Purpose of the flight and payload description

The objective of the flight was the collection of stratospheric particles at 34-36 km using balloon-borne collectors. The particles collected were sent for later analysis in the laboratory where was studied the concentration of particles on the collection surfaces and element concentrations using scanning electron microscope (SEM), and proton-induced X-ray emission analysis respectively. Particle morphologies, elemental composition, and electron diffraction data were obtained on a small number of the collected particles using transmission electron microscope (TEM) techniques.

In the figure at left we have a schematic view of an impactor stack showing the impact and filter surfaces (a) and the Cosmic Dust Collector used to collect stratospheric particles (b).

The IMPACTOR (a) used to collect the particles consisted of a number of "stacks" each composed of a single stage impactor followed by a filter. Each stack contained a "Battelle" impactor with a 2.63 mm diameter jet that impacted onto a 25 mm diameter Nuclepore Membrane Filter (NMF), referred to as an impact surface, followed by a 0.2 micrometer pore size NMF used as a filter. Because of the low pressure at the collection altitude the impactor was used simply to concentrate the particles in a small area on the impact surface.

Three of these stacks were used in the flight. One stack, referred to as the "SEM stack", used NMF's for both the impact surface and filter. The impact surface of a second "TEM stack", used to collect particles for TEM analysis, consisted of nine beryllium TEM grids, coated with "holey" carbon film, glued to a NMF impact surface in a cross pattern followed by a NMF used as a filter. A third "flight blank" stack was configured like the SEM stack but was not attached to a pump and hence received no flow during the flight. To minimize handling after the flight the surfaces were prepared so that they could be inserted directly into the instrument to be used for post-flight analysis. All of the NMF surfaces were coated with silver prior to the flight to enhance the image contrast and reduce sample charging in the SEM while counting particles. The preparation and handling of the impact surfaces and filters took place in a still box under a laminar flow hood in a clean room.

The collection stacks were installed in a sealed stainless steel housing the COSMIC DUST COLLECTOR (b) which was integrated with a payload developed at the National Center for Atmospheric Research (NCAR). The two sampling stacks were plumbed to separate liquid nitrogen cooled molecular sieve sorption pumps in the flight payload. The stacks were sealed by a plate that was opened for sampling at altitude and then closed under automatic control. The payload included instruments to measure ambient pressure and flow rates as well as to monitor internal and external temperatures. All data was transmitted to a mobile ground station for recording.

Details of the balloon flight

Balloon launched on: 5/19/1985 at 13:24 utc
Launch site: Columbia Scientific Balloon Facility, Palestine, Texas, US  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon SF309.91-050-NSCHR-01
Balloon serial number: W11.11-2-01
Flight identification number: 1394P
End of flight (L for landing time, W for last contact, otherwise termination time): 5/20/1985 at 16:55 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 27 h 30 m
Landing site: 29 miles NE Waco, Texas, Us

External references

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