Design,Development, Implementation,and On-orbit Performance of the Dynamic Ionosphere CubeSat Experiment Mission

Funded by the NSF CubeSat and NASA ELaNa programs, the Dynamic Ionosphere CubeSat Experiment (DICE) mission consists of two 1.5U CubeSats which were launched into an eccentric low Earth orbit on October 28, 2011. Each identical spacecraft carries two Langmuir probes to measure ionospheric in-situ plasma densities, electric field probes to measure in-situ DC and AC electric fields, and a science grade magnetometer to measure in-situ DC and AC magnetic fields. Given the tight integration of these multiple sensors with the CubeSat platforms, each of the DICE spacecraft is effectively a “sensor-sat” capable of comprehensive ionospheric diagnostics. The use of two identical sensor-sats at slightly different orbiting velocities in nearly identical orbits permits the de-convolution of spatial and temporal ambiguities in the observations of the ionosphere from a moving platform. In addition to demonstrating nanosat-based constellation science, the DICE mission is advancing a number of groundbreaking CubeSat technologies including miniaturized mechanisms and high-speed downlink communications.     

On choice of turbulence models and grid parameters for computation of flows in diffuser ducts

The results of analyzing the reliability of six turbulence models are presented as applied to calculations of flows in the asymmetric plane diffuser. The influence of grid parameters upon the calculation results is studied and the accuracy of flow separation and reattachment points prediction is determined. Also carried out is the comparison of processor time spent for calculations with the aid of each model.     

Charged particles on the Earth–Jupiter–Europa spacecraft trajectory

Charged particle fluxes on the trajectory of future Russian space research mission to Jupiter and its satellite Europa are investigated. The existing experimental data and models of Jupiter’s main magnetic field and radiation belts are summarized. Preliminary results of computations of energetic particle fluxes and radiation doses for each stage of the flight are given. Special attention is paid to estimation of radiation conditions in Europa’s orbit and on its surface; influence of the satellite on spatial distribution of the fluxes of charged particles of various energies is studied.     

Progress of super-pressure balloon development: A new “tawara” concept with improved stability

The super-pressure balloon (SPB) has been expected to be a flight vehicle that can provide a long flight duration to science. Since 1997, we have developed the SPB. Now we are at the phase of developing an SPB of a practical size. In 2009, we carried out a test flight of a pumpkin-shaped SPB with a 60,000 m³ volume. The undesirable result of this flight aroused us to resolve the deployment instability of the pumpkin-shaped SPB, which has been known as one of the most challenging issues confronting SPB development. To explore this deployment issue, in 2010, we carried out a series of ground tests. From results of these tests, we found that an SPB design modified from pumpkin, named “tawara”, can be a good candidate to greatly improve the deployment stability of the lobed SPB.     

Evidence for ion energy dispersion in the polar cusp related to a northward-directed IMF

Data from the particle experiment aboard the AUREOL-3 polar satellite show that about 30% of the summer cusp crossings are characterised by a clear latitudinal energy dispersion of the solar wind ions. This energy-latitude correlation is observed at very high latitudes, 80° – 85°, near the polar boundary of the cusp, as an increase of the ion average energy with latitude. These structures have a typical latitude extent of 1° – 2° at ionospheric heights and correspond to a northward-directed IMF. These observations are consistent with a sunward convection of the foot of the magnetic flux tubes recently merged with a northward directed interplanetary magnetic field.     

Space development: social and political implications

Far-reaching social and political issues are implicit in any discussion of large-scale space development. This Viewpoint argues that the evolution of appropriate political institutions to deal with these issues is likely to be at least as important as the development of new technology. If large-scale space development is to take place, global international cooperation will be essential and such cooperation will have to be underpinned by enhanced institutional and legal structures. In the shorter term, an appropriate institutional response may be the creation of a World Space Agency. However, in the longer term, we should probably view a world space programme as falling within that class of global concerns that would be most appropriately managed by a federal world government.     

Whistler mode propagation in the earth and planetary magnetospheres and ray tracing techniques

Whistler mode wave phenomena observed in the earth's environment and in the planetary magnetospheres, such as in the vicinity of the Jupiter, Venus, and Saturn are reviewed, Importance of ray tracing technique is stated in connection with the interpretation of these phenomena. A historical review of ray tracing technique is then given. Finally the most recent ray tracing technique, such as 3-D ray tracing in a non-dipolar background magnetic field model is introduced.     

SAMBO-GEOS : Electric field measurements in the disturbed ionosphere and magnetosphere

Measurements of the electric field in the ionosphere and the equatorial plane during the pre-onset and actives phases of a substorm (March 4, 1979) are compared. Correlations and disagrements between the measurements are considered. The preliminary conclusion is reached that the model of electrojet polarisation proposed by CORONITI and KENNEL (1972) could possibly explain part of our observations.     

Adaptive Tracker Field-of-View Variation Via Multiple Model Filtering

Adaptive estimation using multiple model filtering is investigated as a means of changing the field of view as well as the bandwidth of an infrared image tracker when target acceleration can vary over a wide range. The multiple models are created by tuning filters for best performance at differing conditions of exhibited target behavior and differing physical size of their respective fields of view. Probabilistically weighted averaging provides the adaptation mechanism. Each filter involves online identification of the target shape function, so that this algorithm can be used against ill-defined and/or multiple-hot-spot targets. When each individual filter has the form of an enhanced correlator/linear Kalman filter, computational loading is very low. In contrast, an extended Kalman filter processing the raw infrared data directly and assuming a nonlinear constant turn-rate dynamics model provides superior tracking capability, especially for harsh maneuvers, at the cost of a larger computational burden.