Commission H (Waves in Plasmas) Activity Report


November 1, 2002

Y. Omura, T. Okada, and H. Matsumoto


1. Research Project



  The Mars exploring spacecraft Nozomi which ISAS launched in 1998 is currently in a cruising orbit with the Mars orbit injection scheduled for early January 2004. The science instruments onboard Nozomi originally intended for the science observation in Mars orbit have been conducting some observation in the cruising orbit resulting in very fruitful rewards. On April 26(JST) we found a problem with part of communication and attitude control systems and all the science observations have since been suspended. The most likely cause might be due to impact of high energy particles from the sun during CME event accompany with the X1.5 class solar flare starting on April 21 which could have caused a problem with part of the power system onboard Nozomi. We are now in the process of identifying the details of the problem and the way for recovery, but it could take up to 6 months or so. During this period, no science observation will be conducted.



The GEOTAIL spacecraft has been operated without any major troubles. The spacecraft is expected to be in a good condition at least until the next long eclipse in 2003.


(R-3)  EXOS-D

The EXOS-D (Akebono) spacecraft has attained the 13 years of successful operation without any major troubles. The regular data acquisition is continued at stations in Japan, Sweden and Canada. The VLF database including the ground waveform observations have been constructed and are available on request.


(R-4)  Polar Patrol Balloon (PPB) experiment in Antarctica

   National Institute of Polar Research (NIPR) will carry out long-duration balloon experiment in Antarctica in late December 2002 to late January 2003.  Three balloons with identical instrumentation will be launched from Syowa Station successively with longitudinal separation of about 300 km (0.5 hour in MLT). It will take 2 weeks for these balloons to go around the Antarctica along a latitude circle of 69S. We named this experiment as "Polar Patrol Balloon" (PPB). Trajectory of these balloons will traverse magnetic latitude range of 60-80 degrees, crossing various boundary regions in the magnetosphere such as plasma pause, LLBL, PSBL and the cusp. The formation flight of these balloons will be able to separate spatial and temporal variations of the phenomena occurring in these boundary regions. The observed data will be directly transferred to Japan by Iridium satellite telephones, as well as telemetered to the ground at Rothera and Zhongshan Stations in Antarctica in collaboration with UK and Chinese antarctic research expeditions. Onboard instruments are ULF/ELF/VLF wave receiver, aurora X-ray imager, DC electric field instrument, 3-axis fluxgate magnetometer, and the ionospheric total electron content measurement using GPS. The wave instrument measures a magnetic component with a big loop antenna surrounding the balloon itself (40m in diameter). The instrument measures waveform in 0.2-4.0 Hz band, wave intensities at 300, 600, 1200 and 2400 Hz with a sampling rate of 2Hz, and a rough spectrum (5, 10, 20 and 36 kHz) with a sweep period of 5s. NIPR calls for collaboration with scientists operating ground-based ULF/ELF/VLF instruments in Antarctica. Contact person for this experiment is Prof. H. Yamagishi, NIPR (


(R-5)  ELF wave observation at Syowa station, Antarctica

ELF magnetic field observations in the frequency range of 1-500 Hz have been carried out at Syowa station since February 2000, using two horizontal search coil magnetometers. Good waveform of ELF transients were observed in correspondence with sprites and elves identified in the northern hemisphere.


(R-6)  Lunar Radar Sounder experiment on-board SELENE spacecraft

The Lunar Radar Sounder (LRS) experiment on-board the SELENE will provide subsurface stratification and tectonic features in the shallow part (several km depth) of the lunar crust, by using an FM/CW radar technique in HF frequency range. Knowledge of the subsurface structure is crucial to better understanding not only of the geologic history of the moon, but also of the regional and global thermal history of the Moon, and also of the origin of the Earth-Moon system. In addition to the subsurface radar experiment, LRS will provide the spectrum of plasma waves, and solar and planetary radio waves in wide frequency range covering from 10 Hz to 30 MHz. The SELENE spacecraft will be launched in 2005. 


 (R-7)  Wave Form Capture onboard the SELENE spacecraft 

This receiver is a part of the lunar radar sounder (LRS) and is composed of two types of digital receivers, a digital sweep frequency analyzer which covers from 1kHz to 1MHz and a wave form receiver which covers from 100 Hz to 100 kHz.  In the former, the A/D converted signal is converted into a narrow band signal by a programmable down converter (PDC) and its frequency spectrum is obtained by the FFT. Spectra of the whole frequency range are obtained by sweeping the center frequencies of the converted signal. The latter, the A/D converted data are transmitted efficiently by the data compression. This will observe plasma waves in the magnetosphere and the solar wind at the lunar distance and wave phenomena in the lunar wake.


(R-8) Alaska Rocker Project (ARP)

In order to promote and help students and young engineers to learn the space science and technology, a working group named as Society of Alaska Rocket Project has been built up in SGEPPS (the Society of Geomagnetism and Earth, Planetary and Space Science). In order to measure the electron density in the ionosphere in the altitude lower than 70 km which are not clear in the IRI model, the ARP members and ASRP (Alaska Student Rocket Project) members in Alaska launched the SRP-4 rocket carrying an electron DC probe and a radio receiver to observe the LF air-plane navigation wave and AM broadcasting waves. Full wave analysis using data by the rocket experiment and MF radar, the electron density profile at altitude 50-70km was made clear which is different from the IRI model.


2. Past Meetings


l         The 4th YRP Symposium on Cooperation between Industry, Academia and Government, Yokosuka Telecom Research Park, Kanagawa, Japan, 10-11 July 2002.


l         COSPAR Colloquium gFrontiers of Magnetospheric Plasma Physicsh, Institute of Space and Astronautical Science, Sagamihara, Japan, 24-26 July 2002.


l         The 26th NIPR Symposium, Tokyo, Japan, 30-31 July 2002.


l         The 27th General Assembly of the International Union of Radio Science, Maastricht, 17-24 August 2002.


l         2002 Joint Conference of Hokuriku Chapters of Electrical Societies, Fukui University, Fukui, Japan, 18-19 September 2002.


l        The Second Korea-Japan-China Joint Workshop on Space Weather, Rikubetsu, Hokkaido, Japan, 2-4 October, 2002.


l        34th COSPAR Scientific Assembly(2nd World Space Congress) Houston U.S.A., 10-20 October 2002.


l         The 46th Space Sciences and Technology Conference, Communications Research Laboratory, Tokyo, Japan, 23-25 October 2002.



3.  Future Meetings


l         The 112th General Assembly of Society of Geomagnetism and Earth, Planetary and Space Sciences, The University of Electro-Communications, Tokyo, Japan, 11-14 November 2002.


l         AGU 2002 Fall Meeting, San Francisco U.S.A., 6-10 December 2002.


l         IUGG 2003, Sapporo, Japan, June 30 – July 11, 2003.