Radio astronomers like a bit of peace and quiet, so they're sending an historic first radio telescope to the Moon. To block out Earthside radio signals, the Lunar Surface Electromagnetics Experiment (LuSEE-Night) will set up shop on the far side of the Moon.
Radio astronomy has revolutionized our understanding of the universe by opening up the vast electromagnetic spectrum that is invisible to the human eye. With giant radio telescopes to help, we have discovered pulsars, quasars, radio galaxies, interstellar molecules, supermassive black holes, and the microwave echoes of the Big Bang.
Unfortunately, listening to the music of the spheres is a frustrating task because Earth isn't exactly a quiet neighborhood when it comes to radio waves. Never mind terrestrial radio and television broadcasts, or even satellite signals or the ubiquitous presence of cell phones. There are also sparking car engines, microwave ovens, lightning strikes, GPS signals, reflections off the ionosphere, and even bird poop on the antenna to muck things up.
Astronomers try to get around this with electronic and digital filters, and siting telescopes in remote areas like Goonhilly in England or legally protected radio silent zones in the United States, South Africa, Australia and Brazil, but it's still not good enough – especially when it comes to listening to phenomena that's the equivalent of a cosmic pin drop.
Instead of trying to beat all this radio noise, scientists and engineers at the US Department of Energy's Brookhaven National Laboratory, along with NASA, the University of California, Berkeley and Lawrence Berkley Lab have decided to up sticks and move somewhere a lot quieter.
That quieter is the far side of the Moon, where the bulk of our natural satellite acts as a 7.34767309×1019-tonne shield against Earth radio noise.
The first step is the LuSEE-NIght mission, which is tasked with demonstrating that it's possible to set up and run a radio telescope remotely on the Moon that can send back meaningful scientific data.
Part of the commercial Firefly Aerospace's Blue Ghost 2 lunar lander scheduled to fly late this year or early next, LuSEE-Night is a self-contained instrument pack designed to monitor low-frequency radio signals in the frequency range of 0.1 to 50 MHz and help astronomers to build up a complete picture of that band of the spectrum. It's also made to record anything broadcasting on the redshifted 21-cm (8.3-in) line of neutral hydrogen. According to NASA, this is key to unlocking the secrets of the Cosmic Dark Ages, the period after the cosmic microwave background (CMB) formed 380,000 years after the Big Bang and before the formation of the first stars and galaxies.
However, this is another one of those first-catch-your-rabbit things, so before the science stuff can happen the team has to make sure LuSEE-Night works as advertised.
Solar powered, the 1 x 1 x 0. 7-m (3.3 x 3.3 x 2.3-ft) device is based around a 4-channel, 50-MHz Nyquist baseband receiver system and a radio spectrometer to separate out the desired signals collected by four 3-meter-long (9.8-ft) beryllium copper cold-rolled helical pitch spring monopole antennas, arranged to form two orthogonal dipole antennas approximately 6 m (19.7 ft) tip-to-tip. This antenna array is designed to rotate, not only so it can be aimed at a particular part of the sky, but also to help calibrate the antenna telescope with the local electromagnetic environment. In addition, a lunar orbiter will broadcast predetermined code signals to help with the instrument's commissioning.
All that is well and good, except the Moon isn't a very nice place and none of this will do anything positive if the telescope packs up after landing. To prevent this, LuSEE-Night has a shield to reflect the heat of the Sun during the day and a whopping 40 kg-(88.2-lb), 6,500- to 7,160-Wh lithium-ion battery to run heaters to keep the electronics from freezing during the 14-day lunar night when the temperature drops to -173.15 °C (-279.6 °F).
Along with the help of a yet-to-be-determined relay satellite to send signals to and from Mission Control on Earth, LuSEE-Night is expected to remain operational for up to 18 months. If that works out, maybe one day we'll see one of the giant far-side craters turned into a radio dish that will make the defunct Arecibo Observatory look like a toy walkie talkie.
Source: Brookhaven National Laboratory