To unlock the secrets of how the cosmos lit up shortly after the Big Bang, astronomers are turning to one of the quietest locations in the solar system: the far side of the Moon. Researchers have unveiled plans to launch a suitcase-sized satellite called CosmoCube into lunar orbit, aiming to capture elusive radio signals that have traveled across space for over 13 billion years.
The mission targets a faint radio wavelength known as the 21-centimeter line, emitted by neutral hydrogen gas during the universe's formative epochs. As these ancient signals travel through expanding space, their wavelengths stretch—or redshift—providing scientists with a thermal timeline of the early universe. Acting essentially as a cosmic thermometer, the signal could reveal the physical temperature of primordial gas from the "dark ages"—roughly 380,000 years after the Big Bang—through the cosmic dawn when the first stars ignited, up to the epoch of reionization nearly a billion years later.
Detecting this delicate signal from Earth has proven notoriously difficult. Terrestrial radio telescopes must contend with intense human-generated interference from FM broadcasts and aircraft communications, alongside atmospheric distortion caused by Earth’s ionosphere. While previous ground-based experiments, such as the EDGES telescope in Australia, reported potential detections, the findings remain contested within the scientific community.
By operating in the radio shadow of the Moon, CosmoCube aims to bypass Earth's noisy environment entirely. Lead author Professor Eloy de Lera Acedo of the University of Cambridge’s Cavendish Laboratory noted that the shape and amplitude of the 21cm line could also offer unprecedented insights into the mysterious nature of dark matter, which is thought to have influenced gas temperatures during this period.
The two-year CosmoCube mission, estimated to cost just under £50 million, has already secured over £2 million in seed funding from the UK Space Agency, with a launch targeted in approximately five years. However, cosmologists warn that the mission faces an impending clock. With a growing number of commercial and scientific lunar expeditions planned in the coming years, the pristine silence of the Moon's far side may soon be compromised by human-generated radio chatter, making the quest to capture the birth of the universe a high-stakes race against time.