Tiny radio receiver could unlock secrets of the Cosmic Dawn

A tiny digital radio receiver space-based system, based on a compact single-board computer about the size of a credit card, could help astronomers unravel the mysteries of the Cosmic Dawn, the time when the first stars and galaxies formed in the universe. Scientists believe this mysterious period holds the key to understanding the universe as we see it today, making it an irresistible frontier for discovery.

However, very little is known about this period due to a lack of precise observations. Christened PRATUSH (Probing ReionizATion of the Universe using Signal from Hydrogen), the first space payload of its kind in a lunar orbit has been conceptualised by a team from Raman Research Institute (RRI). PRATUSH can detect a faint radio signal emitted from hydrogen atoms, carrying imprints of several events during the Cosmic Dawn.

Capturing this signal is like hearing a whisper in a stadium full of noise, as it’s buried under interference millions of times stronger than the signal itself. On Earth, this whisper from the past is drowned out by radio noise and interference, such as FM transmissions. Therefore, PRATUSH envisions a lunar far-side mission, expected to be the most radio-quiet place in the inner solar system, free from Earth’s interference and ionospheric distortion.

The PRATUSH team has built a laboratory model of their radiometer to demonstrate its suitability for detecting the faint cosmological signal. This research has been published in Experimental Astronomy, a peer-reviewed journal. The radio signals are captured by the antenna, amplified by the analog receiver, and turned into digital data by a receiver.

An advanced powerful chip called Field Programmable Gate Array processes this data, converting it into fine fingerprints representing the sky’s brightness at different radio frequencies. Considering the stringent requirements of space payloads and the focus on low-mass, high-capability payloads, PRATUSH demonstrates how a compact controller can handle precision radio measurements.

The single-board computer (SBC) acts as the master conductor of PRATUSH’s radiometer, coordinating the antenna, receiver, and chip that processes streams of cosmic radio data. Besides recording and storing this information, SBC performs crucial calibrations, capturing high-speed data streams and carrying out preliminary data processing.

“SBCs, as scaled-down versions of desktops or laptops, deliver an appealing balance of size, performance, and efficiency to manage data through software instructions,” said Girish BS, a senior scientist at RRI. Performance tests confirm that this minimalist strategy is highly effective. With newly implemented software enhancements and next-generation space-grade devices, the system is on track for even greater performance, ensuring data integrity.