Wireless Sensor Networks – A potential tool to probe for water on Moon

A Wireless Sensor Network for in situ probing of lunar water/ice is proposed. The mission scenario in single and multi-tier architectures for probing water in a permanently shadowed region of the Moon and different scenarios of exploration are discussed. The ideas presented in the paper are a positive assertion of feasibility for the sensor node hardware, given current levels of technological advancements.     

The possibilities of polar meteorology,environmental remote sensing,communications and space weather applications from Artificial Lagrange Orbit

The ability to observe meteorological events in the polar regions of the Earth from satellite celebrated an anniversary, with the launch of TIROS-I in a pseudo-polar orbit on 1 April 1960. Yet, after 50 years, polar orbiting satellites are still the best view of the polar regions of the Earth. The luxuries of geostationary satellite orbit including rapid scan operations, feature tracking, and atmospheric motion vectors (or cloud drift winds), are enjoyed only by the middle and tropical latitudes or perhaps only cover the deep polar regions in the case of satellite derived winds from polar orbit. The prospect of a solar sailing satellite system in an Artificial Lagrange Orbit (ALO, also known as “pole sitters”) offers the opportunity for polar environmental remote sensing, communications, forecasting and space weather monitoring. While there are other orbital possibilities to achieve this goal, an ALO satellite system offers one of the best analogs to the geostationary satellite system for routine polar latitude observations.     

In situ analysis of Europa ices by short-range melting probes

A key aspect for understanding the astrobiological potential of planets and moons in the Solar system is the analysis of material embedded in or underneath icy layers on the surface. In particular in case of the icy crust of Jupiters moon Europa such investigation would be of greatest interest. For a Europa lander to be launched in the 2020–2030 timeframe, we propose to use a simplified instrumented melting probe which is able to access and sample depths of a few meters without the necessity of heavy and complicated drilling equipment.     

Return to Europa: Overview of the Jupiter Europa orbiter mission

Missions to explore Europa have been imagined ever since the Voyager mission first suggested that Europa was geologically very young. Subsequently, the Galileo spacecraft supplied fascinating new insights into this satellite of Jupiter. Now, an international team is proposing a return to the Jupiter system and Europa with the Europa Jupiter System Mission (EJSM). Currently, NASA and ESA are designing two orbiters that would explore the Jovian system and then each would settle into orbit around one of Jupiter’s icy satellites, Europa and Ganymede. In addition, the Japanese Aerospace eXploration Agency (JAXA) is considering a Jupiter magnetospheric orbiter and the Russian Space Agency is investigating a Europa lander.     

Compact frequency standard using atoms trapped on a chip

We present a compact atomic frequency standard based on the interrogation of magnetically trapped ⁸⁷Rb atoms. Two photons, in the microwave and radiofrequency domain excite the atomic transition. At a magnetic field of 3.23 G this transition from ∣F = 1, m_F = −1〉 to ∣F = 2, m_F = 1〉 is 1st order insensitive to magnetic field variations. Long Ramsey interrogation times can thus be achieved, leading to a projected stability in the low 10⁻¹³ at 1 s. This makes this device a viable alternative to LITE and HORACE as a good candidate for replacing or complementing the rubidium frequency standards and passive hydrogen masers already on board of the GPS, GLONASS, and GALILEO satellites. Here we present preliminary results. We use an atom chip to cool and trap the atoms. A coplanar waveguide is integrated to the chip to carry the Ramsey interrogation signal, making the physics package potentially as small as (5 cm)³. We describe the experimental apparatus and show preliminary Ramsey fringes of 1.25 Hz linewidth. We also show a preliminary frequency stability σ_y = 1.5 × 10⁻¹²τ^−1/2 for 10 < τ < 10³ s. This represents one order of magnitude improvement with respect to previous experiments.     

Pre-storm behaviour of NmF2 and TEC (GPS) over equatorial and low latitude stations in the Indian sector

The pre-storm behavior of NmF₂ and TEC over an equatorial station, Trivandrum (8.47°N, 76.91°E, dip 0.6°S) and a low latitude station, Waltair (17.7°N,83.3°E, dip 20°N) has been studied for a total of 18 strong geomagnetic storms with DST ? −100 nT. The simultaneous measurements of GPS-TEC and NmF₂ over Trivandrum and Waltair during the period 2000–2005 have been considered for the present study. It is found that there is a substantial increase in NmF₂ and TEC before the onset of the storm over Waltair, while the increase is not present at Trivandrum. The origin of pre-storm enhancements in electron density still remains unresolved owing to several conditions in their potential sources and occurrence mechanisms. In the present study an attempt is made to identify the possible mechanisms responsible for such enhancements in electron density of the F-region.     

Characteristics of field line resonance type geomagnetic pulsations and variations of plasmaspheric plasma density distribution

The period of field line resonance (FLR) type geomagnetic pulsations depends on the length of the field line and on the plasma density in the inner magnetosphere (plasmasphere), where field lines are closed. Here as FLR period, the period belonging to the maximum occurrence frequency of the occurrence frequency spectrum (equivalent resonance curve) of pulsations has been considered. The resonance system may be replaced by an equivalent resonant circuit. The plasma density would correspond to the ohmic load. The plasma in the plasmasphere originates from the ionosphere, thus FLR period, occurrence frequency are also affected by the maximum electron density in the ionosphere. The FLR period has shown an enhancement with increasing F region electron density, while the occurrence frequency indicated diminishing trend (possible damping effect). Thus, the increased plasma density may be the cause of the decreased occurrence of FLR type pulsations in the winter months of solar activity maximum years (winter anomaly).     

Spatial variation of the supersonic thermal plasma flow downstream of the termination shock

In this paper we start from the most recently observed fact that the solar wind plasma after passage over the termination shock is still supersonic with a Mach number of about 2. To explain this unexpected phenomenon and to predict the evolution of properties of the downstream plasma flow we here consider a two-fluid proton plasma with pick-up protons as a separate suprathermal, second proton fluid. We then formulate a self-consistent system of hydrodynamical conservation equations coupling the two fluids by dynamical and thermodynamical coupling terms and taking into account the effects of newly incorporated protons due to charge exchange with the H-atoms in the heliosheath. This then allows us to predict that in the most probable case the solar wind protons will become subsonic over a distance of about 30 AU downstream of the shock. As we can also show, it may, however, happen that the plasma mixture later again reconverts to a supersonic signature and has to undergo a second shock before meeting the heliopause.     

A model of the effects of heavy ion radiation on human tissue

In heavy ion radiotherapy and space travel humans are exposed to energetic heavy ions (C, Si, Fe and others). This type of irradiation often produces more severe biological effects per unit dose than more common X-rays. A new Monte Carlo model generates a physical space with the complex geometry of human tissue or a cell culture based model of tissue, which is affected by the passage of ionizing radiation. For irradiation, the model relies on a physical code for the ion track structure; for tissues, cellular maps are derived from two- or three-dimensional confocal microscopy images using image segmentation algorithm, which defines cells as pixilated volumes. The model is used to study tissue-specific statistics of direct ion hits and the remote ion action on cells. As an application of the technique, we considered the spatial pattern of apoptotic cells after heavy ion irradiation. The pattern of apoptosis is modeled as a stochastic process, which is defined by the action cross section taken from available experimental data. To characterize the degree of apoptosis, an autocorrelation function that describes the spatial correlation of apoptotic cells is introduced. The values of the autocorrelation function demonstrate the effect of the directionality of the radiation track on the spatial arrangements of inactivated cells in tissue. This effect is intrinsic only to high linear-energy-transfer radiation.     

Normalized ionization yield function for various nuclei obtained with full Monte Carlo simulations

Several recent results important for production of ion pairs in the Earth atmosphere by various primary cosmic ray nuclei are presented. The direct ionization by various primary cosmic ray nuclei is explicitly obtained. The longitudinal profile of atmospheric cascades is sensitive to the energy and mass (charge) of the primary particle. In this study different cosmic ray nuclei are considered as primaries, namely Helium, Oxygen and Iron nuclei. The cosmic ray induced ionization is obtained on the basis of CORSIKA 6.52 code simulations using FLUKA 2006 and QGSJET II hadronic interaction models. The energy of the primary particles is normalized to GeV per nucleon. In addition, the ionization yield function Y is normalized as ion pair production per nucleon. The obtained ionization yield functions Y for various primaries are compared. The presented results and their application are discussed.