China's scientists have completed a feasibility study of a space radio telescope project that will be placed in the orbit of the Moon and will help Earth's science to look into the dark ages of our universe when it was about 200 million years old. Radio signals from that era can't get through the sound of radio interference on Earth, and the absence of stars at that time makes it impossible to get data in the visible and infrared light, leaving the moon or its orbit, where the effects of noise are much smaller.
Ideally, astronomers would like to build a radio telescope on the back of the Moon; sooner or later, such a project will be implemented, but obviously not in the very near future; it is much easier and cheaper to launch a radio telescope into the orbit of the Moon, so that it can operate at times when the Moon is shielding the radiophone on the planet's side, and it does so very, very well, which, for example, makes it possible to launch satellite transmitters for space missions on the back of the Moon.
On the other hand, the problem with space telescopes is that it is not yet possible to create a large enough antenna to place it in the head of the launch vehicle. The Chinese project Discovering the Sky at the Longest Wavelength or Hongmeng involves the launch into the Moon of a repeater satellite, which will also process data, and a linear array of small satellites with antennas.
In fact, a distributed radio telescope could be deployed in orbit on the Moon, synchronizing the data as signals from a single large antenna. Such a radio telescope would search the sky at the far end of the moon orbit over the dark side of the Moon, and would transmit the data to Earth after passing over the visible side of the satellite.
A team of Chinese scientists has completed a feasibility study of the Hongmeng project this year. Work on the project began in 2015 and included testing selected technologies on drones. Earth-distributed radio telescopes have long been used to observe the sky, but have not yet tried to create a radio telescope at moving objects.
Scientists argue that all the keys to implementing the Hongmeng project on a space scale are tested and can be translated into action. If the project is approved by the Chinese authorities, it will be possible to launch the Moon Observatory in 3.5 years.
The moon's radio telescope will search for signs of atomic hydrogen in the Dark Ages of the Young Universe, which are very, very weak signals that will not be easy to separate from the sound of the surrounding space even on the back of the Moon.