A roadmap towards a space-based radio telescope for ultra-low frequency radio astronomy

Abstract

The past two decades have witnessed a renewed interest in low frequency radio astronomy, with a particular focus on frequencies above 30 MHz e.g., LOFAR (LOw Frequency ARray) in the Netherlands and its European extension ILT, the International LOFAR Telescope. However, at frequencies below 30 MHz, Earth-based observations are limited due to a combination of severe ionospheric distortions, almost full reflection of radio waves below 10 MHz, solar eruptions and the radio frequency interference (RFI) of human-made Email addresses: m.j.bentum@tue.nl (M.J. Bentum), m.k.verma@student.tudelft.nl (M.K. Verma), r.t.rajan@tudelft.nl (R.T. Rajan), boonstra@astron.nl (A.J. Boonstra), C.J.M.Verhoeven@tudelft.nl (C.J.M. Verhoeven), e.k.a.gill@tudelft.nl (E.K.A. Gill), a.j.vanderveen@tudelft.nl (A.J. van der Veen), h.falcke@astro.ru.nl (H. Falcke), m.kleinwolt@astro.ru.nl (M. Klein Wolt), b.monna@hyperiontechnologies.nl (B. Monna), s.engelen@hyperiontechnologies.nl (S. Engelen), j.rotteveel@isispace.nl (J. Rotteveel), lgurvits@jive.eu (L.I. Gurvits)

Sympathetic cooling of a radio-frequency LC circuit to its ground state in an optoelectromechanical system

“…V predicts that optimal laser cooling of the LC resonator occurs when the modified mechanical and rf resonance frequencies of Eqs. (32) and (33) are resonant, ω m = ω LC , rather than their bare counterparts, ω (0)…”

“…Here, we focus on the case of a megahertz rf resonator, for which operation in the quantum domain is more difficult because, due to the lower resonance frequency, it is normally in a thermally excited state even at ultracryogenic temperatures. Radio-frequency signals in the megahertz and kilohertz regimes are used in a large variety of research fields and applications [14], ranging, for example, from astronomical signal detection at long wavelength (astronomical plasmas, sun activity, and exoplanets research) [33] to ultralow magnetic field nuclear magnetic resonance and imaging (superconducting quantum interference device coupled to an LC circuit) [34]. Therefore the possibility of operating in a quantum regime at the megahertz and even kilohertz range with extremely low noise can be advantageous for positioning, timing, and sensing (imaging) applications, and for more fundamental science applications, such as the sensitive detection of rf signals of astrophysical nature.…”

Space VLBI: from first ideas to operational missions

“…It is expected that the first demonstration of ULW VLBI will be attempted in 2019 in the framework of the Chinese-Dutch experiment NCLE aboard the Chinese Lunar mission Chang'E-4 (Jia et al, 2018). Several other ULW VLBI initiatives and projects are under development with the aim of becoming operational in the coming decade (Boonstra et al (2016); Belov et al (2018); Bentum et al (2019) and references therein).…”

System Equivalent Flux Density of a Polarimetric Tripole Radio Interferometer

“…In planetary and solar science, we find tripole antennas as space probes mounted on satellites (Rucker et al 1996;Cecconi & Zarka 2005;Bale et al 2008;Zarka et al 2012;Fischer et al 2021). More recently in radio astronomy, there have been increasing interests in tripole antennas as elements for radio astronomy imaging (Carozzi & Woan 2009), moon-based radio astronomy (Klein Wolt et al 2012), and in particular, for a lunar orbiting radio interferometer (Boonstra et al 2016;Bentum et al 2020;Chen et al 2018;Chen et al 2021;Huang et al 2018;Rajan et al 2016;Arts et al 2019). Space missions are costly, and hence a space mission plan requires a reliable model-based prediction of key system performance such as sensitivity.…”