Scientists Eye Moon to Probe Dark Matter Using Ancient Hydrogen Signals

Scientists from the University of Tsukuba and University of Tokyo are using advanced computer simulations to investigate the nature of dark matter by studying faint radio signals from the Universe’s earliest epoch.

Roughly 400,000 years after the Big Bang, the Universe entered a long, lightless phase known as the Dark Ages, lasting about 100 million years. During this period, hydrogen atoms emitted faint radio waves at a 21-centimeter wavelength, which may hold clues about the Universe’s first structures and the elusive dark matter, which accounts for about 80% of all cosmic matter.

By simulating the distribution of gas and dark matter in the young Universe, the team calculated that hydrogen gas produced a characteristic signal of about 1 millikelvin in sky-averaged radio brightness. Variations of similar magnitude are expected from dark matter, offering a potential way to measure the mass and velocity of dark matter particles.

Several lunar missions, including Japan’s Tsukuyomi Project, aim to establish radio telescopes on the Moon to detect these faint signals. Observing the global 21-cm signal from the Moon could unlock mysteries of dark matter that remain inaccessible from Earth due to atmospheric interference.

The study, titled “The signature of subgalactic dark matter clumping in the global 21-cm signal of hydrogen”, was published in Nature Astronomy on 16 September 2025.