India's PRATUSH Mission aims to hear the universe's earliest whispers

A team of scientists from India's Raman Research Institute (RRI) is developing a space payload designed to study the Cosmic Dawn, the period when the universe's first stars and galaxies formed. This mission, named PRATUSH (Probing ReionizATion of the Universe using Signal from Hydrogen), plans to place a radiometer in lunar orbit. The mission's controller is a compact single-board computer (SBC), a device similar in size to a credit card.

The SBC manages the instrument's key functions, including data collection and processing. It serves as the "master conductor" for the radiometer, coordinating the antenna, the receiver, and a powerful Field Programmable Gate Array (FPGA) chip. The SBC not only records and stores the data but also performs essential calibrations, ensuring the entire system runs smoothly.

The Challenge of the Cosmic Whisper

Scientists hope to capture a faint radio signal from hydrogen atoms, known as the 21-cm signal. This signal carries information about the Cosmic Dawn. Detecting it is extremely difficult because it is buried under interference millions of times stronger. On Earth, human-made radio noise from sources like FM transmissions drowns out this signal.

To overcome this problem, the PRATUSH team aims to place its radiometer on the far side of the Moon, which is shielded from Earth's radio interference. This location is one of the most radio-quiet places in the inner Solar System, making it ideal for this kind of astronomical observation.

A Minimalist Approach to Space Technology

The PRATUSH project demonstrates a shift toward using smaller, more accessible technology for space missions. The team developed a digital receiver system around a commercial Raspberry Pi-based SBC. Using a low-power SBC reduces the payload's size, weight, and power consumption (SWaP), which are critical factors for any space mission.

Research scientists at RRI, including Girish B. S. and Srivani K.S., confirmed that SBCs offer an appealing balance of size, performance, and efficiency. They manage data generated by the FPGA through software instructions. While the current laboratory model uses a commercial Raspberry Pi, the final flight model will feature a space-qualified version.

In lab tests with a reference signal, the receiver's noise was reduced to a few millikelvins, showing its sensitivity to the faint cosmic signal. This performance suggests the approach is effective. The PRATUSH team believes this technology will be crucial for payloads designed to study the universe from the most remote locations. The mission, if successful, may help unlock how the first stars influenced the universe's evolution and could even lead to new discoveries in physics.