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ONE
STEP CLOSER TO JUPITER
UML received a NASA grant to develop
a high-capability Planetary Advanced Radio
Sounder (PARS). This high-power, high-data rate remote-sensing
instrument will provide critical and diverse measurements
necessary for detection of subsurface oceans and for characterization
of ionospheres of moons, magnetosphere-moon interactions,
and permanent or induced magnetic fields for missions to icy
moons and other bodies in the solar system. This information
is critical to determining if life is possible on moons of
this type.
The first opportunity to fly the PARS instrument is on the
nuclear electric power and propulsion (NEPP) enabled Jupiter
Icy Moons Orbiter (JIMO) mission whose scientific objectives
include determining the presence and distribution of subsurface
water in the icy moons and determining the nature of magnetosphere-moon
interactions [Science Forum, 2003].
The
Australian TELSTRA Corporation gave close to two million dollars
to UML for the development of a network of fourteen
Digisondes for deployment in Australia. This network now provides
real time information on the status of the earth's ionosphere
to the Australian Over-the-Horizon Radar Operations Center
that monitors the airplane and ship traffic to control illegal
drug flow into the country.
Started in April 1996, UML and the Communications
Research Laboratory in Tokyo, Japan, jointly sponsored a large
international campaign, the Pacific
Region Equatorial Anomaly Studies in Asia (PREASA). An
eleven year program is planned to investigate the solar cycle
dependence, involving scientists and institutes from Japan,
USA, China, Taiwan, Russia, Australia, Canada, Korea, Thailand,
Indonesia and New Guinea.
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IMAGE
THE INVISIBLE
The matter in space, call plasma, is so tenuous that it is
invisible to human eyes. NASA
launched a satellite named IMAGE equipped with instruments
using cutting edge technology and ideas to take pictures of
the invisible materials in space. Onboard IMAGE is the radio
plasma imager (RPI) built here at UML using the
technologies we developed for ionospheric sounding from the
ground. This new technique, combined with the mathematical
density inversion algorithm, measures the plasma density in
situ at the satellite location and remotely and near instantaneously
along a magnetic field line from one hemisphere to the other
down to as low as half an Earth radius (Re) in altitude. From
these observations, we are developing empirical models that
specify the density as functions of radial distance, latitude,
local time, and distance along the field line from the earth’s
surface, solar wind conditions, geomagnetic conditions, and
other possible factors that affect density distributions.
The models can describe the statistical behaviors of the plasma
distribution and can also provide snapshots of the plasma
conditions on occasions. In one example with 6 continuous
measurements in 20 min, a
two-dimensional (2-D) density snapshot in a morning meridian
plane is derived. Dynamical processes that cause variations
from the average models, such as plasmasphere depletion/refilling
processes, plasma convection tail formation, and polar cap
density enhancements during magnetically active periods can
be studied.
The Air Force Research
Laboratory (AFRL) funded a four-year, three million dollar research
program for studying the electrodynamics of the ionosphere
using digital ionosonde and other HF techniques. The research
involves equatorial ionospheric irregularities, polar
cap monitoring of the ionosphere, ionospheric modification
diagnostics, visualization technique development for display
of multidimensional geophysical data/models, and the development
of a low power and space borne digital ionosonde.
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