Purpose of the flight and payload description
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).
Details of the balloon flight
Balloon launched on: 6/10/2011 at 00:19 utc
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: 619N
End of flight (L for landing time, W for last contact, otherwise termination time): 6/14/2011 at 16:00 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 4 d 16 h
Landing site: Somerset Island, Nunavut, Canada
Payload weight: 1491 kg