From Moon’s Far Side, a Satellite to Look for the First Radio Signal, Pg II

Key Highlights:

• CosmoCube, a small satellite developed by scientists from the Royal Astronomical Society (RAS), is planned for launch to the Moon's far side before the end of this decade.
• Its primary mission is to detect ultra-faint radio signals from neutral hydrogen atoms during the Cosmic Dark Ages, a period before the first stars and galaxies formed.
• The satellite will orbit the Moon for two years, using the lunar far side as a natural shield against Earth's radio interference.
• A study on the CosmoCube project was published in Nature Astronomy on August 14.

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Detailed Insights:

• CosmoCube will spend approximately 40 minutes behind the Moon during each two-hour orbit, ensuring radio silence for its observations.
• It carries a sensitive radiometer operating at low frequencies (10-100 MHz) to identify the characteristic fingerprint of early hydrogen.
• The mission aims to gather over a thousand hours of data to understand the universe's unobserved Cosmic Dark Ages.
• The satellite will also investigate the Hubble tension, a discrepancy in measurements of the universe's expansion rate.
• By studying the period between the Cosmic Microwave Background and the formation of first stars, CosmoCube could test new physics explanations for the Hubble tension, including those involving dark matter.
• The 21-cm signal from neutral hydrogen is extremely faint and buried under much stronger foreground radio emissions, making its detection challenging.
• India also has a proposed lunar orbit radio telescope project named PRATUSH (Probing ReionisATion of the Universe using Signal from Hydrogen).

Scientific/Technical Concepts Involved:

• Cosmic Dark Ages: The period in the early universe, from about 380,000 to 200 million years after the Big Bang, before the first stars and galaxies ignited.
• 21-cm Radiation: A specific radio wavelength emitted by neutral hydrogen atoms due to a spin-flip transition, predicted by Hendrik van de Hulst, which can penetrate interstellar dust.
• Hubble Tension: The observed discrepancy between the expansion rate of the universe measured from the early universe's Cosmic Microwave Background and that measured from nearby celestial systems.
• Cosmic Microwave Background (CMB): The faint afterglow radiation from the Big Bang, providing a snapshot of the universe when it was about 380,000 years old.