The first telescope for the far side of the moon – the LuSEE-Night radio telescope is catching signals from the “dark age” of the universe for the first time.

LUNAR LISTENING SITE: Astronomers will soon install a radio telescope on the far side of the Moon for the first time. Shielded from terrestrial interference, LuSEE-Night’s highly sensitive radio antennas are there to pick up faint signals from the dark age of the universe – the era before the first stars formed. The telescope is currently under construction in the United States and is scheduled to be deployed in 2025 with a lander on the far side of the Moon.

The far side of the Moon has long been considered an ideal location for highly sensitive telescopes. Because unlike the Earth, the satellite does not have an irritating atmosphere that absorbs certain radioactive components and leads to distortions. Because the Moon orbits us in a closed orbit, its hindquarters is permanently deflected from the Earth. As a result, they are well shielded from interference by radio emissions from our terrestrial technologies. During the 14-day lunar night, darkness and radio silence reign — perfect for astronomy.

extreme conditions

But there’s a catch: “Getting to the moon is easier than getting to Mars, but everything else is a real challenge,” explains Paul O’Connor of Brookhaven National Laboratory (BNL). “There is a reason that only one robotic rover has landed on the Moon in the past 50 years, when there have already been six on Mars, which is 100 times as far.” One of the main problems is the harsh conditions: Because there is no atmosphere, the surface of the Moon is exposed to intense cosmic rays that can damage sensitive electronics.

In addition, every two weeks, temperatures alternate between plus 120 degrees during the lunar day and minus 173 degrees on the lunar night. Telescopes and scientific instruments must withstand these extreme fluctuations. A third problem is location: although the far side of the Moon is suitable for undisturbed astronomical observations, it makes data transmission and communication difficult. Radio communication with lander probes and other man-made instruments has only been possible since there are space probes in orbit around the Moon that can act as relay stations.

LuSEE-Night: A radio telescope on the Moon

But all these difficulties will now be overcome by the LuSEE-Night (Lunar Surface Electromagnetics Experiment-Night) project. NASA and a team of scientists from the US National Laboratories plan to place the first radio telescope on the far side of the Moon in the near future. The team has already successfully created and tested a prototype. “The LuSEE-Night is not a standard radio telescope, it’s more like a kind of radio receiver,” explains Anže Slosar of BNL. “The telescope will pick up the signals near the ultra-high frequency range and separate them into their frequencies using a spectrometer.”

The LuSEE Wireless Night Telescope consists of four antennas about three meters long, which are attached to a rotatable base. After the telescope was deployed to the lunar surface by a probe from NASA’s Commercial Lunar Program, the antennas were deployed. The devices are powered by solar cells during the lunar day and batteries during the moonlit night. “But LuSEE-Night will only work in the cold temperatures of a lunar night,” explains NASA’s Joel Cairns.

A landing site for LuSEE-Night has already been identified: the telescope will be installed on a plateau at 23 degrees south latitude and 176 degrees east longitude.

Look first at the dark age of the universe

The mission’s science goal is ambitious: LuSEE-Night aims to pick up weak signals from the dark ages of the early universe for the first time. This era began about 380,000 years after the Big Bang with the formation of the first atoms and the release of cosmic background radiation. It ended with the formation of the first stars and the beginning of the cosmic dawn, about 300 million years after the Big Bang.

Until now, the Dark Age was an unexplored era of cosmic evolution, because even powerful telescopes such as the James Webb telescope or ground-based radio telescopes could only trace back to the time of the first galaxies. “The measurement is very difficult because the radio emission from our galaxy is very bright and the signal of the Dark Age is hidden behind it,” explains Slussar. However, the silent far side of the Moon and the sensitive LuSEE-Night radio spectrometer can identify these faint emissions.

‘Never seen the signs’

Astronomers hope that data from the LuSEE night telescope will provide valuable insights into the era that created the conditions for the formation of the first stars and galaxies. “LuSEE-Night could enable us for the first time to observe previously unseen signals of the Dark Age,” explains Asmeret Asefaw Berhe of the US Department of Energy’s Science Directorate. “We are now laying the groundwork for Dark Ages exploration for decades to come.”

Data from the far side of the Moon can help verify and complement models of cosmic evolution. “So far we can only guess what happened in those early stages of the universe,” Slussar says. “The Dark Age signal could give us new reference data here. And if that data doesn’t fit our theoretical models, we might even detect hints of new physics beyond the Standard Model.”

NASA and the Department of Energy have not yet announced when they will bring LuSEE-Night to the Moon. However, the mission is scheduled for late 2025. Once on the moon, LuSEE-Night should collect astronomical data for at least two years. At the same time, the mission is a test case for a larger follow-up telescope, which could then be built as a dish in one of the lunar craters.

Source: NASA, Brookhaven National Laboratory

March 13, 2023

– Nadia Podbrigar