Development of a microalgae culture monitoring system on-board the ATOM III rocket payload

Abstract

The present work presents a methodological proposal for the evaluation of microalgae cultures
to be shipped into the payload of the ATOM-III rocket, a 3km high apogee rocket of the Rio de
Janeiro Rocket Group (GFRJ). Therefore, the objective was to develop a compact equipment
to carry out the real-time monitoring of Chlorella vulgaris cultures to be used in a CubeSat
loaded on a rocket payload or a weather balloon at high altitudes. So, in addition to the
development and construction of a compact spectrophotometer equipment, it was necessary to
verify the accuracy of the equipment measurements. The equipment was calibrated by
evaluating seven samples of microalgae culture at different densities (between 106 and 107
algae/mL). The methods used in the calibration of the constructed spectrophotometer were:
spectrophotometry in commercial equipment; and counting of microalgae cells in a Neubauer
chamber under an optical microscope (Nikon, 400x). Based on the calibration results, it can be
considered that the spectrophotometer built in LARISA (Laboratory of Industrial Networks and
Automation Systems), whose main component was the light sensor OPT101, and calibrated by
the research group BIOTEMA (Biotechnologies in Treatment of Effluents and Environmental
Monitoring) proved to be suitable for use in a CubeSat with real-time monitoring, as it showed
high correlation with spectrophotometric measurements (r²=0.9996) and with the microalgae
cell count (r²=0.988). It is noteworthy that there are advantages in developing an own
spectrophotometer, such as: developing the electronics to be more efficient, being able to meet
the analytical needs of the project more precisely; be versatile and light due to its reduced size;
and be economically more viable. Finally, we hope that the results obtained can open new doors
for other biological experiments aboard payloads, in addition to highlighting the importance of
encouraging research that includes the aerospace sector.