A small mission to check technology to detect radio waves from the cosmic Dark Ages over 13.4 billion years ago will blast off for the far side of the moon in 2025.
The Lunar Surface Electromagnetic Experiment-Night mission, or LuSEE-Night for brief, is a small radio telescope being funded by NASA and the U.S. Department of Energy with involvement from scientists on the Lawrence Berkeley National Laboratory, the Brookhaven National Laboratory, the University of California, Berkeley and the University of Minnesota. LuSEE-Night will blast off as a part of NASA’s Business Lunar Payloads program.
The Dark Ages are the evocative name given to the time frame after the Big Bang, when the primary stars and galaxies were only just starting to form and ionize the neutral hydrogen gas that filled the universe. Little is thought about this era, despite efforts by the James Webb Space Telescope to start probing into this era.
The neutral hydrogen present throughout the Dark Ages was in a position to absorb a few of the radiation of the cosmic microwave background, making a dip within the intensity of radio waves from that era at frequencies between 0.5 and 50 megaHertz.
“We’re on the lookout for this very tiny dip that’s potentially the Dark Ages signal,” said Kaja Rotermund of the Lawrence Berkeley National Laboratory in a statement.
Earth’s atmosphere, along with terrestrial radio interference, obscures this faint signal. The answer is to go to the far side of the moon, where there isn’t any atmosphere and Earth and all its radio noise isn’t visible.
“In the event you’re on the far side of the moon, you’ve gotten a pristine, radio-quiet environment from which you’ll be able to attempt to detect this signal from the Dark Ages,” said Rotermund. “LuSEE-Night is a mission showing whether we will make these sorts of observations from a location that we have never been in, and in addition for a frequency range that we have never been in a position to observe.”
LuSEE-Night shall be joined on the moon by LuSEE-Lite, which can blast off for Schrödinger Basin, which is situated on the far side near the moon’s south pole, in 2024. LuSEE-Lite will operate in daylight, but LuSEE-Night will test technologies similar to antennas and batteries to see in the event that they can function efficiently within the freezing-cold conditions of lunar night, where the temperature can reach as little as minus 280 degrees Fahrenheit (minus 170 degrees Celsius). While the lunar far side experiences daytime in addition to night-time, night lasts for 2 weeks, so any long-duration mission to the moon has to take care of that. Because LuSEE-Night is not going to have the opportunity to see Earth from the lunar far side, a relay satellite could have to speak with Earth on its behalf.
Rotermund and her colleagues at Berkeley Lab are constructing two pairs of antennas that can fly on LuSEE-Night to attempt to detect the hydrogen absorption within the radio waves from the cosmic Dark Ages. The antennas are 20 feet (6 meters) long from tip to tip, and are spring-loaded and designed to uncoil upon landing.
“The engineering to land a scientific instrument on the far side of the moon alone is a big accomplishment,” said Aritoki Suzuki of Berkeley Labs. “If we will show that this is feasible — that we will get there, deploy and survive the night — that may open up the sector for the community and future experiments.”
The primary-ever successful landing on the lunar far side was in 2019, when China’s Chang’e 4 mission touched down and deployed a small rover named Yutu-2.
LuSEE-Night could possibly be seen as a precursor for a much larger and more ambitious radio telescope. Scientists have long proposed the constructing of a radio telescope on the far side of the moon that might probe everything of the radio spectrum without radio frequency interference from Earth, and subsequently spot frequencies undetectable from our planet. Such a telescope would pose intriguing engineering challenges, similar to the way to construct a big telescope within the moon’s low gravity and cold temperatures.
A bigger, more sensitive telescope could be needed, for LuSEE-Night isn’t necessarily expected to have the opportunity to detect the Dark Ages. Initially it’s a technology demonstrator, and any scientific results that it could actually achieve shall be a bonus.
LuSEE-Night shall be flown to the moon in partnership with Firefly Aerospace, which is constructing the “Blue Ghost” lander that can carry it. The plan is for LuSEE-Night to operate on the moon for 18 months, recharging its batteries using solar energy throughout the two-week long lunar days.