21-cm Hydrogen Signal Detection

India is making strides in space science with the proposed PRATUSH mission, which aims to detect the elusive 21-cm Hydrogen Signal—one of the faintest radio signatures from the early universe.

Developed by the Raman Research Institute (RRI), Bengaluru, this mission could offer unprecedented insights into the Cosmic Dawn, the era when the first stars and galaxies began illuminating the universe, roughly 13 billion years ago.

What is PRATUSH?

PRATUSH stands for Probing Reionization of the Universe using Signal from Hydrogen. It is a lunar radiometer mission designed to study the 21-cm Hydrogen Signal, emitted by neutral hydrogen atoms during the early stages of the universe. Detecting this hydrogen line could provide direct evidence of the Reionization era and help scientists understand how the first cosmic structures formed.

The mission will focus on the Dark Ages and the Cosmic Dawn, key periods in early universe hydrogen line research. By observing the 21-cm Hydrogen Signal, researchers hope to trace the timeline of the first stars and galaxies.

Why the Moon?

Detecting the 21-cm Hydrogen Signal on Earth is extremely challenging due to heavy radio interference from FM transmissions and ionospheric distortions. The far side of the Moon offers a uniquely radio-quiet environment, free from most human-made and natural disturbances. This makes it the ideal location for radio astronomy studies of the early universe.

By placing instruments on the lunar surface, the PRATUSH mission will significantly improve the sensitivity of hydrogen signal astronomy and enhance the chances of capturing the faint neutral hydrogen radio signal from the Cosmic Dawn 21-cm signal.

Role of the Single-Board Computer

Traditionally, space instruments use large, power-hungry controllers. However, RRI’s Electronics Engineering Group has developed a compact single-board computer (SBC), no larger than a credit card, that powers the lab-scale digital receiver for PRATUSH.

The SBC performs several critical tasks:

• Coordinates the antenna, receiver, and FPGA chip

• Records, stores, and pre-processes incoming radio data

• Carries out system calibration

• Offers high efficiency with low power usage

According to Girish B.S., Research Scientist at RRI, this SBC-based system balances size, power, and performance, making it ideal for lunar space applications.

Promising Test Results

The system underwent rigorous testing over 352 hours using a reference signal.

Results showed:

• Noise reduction down to millikelvin levels

• High sensitivity to weak signals

• Stable performance under continuous operation

These tests confirm that the SBC setup is suitable for 21-cm Hydrogen Signal detection in space and other lunar missions to detect 21-cm signals.

Future Potential and Next Steps

The RRI team plans to:

• Upgrade to space-qualified SBCs

• Enhance software for onboard AI-enabled processing

• Integrate the system into a compact payload for lunar deployment

If successful, PRATUSH could mark a milestone in India’s space science efforts, contributing to:

• Understanding the formation of the first cosmic structures

• Mapping the evolution of the early universe

• Exploring new physics beyond current cosmological models

The mission will also play a crucial role in measuring the hydrogen line from Cosmic Dawn and detecting first stars via the 21-cm Hydrogen Signal, bridging gaps in our knowledge about the Epoch of Reionization studies.

Importance for SSC Aspirants

For SSC students, staying updated on missions like PRATUSH is important for:

• Science & Technology current affairs

• Space research and India’s lunar initiatives

• Astrophysics and cosmology awareness

Key terms such as 21-cm Hydrogen Signal, Cosmic Dawn 21-cm signal, and neutral hydrogen radio signal are often asked in SSC Science & Technology sections, making this topic highly relevant.

Final Thoughts

The PRATUSH mission represents a major leap in space science and technology, aiming to unlock the secrets of the Cosmic Dawn. By detecting the faint 21-cm Hydrogen Signal, scientists hope to gain direct observational evidence of the early universe and the formation of the first stars and galaxies. Placing instruments on the far side of the Moon ensures a radio-quiet environment, crucial for capturing such delicate signals without interference. The use of a compact single-board computer (SBC) highlights the importance of efficient, low-power technology in modern space missions.

The successful detection of the 21-cm Hydrogen Signal could transform our understanding of the Reionization era and the Dark Ages, offering insights into neutral hydrogen distribution and the evolution of cosmic structures.

With ongoing advancements in AI-enabled onboard processing and space-qualified instrumentation, PRATUSH exemplifies how innovative engineering and scientific exploration can work together to probe the deepest mysteries of the universe.