours rarely match laboratory reflectance spectra of meteorites owing to a 'space weathering' process that rapidly reddens asteroid surfaces in less than 10(6) years.'Unweathered' asteroids (those having spectra matching the most commonly falling ordinary chondrite meteorites), however, are seen among small bodies the orbits of which cross inside Mars and the Earth. Various explanations have been proposed for the origin of these fresh surface colours, ranging from collisions to planetary encounters. Less reddened asteroids seem to cross most deeply into the terrestrial planet region, strengthening the evidence for the planetary-encounter theory, but encounter details within 10(6) years remain to be shown. Here we report that asteroids displaying unweathered spectra (so-called 'Q-types') have experienced orbital intersections closer than the Earth-Moon distance within the past 5 x 10(5) years. These Q-type asteroids are not currently found among asteroids showing no evidence of recent close planetary encounters. Our results substantiate previous work: tidal stress, strong enough to disturb and expose unweathered surface grains, is the most likely dominant short-term asteroid resurfacing process. Although the seismology details are yet to be worked out, the identification of rapid physical processes that can produce both fresh and weathered asteroid surfaces resolves the decades-long puzzle of the difference in colour of asteroids and meteorites.
More than three dozen scientists journeyed to Washington, D.C., this week to warn lawmakers that a proposed $60 billion U.S. missile defense system, designed to knock incoming warheads out of the sky, is technically flawed because it can't pick out real warheads from decoys. Pentagon officials heatedly deny a new report by one scientist that contractors have rigged trials to hide the problem, although they admit that some tests were simplified to save time. In the wake of these events, a leading Democrat is urging President Bill Clinton to delay a pending decision on building the system.
Department of Chemistry, University of Illinois, Chicago 60680, USA. email@example.com
Hydrogen cyanide polymers--heterogeneous solids ranging in colour from yellow to orange to brown to black--could be major components of the dark matter observed on many bodies of the outer solar system including asteroids, moons, planets and, especially, comets. The presence on cometary nuclei of frozen volatiles such as methane, ammonia and water subjected to high energy sources makes them attractive sites for the ready formation and condensed-phase polymerization of hydrogen cyanide. This could account for the dark crust observed on Comet Halley in 1986 by the Vega and Giotto missions. Dust emanating from its nucleus would arise partly from HCN polymers as suggested by the Giotto detection of free hydrogen cyanide, CN radicals, solid particles consisting only of H, C and N, or only of H, C, N, O, and nitrogen-containing organic compounds. Further evidence for cometary HCN polymers could be expected from in situ analysis of the ejected material from Comet Tempel 1 after collision with the impactor probe from the two-stage Deep Impact mission on July 4, 2005. Even more revealing will be actual samples of dust collected from the coma of Comet Wild 2 by the Stardust mission, due to return to Earth in January 2006 for analyses which we have predicted will detect these polymers and related compounds. In situ results have already shown that nitriles and polymers of hydrogen cyanide are probable components of the cometary dust that struck the Cometary and Interstellar Dust Analyzer of the Stardust spacecraft as it approached Comet Wild 2 on January 2, 2004. Preliminary evidence (January 2005) obtained by the Huygens probe of the ongoing Cassini-Huygens mission to Saturn and its satellites indicates the presence of nitrogen-containing organic compounds in the refractory organic cores of the aerosols that give rise to the orange haze high in the atmosphere of Titan, Saturn's largest moon. Our continuing investigations suggest that HCN polymers are basically of two types: ladder structures with conjugated -C=N- bonds and polyamidines readily converted by water to polypeptides. Thermochemolysis GC-MS studies show that cleavage products of the polymer include alpha-amino acids, nitrogen heterocycles such as purines and pyrimidines, and provide evidence for peptide linkages. Hydrogen cyanide polymers are a plausible link between cosmochemistry and the origin of informational macromolecules. Implications for prebiotic chemistry are profound. Following persistent bolide bombardment, primitive Earth may have been covered by water and carbonaceous compounds, particularly HCN polymers which would have supplied essential components for establishing protein/nucleic acid life.
Istituto di Fisica dello Spazio Interplanetario, INAF ARTOV, Via del Fosso del Cavaliere, 100, 00133 Rome, Italy. firstname.lastname@example.org
The formation of the Earth as a planet was a large stochastic process in which the rapid assembly of asteroidal-to-Mars-sized bodies was followed by a more extended period of growth through collisions of these objects, facilitated by the gravitational perturbations associated with Jupiter. The Earth's inventory of water and organic molecules may have come from diverse sources, not more than 10% roughly from comets, the rest from asteroidal precursors to chondritic bodies and possibly objects near Earth's orbit for which no representative class of meteorites exists today in laboratory collections. The final assembly of the Earth included a catastrophic impact with a Mars-sized body, ejecting mantle and crustal material to form the Moon, and also devolatilizing part of the Earth. A magma ocean and steam atmosphere (possibly with silica vapour) existed briefly in this period, but terrestrial surface waters were below the critical point within 100 million years after Earth's formation, and liquid water existed continuously on the surface within a few hundred million years. Organic material delivered by comets and asteroids would have survived, in part, this violent early period, but frequent impacts of remaining debris probably prevented the continuous habitability of the Earth for one to several hundred million years. Planetary analogues to or records of this early time when life began include Io (heat flow), Titan (organic chemistry) and Venus (remnant early granites).
Philos Trans R Soc Lond B Biol Sci. 2006 Oct 29;361 (1474):1689-700; discussion 1700-2 17008210 Cit:10
NASA Ames Research Center, Mail Stop 245-6, Moffett Field, CA 94035-1000, USA.
One of the greatest puzzles of all time is how did life arise? It has been universally presumed that life arose in a soup rich in carbon compounds, but from where did these organic molecules come? In this article, I will review proposed terrestrial sources of prebiotic organic molecules, such as Miller-Urey synthesis (including how they would depend on the oxidation state of the atmosphere) and hydrothermal vents and also input from space. While the former is perhaps better known and more commonly taught in school, we now know that comet and asteroid dust deliver tons of organics to the Earth every day, therefore this flux of reduced carbon from space probably also played a role in making the Earth habitable. We will compare and contrast the types and abundances of organics from on and off the Earth given standard assumptions. Perhaps each process provided specific compounds (amino acids, sugars, amphiphiles) that were directly related to the origin or early evolution of life. In any case, whether planetary, nebular or interstellar, we will consider how one might attempt to distinguish between abiotic organic molecules from actual signs of life as part of a robotic search for life in the Solar System.
Throughout the history of the Solar System, Earth has been bombarded by interplanetary dust particles (IDPs), which are asteroid and comet fragments of diameter approximately 1-1,000 microm. The IDP flux is believed to be in quasi-steady state: particles created by episodic main belt collisions or cometary fragmentation replace those removed by comminution, dynamical ejection, and planetary or solar impact. Because IDPs are rich in 3He, seafloor sediment 3He concentrations provide a unique means of probing the major events that have affected the IDP flux and its source bodies over geological timescales. Here we report that collisional disruption of the >150-km-diameter asteroid that created the Veritas family 8.3 +/- 0.5 Myr ago also produced a transient increase in the flux of interplanetary dust-derived 3He. The increase began at 8.2 +/- 0.1 Myr ago, reached a maximum of approximately 4 times pre-event levels, and dissipated over approximately 1.5 Myr. The terrestrial IDP accretion rate was overwhelmingly dominated by Veritas family fragments during the late Miocene. No other event of this magnitude over the past approximately 10(8) yr has been deduced from main belt asteroid orbits. One remarkably similar event is present in the 3He record 35 Myr ago, but its origin by comet shower or asteroid collision remains uncertain.
Laboratoire de Sciences de la Terre, CNRS UMR 5570, Ecole Normale Supérieure de Lyon et Université Lyon I, 46 allée d'Italie, 69364 Lyon Cedex 7, France. email@example.com
The accretion of the terrestrial planets from asteroid collisions and the delivery to the Earth of martian and lunar meteorites has been modelled extensively. Meteorites that have experienced shock waves from such collisions can potentially be used to reveal the accretion process at different stages of evolution within the Solar System. Here we have determined the peak pressure experienced and the duration of impact in a chondrite and a martian meteorite, and have combined the data with impact scaling laws to infer the sizes of the impactors and the associated craters on the meteorite parent bodies. The duration of shock events is inferred from trace element distributions between coexisting high-pressure minerals in the shear melt veins of the meteorites. The shock duration and the associated sizes of the impactor are found to be much greater in the chondrite (approximately 1 s and 5 km, respectively) than in the martian meteorite (approximately 10 ms and 100 m). The latter result compares well with numerical modelling studies of cratering on Mars, and we suggest that martian meteorites with similar, recent ejection ages (10(5) to 10(7) years ago) may have originated from the same few square kilometres on Mars.
NASA Langley Research Center, Hampton, VA 23681-2199, USA. firstname.lastname@example.org
Mission scenarios outside the Earth's protective magnetic shield are being studied. Included are high usage assets in the near-Earth environment for casual trips, for research, and for commercial/operational platforms, in which career exposures will be multi-mission determined over the astronaut's lifetime. The operational platforms will serve as launching points for deep space exploration missions, characterized by a single long-duration mission during the astronaut's career. The exploration beyond these operational platforms will include missions to planets, asteroids, and planetary satellites. The interplanetary environment is evaluated using convective diffusion theory. Local environments for each celestial body are modeled by using results from the most recent targeted spacecraft, and integrated into the design environments. Design scenarios are then evaluated for these missions. The underlying assumptions in arriving at the model environments and their impact on mission exposures within various shield materials will be discussed.
Background and applications of astrodynamics for space missions of the johns hopkins applied physics laboratory.
Applied Physics Laboratory, Johns Hopkins University, Baltimore, MA, USA. email@example.com
This paper describes astrodynamic techniques applied to develop special orbital designs for past and future space missions of the Applied Physics Laboratory (APL) of Johns Hopkins University, and background about those techniques. The paper does not describe the long history of low Earth-orbiting missions at APL, but rather concentrates on the astrodynamically more interesting high-altitude and interplanetary missions that APL has undertaken in recent years. The authors developed many of their techniques in preparation for, and during, the Third International Sun-Earth Explorer (ISEE-3) halo orbit mission while they worked for the Goddard Space Flight Center (GSFC) of NASA during the 1970s and 1980s. Later missions owed much to the ground breaking work of the trajectory designs for ISEE-3 (later known as the International Cometary Explorer, or ICE). This experience, and other new ideas, were applied to the APL near Earth asteroid rendezvous (NEAR) and comet nucleus tour (CONTOUR) discovery missions, as well as to APL's future MESSENGER, STEREO, and New Horizons missions. These will be described in the paper.
Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA. firstname.lastname@example.org
Asteroid collisions in the main belt eject fragments that may eventually land on Earth as meteorites. It has therefore been a long-standing puzzle in planetary science that laboratory spectra of the most populous class of meteorite (ordinary chondrites, OC) do not match the remotely observed surface spectra of their presumed (S-complex) asteroidal parent bodies. One of the proposed solutions to this perplexing observation is that 'space weathering' modifies the exposed planetary surfaces over time through a variety of processes (such as solar and cosmic ray bombardment, micro-meteorite bombardment, and so on). Space weathering has been observed on lunar samples, in Earth-based laboratory experiments, and there is good evidence from spacecraft data that the process is active on asteroid surfaces. Here, we present a measurement of the rate of space weathering on S-complex main-belt asteroids using a relationship between the ages of asteroid families and their colours. Extrapolating this age-colour relationship to very young ages yields a good match to the colour of freshly cut OC meteorite samples, lending strong support to a genetic relationship between them and the S-complex asteroids.