Lunar Crater Radio Telescope (LCRT) on the Far-Side of the Moon: NASA Innovative Advanced Concepts (NIAC) Phase 2 Report

An ultra-long-wavelength radio telescope on the far-side of the Moon has significant advantages compared to Earth-based and Earth-orbiting telescopes, including:
• Enabling observations of the early Universe at wavelengths longer than 10 meters (i.e., frequencies below 30 MHz), at which critical cosmological signatures from the “Dark Ages” are predicted to appear [1]. These wavelengths cannot be observed from Earth-surface or Earth-orbit, due to ionospheric absorption and reflection [2, 3].
• The Moon acts as a physical shield, isolating a lunar surface telescope from radio interference or noise sources from the Earth’s surface, the ionosphere, Earth-orbiting satellites, and the Sun’s radio emission during the lunar night [4].
We propose to design a Lunar Crater Radio Telescope (LCRT) on the far side of the Moon. We will deploy a wire mesh in a 1.3 km diameter lunar crater on the far side, with suitable depth-to-diameter ratio, to form a parabolic reflector with a 350 m diameter. LCRT will be one of the largest filled-aperture radio telescopes in the Solar System; larger than the former Arecibo telescope (305 m diameter, 3 cm–1 m wavelength band, 0.3 GHz–10 GHz frequency band) [5] but smaller than the Five-hundred-meter Aperture Spherical radio Telescope (FAST) (500 m diameter, 0.1–4.3 m wavelength band, 60 MHz–3000 MHz frequency band) [6] on Earth. LCRT would enable important scientific discoveries in the field of cosmology by observing the early Universe in the 6–64 m wavelength band (i.e. 4.7–47 MHz frequency band), which has not been explored for cosmological observations to date.