Low-frequency observations using high-altitude balloon experiments (LOBE)

The frequency range below 30 MHz remains one of the last unexplored frequency ranges in radio astronomy However, Earth-based observations at these wavelengths are severely impeded, due to man-made radio frequency interference (RFI) and atmospheric opacity. To overcome this impediment, various space-based radio astronomy studies have been proposed in the past decade, notably the OLFAR (Orbiting low Frequency Antennas for Radio Astronomy) study, which proposed a satellite swarm for ultra-long wavelength observation. To realize this mission, various technological challenges of a satellite swarm are currently being addressed, particularly antenna design, navigation, communication, distributed processing, and overall system and mission design. Secondly, the RFI levels at various altitudes from Earth is currently unknown, which is a hindrance in general for radio astronomy. To this end, we propose the use of high-altitude ballooning experiments to validate OLFAR sub-systems in pseudo-representative conditions. Furthermore, these ballooning experiments will measure the RFI in the ultra-long wavelength spectrum at various altitudes from Earth. Our project is termed LOBE (Low-frequency observations using high-altitude Balloon Experiments), and in this paper, we present an overview of the science objectives, payload, and the technological and programmatic challenges of the LOBE project.