The Magnetic Field of the Earth’s Lithosphere

The lithospheric contribution to the Earth’s magnetic field is concealed in magnetic field data that have now been measured over several decades from ground to satellite altitudes. The lithospheric field results from the superposition of induced and remanent magnetisations. It therefore brings an essential constraint on the magnetic properties of rocks of the Earth’s sub-surface that would otherwise be difficult to characterize. Measuring, extracting, interpreting and even defining the magnetic field of the Earth’s lithosphere is however challenging. In this paper, we review the difficulties encountered. We briefly summarize the various contributions to the Earth’s magnetic field that hamper the correct identification of the lithospheric component. Such difficulties could be partially alleviated with the joint analysis of multi-level magnetic field observations, even though one cannot avoid making compromises in building models and maps of the magnetic field of the Earth’s lithosphere at various altitudes. Keeping in mind these compromises is crucial when lithospheric field models are interpreted and correlated with other geophysical information. We illustrate this discussion with recent advances and results that were exploited to infer statistical properties of the Earth’s lithosphere. The lessons learned in measuring and processing Earth’s magnetic field data may prove fruitful in planetary exploration, where magnetism is one of the few remotely accessible internal properties.     

The lunar dust pendulum

An analytic model for the motion of a positively charged lunar dust grain in the presence of a shadowed crater at a negative potential in vacuum is presented. It is shown that the dust grain executes oscillatory trajectories, and an expression is derived for the period of oscillation. Simulations used to verify the analytic expression also show that because the trajectories are unstable, dust grains are either ejected from the crater’s vicinity or deposited into the crater forming “dust ponds.” The model also applies to other airless bodies in the solar system, such as asteroids, and predicts that under certain conditions, particularly near lunar sunset, oscillating dust “canopies” or “swarms” will form over negatively charged craters.     

Preliminary application of a novel algorithm to monitor changes in pre-flight total peripheral resistance for prediction of post-flight orthostatic intolerance in astronauts

Orthostatic intolerance (OI) is a significant challenge for astronauts after long-duration spaceflight. Depending on flight duration, 20–80% of astronauts suffer from post-flight OI, which is associated with reduced vascular resistance. This paper introduces a novel algorithm for continuously monitoring changes in total peripheral resistance (TPR) by processing the peripheral arterial blood pressure (ABP). To validate, we applied our novel mathematical algorithm to the pre-flight ABP data previously recorded from twelve astronauts ten days before launch. The TPR changes were calculated by our algorithm and compared with the TPR value estimated using cardiac output/heart rate before and after phenylephrine administration. The astronauts in the post-flight presyncopal group had lower pre-flight TPR changes (1.66 times) than those in the non-presyncopal group (2.15 times). The trend in TPR changes calculated with our algorithm agreed with the TPR trend calculated using measured cardiac output in the previous study. Further data collection and algorithm refinement are needed for pre-flight detection of OI and monitoring of continuous TPR by analysis of peripheral arterial blood pressure.     

“Space superiority”: Wernher von Braun's campaign for a nuclear-armed space station, 1946–1956

The literature on the history of spaceflight has depicted the early 1950s Collier’s articles mostly as a forerunner to the peaceful and scientific exploration of space. Yet the centerpiece of Wernher von Braun's plan was a manned space station that would serve as reconnaissance platform and orbiting battle station for achieving “space superiority” over the USSR. One its roles could be the launching of nuclear missiles. When challenged as to the station's defensibility, von Braun even posited pre-emptive atomic strikes from space as a response to the development of a hostile anti-satellite capability.     

Towards a lunar base programme

When the requisite technology exists, the US political process will inevitably include lunar surface activities as a major space objective. This article examines a manned lunar base in terms of three distinct functions: the scientific investigation of the Moon and its environment; development of the capability to use lunar resources for beneficial purposes throughout the Earth-Moon systems; and conduct of R&D leading to a self-sufficient and self-supporting manned lunar base. Three scenarios are outlined with respect to each possible function.     

Application of Ground/Air Data Link to General Aviation Operations

The Federal Aviation Administration (FAA) is currently upgrading secondary surveillance radars with systems which will have an integral data link capability, the Mode Select (Mode S) beacon system. These new systems will allow two-way data communications between ground systems (e.g., weather databases and Air Traffic Control (ATC) systems) and aircraft that are equipped with data link compatible Mode S transponders and suitable display and input devices. Initial data link services include both weather information and ATC advisories. The MITRE Corporation* is developing an in-house capability to perform end-to-end operational evaluation of data link services. Initially, a low-cost, portable pilot position man-machine interface is being developed for use in general aviation operations. The objective is to explore operational issues in laboratory and limited flight test environments, and to demonstrate these services on a data link I/O device, a laptop portable personal computer (PC) with touch panel. A group of pilots will bench test the interface design, and the results will be incorporated into the design used in flight testing. This paper describes the project's objectives and results to date, including implementation details and pilot test results.     

The Scientific Measurement System of the Gravity Recovery and Interior Laboratory (GRAIL) Mission

The Gravity Recovery and Interior Laboratory (GRAIL) mission to the Moon utilized an integrated scientific measurement system comprised of flight, ground, mission, and data system elements in order to meet the end-to-end performance required to achieve its scientific objectives. Modeling and simulation efforts were carried out early in the mission that influenced and optimized the design, implementation, and testing of these elements. Because the two prime scientific observables, range between the two spacecraft and range rates between each spacecraft and ground stations, can be affected by the performance of any element of the mission, we treated every element as part of an extended science instrument, a science system. All simulations and modeling took into account the design and configuration of each element to compute the expected performance and error budgets. In the process, scientific requirements were converted to engineering specifications that became the primary drivers for development and testing. Extensive simulations demonstrated that the scientific objectives could in most cases be met with significant margin. Errors are grouped into dynamic or kinematic sources and the largest source of non-gravitational error comes from spacecraft thermal radiation. With all error models included, the baseline solution shows that estimation of the lunar gravity field is robust against both dynamic and kinematic errors and a nominal field of degree 300 or better could be achieved according to the scaled Kaula rule for the Moon. The core signature is more sensitive to modeling errors and can be recovered with a small margin.     

Regulatory Compliance-The Real World

An introduction to the real world of product safety liaison. As the ``World Market' matures, the stature of the safety liaison process increases in importance. Means for accelerating the regulatory process are detailed and pertinent standards are identified. The redesign of a domestic switching power supply to ``World Standards' is described.     

Integrating Avionics in the Conceptual Design Phase

The avionics components of modern military aircraft significantly impact the cost and effectiveness of the total aeronautical system. In the early conceptual phase, aeronautical system designers give scant attention to designing the avionics components. The design team generally provides weight, volume and power considerations for the desired avionics functions and assumes that an avionics suite can be assembled. Less than comprehensive attention is given to the interacting effect avionics have with the other system components. In contrast, the designers expend a very large effort on finding the best balanced combination of airframe and propulsion components which satisfy the design objectives. This paper shows why avionics must be a co-equal member of the aeronautical system along with airframe, propulsion, and armament. To become a co-equal partner, avionics must be an element of the system design iterations and analysis commencing with the early conceptual design phase of a new aeronautical system.     

The NASA Astrobiology Roadmap

The NASA Astrobiology Roadmap provides guidance for research and technology development across the NASA enterprises that encompass the space, Earth, and biological sciences. The ongoing development of astrobiology roadmaps embodies the contributions of diverse scientists and technologists from government, universities, and private institutions. The Roadmap addresses three basic questions: How does life begin and evolve, does life exist elsewhere in the universe, and what is the future of life on Earth and beyond? Seven Science Goals outline the following key domains of investigation: understanding the nature and distribution of habitable environments in the universe, exploring for habitable environments and life in our own solar system, understanding the emergence of life, determining how early life on Earth interacted and evolved with its changing environment, understanding the evolutionary mechanisms and environmental limits of life, determining the principles that will shape life in the future, and recognizing signatures of life on other worlds and on early Earth. For each of these goals, Science Objectives outline more specific high-priority efforts for the next 3-5 years. These 18 objectives are being integrated with NASA strategic planning.