African scientists and engineers are preparing to place a working radio telescope array on the surface of the Moon.
The instrument, known as Africa2Moon, is the first all-African space exploration mission, and Rhodes University’s distinguished professor Oleg Smirnov is the principal investigator for radio astronomy for the mission.
Selected in 2025 to fly aboard China’s Chang’e-8 mission to the lunar south pole, scheduled for 2029, Africa2Moon aims to become the first radio interferometer to operate on the lunar surface.
“Africa2Moon has always been about more than a single instrument on the Moon,” says Dr Adriana Marais, lead author, director of the Foundation for Space Development Africa and head of science for the mission.
“It is proof that African scientists and engineers can imagine something audacious and then build it, together. We are opening a window on the Universe that few have been able to look through before, and we are doing it from Africa, for the world.”
In a statement, Rhodes University says for a century, radio astronomy has reshaped our understanding of the Universe, revealing objects and events that are invisible to ordinary telescopes. Yet one window has stayed almost entirely closed, it says.
According to the university, radio waves at the lowest frequencies, below 20MHz, are blocked by Earth’s atmosphere, leaving a whole stretch of the cosmic radio spectrum that astronomers on the ground simply cannot see.
It explains that the Moon offers a way through. “With almost no atmosphere, and, on its far side at night, near-total shielding from human-made radio noise and the Sun, it is the most radio-quiet place within reach. Put a radio telescope there, and the last unexplored band of the radio sky finally opens up.”
“The lowest-frequency radio sky is one of the last unexplored frontiers in astronomy, and you cannot see it from the ground,” says Smirnov, research chair in radio astronomy techniques and technologies at Rhodes University.
“To reach it, you can go to space, and what better place than the Moon. What excites me is that the very expertise South Africa has built through MeerKAT and the SKA [Square Kilometre Array] is what this mission needs. This is Rhodes University, and African radio astronomy, stepping off the planet.”
Technosignature search
The Africa2Moon mission concept consists of a set of spheres, referred to as BALLS, short for Bounced African Low Lunar Spheres.
Once delivered to the Moon, the spheres are designed to roll freely across the surface, spreading out to work together as a single telescope.
Rhodes University notes the technology demonstrator selected for the Chang’e-8 mission consists of three of these spheres, each about 30cm across, weighing less than 4kg, and carrying its own antennas, electronics and solar power.
It explains that each of the BALLS is an independent radio receiver expected to operate for at least six Earth days.
During that time the array will listen to the Earth, the Sun, the Galaxy and the lunar surface itself, and will search for technosignatures, possible signs of technology beyond Earth.
Professor Smirnov and his group at Rhodes University, the Centre for Radio Astronomy Techniques and Technologies have helped build South Africa’s reputation for turning raw radio signals into science, including work on the MeerKAT telescope and the SKA.
That expertise is central to Africa2Moon. Reading faint signals from a handful of small antennas scattered across the Moon, and combining them into a single sharp picture of the sky, is exactly the kind of problem Rhodes University researchers have spent more than a decade solving on Earth.
Africa2Moon builds on a decade of rapid growth in African radio astronomy, the university notes. The SKA and precursors such as MeerKAT have made the continent a serious contributor to global space science, it adds. The skills developed for telescopes on the ground are now being carried into space.
Empowering Africa’s youth
Among the authors is Dr Carla Sharpe Mitchell, the founding director of the Foundation for Space Development Africa and mission director of Africa2Moon:
“Africa2Moon shows what becomes possible through collaboration, which is not only taking African technology to the Moon, but empowering Africa’s youth to see that they too can shape a collaborative and resilient future for our continent,” says Dr Mitchell.
Rhodes University points out that the three-sphere demonstrator is only a first step. The full Africa2Moon mission aims to place 55 antennas on the far side of the Moon, one for each African nation.
Beyond the science, the project is a training ground, drawing in students, universities, research institutions and engineering companies across the continent, and building expertise in radio engineering, systems integration and space mission design.
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