PATHFINDER

A Pathfinder, in scientific jargon, is an exploratory balloon that is launched to check the stability or direction of stratospheric winds before an important mission, or when it is necessary to ensure that a balloon mission will follow a more or less precise route. Under NASA's Antarctic balloon program, these flights are used to test the formation of the polar vortex each summer. That vortex is a counterclockwise wind pattern around the south pole that, between December and January of each year, allows a balloon to maintain a circular path around the white continent without drifting over the ocean.

For Pathfinder missions, small polyethylene balloons are used that can remain in the air for several days, and even circle Antarctica completely. The payload on board is simply made up of a GPS system and a satellite communication module to track its flight path in real time.

Balloon launched on: 12/9/2003 at ~ 13:00 local
Launch site: Williams Field, McMurdo Station, Antarctica  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon 144.000 cuft
End of flight (L for landing time, W for last contact, otherwise termination time): 12/0/2003
Landing site: Lost over Pacific Ocean.

• Lauren Scott's journal in Antarctica Washington University