The radio environment for a space-based low-frequency radio astronomy instrument

Opening the last frequency window for radio astronomy in the sub - 30 MHz region includes a few challenges. First of all, at frequencies below 30 MHz the Earths ionosphere severely distorts radio waves originating from celestial sources, and it completely blocks radio waves below 10 MHz. This means that radio astronomy and astrophysics below ∼ 30 MHz is best conducted from space. Secondly, the radio spectrum below 30 MHz is filled with very strong transmitters signals, making it difficult to do Earth-based radio observations. Most low frequency space-based radio telescope studies and initiatives aim to place a swarm of satellites far away from the Earths radio interference. Deployment location options include a lunar orbit, the Earth-Moon Lagrangian point behind the Moon (L2), and an Earth leading or trailing location. There is little knowledge about the radio frequency interference (RFI) environment outside the ionosphere. However, to determine the location of the radio telescope, it is important to understand the radio environment at possible deployment locations. In this paper we will address the radio environment for space-based low frequency radio astronomy. To do so, we will use the data of the WIND/WAVES instrument. The data from November 1994 till November 2016 is used for this analysis. Analysing the data results in addressing the best location for a space-based low frequency radio telescope.