NASA Might Put a Huge Telescope on the Far Side of the Moon

One of the most ambitious proposals would build the Lunar Crater Radio Telescope, the largest (by a lot) filled-aperture radio telescope dish in the universe. While they are still hypothetical, and years away from reality, the findings from these projects could reshape our cosmological model of the universe.“With our telescopes on the moon, we can reverse-engineer the radio spectra that we record, and infer for the first time the properties of the very first stars,” said Jack Burns, a cosmologist at the University of Colorado Boulder and the co-investigator and science lead for both FarSide and FarView. Scientists refer to this period without visible or infrared light as the “Cosmic Dark Ages.” During this epoch, it seems likely that the universe was very simple, consisting mostly of neutral hydrogen, photons, and dark matter. For incredibly long wavelengths, it’s a perfect port of call.To capture them, Burns’s FarSide and FarView proposals eschew a solid-aperture radio telescope (imagine the late Arecibo) in favor of a vast array of simple dipole antennas—much like the rabbit ears on your grandpa’s old TV. “We are going to use our radio telescopes like a particle detector to understand the kind of physics that was operating in this un-sampled time in the universe.”“This is a very important part of the story of the thermal history of the universe,” agrees Mather. “Was the expansion of the universe cooling this matter, or were objects like stars turning on and warming the matter up again?”Burns’s twin projects are the endpoint of more than 35 years of research, including an article he wrote for Scientific American in 1990 that laid out the obstacles to building a 10- to 15-meter lunar radio telescope at the time. It will capture redshifted 21-centimeter radio wavelengths on the far side before downloading its data to Earth via a lunar-orbiting relay satellite.But still, there’s an even more jaw-dropping idea: NASA Jet Propulsion Labs’ Lunar Crater Radio Telescope, which just received $500,000 in Round II NIAC funding. Its parabolic dish would catch long-wavelength radio waves traveling through space and direct them to a receiver suspended over the crater.Saptarshi Bandyopadhyay, the roboticist who’s the mastermind behind the concept, was inspired by Burns’s 1990 paper on why a radio telescope in a lunar crater wouldn’t work. “Another idea is to not use robots, but to fire harpoons into the crater wall” from the landing craft at the bottom of the crater, he says, with the rovers helping to tension the aluminum mesh dish.Needless to say, all three project concepts are up against some major challenges.