Voyager 2 Observations of Corotating Interaction Regions (CIRs) in the Outer Heliosphere

We review observations from Voyager 2 of CIRs and merged CIRs in the outer heliosphere. The rather simple characteristics of the CIR-associated changes in plasma, magnetic field, and particles become more complex as observations are made at greater and greater distances. Pickup ions from charge exchange undoubtedly play an important role in the structure, but the full details are not yet understood. This revised version was published online in August 2006 with corrections to the Cover Date.     

Aircraft Interrogation Scheduling with ASTRO-DABS

In the ASTRO-DABS concept for surveillance and data link, aircraft are interrogated by one of three geostationary transmitter satellites, each covering 1/3 of the contiguous United States. Interrogation scheduling involves a roll call such that aircraft responses to receiving satellites do not overlap (garble). A simple approach is developed which utilizes range ordering of aircraft with respect to transmitter satellites, but is independent of receiver satellite locations and aircraft distribution. Bounds on roll-call duration are established, showing that interrogation of 80 000 aircraft requires between 4.0 and 6.4 seconds with the ASTRO-DABS transmission format. If aircraft distribution is regionally concentrated (i.e., clustered), the roll-call duration nears the lower bound, since fewer gaps between interrogations are needed to preclude garbling.     

Mechanism for assembling antenna in space

The development of large and precise space antennas is one of the most important topics in constructing space infrastructures. We evaluated an approach to assembling large and accurate space antennas which uses space robots. The assembly mechanism was launched together with the ETS-VII, the first telerobotic satellite from Japan, and its performance, including fully automatic assembling, was verified. The assembling-type antenna and the results of antenna assembly experiments are discussed     

Comparison of Antarctic riometer radio wave absorption and THEMIS mission energetic electron fluxes

Simultaneous observations of in situ plasma properties in the tail of the Earth’s magnetosphere and of ground based instruments, lying on the same geomagnetic field lines, have recently proved to yield significant new results. In most cases magnetosphere ionosphere interactions during the night-time northern hemisphere conditions are studied. Here, observations of energetic electrons in the tail of the Earth’s magnetosphere made by the THEMIS mission satellites are compared with auroral radio wave absorption determined by riometers in the Antarctic for sunlit conditions. Days for which satellites and riometers are connected by the same geomagnetic field line are selected using a geomagnetic field model. The six days analysed show clear associations between fluxes and absorptions in some cases. However, these do not necessarily correspond to conjugacy intervals. Hours of positive associations are 1.65 times those for negative associations, all hours and days considered (1.42–3.6 on five days and 0.58 on the other day). These computations are assumed appropriate since the footprints of the satellites used approximately follow corrected geomagnetic parallels for all six days studied. The use of a finer parameterization of geomagnetic models to determine conjugacy may be needed.