RPC-IES: The Ion and Electron Sensor of the Rosetta Plasma Consortium

The ion and electron sensor (IES) is part of the Rosetta Plasma Consortium (RPC). The IES consists of two electrostatic plasma analyzers, one each for ions and electrons, which share a common entrance aperture. Each analyzer covers an energy/charge range from 1 eV/e to 22 keV/e with a resolution of 4%. Electrostatic deflection is used at the entrance aperture to achieve a field of view of 90°× 360° (2.8π sr). Angular resolution is 5°× 22.5° for electrons and 5°× 45° for ions with the sector containing the solar wind being further segmented to 5°× 5°. The three-dimensional plasma distributions obtained by IES will be used to investigate the interaction of the solar wind with asteroids Steins and Lutetia and the coma and nucleus of comet 67P/Churyumov–Gerasimenko (CG). In addition, photoelectron spectra obtained at these bodies will help determine their composition.     

Advanced techniques for plasma composition and dynamics measurements

Magnetic and RF mass spectrometers have been used routinely in ionospheric research, while traditional ionospheric, magnetospheric, and interplanetary plasma measurements have been made with several types of electrostatic analyzers. Proper interpretation of these data is possible if the spectral peaks are well defined, although ambiguities between fast, light ions and slow, heavy ions cannot always be satisfactorily resolved. Recent and planned experiments involve the study of plasmas which are sufficiently energetic that the spectral peaks overlap. Furthermore, these studies of ionosphere/magnetosphere coupling and of the interaction of the solar wind with the atmospheres of Venus and comets require unambiguous identification of the ion masses with simultaneous mapping of the three-dimensional velocity distribution function of each ion species. This challenge has been partially met by several new types of instruments; the two most common types involve either (1) sequential electrostatic and magnetic analyses or (2) sequential electrostatic and time-of-flight analyses. Some new instruments have also incorporated measurements of total kinetic energy, electric charge, or secondary emission coefficients as diagnostic tools. This paper reviews these recent advances and points out areas where further development is expected and needed.     

外海上璀璨的明珠

在赫尔辛基外海的一串小岛上,芬兰城堡静静地矗立着。一眼望去,她无疑是外海上璀璨的明珠......芬兰城堡建于250多年前,是现存于世的海防军事要塞之一,且在规模上令人惊叹。1991年,芬兰城堡已经被联合国教科文组织列入了世界遗产名录。     

The Solar Wind - Inner Heliosphere

The solar wind in the inner heliosphere, inside ~ 5 AU, has been almost fully characterized by the addition of the high heliographic latitude Ulysses mission to the many low latitude inner heliosphere missions that preceded it. The two major omissions are the high latitude solar wind at solar maximum, which will be measured during the second Ulysses polar passages, and the solar wind near the Sun, which could be analyzed by a Solar Probe mission. Here, existing knowledge of the global solar wind in the inner heliosphere is summarized in the context of the new results from Ulysses.     

The three-dimensional extent of a high speed solar wind stream

A primary goal of the Ulysses mission is to study the 3-dimensional structures making up the interplanetary medium, and example of which is the high speed solar wind stream observedin situ by Ulysses beginning in July 1992. In order to study the longitudinal extent of this stream as a function of Ulysses' increasing heliographic latitude, a second point of reference is required to separate spatial and temporal variations. Such a reference point is provided at Jupiter by a class of Jovian radio bursts, whose occurrence rate varies in a predictable way with solar wind speed. Using thein situ and remote observations from Ulysses, the extent of the high speed stream at 5 AU is mapped and compared to the associated coronal hole boundary on the Sun.     

Tests of a full-sized mechanically rechargeable zinc-air battery inan electric vehicle

A mechanically rechargeable zinc-air battery that has high power density and fast refueling capability is described. The battery is built from modules of 32 or 44 cells connected in series, and the modules can be arranged in any combination of series and parallel connections, and in practical quantity, according to the requirements of the vehicle, motor, and controller. The results of laboratory and in-vehicle tests of a zinc-air battery consisting of two 32-cell modules connected in series, with nominal voltage of 75 V and nominal capacity of 216 Ah, are presented     

Ulysses observations of solar wind plasma parameters in the ecliptic from 1.4 to 5.4 AU and out of the ecliptic

We report observations of radial and latitudinal gradients of Ulysses plasma parameters. The solar wind velocity increased rapidly with latitude from 0° to 35°, then remained approximately constant at higher latitudes. Solar wind density decreased rapidly from 0° to 35° of latitude, and also was approximately constant beyond that latitude. The mass flux similarly decreased away from the equator (but less than the density), whereas the momentum flux was relatively constant. The radial gradient of the entropy at high latitude indicated a value for the polytrope index of about 1.72 (close to adiabatic); the in-ecliptic estimates of radial gradients for temperature and entropy may be biased by temporal variation. A striking increase in the alpha particle-proton velocity difference with latitude is found.     

Investigation Into Cost-Effective Propulsion System Options for Small Satellites

The paper summarizes research into cost-effective propulsion system options for small satellites. Research into the primary cost drivers for propulsion systems is discussed and a process for resolving them is advanced. From this analysis, a new paradigm for understanding the total cost of propulsion systems is defined that encompasses nine dimensions – mass, volume, time, power, system price, integration, logistics, safety and technical risk. This paradigm is used to characterize all near-term propulsion technology options. From this effort, hybrid rockets emerges as a promising but underdeveloped technology with great potential for cost-effective application. A dedicated research program was completed to characterize this potential. This research demonstrated that hybrid rockets offer a safe, reliable upper stage option that is a versatile, cost-effective alternative to solid rocket motors. Finally, an innovative technique was derived to parametrically combine the diverse cost dimensions into a useful, quantifiable figure of merit for mission and research planning. Overall, it is shown that the most cost-effective solution is found by weighing all options along the nine dimensions of the cost paradigm within the context of a specific mission.     

Radiative damping of gravity waves in the solar atmosphere

The nonlocal character of the radiation field sianificantly modifies the radiative damping of perturbations in the solar photosphere. Gravity waves are not usually considered to exist in the solar photosphere because the radiative damping time, when based on the Newtonian approximation, is too short. However, this restriction does not apply to low order gravity waves. In fact, with the inclusion of nonlocal effects, the radiative damping for low order gravity waves becomes negative for some region in the photosphere and thus acts as a driving mechanism for gravity waves there.