Influence Analysis of the Second Bypass Air Bleed Parameters on the Engine Performance

This paper considers double bypass aircraft engine with controlled air bleed to the second bypass duct. Its performance is evaluated by mathematical modeling techniques. The second bypass air bleed amount is determined to provide the best engine efficiency at various operating modes.     

Plasma Jet Motion Across the Geomagnetic Field in the “North Star” Active Geophysical Experiment

The active geophysical rocket experiment North Star was carried out in the auroral ionosphere on January 22, 1999, at the Poker Flat Research Range (Alaska, USA) using the American research rocket Black Brant XII with explosive plasma generators on board. Separable modules with scientific equipment were located at distances of from 170 to 1595 m from the plasma source. The experiment continued the series of the Russian–American joint experiments started by the Fluxus experiment in 1997. Two injections of aluminum plasma across the magnetic field were conducted in the North Star experiment. They were different, since in the first injection a neutral gas cloud was formed in order to increase the plasma ionization due to the interaction of neutrals of the jet and cloud. The first and second injections were conducted at heights of 360 and 280 km, respectively. The measurements have shown that the charged particle density was two orders of magnitude higher in the experiment with the gas release. The magnetic field in the first injection was completely expelled by the dense plasma of the jet. The displacement of the magnetic field in the second injection was negligible. The plasma jet velocity in both injections decreased gradually due to its interaction with the geomagnetic field. One of the most interesting results of the experiment was the conservation of high plasma density during the propagation of the divergent jet to considerable distances. This fact can be explained by the action of the critical ionization velocity mechanism.     

Magnetic Cusp as a Source of Dust Swarms in the Near-Earth Space

Within the framework of the concept of steady-state flow of a flux of dust particles through the cusp channel of the Earth's magnetosphere, we develop the idea that the magnetic cusp is a generator of dust swarms in the near-Earth space. The analytical dependencies for the density (concentration) of dust particles in the cusp and near-Earth space region are obtained.     

Issues relating to civilian and military dual uses of GNSS

This paper discusses the civilian and military dual uses of Global Navigation Satellite Systems (GNSS). Its focus is on the primary GNSS provider: the United States dual use Global Positioning System (GPS). The Russian Glonass is also dual use but this is used much less than GPS. It is difficult for the US Department of Defense to accommodate the requirements of all the civilian users. Resolution of some dual use problems is accomplished through pressure and negotiation. International civilian users exacerbate the dual use problem by demanding service guaranties and a share of control over GPS. Additionally, Europeans seek to obtain a share of the promising GNSS industry and employment by building their own GNSS provider Galileo.     

Using electrical impedance spectroscopy to detect water in planetary regoliths

We present data in examination of the utility of electrical impedance spectroscopy measurements for in situ surveys to determine the water content, distribution, and phase in unconsolidated planetary regolith. We conducted calibration experiments under conditions relevant to Mars: the concentration of electrolytes in solution was varied up to 1 M to simulate the effects of unsaturated dissolved minerals and brines. We also varied the water content of heterogeneous water/sand mixtures, made with these electrolytic solutions from 0.01 wt% to 10 wt%. Tests were performed at temperatures from +25 degrees C to -65 degrees C. Conductivity and dielectric permittivity calculated from the impedance measurements indicate an expected dependence on electrolyte concentration and relative independence from electrolyte type for both liquid water and water ice. Conductivity and calculated dielectric relaxation times for these aqueous solutions agree with existing data in the literature. The relative permittivity for heterogeneous water/sand mixtures is dominated by polarization effects for the electrode configuration used. However, the characteristic orientational relaxation of ice is still visible. The conductivity retains the strong dependence on electrolyte concentration, and the permittivity is still not affected by electrolyte type. A "universal" curve between conductivity and water content establishes detectability limits of <0.01 wt% and approximately 0.3 wt% for water/sand mixtures containing liquid water and ice, respectively.     

DAME: planetary-prototype drilling automation

We describe results from the Drilling Automation for Mars Exploration (DAME) project, including those of the summer 2006 tests from an Arctic analog site. The drill hardware is a hardened, evolved version of the Advanced Deep Drill by Honeybee Robotics. DAME has developed diagnostic and executive software for hands-off surface operations of the evolved version of this drill. The DAME drill automation tested from 2004 through 2006 included adaptively controlled drilling operations and the downhole diagnosis of drilling faults. It also included dynamic recovery capabilities when unexpected failures or drilling conditions were discovered. DAME has developed and tested drill automation software and hardware under stressful operating conditions during its Arctic field testing campaigns at a Mars analog site.     

Optimization of transfers under constraints on the thrust direction: I

Transfers with a low thrust are considered under constraints imposed on the thrust vector direction. These constraints can be caused by peculiarities of the attitude control system and the mode of stabilization of a spacecraft, and, in the general case, they are functions of the time and state vector. The constraints specified by equalities and inequalities are investigated. It is shown that the optimal thrust is directed along the projection of the Lawden’s primer vector onto the restricting set.     

Spacecraft Design-for-Demise implementation strategy & decision-making methodology for low earth orbit missions

Space missions designed to completely ablate upon an uncontrolled Earth atmosphere reentry are likely to be simpler and cheaper than those designed to execute controlled reentry. This is because mission risk (unavailability) stemming from controlled reentry subsystem failure(s) is essentially eliminated. NASA has not customarily implemented Design-for-Demise meticulously. NASA has rather approached Design-for-Demise in an ad hoc manner that fails to entrench Design-for-Demise as a mission design driver. Thus, enormous demisability challenges at later formulation stages of missions aspired to be demisable are evident due to these perpetuated oversights in entrenching Design-for-Demise practices. The investigators hence propose a strategy for a consistent integration of Design-for-Demise practices in all phases of a space mission lifecycle. Secondly, an all-inclusive risk-informed, decision-making methodology referred to as Analytic Deliberative Process is proposed. This criterion facilitates in making a choice between an uncontrolled reentry demisable or controlled reentry. The authors finally conceive and synthesize Objectives Hierarchy, Attributes, and Quantitative Performance Measures of the Analytical Deliberative Process for a Design-for-Demise risk-informed decision-making process.     

S5 0716+714: GeV variability study

The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV–300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ∼75 and ∼140 days, respectively. We also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from a simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. We discuss several possible scenarios to explain the observed spectral break.     

Compact high-sensitivity accelerometer-seismometer

Design of a three-axial accelerometer-seismometer, constructed on the basis of two-coordinate sensors (sensitive elements) of high and low accelerations, is considered in the paper. This instrument is applied for gravi-inertial measurements. Basic characteristics of the instrument are described, as well as the technique and results of its standardization.