The unifying theme of the three sessions in this Meeting in a Meeting proposal was the Moon as a unique platform from which to conduct advanced observations of the Sun, the high redshift (z>10) early Universe, and Gravitation.
Cosmic Dawn, Reionization, & Low Frequency Astrophysics (Chaired by S. Furlanetto, Warner Prize lecturer)
This session discussed advances in theory, observations, and instrumentation for low frequency astrophysics and cosmology from the ground and from the Moon. As one example, the Astro2020 Decadal Report New Worlds, New Horizons in Astronomy & Astrophysics singles out Cosmic Dawn as a top science objective for this decade. When and how did the first galaxies form out of cold clumps of hydrogen gas? What signatures did the first stars leave on their surroundings? When and how did reionization occur? The highly redshifted (z≈6-35) 21-cm hyperfine transition from neutral hydrogen at 40-200 MHz is a powerful probe of this epoch. Concepts for low frequency telescopes, including dipoles in lunar orbit and arrays on the radio-quiet lunar farside, were presented in this session that will constrain Cosmic Dawn as COBE and WMAP did for the CMB.
Precision Measurements in Gravitational Physics
The New Worlds, New Horizons Particle Astrophysics & Cosmology Panel of the Astro2010 Decadal Survey emphasized the unique role of the Moon where Lunar Laser Ranging (LLR) “offers a promising and cost-effective way to test General Relativity and other theories of gravity”. The report recommended “deploying a global, long-lived [LLR] network on the Moon,” especially since the Apollo arrays have already demonstrated most of the best tests of GR. LLR is also complementary to the recently-launched GRAIL mission for studying the Moon’s interior, providing more detailed data on the inner core region. In this session, recent advances in LLR were presented including the first laser signals recovered from Lunokhod 1 and next generation retro-reflectors that may be emplaced on the Moon within the next few years by potential commercial spacecraft (Google Lunar X-Prize). This “Lunar Laser Ranging Retroreflector for the 21st Century” will increase the accuracy supported by the lunar emplacement by a factor of 10 to 100.
Heliophysics, Coronal Mass Ejections, & Space Weather
High energy particle acceleration occurs in diverse environments including the Sun, stars, supernovae, and AGNs. Fundamental problems include understanding the mechanisms and sites of this acceleration, in particular the roles of shock waves and magnetic reconnection. This session discussed current observations and models of Coronal Mass Ejections, their impact on the near-Earth environs, and the radio bursts they produce. The design and deployment of proposed ν<10 MHz imaging arrays on the Moon were presented. The arrays and their deployers also have other science applications. Examples include detection of interplanetary and interstellar dust striking polyimide antennas on the lunar surface and deployment of a range of detectors for other science targets.