How to Deploy a 10-km Interferometric Radio Telescope on the Moon with Just Four Tethered Robots

Abstract

The Far-side Array for Radio Science Investigations of the Dark ages and Exoplanets (FARSIDE) is a proposed mission concept to the lunar far side that seeks to deploy and operate an array of 128 dual-polarization, dipole antennas over a region of 100 square kilometers. The resulting interferometric radio telescope would provide unprecedented radio images of distant star systems, allowing for the investigation of faint ra-dio signatures of coronal mass ejections and energetic particle events and could also lead to the detection of magnetospheres around exoplanets within their parent star's habitable zone. Simultaneously, FARSIDE would also measure the ‘Dark Ages' of the early Universe at a global 21-cm signal across a range of red shifts (z ~50-100). Each discrete antenna node in the array is connected to a central hub (located at the lander) via a communication and power tether. Nodes are driven by cold-operable electronics that continuously monitor (for 5 or more years) an extremely wide-band of frequencies (200 kHz to 40 MHz), which surpass the capabilities of Earth-based telescopes by two orders of magnitude. Achieving this ground-breaking capability requires a robust deployment strategy on the lunar surface, which is feasible with existing, high-TRL technologies (demonstrated or under active development) and is capable of delivery to the surface on next-generation commercial landers, such as Blue Origin's Blue Moon Lander. This paper presents an antenna packaging, placement, and surface deployment trade study that leverages recent advances in tethered mobile robots under development at NASA's Jet Propulsion Laboratory, which are used to deploy a flat, antenna-embedded, tape tether with optical communication and power transmission capabilities. We investigate the feasibility of deploying 4 separate 12-km tethers, each with 64 remotely powered electronics nodes, using just four rovers that trace out a large spiral pattern that is over 10-km in diameter, where each arm in the spiral is precisely laid out and aligned with respect to a global heading (NSEW) to provide dual polarization across the entire array. Further, we provide a detailed design for an instrument/antenna-embedded tether, detail its accommodation within and deployment from a two-wheeled rover, and show how the entire system can be packaged and deployed from a commercial lunar lander system.