Cubesats: Cost-effective science and technology platforms for emerging and developing nations

The development, operation, and analysis of data from cubesats can promote science education and spur technology utilization in emerging and developing nations. This platform offers uniquely low construction and launch costs together with a comparative ubiquity of launch providers; factors that have led more than 80 universities and several emerging nations to develop programs in this field. Their small size and weight enables cubesats to “piggyback” on rocket launches and accompany orbiters travelling to Moon and Mars. It is envisaged that constellations of cubesats will be used for larger science missions. We present a brief history, technology overview, and summary of applications in science and industry for these small satellites. Cubesat technical success stories are offered along with a summary of pitfalls and challenges encountered in both developed and emerging nations. A discussion of economic and public policy issues aims to facilitate the decision-making process for those considering utilization of this unique technology.     

Data and performances of selected aircraft and rotorcraft

The purpose of this article is to provide a synthetic and comparative view of selected aircraft and rotorcraft (nearly 300 of them) from past and present. We report geometric characteristics of wings (wing span, areas, aspect-ratios, sweep angles, dihedral/anhedral angles, thickness ratios at root and tips, taper ratios) and rotor blades (type of rotor, diameter, number of blades, solidity, rpm, tip Mach numbers); aerodynamic data (drag coefficients at zero lift, cruise and maximum absolute glide ratio); performances (wing and disk loadings, maximum absolute Mach number, cruise Mach number, service ceiling, rate of climb, centrifugal acceleration limits, maximum take-off weight, maximum payload, thrust-to-weight ratios). There are additional data on wing types, high-lift devices, noise levels at take-off and landing. The data are presented on tables for each aircraft class. A graphic analysis offers a comparative look at all types of data. Accuracy levels are provided wherever available.     

Stability,flying qualities and longitudinal parameter estimation of a twin-engine CS-23 certified light aircraft

This paper presents some results of the flight test campaign conducted on the Tecnam P2006T aircraft, on the occasion of its certification process. This twin-engine propeller airplane is certified under the normal category CS-23 and FAR 23. A prototype of this light aircraft has been tested in flight for a post-design performance optimization and for the assessment of flight qualities. These experiences have led to the application of two winglets to the original wing. The final configuration has been extensively tested for the achievement of CS-23 certification. The longitudinal and lateral-directional response modes have been assessed and quantified. At the same time the longitudinal airplane model, through a dedicated set of flight maneuvers, has been characterized by means of parameter estimation studies. The aircraft stability derivatives have been estimated from the acquired flight data using the identification technique known as Output Error Method (OEM). Some estimated stability derivatives have been also compared with the corresponding values extracted from leveled flight tests and from wind tunnel tests performed on a scaled model of the aircraft.     

空间核电源热管式辐射散热器热分析与参数优化

针对空间热管辐射散热器的特殊工况对散热器进行热分析建模，通过分析其传热原理，建立出热阻模型，并通过和实际设计进行对比，验证模型和计算方法的可行性。选取翅根温度、翅片长度和翅片厚度等参量作为约束条件，分别对热管式空间辐射散热器的翅片散热效率和系统质量特性进行优化分析，获得最优设计参数。     

Keeping Ma’at: An astronomical approach to the orientation of the temples in ancient Egypt

For various reasons, Archaeoastronomy has not been one of the favourite disciplines of the Egyptologists in the past. Probably because of that, important questions such as the orientation of Egyptian temples and the relevance of astronomy in this respect had never been afforded with the necessary seriousness and deepness. The Egyptian–Spanish Mission for the Archaeoastronomy of ancient Egypt has, among its various priorities, the solution of this problem. In order to achieve that, we have measured the orientation of some 330 temples in the Valley, the Delta, the Oases and the Sinai so far. The aim is to find a correct and almost definitive answer to the question of whether the ancient Egyptian sacred constructions were astronomically aligned or not. Our data seem to answer this question in the affirmative sense. Besides, they offer a very interesting new perspective in the field of landscape archaeology, a new discipline hardly worked in Egypt so far, in which terrestrial landscape, dominated by the Nile, and celestial landscape, dominated by the sun and the stars, would combine in order to permit the establishment of Ma’at, the Cosmic Order, on Earth.     

Towards a One Percent Measurement of Frame Dragging by Spin with Satellite Laser Ranging to LAGEOS, LAGEOS 2 and LARES and GRACE Gravity Models

During the past century Einstein’s theory of General Relativity gave rise to an experimental triumph; however, there are still aspects of this theory to be measured or more accurately tested. Today one of the main challenges in experimental gravitation, together with the direct detection of gravitational waves, is the accurate measurement of the gravitomagnetic field generated by the angular momentum of a body. Here, after a brief introduction on frame-dragging, gravitomagnetism and Lunar Laser Ranging tests, we describe the past measurements of frame-dragging by the Earth spin using the satellites LAGEOS, LAGEOS 2 and the Earth’s gravity models obtained by the GRACE project. We demonstrate that these measurements have an accuracy of approximately 10%. We then describe the LARES experiment to be launched in 2010 by the Italian Space Agency for a measurement of frame-dragging with an accuracy of a few percent. We finally demonstrate that a number of claims by a single individual, that the error budget of the frame-dragging measurements with LAGEOS-LAGEOS 2 and LARES has been underestimated, are indeed ill-founded.     

Review Article: MHD Wave Propagation Near Coronal Null Points of Magnetic Fields

We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfvén speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfvén wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfvén-speed profile. In a ??=0 plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfvén wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfvén wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfvén wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing.     

An overview of RADOM results for earth and moon radiation environment on Chandrayaan-1 satellite

The RADiatiOn Monitor (RADOM) is a miniature dosimeter-spectrometer that flew onboard the Chandrayaan-1 lunar mission in order to monitor the local radiation environment. Primary objective of the RADOM experiment was to measure the total absorbed dose, flux of surrounding energetic particles and spectrum of the deposited energy from high energy particles both en-route and in lunar orbit. RADOM was the first experiment to be switched on after the launch of Chandrayaan-1 and was operational until the end of the mission. This paper summarizes the observations carried out by RADOM during the entire life time (22 October 2008–31 August 2009) of the Chandrayaan-1 mission and compares the measurement by RADOM with the radiation belt models such as AP-8, AE-8 and CRRESS.