Probing dark matter with lunar radio telescopes
University of Tsukuba
image:
Simulated distributions of cold and warm dark matter are shown using particles color-coded by temperature, accompanied by an illustration of lunar telescopes.
view moreCredit: Hyunbae Park, University of Tsukuba
Tsukuba, Japan—The Universe was born 13.8 billion years ago during a rapid expansion known as the Big Bang. Around 400,000 years later, it entered a period known as the "Dark Ages," which lasted for about 0.1 billion years until the first stars and galaxies began emitting light. During this time, hydrogens atoms are thought to have emitted faint radio waves at a wavelength of 21 cm, which likely carry important clues about the beginning of the Universe.
Through numerical simulations, researchers at University of Tsukuba and The University of Tokyo predicted the intensity of the 21-cm radio signal in different models of dark matter, the mysterious invisible substance that comprises around 80% of the matter in the Universe. By reproducing the distribution of gas and dark matter in the early Universe on supercomputers, the team calculated the intensity of the radio waves during the Dark Ages with unprecedented precision.
The results imply that hydrogen gas in the dark ages produced a characteristic signal of about 1 millikelvin (one-thousandth of a degree) in the brightness temperature of sky-averaged radio emission. Crucially, dark matter is expected to produce variations of similar magnitude in this signal. Observing the global signal across a broad frequency band (~45 MHz) could therefore reveal the mass and velocity of dark matter particles.
Several lunar missions, including Japan's Tsukuyomi Project, are now aiming to build radio telescopes on the Moon. If such telescopes can detect this faint signal, they will help unlock the mystery of dark matter.
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H.P. was supported in part by grant NSF PHY-2309135 to the Kavli Institute for Theoretical Physics (KITP). N.Y. acknowledges financial support from JSPS International Leading Research 23K20035. R.B. and N.Y. acknowledge JSPS Invitational Fellowship S24099.
Original Paper
Title of original paper:
The Signature of Sub-Galactic Dark Matter Clumping in the Global 21-cm Signal of Hydrogen
Journal:
Nature Astronomy
DOI:
10.1038/s41550-025-02637-0
Correspondence
Researcher Hyunbae Park
Center for Computational Sciences, University of Tsukuba
Project Professor YOSHIDA, Naoki
Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), The University of Tokyo Institute for Advanced Study (UTIAS), The University of Tokyo
Related Link
Center for Computational Sciences
Journal
Nature Astronomy
Article Title
The signature of subgalactic dark matter clumping in the global 21-cm signal of hydrogen
By AFP
October 9, 2025
The SpaceX Starship rocket launches from Starbase, Texas, as seen from South Padre Island on May 27, 2025 - Copyright AFP/File Sergio FLORES
Olga Nedbaeva and Bénédicte Rey
Europe must quickly get its own reusable rocket launcher to catch up to billionaire Elon Musk’s dominant SpaceX, European Space Agency director Josef Aschbacher told AFP in an interview.
While the US company has an overwhelming lead in the booming space launch industry, a series of setbacks, including Russia’s withdrawal of its rockets, left Europe without an independent way to blast its missions into space.
That year-long hiatus ended with the first launch of Europe’s much-delayed Ariane 6 rocket in July 2024. But the system is not reusable, unlike SpaceX’s Falcon 9 workhorse.
“We have to really catch up and make sure that we come to the market with a reusable launcher relatively fast,” Aschbacher said at AFP’s headquarters in Paris.
“We are on the right path” to getting this done, he added.
– ‘Paradigm shift’ –
European Space Agency director Josef Aschbacher is calling on Europe to pay up to compete in a booming space economy – Copyright AFP JOEL SAGET
The ESA has already announced a shortlist of five European aerospace companies bidding to build the continent’s first reusable rocket launch system.
That number will be narrowed down to two — or even one — at the agency’s ministerial council in the German city of Bremen next month, Aschbacher said.
“Ariane 6 is an excellent rocket — it’s very precise,” Aschbacher said. “We have now had three launches,” with two more expected before the year’s end, he added.
Despite finally getting Ariane 6 and the new, smaller Vega C launcher off the ground, the ESA has decided on a “paradigm shift”, Aschbacher said.
“The next generation of launchers will be very different,” he told AFP.
When Ariane 6 was being planned more than a decade ago, reusability was not considered worth the extra cost and time.
But it has come under criticism when compared to the relatively cheap, reusable Falcon 9, which has completed well over 100 launches this year alone.
So the ESA has decided to emulate NASA, which also used to develop its own rockets but now outsources its launches to private companies such as SpaceX or Jeff Bezos’s Blue Origin.
– A European Starlink? –
Many of the Falcon 9 flights have carried the more than 8,000 satellites that make up Musk’s Starlink internet network into space.
The European Union is planning to create its own internet satellite constellation called IRIS2, scheduled to become operational in 2030.
“Europe needs it absolutely urgently,” Aschbacher said.
“We have to make sure that we have the rockets to bring our satellites to space.”
He stressed that IRIS2 would be “very different” from Starlink, with fewer satellites, while focusing more on “secure communication”.
The constellation will mark a technological leap forward, even though Europe sometimes lags “a few years behind” its competitors, Aschbacher said.
Aschbacher noted that the EU’S navigation satellite system Galileo and Earth observation programme Copernicus started out 10 to 15 years behind US competitors GPS and Landsat.
Now both EU programmes are “the best in the world”, he said.
Aschbacher lamented that European public investment in space is declining, even as the global space economy grows.
He called for “very strong financial engagement” from the ESA’s 23 member states, which includes the United Kingdom, at next month’s ministerial council.
– Impact of Trump cuts? –
In the United States, President Donald Trump’s administration has proposed slashing NASA’s budget, signalling it wants to cancel the joint Mars Sample Return mission with the ESA.
If the cuts go ahead, Aschbacher said, they could also affect shared missions such as the use of the International Space Station and the Artemis programme to put astronauts back on the Moon, he said.
The three ESA missions most likely to be affected are the EnVision mission to Venus, LISA gravitational wave observatory and NewAthena X-ray telescope, Aschbacher said.
However, Europe intends to complete these “flagship missions” even if the United States pulls out — perhaps by bringing in other partners, he added.
Aschbacher also said there had been “interest from our colleagues in the United States” in applying for jobs at the ESA.
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