Aug 12, 1996

Scientists "de-SCIFER" Physicsof the Earth's Plasma Fountain

The Earth's plasma "fountain"
August 12, 1996: A recent rocket flight carrying two Space Sciences Laboratory instruments from the Marshall Space Flight Center has returned data that has offered a better understanding of a portion of the Earth's magnetosphere. Much of these data were recently published in a special issue of Geophysical Research Letters (GRL), a science journal for timely, cutting edge research results in geophysics. In all, seven different papers in the July 1 edition of GRL describe the initial results from the SCIFER rocket, which flew in January 1995.

SCIFER, which stands for Sounding of the Cleft Ion Fountain Energization Region, carried two experiments from SSL designed to measure various plasma components in a particular region of the Earth's magnetosphere. The Cleft Ion Fountain is a plasma fountain that sprays plasma made from our atmosphere up over the poles and feeds the plasma storm process on the night side of the Earth. The SCIFER observations show that this region is richer in hydrogen plasma and depleted of oxygen plasma relative to earlier MSFC observations made from the Dynamics Explorer (DE) satellite. Scientists have attributed this result to a difference between high solar activity during the DE flight period and low solar activity during the SCIFER flight.

SCIFER also shows that the fountain heating or "energization region", has a very sharp boundary in the direction of the Earth's equator, only about 1 km thick. Furthermore, plasma in the energization region displays an inverse relationship between the density and temperature; where the temperature is high, the density is low, and vice-versa. This behavior is seen in both the electrons and the ions which make up the plasma. The physics involved in the heating region are not completely understood, however these are significant clues to the operative mechanisms of this heating.

A similar rocket payload named CAPER with two additional MSFC experiments has been selected for launch in early 1998 to further explore this region and better determine the mechanisms of heating.

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Authors: John Horack , Tom Moore
Curator: Bryan Walls
NASA Official: John M. Horack