IMAGE
First Light
NASA's IMAGE mission, a unique
satellite dedicated to space storms, has returned its
first pictures of electrified gas surrounding our
planet.
June
5, 2000 -- "First-light" pictures from
NASA's Imager for Magnetopause to Aurora Global
Exploration (IMAGE) spacecraft have revealed the
global ebb and flow of hot, electrified gas (plasma)
around the Earth in response to the solar wind. Severe
disturbances in this region controlled by the Earth's
magnetic field (the magnetosphere) are capable of
disrupting satellites, telephone and radio
communications, and power systems.
"IMAGE is the first weather
satellite for space storms," said Dr. James L.
Burch, Principal Investigator for IMAGE at Southwest
Research Institute, San Antonio, Texas. "This
revolutionary spacecraft makes these invisible storms
visible. In a sense, IMAGE allows us to view the Earth
through plasma-colored glasses. We eagerly anticipate
the arrival of severe solar weather associated with
solar maximum, which we are now entering."
Above: This picture, recorded by
IMAGE's Extreme Ultraviolet Imager, shows solar
ultraviolet radiation scattered from ionized helium in
the Earth's extended atmosphere. The ionized helium
envelope is 2 to 3 times the size of the Earth.
Irregularities at the fringe of the image (upper left)
indicate magnetic storm activity. This is the first
time such features have been imaged. This is a
selected frame from a sequence which is available as a
1.6
Mb Quicktime movie.
Previous spacecraft explored the
turbulent magnetosphere by detecting particles and
fields in the immediate vicinity of the spacecraft.
This technique limited their vision to small portions
of this vast and dynamic region, which extends beyond
the Moon on the Earth's night side.
"The old way of tracking
magnetic storms is like trying to understand severe
thunderstorms in the Midwest by driving around with a
rain gauge out the window," said Dr. Thomas
Moore, IMAGE Project Scientist at NASA's Goddard Space
Flight Center, Greenbelt, Md. "With IMAGE, we
will see the big picture, just like entire storm
systems appear on the evening news with weather
satellites."
The first pictures from IMAGE were
presented at a press conference during the spring
meeting of the American Geophysical Union May 31 in
Washington, D.C.
"These first images are an
enticing glimpse at the spectacular results expected
from IMAGE once we encounter really heavy weather in
space," said Dr. James Green, Deputy Project
Scientist for IMAGE at Goddard.
All
spacecraft systems have been successfully deployed and
are operating normally. All scientific
instruments are operating as expected and are
returning images.
The Radio Plasma Imager instrument
provides a three-dimensional view of the plasmasphere
by sounding it with radio pulses, like an ultrasound
image of the human body. To accomplish this, it uses
the longest antennas ever deployed in space, longer
than the height of the Empire State Building.
Left: The Radio Plasma Imager (RPI)
on IMAGE is the first-of-its-kind instrument designed
to study the dynamics of the magnetosphere by using
radar techniques. In order to generate very low
frequency radio waves and to receive the resulting
echoes, RPI uses very long dipole antennas. IMAGE has
2 spin-plane dipole antennas (along the spacecraft X
and Y axis) and one spin-axis dipole antenna (along
the spacecraft Z axis). The X and Y axis antennas are
1647 ft or 500 meters tip-to-tip each. These antennas
are 182 ft longer than the height of the Empire State
Building, making the IMAGE spacecraft the largest
dipole antenna system currently in space. This is a
selected frame from a sequence which is available as a
100
kb Quicktime movie.
A suite of three Neutral Atom
Imaging instruments is recording the glow of fast
atoms coming from throughout the Earth's magnetic
field. This reveals the shape and motion of the clouds
of plasma that make up a magnetic storm.
The
Far Ultraviolet Imaging instrument is collecting the
first-ever images from space of the Earth's proton
aurora. The aurora, commonly known as the northern and
southern lights, is a ghostly light show seen most
often at high latitudes of Earth. The dance of lights
that is visible from the ground is caused by electrons
striking and lighting up the atmosphere much like
electricity lights up a television screen. The proton
aurora is invisible to the naked eye and has never
been viewed from space; from the ground, it is visible
only in far-ultraviolet wavelengths.
Right: Aurora are caused by the
interaction of precipitating charged particles
(electrons and ions) with the neutral gases of our
atmosphere. Light from the Earth's aurora occur
principally in two oval-shaped bands lying between ~65
and 75 degrees magnetic latitude and centered on the
northern (aurora borealis) and southern (aurora
australis) magnetic poles. IMAGE observes the aurora
in several important wavelengths and has captured its
first geomagnetic substorm (pictured above). These
observations are caused by precipitating electrons.
This is a selected frame from a sequence which is
available as a 145
kb Quicktime movie.
The Extreme Ultraviolet Imager is
capturing the first global images of the plasmasphere,
which is the tenuous extension of the Earth's
electrically charged upper atmosphere, or ionosphere.
The plasmasphere extends about 12,500 miles (20,000
kilometers) into space. Images from this region will
provide a sensitive indicator of the onset of magnetic
storm activity.
Southwest Research Institute manages
the IMAGE project and leads the IMAGE science
investigation. The IMAGE Principal Investigator is
James L. Burch.
Related Links:
IMAGE
First Light Movies and Pictures - from NASA/GSFC
IMAGE
home page - from the Southwest Research
Institute
IMAGE
home page - from NASA/GSFC
More Science@NASA stories about
IMAGE:
Innovative
Space Weather Mission Nears Launch -- Feb. 24,
2000
The
RADAR Cop in Space -- March 24, 2000
Space
Weather Satellite Blasts Off -- March 27, 2000
Instruments on IMAGE include:
The Radio
Plasma Imager. The RPI will use radar echoes
in the frequency range 3 kHz to 3 MHz to detect and
monitor ionized gas (plasma) inside the
magnetosphere.
Far
Ultraviolet Imager. The FUI will take
pictures and spectra of the entire Earth along with
the auroral oval at ultraviolet wavelengths. The 3
instruments that combine to form the FUI instrument
package (GEO,
SI
and WIC)
will provide almost constant monitoring of auroral
activity from above our planet. The Earth is
surrounded by a cloud of neutral atoms and molecules
that is largely invisible from the ground. The
so-called 'geocorona' is an extension of Earth's
atmosphere into space. It is mostly made up of
hydrogen, because it's the lightest element. GEO
will also be used to detect these neutral atoms,
measure their energy and map their distribution.
Neutral
Atom Imagers. The neutral atom cameras will
detect neutral atoms created by ring
current ions and escaping auroral
ions that collide and exchange charge with the
cold, geocoronal hydrogen gas. This will allow
scientists to indirectly monitor and explore the
ring current and auroral ion fountains.
Extreme
Ultraviolet Imager. The EUVI will detect
ultraviolet photons from the Sun that are scattered
by helium ions in the plasmasphere, a torus of cold
dense plasma surrounding the Earth in the inner
magnetosphere. A sophisticated deconvolution
technique will be used to translate the photon
counts into images of the plasmasphere.
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