NASA wants a telescope on the far side of the Moon
Aims to look at the universe's dark ages without interference from Earth
NASA and the US Department of Energy hope to build a lunar telescope on the far side of the Moon that will hunt for ancient radio waves, emitted just 380,000 years after the Big Bang.
Studying the origins of the universe is difficult – there isn't much data and astronomers form hypotheses by piecing together bits of evidence from astronomical observations. The best proof supporting the Big Bang – which describes how the universe formed and rapidly expanded roughly 13.8 billion years ago – is the cosmic microwave background.
Before the first stars formed, the universe was in the so-called Dark Ages. Atoms were just starting to form and emitting photons. The energy from these photons has stretched as the universe has expanded over time to become a hypothetical source of radio energy known as the Dark Ages Signal.
Now, NASA and the DoE have launched a project – named the Lunar Surface Electromagnetics Experiment-Night (LuSEE-Night) – in hopes of finding this ancient signal left over from the Big Bang.
"Modeling the universe is easier before stars have formed. We can calculate almost everything exactly," Anže Slosar, a physicist leading the DOE's efforts for the project at Brookhaven National Laboratory, said in a statement.
"So far, we can only make predictions about earlier stages of the universe using a benchmark called the cosmic microwave background. The Dark Ages Signal would provide a new benchmark. And if predictions based on each benchmark don't match, that means we've discovered new physics."
Finding the signal amongst noise and interference from other radio sources, however, requires placing a probe somewhere incredibly isolated – like the far side of the Moon.
"The Moon and Earth are tidally locked, which means that the Moon rotates around its own axis with the same velocity as it does around the Earth," Slosar explained. "This is why we always see the same side of the Moon. But the side we can't see, the lunar far side, is shielded from many sources of radio interference at night by the Moon's own mass."
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The far side of the Moon is a much more difficult environment from which to operate. The LuSEE-Night telescope must be able to generate enough power to keep running in temperatures that can vary wildly. Communications between Earth and the far side of the Moon are also slower, and astronomers back at home will have to wait 40 days to receive the first signal back from the probe.
"The Moon is easier to reach than Mars, but everything else is more challenging," said Paul O'Connor, a senior scientist in Brookhaven's Instrumentation Division and LuSEE-Night Project Instrument Scientist.
"There's a reason only one robotic rover has landed on the Moon in the last 50 years, while six went to Mars, which is 100 times farther away. It's a vacuum environment, which makes removing heat difficult, and there's a bunch of radiation."
The goal is to send a robotic lander to touch down on the lunar surface and deploy the telescope. Four antennas, measuring three meters long, developed by researchers at the Lawrence Berkeley National Laboratory, will unfold to find radio waves from the Dark Ages Signal. The mission is expected to launch in 2025 as part of NASA's Commercial Lunar Payload Services – an initiative to expand lunar spaceflight contracts to private companies.
"LuSEE-Night is not a standard radio telescope," Slosar said. "It's more of a radio receiver. It will work like an FM radio, picking up radio signals in a similar frequency band. The spectrometer is at the heart of it. Like a radio tuner, it can separate out radio frequencies, and it turns signals into spectra."
These spectra will help cosmologists figure out the greatest mystery of all time: how did the universe begin? ®