EQUULEUS: Mission to Earth - Moon Lagrange Point by a 6U Deep Space CubeSat

Abstract

A 6U Deep Space CubeSat EQUULEUS (EQUilibriUm Lunar-Earth point 6U Spacecraft) will be the world’s smallest spacecraft to explore the Earth―Moon Lagrange point. T he spacecraft is jointly developed by the University of Tokyo and JAXA and will belaunched by NASA’s SLS (Space Launch System) EM-1 (Exploration Mission-1) in 2018. The spacecraft will fly to a libration orbit around the Earth-Moon L2 point and demonstrate trajectory control techniques within the Sun-Earth-Moon region (e.g. low-energy transfers using weak stability regions) for the first time by a nano spacecraft. This mission will contribute to the realization of the future efficient cargo transfers to deep space ports located at the Lagrange points. This mission also carries several scientific observation instruments. The first one, named PHOENIX (Plasmaspheric Helium ion Observation by Enhanced New Imager in eXtreme ultraviolet), will conduct the imaging of the Earth\u27s plasmasphere by extreme UV wavelength. The observation will complement and enhance the geospace in-situ observation conducted by the ERG (JAXA\u27s small space science mission to be launched in 2016) and Van Allen probe (NASA) missions. As a result, we can improve our understanding of the radiation environment around the Earth, which is one of the critical issues for human cis-lunar exploration. The second scientific observation instrument, named CLOTH (Cis-Lunar Object Detector within Thermal Insulation), will detect and evaluate the meteoroid impact flux in the cis-lunar region by using dust detectors implemented in the spacecraft’s MLI (Multi-Layer Insulation). The goal of this mission is to understand the size and spatial distribution of solid objects in the cis-lunar space. The third scientific observation instrument, named DELPHINUS (DEtection camera for Lunar impact PHenomena IN 6U Spacecraft), will observe the impact flash at the far side of the moon from Earth—Moon L2 point (EML2) for the first time. This observation will characterize the flux of impacting meteors, and the results will contribute to the risk evaluation for future human activity and/or infrastructure on the lunar surface. EQUULEUS will use X-band and Ka-band frequencies for the deep space telecommunication. Japanese deep space antenna (64-meter antenna and 34-meter antenna) will be nominally used for the spacecraft operation, and the support from DSN (Deep Space Network) of JPL is also being planned. This paper describes mission outline, spacecraft system design, and some newly developed technologies