Description of the payload

Developed by the Delaware University in the early 90's is an instrument which measures the energy spectrum of comic ray electrons using mainly a permanent magnet and a spark chamber hodoscope to determine the charge sign of the electron.

As we can see in the scheme (click to enlarge) AESOP chambers contain 5 parallel aluminum plates connected, in alternate order, to ground and a high voltage pulser. The medium between plates is a slow moving noble gas mixture of neon and helium. As a charged particle transverses a chamber it leaves behind an ion trail in the gas. If the scintillator detectors, mounted above and below the chamber, detect coincidence light pulses from the resulting ionization track, a 10,000 volt pulser is triggered. In the presence of a high electric field, the ions in the gas are accelerated toward the plate surface producing more ions with each ion-atom collision. These multiple collisions form an ion cascade which ultimately results in a high voltage breakdown very near the original ion trail. This breakdown in each gap produces a bright red verticle spark which is digitized and recorded using a linear CCD camera.

The instrument was flown several times in a same gondola with another complementary instrument called LEE (Low Energy Electrons).

Video of the launch operations

Details of the balloon flight and scientific outcome


Launch site: European Space Range, Kiruna, Sweden  
Balloon launched by: Columbia Scientific Balloon Facility (CSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon Winzen - 39.570.000 cuft (0.8 mil)
Flight identification number: 595N

The balloon was launched by dynamic method with assistance from launch vehicle (Hercules) on June 6th at 22:05 UTC. At launch part of the frame holding the solar panels struck the launch vehicle and was damaged, but besides that and after a nominal ascent phase, the balloon reached float altitude on June 7th at 1:10 UTC without troubles, starting a westward path as can be seen in the map at right (click to enlarge).

The crossing of the Atlantic Ocean took 3 days and 17 hours. The payload was separated from the balloon the southwestern part of the Ellesmere Island in Canada.

The rescue operation was acomplished by a team of the Columbia Scientific Balloon Facility deployed to Yellowknife a few days before the start of the Sweden campaign.

According to NASA sources the instrument performed very well during the entire trip.

External references and bibliographical sources

Images of the mission