Abstract
The past decade has seen the rise of various radio astronomy arrays, particularly for low-frequency observations below 100MHz. These developments have been primarily driven by interesting and fundamental scientific questions, such as studying the dark ages and epoch of re-ionization, by detecting the highly red-shifted 21cm line emission. However, Earth-based radio astronomy below frequencies of 30MHz is severely restricted due to man-made interference, ionospheric distortion and almost complete non-transparency of the ionosphere below 10MHz. Therefore, this narrow spectral band remains possibly the last unexplored frequency range in radio astronomy. A straightforward solution to study the universe at these frequencies is to deploy a space-based antenna array far away from Earths' ionosphere. Various studies in the past were principally limited by technology and computing resources, however current processing and communication trends indicate otherwise. We briefly present the achievable science cases, and discuss the system design for selected scenarios, such as extra-galactic surveys. An extensive discussion is presented on various sub-systems of the potential satellite array, such as radio astronomical antenna design, the on-board signal processing, communication architectures and joint space-time estimation of the satellite network. In light of a scalable array and to avert single point of failure, we propose both centralized and distributed solutions for the ULW space-based array. We highlight the benefits of various deployment locations and summarize the technological challenges for future space-based radio arrays.
Highlights
The success of Earth-based radio astronomy in the frequencies between 30 MHz and 3 GHz is jointly credited to Earth’s transparent ionosphere and the steady technological advancements during the past few decades
Advanced calibration and mitigation techniques are employed in the LOw Frequency ARray (LOFAR) telescope array, which can be used to remove these distortions, provided the time scale of disturbances is much longer than the time needed for calibration [77]
For a first space-based Ultra-Long Wavelength (ULW) array with possibly only a few satellite nodes, extra-galactic surveys and study of transients are among the best suited science cases [14], which we present as case studies
Summary
The success of Earth-based radio astronomy in the frequencies between 30 MHz and 3 GHz is jointly credited to Earth’s transparent ionosphere and the steady technological advancements during the past few decades. Radio astronomy has seen the advent of a large suite of radio telescopes, towards the longer observational wavelengths, i.e., ≥ 3 m These arrays include the Murchison Widefield Array (MWA) [47], LOw Frequency ARray (LOFAR) [74] and the Long Wavelength Array (LWA) [27] to name a few. An unequivocal solution to observe the radio sky at ULW with the desired resolution and sensitivity is to deploy a dedicated satellite array in outerspace Such a space-based array must be deployed sufficiently far away from Earths’ ionosphere, to avoid terrestrial interference and offer stable conditions for calibration during scientific observations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
