Commission H (Waves in Plasmas) Activity Report
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.
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
Patrol Balloon (PPB) experiment in
National Institute of Polar Research (NIPR) will carry out long-duration
balloon experiment in
wave observation at Syowa station,
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.
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.
COSPAR Colloquium gFrontiers
of Magnetospheric Plasma Physicsh, Institute of Space
and Astronautical Science,
The 26th NIPR Symposium,
The 27th General Assembly of
2002 Joint Conference of
Hokuriku Chapters of Electrical Societies,
Second Korea-Japan-China Joint Workshop on Space Weather,
COSPAR Scientific Assembly(2nd World Space Congress)
The 46th Space Sciences and
Technology Conference, Communications Research Laboratory,
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.