| Author(s) and Co-Author(s) with Affiliation: Bharat Chandra P(Raman Research Institute, Bengaluru - 560080, India), Mayuri S Rao(Raman Research Institute, Bengaluru - 560080, India), Saurabh Singh(Raman Research Institute, Bengaluru - 560080, India), Vishakha S. Pandharpure(Raman Research Institute, Bengaluru - 560080, India), Keerthipriya S(Raman Research Institute, Bengaluru - 560080, India), Somashekar R(Raman Research Institute, Bengaluru - 560080, India), Srivani K.S(Raman Research Institute, Bengaluru - 560080, India), Girish B.S(Raman Research Institute, Bengaluru - 560080, India), Jayadev Ashok T(Raman Research Institute, Bengaluru - 560080, India), Narendra S(Raman Research Institute, Bengaluru - 560080, India), Yash Agrawal(Raman Research Institute, Bengaluru - 560080, India) |
| Abstract: The Dark Ages and Cosmic Dawn are the poorly understood epochs in cosmology; they can be studied through observations of the redshifted 21-cm signal from neutral hydrogen. Although this signal provides a unique probe of early astrophysics and cosmology, its detection remains difficult from Earth due to ionospheric effects, antenna near field effects, and terrestrial radio frequency interference (RFI). While lunar farside experiments offer an ideal environment, their feasibility is limited by cost and a lack of quantified levels of RFI.
We propose the development and operation of a compact low-frequency radio spectrometer payload, targeting the 30–150 MHz band over a LEO or Moon mission. The payload will consist of a broadband antenna, a calibrated receiver chain, and an FPGA-based spectrometer capable of producing spectrally and temporally resolved data with precise attitude tagging. This configuration enables the separation of Earth-origin and sky-origin signals.
The primary objective is to deliver the first calibrated map of RFI power and occupancy in the orbits, capturing geographic and diurnal variability. Secondary science includes observations of solar radio bursts, meteor-induced scattering, transient luminous events, ionospheric variability, and measurements of the Galactic low-frequency spectrum above the ionosphere.
The results will directly inform the design of future space-based 21-cm experiments, including PRATUSH. We have developed an initial design concept for the analog front end, consisting of a dipole antenna with a matching network and an FPGA-based spectrometer. The project is now progressing toward assembly of a benchtop model, which will be followed by development of the engineering model of the payload. We will be presenting the current status of PRATUSH-0, summarizing the system design and development progress.
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