Development of the All-Sky Electrostatic Analyzer for a Lunar Rover

All-Sky Electrostatic Analyzer (A-ESA) is a scientific payload that will be mounted on a lunar rover and is designed to observe the variations of plasma environment on the Moon. A-ESA is composed of an electrostatic analyzer on the top, and an MCP assembly, power supply units and electronics are located under it. A-ESA has the entrance scanning deflectors and the inner scanning deflectors. The entrance of A-ESA is electrically scanned within ~90∘in vertical direction, i.e. A-ESA has hemi-spherical field of view (FOV). When A-ESA is operating in observation mode, the collection of science data is divided into 8 parts in horizontal direction and 6 parts in vertical direction. And it generates 16 energy levels via sweeping high voltage. Therefore it can measure the plasma distribution function and charged particle energy in hemi-sphere space on the lunar surface. Since the launch of the science payload project, PDR, CDR, TRR and PAR reviews have been completed. Now we are carrying out function tests and performance tests. Initial function tests between A-ESA and the lunar rover have been performed too. At the end of 2024, the A-ESA has been delivered to Taiwan Space Agency (TASA).