Conventional rockets are not a suitable technology for interstellar missions. Chemical rockets require a very large weight of propellant, travel very slowly compared to light speed, and require significant energy to maintain operation over periods of years. For example, the 722 kg Voyager spacecraft required 13,600 kg of propellant to launch and would take about 80,000 years to reach the nearest star, Proxima Centauri, about 4.3 light years away. There have been various attempts at developing ideas on which one (...) might base a spacecraft that would permit interstellar travel, such as spacewarps. In this paper we consider another suggestion from science fiction and explore how the quantum vacuum might be utilized in the creation of a novel spacecraft. The spacecraft is based on the dynamic Casimir effect, in which electromagnetic radiation is emitted when an uncharged mirror is properly accelerated in vacuum. The radiative reaction produces a dissipative force on the mirror that tends to resist the acceleration of the mirror. This force can be used to accelerate a spacecraft attached to the mirror. We also show that, in principle, one could obtain the power to operate the accelerated mirror in such a spacecraft using energy extracted from the quantum vacuum using the standard Casimir effect with a parallel plate geometry. Unfortunately the method as currently conceived generates a miniscule thrust, and is no more practical than a spacewarp, yet it does provide an interesting demonstration of our current understanding of the physics of the quantized electromagnetic field in vacuum. (shrink)

Fundamentals of Spacecraft Charging is the definitive reference on the physics of spacecraft charging and is suitable for advanced undergraduates, graduate-level students, and professional space researchers.

All civilian, government-sponsored spacecraft, despite ostensibly having the primary purpose of scientific data-collection, are, within the advanced cultures that produce them, primarily symbolic objects, created by the people as a means of indicating, both to themselves and to all the world, what is in their hearts: what they value. These craft are a statement that we value learning, exploration, adventure, difficult endeavors, teamwork, precision, self-discipline, and intelligence. All such spacecraft are, fundamentally, semiotic objects. The fact that they collect (...) data, although proffered as their primary function, is in fact secondary. In this paper I propose a thought-experiment, involving consideration of a spacecraft expressly intended for a symbolic, semiotic, psychological purpose: a kind of interstellar library, a Noah's Ark of Documents, the "Milky Way Messenger." By taking an idea that was originally merely a concept to be featured in a science-fiction story and exploring whether it might be feasible to accomplish it in the real world, the paper is intended to trigger thought and discussion concerning the conscious creation of such objects. The paper concludes with suggestions concerning the semiotic psychological function of certain government programs. (shrink)

Around 3 decades ago, Jayant Narlikar & Halton Arp argued on possible variable mass hypothesis cosmology (VMH). In the meantime, the Earth expansion problem has attracted great interest, and recent study gives geodetic evidence that the Earth has been expanding, at least over the recent several decades. Therefore, in the present article discusses some interesting effects related to varying G, but here we argue that instead of varying G we can think of varying mass (M). Among other things we discuss (...) receding planets from the Sun, calculation of Pioneer spacecraft anomaly as proposed by B.G. Sidharth, and also possible slight change of LAGEOS Satellite. Further observation to verify or refute this conjecture is recommended, especially based on geological evidence of expanding earth. (shrink)

This study addresses the challenge of attitude tracking control for a rigid-flexible spacecraft with high-inertia rotating appendages. The Lagrange method was used to establish the kinematic and dynamic models of the spacecraft. The translation and rotation of the spacecraft, vibrations of solar panels, and imbalance caused by the rotating appendages, which cause a complex control problem, were considered. To address the complex control problem, a novel, fast nonsingular integral sliding mode control method is proposed to perform the (...) attitude tracking function of spacecraft. A sliding mode control law was established for the high-inertia appendages to maintain an appropriate angular velocity during rotation. Finally, the effectiveness of the proposed attitude control law was verified by numerical simulations for a spacecraft with high-inertia rotating appendages and symmetrical flexible solar panels. (shrink)

Aiming at the oscillation suppression of spacecraft with large flexible appendages, we propose a control strategy using H∞ control. The weighting functions are designed for the specific flexible modes of the spacecraft and the frequency of harmonic interference in its operating environment. Taking into account the structural uncertainty of systematic modeling and the comprehensive performance requirements of system bandwidth constraint and attitude stability, the H∞ comprehensive performance matrix is constructed. A space telescope with a large flexible solar array (...) is presented as an illustrative example, and a control design that meets the requirement for pointing accuracy is proposed. The simulation results show that the designed controller satisfies the requirements of attitude stability and high pointing accuracy and has effectively suppressed the disturbance of endemic frequency. The design scheme and selection method of the weight function shown in this paper can be a reference for the controller design for oscillation suppression of this type of spacecraft with flexible structures. (shrink)

This paper investigates the fixed-time coordinated control problem of six-degree-of-freedom dynamic model for multiple spacecraft formation flying with input quantization, where the communication topology is assumed directed. Firstly, a new multispacecraft nonsingular fixed-time terminal sliding mode vector is derived by using neighborhood state information. Secondly, a hysteretic quantizer is utilized to quantify control force and torque. Utilizing such a quantizer not only can reduce the required communication rate but also can eliminate the control chattering phenomenon induced by the logarithmic (...) quantizer. Thirdly, a 6-DOF fixed-time coordinated control strategy with adaptive tuning laws is proposed, such that the practical fixed-time stability of the controlled system is ensured in the presence of both upper bounds of unknown external disturbances. It theoretically proves that the relative tracking errors of attitude and position can converge into the regions in a fixed time. Finally, a numerical example is exploited to show the usefulness of the theoretical results. (shrink)

This paper addresses the simultaneous attitude and position tracking of a target spacecraft in the presence of general unknown bounded disturbances in the framework of dual quaternions, which provides a concise and integrated description of the coupled rotational and translational motions. By virtue of the newly introduced dual direction cosine matrix, the dimension of the dual quaternion-based relative motion dynamics written in vector/matrix form can be lowered to six. Treating the disturbances as unknown parameters, a modular adaptive pose tracking (...) control scheme composed of two separately designed parts is then derived. One part is the adaptive disturbance estimator designed based on the immersion and invariance theory. Driven by the disturbance estimation errors, it can realize exponential convergence of the estimations and has the nice “parameter lock” property, which can hardly be expected in the conventional certainty equivalent adaptive controllers. The other part is a proportional-derivative-like pose tracking controller where the estimated disturbances are directly used. The closed-loop stability of the relative motion system under different kinds of disturbances is proven by Lyapunov stability analysis. Simulations and comparisons with two previous dual quaternion-based controllers demonstrate the novel features and performance improvements of the proposed control scheme. (shrink)

This study analyses the predictions of the General Theory of Relativity (GTR) against a slightly modified version of the standard central mass solution (Schwarzschild solution). It is applied to central gravity in the solar system, the Pioneer spacecraft anomalies (which GTR fails to predict correctly), and planetary orbit distances and times, etc (where GTR is thought consistent.) -/- The modified gravity equation was motivated by a theory originally called ‘TFP’ (Time Flow Physics, 2004). This is now replaced by the (...) ‘Geometric Model’, 2014 [20], which retains the same theory of gravity. This analysis is offered partially as supporting detail for the claim in [20] that the theory is realistic in the solar system and explains the Pioneer anomalies. The overall conclusion is that the model can claim to explain the Pioneer anomalies, contingent on the analysis being independently verified and duplicated of course. -/- However the interest lies beyond testing this theory. To start with, it gives us a realistic scale on which gravity might vary from the accepted theory, remain consistent with most solar-scale astronomical observations. It is found here that the modified gravity equation would appear consistent with GTR for most phenomena, but it would retard the Pioneer spacecraft by about the observed amount (15 seconds or so at time). Hence it is a possible explanation of this anomaly, which as far as I know remains unexplained now for 20 years. -/- It also shows what many philosophers of science have emphasized: the pivotal role of counterfactual reasoning. By putting forward an exact alternative solution, and working through the full explanation, we discover a surprising ‘counterfactual paradox’: the modified theory slightly weakens GTR gravity – and yet the effect is to slow down the Pioneer trajectory, making it appear as if gravity is stronger than GTR. The inference that “there must be some tiny extra force…” (Musser, 1998 [1]) is wrong: there is a second option: “…or there may be a slightly weaker form of gravity than GTR.” . (shrink)

The theme of human extinction is increasingly at the center of the current debate on moral philosophy and bioethics. We look at space missions and station construction projects capable of accommodating a large population and at the colonization of other planets with great hope. However, solutions are not excluded either, which for now certainly appear to be much more original. One of the most original projects involves launching a spacecraft containing cryopreserved human embryos, which, once they arrive at destination (...) on another planet, must be thawed and birthed by intelligent machines through artificial wombs (ectogenesis). In this paper, I do not intend to analyze whether the embryo space colonization project is indeed feasible. Instead, I will focus on examining the primary moral questions raised by the embryo space colonization project to determine whether, at least prima facie, it can be deemed morally acceptable. I will begin by discussing the objection advanced by Konrad Szocik (2021), according to which any embryo space colonization project is doomed to failure because it cannot offer the hoped-for solution to the problem of the extinction of the human species (second paragraph). In the third paragraph, then, I will ask whether embryo space colonization is able to ensure the people it brings into the world an adequate or at least the morally appropriate quality of life. Finally, in the fourth and last paragraph, I will examine the question of the morality of human reproduction that passes through the guidance and choice of intelligent machines. I will argue that to evaluate the morality of this project we should consider not only the interests and quality of life of the first people who could be born but also the interests of all possible subsequent generations. (shrink)

I explore how the nature, scope, and limits of the knowledge obtained in orbital dynamics has changed in recent years. Innovations in the design of spacecraft trajectories, as well as in astronomy, have led to new logics of theory-testing—that is, new research methodologies—in orbital dynamics. These methodologies—which combine resonance overlap theories, numerical experiments, and the implementation of space missions—were developed in response to the discovery of chaotic dynamical systems in our solar system. In the past few decades, they have (...) replaced the methodology that dominated orbital research in the centuries following Newton's Principia. As a result, the kind of knowledge achieved by orbital research has changed: we can know how orbiting bodies in chaotic systems behave, but only over sufficiently short time scales; and we can reliably measure those temporal limitations, using Lyapunov time. (shrink)

Achieving space domain awareness requires the identification, characterization, and tracking of space objects. Storing and leveraging associated space object data for purposes such as hostile threat assessment, object identification, and collision prediction and avoidance present further challenges. Space objects are characterized according to a variety of parameters including their identifiers, design specifications, components, subsystems, capabilities, vulnerabilities, origins, missions, orbital elements, patterns of life, processes, operational statuses, and associated persons, organizations, or nations. The Space Object Ontology provides a consensus-based realist framework (...) for formulating such characterizations in a computable fashion. Space object data are aligned with classes and relations in the Space Object Ontology and stored in a dynamically updated Resource Description Framework triple store, which can be queried to support space domain awareness and the needs of spacecraft operators. This paper presents the core of the Space Object Ontology, discusses its advantages over other approaches to space object classification, and demonstrates its ability to combine diverse sets of data from multiple sources within an expandable framework. Finally, we show how the ontology provides benefits for enhancing and maintaining longterm space domain awareness. (shrink)

Achieving space situational awareness requires, at a minimum, the identification, characterization, and tracking of space objects. Leveraging the resultant space object data for purposes such as hostile threat assessment, object identification, and conjunction assessment presents major challenges. This is in part because in characterizing space objects we reference a variety of identifiers, components, subsystems, capabilities, vulnerabilities, origins, missions, orbital elements, patterns of life, operational processes, operational statuses, and so forth, which tend to be defined in highly heterogeneous and sometimes inconsistent (...) ways. The Space Domain Ontologies are designed to provide a consensus-based realist framework for formulating such characterizations in a way that is both consistent and computable. Space object data are aligned with classes and relations in a suite of ontologies built around the existing Space Object Ontology. They are stored in a dynamically updated Resource Description Framework triple store, which can be queried to support space situational awareness and the needs of spacecraft operators and analysts. This paper provides an overview of the Space Domain Ontologies and their development and use. It presents the motivation for and advantages of the Space Domain Ontologies, including the benefits they provide for enhancing and maintaining long-term space situational awareness. (shrink)

The week, twenty-five years ago, of the Apollo spacecraft's return visit to the moon was described by Richard Nixon as the greatest since the Creation. Across the Atlantic, a French Academician judged the same event to matter less than the discovery of a lost etching by Daumier. Attitudes to technological achievement, then, differ. And they always have. Chuang-Tzu, over 2,000 years ago, relates an exchange between a Confucian passer-by and a Taoist gardener watering vegetables with a bucket drawn from (...) a well. ‘Don't you know that there is a machine with which 100 beds are easily watered in a day?’—‘How does it work?’—‘It's a counterbalanced ladle’—‘too clever to be good … all machines have to do with formulae, artificiality [which] destroy native ingenuity … and prevent the Tao from residing peacefully in one's heart’. ‘Engines of mischief, in the words of the Luddite song, or testaments to ‘the nobility of man [as] the conqueror of matter’, in those of Primo Levi, the products of technology continue to inspire phobia and philia. (shrink)

He also tells a very interesting personal story of his battles to get these trajectories used, and how he was able to save the Hiten spacecraft and get it to the moon. This is a great story, and he tells it very well.

Our natural world has been irretrievably altered by humans, for humans. From domesticated wheat fields to nuclear power plants and spacecraft, everything we see and interact with has in some way been changed by the presence of our species, starting from the Neolithic era so many centuries ago. This book provides a crash course on the issues and debates surrounding technology’s shifting place in our society. It covers the history of our increasingly black-box world, which some theorize will end (...) with technology accelerating beyond our understanding. At the same time, it analyzes competing trends and theories, the lack of scientific knowledge of large sections of the population, the dogmas of pseudoscience, and the growing suspicion of science and technology, which may inevitably lead to scientific stagnation. What will the future of our civilization look like? How soon might scientific acceleration or stagnation arrive at our doorstep, and just how radically will such technological shifts change our culture? These are issues that we must address now, to insure our future goes the way we choose. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:BOOK REVIEWS The Inference That Makes Science. By ERNAN McMULLIN. The Aquinas Lecture, 1992. Milwaukee: Marquette University Press, 1992. Pp. iv +112. In this ambitious lecture Father Ernan McMullin recapitulates and refines a thesis that has guided his thought for the past forty years. In essence the thesis is this: precisely how science is made has eluded the best minds for centuries, and only in the work of Charles (...) Sanders Peirce, suitably emended by McMullin, has the puzzle finally been solved. " Retroduction " is the inference that makes science. Once this is understood, errors on what constitutes scientific method-those of Aristotle, Aquinas, Galileo, Newton, Bacon, Hume, et al.-can be rectified and one can see science for what it truly is: a complex process of theory appraisal that yields, not definitive truth, but well-established results to which assent can be given with at best "practical certainty," whatever that might be (pp. 91-96). Why McMullin should have chosen such a theme for an Aquinas Lecture is a question that defies reasonable answer. Surely one does not have to he so negative about the thought of Aristotle, Aquinas, and Galileo to advance one's ideas about science in the present day. What McMullin could easily have done, and he hints at this in the last two paragraphs of his lecture (pp. 97-98), is show how retroduction is itself simply a relaxed version of the demonstrative regress, the method actually endorsed by Aristotle, Aquinas, and Galileo. Such a retroductive version, fair enough, yields knowledge of a probable cause, the type of knowledge most typical of modern science. McMullin did not have to embark on the dangerous course of trying to prove that proof and certainty are forever beyond the grasp of science, or that never in the history of science has anyone established a definitive truth. That, in effect, is what McMullin has tried to do, and in the attempt to make the point he fumbles at almost every juncture throughout a very long lecture. To set the record straight more than a review is being re--·quested; perhaps a book, and even that might not suffice for those whose minds are made up. To understand the import of the lecture one must appreciate that it is hut a brief episode in a debate over demonstration in science that has been going on since McMullin first came to the University of Notre Dame in 1954. I myself have published many hooks and articles that engage the very point of his lecture and provide the contra evidence to 131 132 BOOK REVIEWS show elements of continuity in scientific method from Aristotle to the present. My last two volumes, in press at the same time as McMullin's Aquinas Lecture, answer in detail the aporiai he there raises.1 I need 1 Galileo's Logic of Discovery and Proof. The Backgrnund, Content, and Use of His Appropriated Treatises on Aristotle's Posterior Analytics. Boston Studies in the Philosophy of Science 137. Dordrecht-Boston-London: Kluwer Academic Publishers, 1992, xxiii + 323 pp.; Galileo's Logical Treatises. A Translation, with Notes and Commentary, of His Appropriated Questions on Aristotle's Posterior Analytics. Boston Studies in the Philosophy of Science 138. DordrechtBoston -London: Kluwer Academic Publishers, 1992, xix + 239 pp. only refer the interested reader to them for an extended and documented reply to his arguments. Some idea of the flavor of our debate, however, can be gained from the following. To support his thesis, McMullin has to maintain that Aristotle's proof that the moon is a sphere (from its having phases) and that Galileo's proofs that there are mountains on the moon, that Jupiter has satellites, and that Venus circles the sun (all based on telescopic observations) are not strictly demonstrative, that is, they do not yield true and certain conclusions. He declines to answer a query I have often tendered whether he personally is certain on the basis of pre-spacecraft evidence that the moon is a sphere, that there are mountains on it, that Jupiter has satellites, and so on. Instead he offers the categorical response "that planetary science is not an apodictic science, indeed that no natural science is... (shrink)

The week, twenty-five years ago, of the Apollo spacecraft's return visit to the moon was described by Richard Nixon as the greatest since the Creation. Across the Atlantic, a French Academician judged the same event to matter less than the discovery of a lost etching by Daumier. Attitudes to technological achievement, then, differ. And they always have. Chuang-Tzu, over 2,000 years ago, relates an exchange between a Confucian passer-by and a Taoist gardener watering vegetables with a bucket drawn from (...) a well. ‘Don't you know that there is a machine with which 100 beds are easily watered in a day?’—‘How does it work?’—‘It's a counterbalanced ladle’—‘too clever to be good … all machines have to do with formulae, artificiality [which] destroy native ingenuity … and prevent the Tao from residing peacefully in one's heart’. ‘Engines of mischief, in the words of the Luddite song, or testaments to ‘the nobility of man [as] the conqueror of matter’, in those of Primo Levi, the products of technology continue to inspire phobia and philia. (shrink)

The Schwarzschild solution (Schwarzschild, 1915/16) to Einstein’s General Theory of Relativity (GTR) is accepted in theoretical physics as the unique solution to GTR for a central-mass system. In this paper I propose an alternative solution to GTR, and argue it is both logically consistent and empirically realistic as a theory of gravity. This solution is here called K-gravity. The introduction explains the basic concept. The central sections go through the technical detail, defining the basic solution for the geometric tensor, the (...) Christoffel symbols, Ricci tensor, Ricci scalar, Einstein tensor, stress-energy tensor and density-pressure for the system. The density is integrated, and some consistency properties are demonstrated. A notable feature is the disappearance of the event horizon singularity, i.e. there are no black holes. So far this is for a single central mass. A generalization of the solution for multiple masses is then proposed. This is required to support K-gravity as a viable general interpretation of gravity. Then the question of empirical tests is discussed. It is argued that current observational data is almost but not quite sufficient to verify or falsify K-gravity. The Pioneer spacecraft trajectory data is of particular interest, as this is capable of providing a test; but the data (which originally showed anomalies that match K-gravity) is now uncertain. A new and very practical experiment is proposed to settle the matter. This would provide a novel test of GTR, and a novel test of the cause of the Pioneer anomalies. In conclusion, K-gravity has extensive ramifications for gravitational physics and for the philosophy of GTR and space-time. (shrink)

We will survey a range of ontologies relevant to space and ground system domains. The ontologies form part of the Common Core Ontology ecosystem (CCO) developed under the IARPA KDD initiative. We focus specifically on the Space Domain Ontologies, a suite of ontologies to support space situational awareness, including the Spacecraft Mission Ontology, Spacecraft Ontology, Space Event Ontology and Space Object Ontology.

The overall goal of the approach developed in this paper is to estimate the likelihood of a given kinetic kill scenario between hostile spacebased adversaries using the mathematical framework of Complex Conceptual Spaces Single Observation. Conceptual spaces are a cognitive model that provide a method for systematically and automatically mimicking human decision making. For accurate decisions to be made, the fusion of both hard and soft data into a single decision framework is required. This presents several challenges to this data (...) fusion framework. The first is the challenge involved in handling multiple complex terminologies, which is addressed by drawing on a set of Space Domain Ontologies. Another challenge is the complex combinatorics involved when considering all possible feature combinations. This can be mitigated by using integer linear programming optimization that is outlined by the Complex Conceptual Spaces Single Observation mathematical model framework. A third challenge is the complicated physics that is involved in a spacecraft collision that must be addressed to obtain a better understanding of threat assessment. Overcoming these various challenges allows for a quantitative ranking for the potential of a kinetic kill collision across multiple spacecraft pairs. In addition to overcoming these challenges this paper will break down threat assessment into four domains and identify a ranking of threat both for each individual domain and for the four domains combined. Simulation results are shown to verify the developed concepts. (shrink)

This is an examination of an avian-shaped feature that rests below a network of cellular structures found on a mound within the Argyre Basin of Mars. The area examined is located near 48.0° south and 55.1° west. A set of four supportive images provided by the Mars Global Surveyor and Mars Reconnaissance Orbiter spacecraft show the feature is persistent over a period of more than 20 years. The images reveal defining aspects of this avian feature, including a head, beak, (...) body, eye, legs, feet, toes, wing, and feathers. When taken together, these components induce the visual impression of an avian-shaped formation that exhibits a unique set of proportional features. The claim of artificial construction is offered and the geoscientist author will examine natural mechanisms that could contribute to the creation of this feature and the testimony of three veterinarians will provide a critical analysis of the avian features. A terrestrial comparison of aesthetic and iconographic motifs is investigated. The request for further study and additional images of these structural components are also encouraged. (shrink)

The philosophical tradition of phenomenology, with its focus on human bodily perception, can be used to explore the ways scientific instrumentation shapes a user’s experience. Building on Don Ihde’s account of technological embodiment, I develop a framework of concepts for articulating the experience of image interpretation in science. These concepts can be of practical value to the analysis of scientific debates over image interpretation for the ways they draw out the relationships between the image-making processes and the rival scientific explanations (...) of image content. As a guiding example, I explore a contemporary debate over images of the surface of Mars which reveal a landmass that resembles river delta formations on Earth, and which thus has important implications for the history of Martian climate and water flow. The phenomenological framework I develop can be used to help evaluate the different interpretations on offer for these images, and to analyze the roles in this discussion played by spacecraft equipped with cameras and laser and thermal imaging devices. (shrink)

The article presents the results of a study of the interaction between the public and private sectors in the field of outer space exploration. The purpose of the study was to identify the peculiarities of interaction between public authorities and private companies involved in space activities. It has been established that all leading space powers create favorable conditions for attracting private companies to space exploration. The main areas of space activity that are most attractive for private investment are identified: 1) (...) production, launch and operation of spacecraft and launch vehicles; 2)production and operation of ground equipment; 3) space research; 4) satellite observation of the Earth; 5) TV and radio broadcasting and lease of repeaters; 6) satellite internet; 7) mining in space; 8) space tourism; 9) space waste management; 10) cargo delivery to Earth orbit, etc. The current state of the space industry in Ukraine is determined. The main obstacles to space commercialization in Ukraine are also highlighted: 1) legal regulation lags far behind and does not meet the needs of space activities in Ukraine; 2) international agreements are not in line with the level of national regulation of advanced countries and new global trends; 3) Ukraine’s space industry is focused mainly on less profitable areas of the space economy, which reduces the attractiveness for private investors; 4) there is no clear distinction between national interests and commercial activities in space; 5) mechanisms for coordinating private, state and public interests in the context of space commercialization are either absent or extremely ineffective; 6) there are no effective mechanisms for attracting foreign capital to space exploration. The authors identify two main competitive models of the interplay between the public and private sectors in space exploration: “American” and “European.” It is emphasized that both models can serve as a model for the space policy implementation in Ukraine. However, given a number of considerations, it is determined that the “European” model is more optimal. (shrink)

The paper investigates the evolution of the first manned international space mission – a rendezvous and docking between a US and a Soviet spacecraft in 1975 known as the Apollo-Soyuz Test Project. The aim is to reconsider the rationales behind the ASTP from both a conceptual and an empirical perspective in order to get a better understanding of the evolution of international cooperation in the highly competitive and strategic field of space technology. Based on archival sources from Moscow, it (...) sheds some light on those factors that led to a change in the previous reluctance of Soviets to cooperate with the US in the manned spaceflight. From the theoretical point of view, it argues that the ASTP was as much a tool of competition as one of cooperation and resulted from an interplay between cooperative and competitive logics. To explain the turn towards cooperative practices, the article looks at the complex constellation of competitive relations that existed within the national and international context of space exploration and changed in the late 1960s and early 1970s. The decisive role in those changes was played by factors that can be subsumed under the notion of the so-called “third.”. (shrink)

Lithopanspermia is a theory proposing a natural exchange of organisms between solar system bodies as a result of asteroidal or cometary impactors. Research has examined not only the physics of the stages themselves but also the survival probabilities for life in each stage. However, although life is the primary factor of interest in lithopanspermia, this life is mainly treated as a passive cargo. Life, however, does not merely passively receive an onslaught of stress from surroundings; instead, it reacts. Thus, planetary (...) ejection, interplanetary transport, and planetary entry are only the first three factors in the equation. The other factors are the quality, quantity, and evolutionary strategy of the transported organisms. Thus, a reduction in organism quantity in stage 1 might increase organism quality towards a second stress challenge in stage 3. Thus, robustness towards a stressor might in fact be higher in the bacterial population surviving after transport in stage 3 than at the beginning in stage 1. Therefore, the stages of lithopanspermia can themselves facilitate evolutionary processes that enhance the ability of the collected organisms to survive stresses such as pressure and heat shock. Thus, the multiple abiotic pressures that the population encounters through the three stages can potentially lead to very robust bacteria with survival capacities considerably higher than might otherwise be expected. This analysis details an outcome that is possible but probably rare. However, in addition to lithopanspermia, spacecraft mediated panspermia may also exist. The analogous stages in a spacecraft would result in a greater likelihood of increasing the stress tolerance of hitchhiking organisms. Furthermore, missions seeking life elsewhere will frequently be sent to places where the possibility of life as we know it is assumed to exist. Thus, we not only can transport terrestrial organisms to places where they are potentially more likely to survive but also may increase their invasive potential along the way. This analysis highlights further requirements that planetary protection protocols must implement and also provides a framework for analyses of ecological scenarios regarding the transmission of life, natural or artificial, between worlds in a solar system. (shrink)

New Cosmic Horizons was written by a project manager, originally trained as a physicist, who worked in the European space world and in business for about twenty‐five years and then returned to academia to complete his Ph.D. It is a well‐written, comprehensive compilation of major scientific results in space astronomy obtained during the latter half of the twentieth century. As the book jacket explains, “it explores the triumphs of space experiments and spacecraft designs and the amazing astronomical results that (...) they have produced.” It is particularly useful because it does not just concentrate on American contributions in this area, as important as they have been, but tries to redress the transatlantic balance by including scientific work in the Soviet Union and Europe, notably the European Space Agency. The blurb claims that David Leverington relates the changes in space astronomy programs in these various countries to their “changing political imperatives.” This is done very sketchily, however, and merely by way of a backdrop to his main objective.Practicing astronomers, be they amateur or professional, and historians of science who could use a survey of the major milestones in space astronomy will find this a useful guide. It is seriously marred as a reference work, however, by the total absence of any reference to primary or secondary material in the text. There is a bibliography of what Leverington calls “general sources used in the preparation of this book” , which includes standard histories of space and of space science. None of these books, nor any scientific papers, are cited in the body of the argument. Everything that is said, or claimed, has to be taken on the authority of the author, an extraordinary approach that can only undermine and discredit what was otherwise a laudable objective. (shrink)