By Martin Burkey
An instrument built by Marshall Space Flight Center may soon help scientists answer questions about what creates the northern lights, those luminous streams that dance in the night skies of the arctic.
It is one of two instruments built by Marshall Space Flight Center that will be part of the 2,216 pound Polar spacecraft that is scheduled to begin its three-year mission with a launch Thursday from Vandenberg Air Force Base, Calif.
For space physicists, said Dr. Robert Carovillano, the Polar program scientist at NASA headquarters, "Polar is the main link in a very critical chain of laboratories in space which will study ... the chain of processes which intimately connects the sun to the Earth and the other planets."
Polar's orbit will loop over Earth's poles to study the movement of energetic particles above the polar regions. The launch represents the payoff for more than seven years of work by Marshall scientists and others.
Energetic particles, including electrons and protons, flow from the sun to create the solar wind, scientists say, speeding by Earth at up to a million mph. They are redistributed and accelerated by Earth's magnetic field, channeling large amounts of energy, as much as 100 million kilowatts each day, into Earth's polar regions.
Those particles collide with particles of the upper atmosphere, creating the aurora, sometimes call the northern lights.
The craft's Ultraviolet Imager is a camera designed to detect and to produce images of ultraviolet light of the aurora day and night, said Marshall's Dr. James Spann, co-investigator for the instrument.
Spann said the Ultraviolet Imager was developed and built by Marshall, The University of Alabama in Huntsville and Science and Engineering Associates of Albuquerque, N.M. It was assembled and tested at Marshall. The optics were aligned at UAH.
"It will allow us to look at the aurora with greater precision ... due to the fact we will not be bothered by visible sunlight as much as instruments in the past," he said.
"The big thing we don't know is ... the source that causes the aurora," he said. "There are a lot of questions as to what generates the substorm where these charged particles come from. We will be better able to measure the energy flux and make some assessment ... of processes have caused them to come down onto Earth."
On another front, Dr. Tom Moore, principle investigator for the Thermal Ion Dynamics Experiment, said his instrument should settle a controversy among scientists about whether the particles of a magnetic storm originate in space or from Earth's atmosphere.
"We are going to fly an instrument that is almost 100 times more sensitive than other instruments that we have flown," he said. "Basically, it's going to be looking at the flux of winds and temperature and pressure of plasmas that originate in Earth's atmoshpere and flow out into space and participate in space plasma storms."
The instrument's major subsystems were built at Marshall and Los Alamos with final assembly at Southwestern Research Institute in San Antonio.
[Editor's note: The sentence should read that the instrument's major subsystems were built at Marshall, Southwest Research Institute, and Los Alamos, with final test and calibration at Marshall Space Flight Center]
The instrument, one of 11 on the satellite, will allow scientist to follow particles from Earth's ionosphere to the magnetosphere where they are energized and form storm plasmas, Moore said. At least that's the theory advanced by Moore and others.
"There is a fair amount of controversy over whether storm plasmas originate in the sun or whether they originate from material flowing out of Earth's atmosphere," he said."If we're right, we will re-write all the encyclopedias and popular accounts almost completely."
Magnetic storms eat into electronic circuitry, flip memory bits in computers and cause insultators to break down in electrical systems, scientists said. They hope the knowledge will be useful not only to the basic understaning of the Earth's atmosphere but to improved satellite electronics.
To make sure their own satellite survives the solar storms, Marshall scientists built a neutralizer that emits inert plasma to counter the space plasma.
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