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| Selfie with Dr. Marc Klein Wolt |
I attended the lecture by Dr. Marc Klein Wolt which spoke of his mission to the back side of the Moon and his ideas about installing huge antenna's on the back side of the Moon.
Dr. Marc Klein Wolt, astrophysicist at Radboud University Nijmegen and director of the Radboud Radio Lab, is exploring the origin of the Universe by studying the redshifted 21-centimeter hydrogen line. This signal, emitted by neutral hydrogen, allows scientists to probe the so-called Cosmic Dark Ages, the era after the Big Bang and before the first stars and galaxies ignited.
As the Universe expanded, the original 21-cm signal was stretched, or redshifted, to much longer radio wavelengths (100m and more). Detecting this extremely faint radiation from Earth is nearly impossible due to radio interference and the blocking effects of Earth’s ionosphere. Therefor the idea to install equipment at the back side of the Moon.
In 2019, a radio antenna developed by Klein Wolt’s team flew with the Chinese Chang’e-4 mission, using the Queqiao relay satellite positioned behind the Moon. This location, permanently shielded from Earth’s radio noise, offers one of the quietest environments in the Solar System for radio astronomy.
By observing from lunar orbit, Klein Wolt aims to trace how the first cosmic structures formed from primordial hydrogen. His long-term vision includes building radio antennas on the lunar surface itself. These plans align with future European Space Agency (ESA) lunar initiatives, in which Europe seeks a scientific presence on and around the Moon.
The scientific importance of the 21-cm line is underscored by its inclusion on the Voyager Golden Record, sent into interstellar space as a universal cosmic reference. Together, lunar radio astronomy and international missions may soon reveal how darkness in the early Universe gave way to the first light.
The cosmic microwave background (CMB) was released about 380,000 years after the Big Bang during recombination, when electrons and protons combined to form neutral hydrogen. This was the first light that could travel freely through the universe. After that came the cosmic dark ages (roughly 380,000 to 100 million years), when the universe was mostly neutral hydrogen and no stars had formed yet. During this period, the 21 cm line from neutral hydrogen can be used to trace the distribution of matter. Later, the first stars and galaxies formed (~100–400 million years), emitting ultraviolet light that ionized hydrogen, beginning the reionization process, which was largely complete by about 1 billion years, weakening the 21 cm signal in ionized regions.
