UAF Physics Department § Journal Club

This talk will describe a recent NASA sounding rocket mission to study mechanisms responsible for establishing and maintaining two permanent density enhancements that have been observed to occur in Earth's thermosphere near the footprints of the geomagnetic cusps, and at altitudes near 400 km. These features are of operational interest because they are expected to cause small but important and currently unpredictable perturbations to the orbits of spacecraft flying through them. On November 24, 2014, a Black-Brant 12 sounding rocket was launched from Andoya Space Center out over the Greenland Sea, and into the enhancement region associated with the ionospheric footprint of the northern geomagnetic cusp. It released ten rocket-propelled "grenades" that dispersed barium strontium tracer clouds into the thermosphere throughout a 3D volume extending over many tens of km around the main trajectory, and spanning heights from 190 to 400 km. Subsequent motions of the ionized barium and neutral barium/strontium components of the clouds were determined by photographic triangulation, using cameras based at Longyearbyen, Ny-Alesund, and aboard a NASA aircraft flying just south of Svalbard. Here I will describe the extensive development effort that made this mission possible, show some example data and initial analysis results, and discuss implications of these results for possible mechanism(s) that may establish these density anomalies.


	ABSTRACT This talk will describe a recent NASA sounding rocket mission to study mechanisms responsible for establishing and maintaining two permanent density enhancements that have been observed to occur in Earth's thermosphere near the footprints of the geomagnetic cusps, and at altitudes near 400 km. These features are of operational interest because they are expected to cause small but important and currently unpredictable perturbations to the orbits of spacecraft flying through them. On November 24, 2014, a Black-Brant 12 sounding rocket was launched from Andoya Space Center out over the Greenland Sea, and into the enhancement region associated with the ionospheric footprint of the northern geomagnetic cusp. It released ten rocket-propelled "grenades" that dispersed barium strontium tracer clouds into the thermosphere throughout a 3D volume extending over many tens of km around the main trajectory, and spanning heights from 190 to 400 km. Subsequent motions of the ionized barium and neutral barium/strontium components of the clouds were determined by photographic triangulation, using cameras based at Longyearbyen, Ny-Alesund, and aboard a NASA aircraft flying just south of Svalbard. Here I will describe the extensive development effort that made this mission possible, show some example data and initial analysis results, and discuss implications of these results for possible mechanism(s) that may establish these density anomalies.

	Friday, 11 September 2015
	Globe Room, Elvey Building
	3:45 PM