Automated VOR Ground Check Techniques

Field conversions of many conventional VOR and VORTAC facilities to remote maintenance monitoring, which includes provisions for automated VOR ground check procedures, has been under way in the United States since 1982. A question that has arisen as a result of this effort concerns the minimum number of ground-check points that must be used in order that the bearing-error function can be resolved into its octantal as well as its quadrantal and "duantal" components. Some fundamental considerations relating to that question are examined here.     

Range Correction Computations for Weapons Dropped from Aircraft

A general set of equations is developed from which the effects of initial condition perturbations upon weapon impact point are readily evaluated. Data are presented to illustrate the accuracy with which predictions can be made. Results obtained from the actual ballistic equations, from the time-varying perturbation equations, and from a time-invariant approximation of the perturbation equations are compared. It is shown that reasonable impact point predictive accuracy can be provited for fairly large changes in initial conditions.     

Stars and Stellar Systems at z > 5: Implications for Structure Formation and Nucleosynthesis

Enough UV radiation was generated before z = 5 to have ionized the intergalactic medium. If this comes from stars (probably aggregated in systems of subgalactic scale), one straightforwardly calculates that the associated nucleosynthesis would be sufficient to produce a universal abundance of order 1 percent of solar. The first pre-galaxies may eventually be detectable by their direct UV emission, with characteristic spectral features at Lyman alpha; high-z supernovae may also be detectable. Other probes of the IGM beyond z = 5, and of the epochs of reheating and reionization, are discussed, along with possible links between the diffusion of pregalactic metals and the origin of magnetic fields.     

The Radiation Assessment Detector (RAD) Investigation

The Radiation Assessment Detector (RAD) on the Mars Science Laboratory (MSL) is an energetic particle detector designed to measure a broad spectrum of energetic particle radiation. It will make the first-ever direct radiation measurements on the surface of Mars, detecting galactic cosmic rays, solar energetic particles, secondary neutrons, and other secondary particles created both in the atmosphere and in the Martian regolith. The radiation environment on Mars, both past and present, may have implications for habitability and the ability to sustain life. Radiation exposure is also a major concern for future human missions. The RAD instrument combines charged- and neutral-particle detection capability over a wide dynamic range in a compact, low-mass, low-power instrument. These capabilities are required in order to measure all the important components of the radiation environment. RAD consists of the RAD Sensor Head (RSH) and the RAD Electronics Box (REB) integrated together in a small, compact volume. The RSH contains a solid-state detector telescope with three silicon PIN diodes for charged particle detection, a thallium doped Cesium Iodide scintillator, plastic scintillators for neutron detection and anti-coincidence shielding, and the front-end electronics. The REB contains three circuit boards, one with a novel mixed-signal ASIC for processing analog signals and an associated control FPGA, another with a second FPGA to communicate with the rover and perform onboard analysis of science data, and a third board with power supplies and power cycling or “sleep”-control electronics. The latter enables autonomous operation, independent of commands from the rover. RAD is a highly capable and highly configurable instrument that paves the way for future compact energetic particle detectors in space.     

感知"角秒"——ERA 4000系列角度编码器

高效的驱动系统需要精确的位置信息.一种特殊的光栅鼓栅线制造工艺和独特的扫描原理使海德汉新系列的角度编码器具有很高的精度.     

Radiance calibration of CRISTA-NF

The CRISTA-NF instrument is the airborne version of the CRISTA satellite infrared limb sounder. It has been successfully flown on the Geophysica research airplane during a test campaign in July 2005, during the SCOUT-O3 Tropical Aircraft Campaign in November/December 2005 and during the AMMA campaign in August 2006. Radiance calibrations of the airborne instrument are more complex compared to the satellite instrument because the vacuum shell of CRISTA-NF is confined by a ZnSe (zinc–selenide) window and the detectors can thermally drift during measurement flights. By comprehensive radiance calibrations with a blackbody source the window’s emissivity and transmissivity are determined and the dependence of the instrument sensitivity on the detector temperature is characterized. Taking these effects into account, the remaining radiance error of the calibration is smaller than 3%.     

Hemispheric asymmetry of chemical species and its effect on stratospheric ozone: Emphasis on halogen loading

Differences between the dynamical characteristics of the northern hemisphere (NH) and southern hemisphere (SH) stratosphere (e.g., the temperature, the strength of polar vortex, and the mean meridional circulation) produce hemispherically asymmetrical distributions of chemical species. In this paper, we use global models to briefly discuss various effects on chemical species caused by this asymmetrical distribution, especially on stratospheric ozone. The role of hemispheric asymmetries in chlorine and bromine loadings on mid- and high latitude ozone depletion is particularly discussed.     

Design and Performance of the ICON EUV Spectrograph

We present the design, implementation, and on-ground performance measurements of the Ionospheric Connection Explorer EUV spectrometer, ICON EUV, a wide field (\(17^{\circ}\times 12^{\circ}\)) extreme ultraviolet (EUV) imaging spectrograph designed to observe the lower ionosphere at tangent altitudes between 100 and 500 km. The primary targets of the spectrometer, which has a spectral range of 54–88 nm, are the Oii emission lines at 61.6 nm and 83.4 nm. Its design, using a single optical element, permits a $0\stackrel{{}^{°}}{.}26$ imaging resolution perpendicular to the spectral dispersion direction with a large (\(12^{\circ} \)) acceptance parallel to the dispersion direction while providing a slit-width dominated spectral resolution of \(R\sim25\) at 58.4 nm. Pre-flight calibration shows that the instrument has met all of the science performance requirements.     

The Mars Environment Analogue Platform long duration balloon flight

The MEAP (Mars Environment Analogue Platform) mission was to fly a stratospheric balloon on a semicircular trajectory around the North Pole in summer 2008. The balloon platform carried the high-resolution neutral gas mass spectrometer P-BACE (Polar Balloon Atmospheric Composition Experiment) as scientific payload. MEAP/P-BACE is a joint project between the Esrange Space Center, Sweden, the University of Bern, Switzerland and the Swedish Institute of Space Physics (IRF), Kiruna, Sweden. Mission objectives were to validate the platform for future long duration flights around the North pole, to validate the P-BACE instrument design for planetary mission applications (conditions in the Earth stratosphere are similar to the conditions at the Mars surface), to study variation of the stratospheric composition during the flight and to gain experience in balloon based mass spectrometry. All objectives were fulfilled.     

Sources of inner radiation zone energetic helium ions: Cross-field transport versus in-situ nuclear reactions

Radial transport theory for inner radiation zone MeV He ions has been extended by combining radial diffusive transport, losses due to Coulomb friction and charge exchange reaction with local generation of ³He and ⁴He ions due to nuclear reactions taking place on the inner edge of the inner radiation zone. From interactions between high energy trapped protons and upper atmospheric constituents we have included a nuclear reaction yield helium flux source that was numerically derived from a nuclear reaction model originally developed at the Institute of Nuclear Researches of Moscow, Russia and implemented in the computer system at the University of Campinas, Brazil. Magnetospheric transport computations have been made covering the L-shell range L=1.0 to 1.6 and the resulting MeV He ion flux distributions show a strong influence of the local nuclear source mechanism on the inner zone energetic He ion content.