Investigation Into the Applicability of Solar Panels in Powering HiCal2

Investigation Into the Applicability of Solar Panels in Powering HiCal2

Names:

Finn Dobbs, Lawrence Free State High School, Lawrence, KS

Roxanna Hamidpour, Blue Valley North High School

Sabrea Platz, Lawrence Free State High School, Lawrence, KS

Asher Supernaw, Lawrence Free State High School, Lawrence, KS

Research Teacher Mentor:

James Deane, Ottawa High School, Ottawa, KS

Research Mentor:

Prof. Dave Besson, University of Kansas, Lawrence, KS

Purpose: Our purpose is to investigate the use of solar power for the HiCal2 balloon payload. The original battery system design limited the HiCal2 to 24 total hours of use in a 240 hour flight. Testing of solar panels in real world conditions is required to determine if the solar panels are sturdy enough to withstand the conditions at normal altitude in the antarctic atmosphere.

Methods: We tested the antenna efficacy by determining if a signal could be seen from thirty kilometers away. Successful signal transmission and reception at a distance of 30km is required because HiCal2 will fly from 25km-30km above the ground level in Antarctica on its flight. Antenna testing was accomplished by transmitting a signal and receiving on an ARIANNA antenna, then measuring this signal’s strength at 30 dBm above surrounding noise.

Once this data was collected, we began construction on an antenna to be flown on a weather balloon. Through testing multiple antenna designs with SWR measurements and wind resistance exercises for optimization of geometry, the Chicken Wire Antenna (CWA) was determined to be satisfactory for our experiment. With a proper transmission implement in place, a data collection strategy was devised. The CWA would transmit a signal, which would then be received by the ARIANNA antennas. An oscilloscope connected to the ARIANNA antenna record a waveform to floppy disk.  

Aside from the CWA, the payload consisted of a data logger, GPS, amplifier, solar panel, and a voltage controlled oscillator (VCO). The data logger was monitored by the solar panel and served to ensure that the solar panel continuously supplied power to the payload. When devising a plan to transmit the signal, an amp circuit system was investigated, but the transmitted signal was variable and unpredictable. Instead of this amp circuit system, we used the VCO as the means of producing a signal that would then be transmitted by the CWA. The VCO’s tuning input voltage was directly connected to the solar panel, meaning that the frequency of the signal transmitted by the CWA correlated directly to the voltage supplied by the solar panel. This payload was then constructed and secured to the balloon.

Results: The weather balloon and payload were launched successfully, but we could not successfully retrieve ground station and logged data. The ground station based oscilloscope saved the same waveform multiple times rather than the expected real-time data. Without long-term data from the received VCO signal, we cannot determine the stability of the solar panel system voltage over time.  After the flight, we were unable to locate the payload, and as of the writing of this abstract it remains lost. If we do retrieve the payload, we could analyze data from the data logger to determine the performance of the solar panel system voltage over time.

Meaning to Larger Project: The purpose of our summer research was to devise an alternate power source for the HiCal2 experiment that was lighter and more reliable than batteries. We wanted to test solar panels in a real world environment with both temperature inversion and potential weather conditions. We were not able to answer these questions conclusively with this launch, but future balloon launches will build on these successes and failures.

Future Research: A second balloon launch is planned for the near future, which will include a more reliable retrieval process. A reliable retrieval is vital in developing confidence in future balloon launches so that costly equipment can be used without fear of significant losses.

Acknowledgements:

We appreciate the assistance and guidance of the following students during this project.

• Conner Brown: Undergraduate Student, University of Kansas

• Joshua Macy: Senior Lead Undergraduate Student, University of Kansas