Purpose of the flight and payload description

The ANITA HiCal (High-altitude Calibration) balloon-borne transmitter is a calibration pulsing unit that emulates the radio signals produced by ultra-high energy cosmic rays (HECR). The instrument, developed by a team from the University of Kansas, is a complementary project of the ANtarctic Impulsive Transient Antenna (ANITA) project, which surveys by means of a special balloon-borne receiver the Antarctic ice looking for radio signals produced by ultra-high energy (UHE) neutrinos and cosmic rays. The HiCal payload is launched on a second balloon in conjunction with ANITA, with the objective of transmitting pulses that would be received by ANITA both directly and as signals re?ected from the ice surface. A ratio of the amplitudes of re?ected to direct signals would provide a direct measurement of any decoherence effects caused by surface roughness.

The HiCal-1 transmitter is based on a small ceramic piezo-electric which translate the mechanical energy of impact of a solid "actuator" with a piezo ceramic into a ~10 nanosecond-duration burst of electrical energy, and are capable of generating kiloVolt-scale radio-frequency signals. It also incorporates a "Micro-Instrumentation Package" or MIP which is a standard unit for NASA balloon missions, containing hardware for communications, telemetry, and GPS time and location information of the payload. Below the MIP, the "actuator" comprises a motor turning at a rep rate of approximately 0.33 Hz which drives a camshaft, designed to depress the spring-loaded piezo electric at the same 0.33 Hz frequency. Signals from the piezo are directed into a dipole antenna. A dedicated pressure vessel, constructed from lightweight ABS (Acrylonitrile-Butadiene-Styrene), was built to enclose the dipole and piezo in a sealed, 1000 mB environment. A second GPS board time stamps the RF signals being emitted by the dipole.

Details of the balloon flight

Balloon launched on: 1/6/2015
Launch site: Williams Field, McMurdo Station, Antarctica  
Balloon launched by: Columbia Scientific Balloon Facility (CSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon  
Flight identification number: 661N
End of flight (L for landing time, W for last contact, otherwise termination time): 1/11/2016
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): 5 d 13 h
Landing site: Payload no recoverable

This was the second flight attempt -dubbed "HiCal-1B" and was carried out on January 5th, 2015, after ANITA III completed one circuit around the pole and was in the proximity of McMurdo station. A first attempt to launch a similar payload on December 19, 2014 (just one day after ANITA III launch) failed as the balloon had insufficient lift and then when launched Hi-Cal instrument worked erratically. This time, almost immediately after turning on the HiCal transmitter during ascent, ANITA began registering signals, the ~700 km separation distance notwithstanding. After HiCal reached its 38-km float altitude, signals continued to be recorded for the subsequent 48 hours (after which time the ANITA flight was terminated), at ANITA-HiCal separations between 650 and 800 km. In the map we can see in green the flight track of the balloon.

External references

Images of the mission

Launch of the HICAL1b mission (Image Brian Hill) Launch of the HICAL1b mission (Image Brian Hill) Launch of the HICAL1b mission (Image Brian Hill) Launch of the HICAL1b mission (Image Brian Hill)

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