Investigation of natural and artificial stimulation of the ionospheric Alfvén resonator at high latitude

A brief review is provided of recent progress in understanding the ionospheric Alfvén resonator (IAR) at high latitude. Firstly, naturally occurring resonances of the IAR as detected by pulsation magnetometers in the auroral zone at Sodankylä and in the polar cap at Barentsburg are considered. The characteristics of the IAR in the two regions are broadly similar, although the effects of solar illumination are less clear at the higher latitudes. Secondly we review recent attempts to stimulate the IAR through high-power radio frequency experiments both in the auroral zone at Tromsø with the European Incoherent SCATter (EISCAT) heater, and within the polar cap at Longyearbyen with the Space Plasma Exploration by Active Radar (SPEAR) facility. In the auroral zone at, Tromsø the stimulated IAR has been observed by ground-based magnetometers, and through electron acceleration observed on the FAST spacecraft. At SPEAR in the polar cap, the stimulated IAR has been investigated, with ground magnetometers, with the first results indicative of a positive detection.     

Experimental investigations of the 10 N catalytic hydrazine thruster

Experimental investigations of the 10 N catalytic hydrazine thruster are reported. These thrusters find applications in orbit raising functions of a spacecraft. The hardware was realized and tested in a vacuum chamber (10^?3 mbar vacuum) for its performance. When tested at the design propellant supply pressure of 21.5 bar the thruster developed 10.25 N thrust at an operating chamber pressure of 16.4 bar. The thruster was also tested for off-design conditions (24, 18 and 14.5 bar propellant supply pressures) of operation to determine the steady-state performance. The chamber pressure and vacuum thrust follow more or less a linear law with the propellant-supply pressure. The thruster was also tested for its response characteristics for short (100 ms) firing durations at various propellant-supply pressures (15.5, 18.8, 22.5, 25.6 and 29.5 bar) and the experimental results are reported and discussed. The hydrazine was injected at the room temperature (300^±5 K).     

ISEE-1 and 2 observations of field-aligned currents in the distant midnight magnetosphere

Magnetic field measurements obtained in the nightside magnetosphere by the co-orbiting ISEE-1 and 2 spacecraft have been examined for signatures of field-aligned currents (FAC). Such currents are found on the boundary of the plasma sheet both when the plasma sheet is expanding and when it is thinning. Plasma sheet boundary layer current structure and substorm associated dynamics can be determined using the two spacecraft, although for slow traversals of the FAC sheet the spatial/temporal ambiguity is still an issue. We often find evidence for the existence of waves on the plasma sheet boundary, leading to multiple crossings of the FAC sheet. At times the boundary layer FAC sheet orientation is nearly parallel to the X-Z GSM plane, suggesting ‘protrusions’ of plasma sheet into the lobes. The boundary layer current polarity is, as expected, into the ionosphere in the midnight to dawn local time sector, and outward near dusk. Current sheet thicknesses and velocities are essentially independent of plasma sheet expansion or thinning, having typical values of 1500 km and 20–40 km/s respectively. Characteristic boundary layer current densities are about 10 nanoamps per square meter.     

The Broad Band X-Ray Telescope

The Broad-Band X-Ray Telescope (BBXRT) has been designed to perform high sensitivity, moderate resolution spectrophototnetry of X-ray sources in the 0.3–12 keV band from the Shuttle. It consists of a coaligned pair of high throughput, conical X-ray imaging mirrors, with a cryogenically-cooled, multiple element, Si(Li) spectrometer at the focus of each. On axis, BBXRT will have an effective area of 580 cm² at 2 keV and 250 cm² at 7 keV, and a spectral resolution of 110 eV at 2 keV and 150 eV at 7 keV. A 10⁴ s observation with BBXRT will allow a determination of the continuum spectral shape for sources near the Einstein deep survey limit.     

Analysis of solar degradation to TDRS S-band phased array antenna

A study of the distribution of gain-to-noise-temperature (G/T) values for the Tracking and Data Relay Satellite (TDRS) satellite is described. The statistics of the G/T values are determined by a Monte Carlo simulation of the orbital geometry of the Sun and Moon, and the gain and noise temperature calculations is included. The results and their underlying assumptions are described     

RF communications subsystem for the Radiation Belt Storm Probes mission

The NASA Radiation Belt Storm Probes (RBSP) mission, currently in Phase B, is a two-spacecraft, Earth-orbiting mission, which will launch in 2012. The spacecraft's S-band radio frequency (RF) telecommunications subsystem has three primary functions: provide spacecraft command capability, provide spacecraft telemetry and science data return, and provide accurate Doppler data for navigation. The primary communications link to the ground is via the Johns Hopkins University Applied Physics Laboratory's (JHU/APL) 18 m dish, with secondary links to the NASA 13 m Ground Network and the Tracking and Data Relay Spacecraft System (TDRSS) in single-access mode. The on-board RF subsystem features the APL-built coherent transceiver and in-house builds of a solid-state power amplifier and conical bifilar helix broad-beam antennas. The coherent transceiver provides coherency digitally, and controls the downlink data rate and encoding within its field-programmable gate array (FPGA). The transceiver also provides a critical command decoder (CCD) function, which is used to protect against box-level upsets in the C&DH subsystem. Because RBSP is a spin-stabilized mission, the antennas must be symmetric about the spin axis. Two broad-beam antennas point along both ends of the spin axis, providing communication coverage from boresight to 70°. An RF splitter excites both antennas; therefore, the mission is designed such that no communications are required close to 90° from the spin axis due to the interferometer effect from the two antennas. To maximize the total downlink volume from the spacecraft, the CCSDS File Delivery Protocol (CFDP) has been baselined for the RBSP mission. During real-time ground contacts with the APL ground station, downlinked files are checked for errors. Handshaking between flight and ground CFDP software results in requests to retransmit only the file fragments lost due to dropouts. This allows minimization of RF link margins, thereby maximizing data rate and thus data volume.     

Hardware-in-the-loop testing technology for integrated control and condition monitoring systems of aircraft gas turbine engines

Hardware-in-the-loop testing technology for automatic control, condition monitoring and diagnostics systems of gas turbine engines is described. The technology proposed makes it possible to simulate combinations and chains of unexpected and gradual failures of engines, transducers and actuators.     

Application of interference holography method for diagnostics of turbomachine part technical condition

Examples of application of the interference holography method for diagnostics of failure, technical condition and in nondestructive check of turbomachine parts are presented.     

Algorithmic support of a small-sized navigation system on the basis of the magnetoinertial course transmitter

The algorithmic support of a small-sized navigation system on the basis of the magnetoinertial course transmitter is considered; the support makes it possible to significantly reduce accumulating errors that are due to incomplete data on wind parameters and decrease requirements for random errors of initial data sensors.     

A set of systems for labor standards computer-aided design

A set of systems for labor standard computer-aided design is described, namely, initial developments, advance and state-of-the art.