Ionospheric wave processes during HF heating experiments

Effects of ionospheric modification produced by powerful high frequency radio waves are studied using the method of field-aligned scattering of diagnostic HF radio signals. Observations of scattered HF signals have been made by the Doppler spectrum method. Analysis of the experimental data shows the appearance of quasiperiodic variations in Doppler frequency shift f_d, with periods 30–60 s during the heating cycles. Powerful HF waves are assumed to excite the Alfvén resonator generating oscillations of the magnetic field lines in the heated region and giving rise to f_d artificial variations and magnetic pulsations. In the case of continuous action of the powerful HF transmitter ionospheric waves are sometimes observed with periods 12–25 min, typical of medium-scale travelling ionospheric disturbances.     

Need and effect of reconditioning of nickel/hydrogen batteries

There has been a debate about the need for reconditioning nickel/hydrogen batteries in geosynchronous satellites. A study was done as part of life cycling, to determine the necessity of reconditioning and its effect on the cell performance. A 36 Ah nickel/hydrogen cell was put on a GEO simulated cycling at 15°C without reconditioning up to four eclipse seasons. The effect of reconditioning on the fifth and sixth eclipse seasons was studied. The study has conclusively proven the need for reconditioning and has shown the benefits of a high rate reconditioning. It has also been possible to draw some conclusions about the effect of a long duration trickle charge on the positive electrode     

Raindrops on Titan.

Some of the aspects of methane precipitation on Titan are considered. In particular, descent velocities are computed. It is found that raindrops fall much slower than on Earth. Additionally, the maximum size of raindrops on Titan is over 9 mm, compared with under 6 mm on Earth. The composition of drops will vary with altitude. Implications of these properties for Titan and the Huygens mission are considered.     

Measurements of electrical breakdown in the vicinity of a sounding rocket differentially charged to 10 kV

During the initial period of high voltage biasing of the SPEAR-3 sounding rocket payload, it was observed that electrical breakdown occurred in the gas surrounding the rocket. The breakdown occurred almost all the way to apogee of 289 km on the upleg, but did not recur on the downleg until the payload reached an altitude of 100 km. It is suggested that this behavior can be attributed to payload outgassing on the upleg leading to abnormally high gas pressure near the payload skin. Consideration of a modified Paschen discharge process with varying pressure along the discharge path was found to be consistent with the results.     

Weapons System Open Architecture - a bridge between "embedded" and "off-board"

A demonstration program is described: Weapons System Open Architecture (WSOA) - funded jointly by the Air Force Research Laboratory (AFRL), DARPA, and the Open Systems Joint Task Force (OSJTF). WSOA provides an open systems "bridge" between legacy embedded mission systems and off-board C3I sources and systems. This "bridge" is used to support Internet-like connectivity between command and attack nodes. The foundation of this bridge is the creation of a Common Object Request Broker Architecture (CORBA) layer over Link 16. In addition, application of quality of service techniques and resource management technologies will ensure the timely exchange and processing of mission critical information by both attack and command nodes in even the most time-sensitive situations.     

End-to-End Modeling of the Solar Terrestrial System

Traditionally modeling for space science has concentrated on developing simulations for individual components of the solar terrestrial system. In reality these regions are coupled together. This coupling can be as simple as the driving of the magnetosphere – ionosphere – thermosphere system by the solar wind or as a complicated as the feedback of the ionospheric conductivity and currents on the magnetosphere. As part of the CISM project we are beginning a concentrated effort to compressively model the entire system. This approach includes chains of models. In the first chain physics based numerical models are utilized while in the second chain empirical models are coupled together. The first half of this paper discusses the numerical modeling approach by highlighting the coupling of pairs of regions within the system. In the second section we present results from empirical models which are combined to make long term forecasts of conditions in the geospace environment. It is expected that a validated and reliable forecast model for space weather can be obtained by combining the strongest elements of each chain.     

Defense radar development in Australia: 1939 to the present

Defense radar research and development in Australia is today largely, but not exclusively, confined within Australia's Defense Science and Technology Organization, DSTO, and its R&D collaborators in universities. Radar has a long history in Australia, dating back to World War II links with British defense radar development, and radar R&D continues to be an important focus within DSTO. It is impossible, in the context of a brief conference paper, to give other than the broadest-brush picture of Australian radar development over a half-century or more. So the approach taken is necessarily highly selective and focuses specifically on several illustrative development projects, in an attempt to convey the flavor of national radar research priorities, the way they drive R&D and likely future directions. Despite the escalating requirement for a national skills base in defense radar and allied technologies, there are currently legitimate concerns about the robustness of this base. Recruitment of high-caliber researchers into the field of radar and management of radar research careers are issues currently presenting major challenges. A number of initiatives are in place linking DSTO with university research; a recent effort to enhance the stature and visibility of radar research in Australia is the establishment of the Centre of Expertise in Microwave Radar as a joint venture between DSTO and Adelaide University.     

Influence of high concentrations of mineral salts on production process and NaCl accumulation by Salicornia europaea plants as a constituent of the LSS phototroph link.

Use of halophytes (salt-tolerant vegetation), in a particular vegetable Salicornia europaea plants which are capable of utilizing NaCl in rather high concentrations, is one of possible means of NaCl incorporation into mass exchange of bioregenerative life support systems. In preliminary experiments it was shown that S. europaea plants, basically, could grow on urine pretreated with physicochemical processing and urease-enzyme decomposing of urea with the subsequent ammonia distillation. But at the same time inhibition of the growth process of the plants was observed. The purpose of the given work was to find out the influence of excessive quantities of some mineral elements contained in products of physicochemical processing of urine on the production process and NaCl accumulation by S. europaea plants. As the content of mineral salts in the human liquid wastes (urine) changed within certain limits, two variants of experimental solutions were examined. In the first variant, the concentration of mineral salts was equivalent to the minimum salt content in the urine and was: K - 1.5 g/l, P - 0.5 g/l, S - 0.5 g/l, Mg - 0.07 g/l, Ca - 0.2 g/l. In the second experimental variant, the content of mineral salts corresponded to the maximum salt content in urine and was the following: K - 3.0 g/l, P - 0.7 g/l, S - 1.2 g/l, Mg - 0.2 g/l, Ca - 0.97 g/l. As the control, the Tokarev nutrient solution containing nitrogen in the form of a urea, and the Knop nutrient solution with nitrogen in the nitrate form were used. N quantity in all four variants made up 177 mg/l. Air temperature was 24 degrees C, illumination was continuous. Light intensity was 690 micromoles/m2s of photosynthetically active radiation. NaCl concentration in solutions was 1%. Our researches showed that the dry aboveground biomass of an average plant of the first variant practically did not differ from the control and totaled 11 g. In the second variant, S. europaea productivity decreased and the dry aboveground biomass of an average plant totaled 8 g. The increase of K quantity in the experimental solutions resulted in an elevated content of the element in the plants. The increase of K uptake in the second experimental variant was accompanied by a 30-50% decrease of Na content in comparison with the other variants. Comparative Na content in the other variants was practically identical. N, Mg and P content in the control and experimental variants was also practically identical. The increase of S quantity in the second experimental variant also increased S uptake by the plants. But Ca quantity, accumulated in aboveground plants biomass in the experimental variants was lower than in the control. NaCl uptake by plants, depending on the concentration of mineral salts in the experimental solutions, ranged from 8 g (maximum salt content) up to 15 g (minimum salt content) on a plant growth area that totaled 0.032 m2. Thus, high concentrations of mineral salts simulating the content of mineral salts contained in urine did not result in a significant decrease of S. europaea productivity. The present work also considers the influence of higher light intensity concentrations on productivity and NaCl accumulation by S. europaea plants grown on experimental solutions with high salt content.