A low-frequency radio array for space

Abstract

At the lowest radio frequencies (<30 MHz), the Earth's ionosphere transmits poorly or not at all. This relatively unexplored region of the electromagnetic spectrum is thus an area where high resolution, high sensitivity observations from space can open a new window for astronomical investigations. An array of free flying spacecraft which work as a coherent interferometer will be able to probe this frequency range. Operating from ≡1 to ≡30 MHz, such a telescope will extend astronomy from just above the ionospheric cutoff, where ground based observations can still be done, down to the fundamental physical limit where observations at still lower frequencies from within the Milky Way are impossible due to absorption by diffuse, ionized interstellar hydrogen. The scientific rewards of such a space mission are likely to be great.