Jim Sahli							Embargoed Until
Goddard Space Flight Center			9 a.m. EDT, May 23, 1996
Greenbelt, Md.  
(301) 286-0697

RELEASE NO:  96-34

Spacecraft Sends Best Images Yet Of Earth's "Northern And Southern Lights"

	Investigators working with NASA's new POLAR satellite are releasing today the 
best images ever made from space of the Earth's aurora.  The images are being 
presented and described at the meeting of the American Geophysical Union in 
Baltimore, Md.

	The new spacecraft data include "remarkably clear views of the aurora borealis 
in the daytime," says Dr. Louis A. Frank of the University of Iowa, Iowa City.  Frank 
is principal investigator for one of POLAR's onboard instruments, the Visible Imaging 
System.

	The new images and information will help scientists to better understand the 
transport of energy from the Sun to the Earth by the "solar wind."   The "wind" is a 
torrential and turbulent outflow of electrified, magnetized gas that flows from the 
Sun's outer atmosphere or corona and streams through the solar system, reaching 
past the orbits of all the known planets.

	POLAR also has acquired the first global images of the Earth's aurora in X-
rays, with samples released at the AGU meeting and by NASA today.  "The 
average person doesn't realize that the Northern Lights also shine in X-rays 
and other radiation that the human eye can't see," says Dr. David Chenette of the 
Lockheed Martin Advanced Technology Center, Palo Alto, California.  "The 
X-ray images will help us to understand the effects of energetic electrons 
hitting the upper atmosphere of the Earth," Chenette adds.  "The more powerful the 
stream of incoming electrons, the stronger the X-rays they stimulate in the aurora."  
Chenette is principal investigator for another onboard instrument, the PIXIE or 
POLAR Ionospheric X-ray Imaging Experiment.
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	"The aurora also emits a lot of light at far ultraviolet wavelengths" says  Dr. 
George E. Parks, University of Washington, Seattle.  "I'm thrilled by the ultraviolet 
images from POLAR," he adds.  Parks is principal investigator for POLAR's UltraViolet 
Imaging experiment.  "The images are of unprecedented clarity and sensitivity for 
simultaneous views of an entire auroral oval."  There are two auroral ovals on Earth, 
one each surrounding the north and south geomagnetic poles.  "We can see how the 
entire oval reacts around the world as a magnetic storm or other disturbance 
develops.  Already we see major differences in the response of the dayside and 
nightside aurora."

	POLAR was launched from Vandenberg Air Force Base, Calif., Feb. 24 aboard a 
Delta rocket.  It is orbiting the Earth every 17 1/2 hours in a large, elliptical orbit 
that carries the satellite high over the northern polar region.  The satellite joins the 
previously launched WIND spacecraft as principal components of NASA's Global 
Geospace Science program, the first phase of NASA's Solar Connections Program and 
the primary U.S. contribution to the International Solar Terrestrial Physics Program 
(ISTP).  Both spacecraft were built for NASA by the Lockheed Martin Corp. of East 
Windsor, N.J.. 

	Data from the two spacecraft are transmitted several times each day via the 
Deep Space Network to NASA's Goddard Space Flight Center in Greenbelt, Md., 
where it is processed and distributed for analysis to the teams of scientists 
associated with the scientific instruments.  Goddard is managing the program and is 
responsible for operating the spacecraft.

	"POLAR is crucial to the ISTP as it shows the reaction of the upper atmosphere 
to magnetospheric  disturbances triggered by moving phenomena in the solar wind," 
says Dr. Mario Acuna of the Goddard Center.  Acuna is ISTP Project Scientist and a 
veteran investigator of magnetic fields in the solar system.  "WIND measures the 
incoming solar wind activity,  while several other spacecraft, including POLAR, 
observe the response of the magnetosphere.  POLAR also tells us how and where 
energy is deposited in our atmosphere as a result of these events."  

	"The ultimate goal of this research is to be able to predict when and where 
disturbances might occur in the magnetosphere and ionosphere, and how severe they 
might be. Electromagnetic disturbances in space have been 
found to affect a number of complex high technology systems on which society is 
becoming more dependent," said Acuna.

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