Lessons Learned From Operations Planning and Preparation for EQUULEUS Launched Toward the Moon by SLS Artemis-1

EQUULEUS (EQUilibriUm Lunar-Earth point 6U Spacecraft) will be the world\u27s smallest spacecraft to explore around the Earth–Moon Lagrange point, which was launched on November 16, 2022, by NASA\u27s SLS (Space Launch System) Artemis-1. The primary mission of spacecraft is a trajectory control experiment, and its objective is to develop and demonstrate trajectory control techniques within the Sun-Earth-Moon region by flying to a libration orbit around the Earth-Moon Lagrange point L2 (EML2) along a low-energy transfer. EQUULEUS must perform a maneuver before the lunar flyby to stay within the Sun-Earth-Moon region. To perform DV1, we need to calculate and optimize the trajectory from launch to EML2. In addition, it is necessary to optimize the operation plan until the first lunar flyby, which is less than a week after launch. The reason for this is that the EQUULEUS trajectory will be significantly changed by the first lunar flyby, so appropriate trajectory control must be performed by that time. This paper presents the lessons learned in the operational preparation of EQUULEUS and those that should be applied to future missions to explore deep space, including the Moon and planets, by small and micro-satellites

EQUULEUS: Initial Operation Results of an Artemis-1 CubeSat to the Earth—Moon Lagrange Point

EQUULEUS is a 6U CubeSat developed by the Japan Aerospace Exploration Agency (JAXA) and the University of Tokyo, aiming to reach the Earth-Moon second Lagrange point (EML2) and perform scientific observations there. After being inserted into a lunar transfer orbit by SLS Artemis-1 on November 16, 2022, the spacecraft completed checkout operations and successfully performed a delta-V maneuver and subsequent trajectory correction maneuver. This enabled a precise lunar flyby as planned and successful insertion into the orbit toward EML2, which will take advantage of multiple lunar gravity assists and the gravity of the Sun. EQUULEUS is equipped with a water propulsion system newly developed by the University of Tokyo, and became the first spacecraft in the world to successfully control its orbit beyond low Earth orbit using water propulsion. The successful precise orbit control in the Sun–Earth–Moon region by EQUULEUS, a 6U CubeSat weighing only 10kg, has opened the possibility of full-scale lunar and planetary exploration by CubeSats. This paper describes the early operational results of EQUULEUS during its flight to EML2, with special emphasis on its precise orbit determination, guidance, and control results

Initial Results for Science Instruments Onboard EQUULEUS During the Cruising Phase Toward the Earth Moon Lagrange Point

EQUULEUS (EQUilibriUm Lunar-Earth point 6U Spacecraft) is a spacecraft to explore the cis-lunar region including the Earth-Moon Lagrange point L2 (EML2). The spacecraft is being jointly developed by JAXA, the University of Tokyo, and several other universities in Japan. After being launched into a lunar transfer orbit by NASA\u27s SLS (Space Launch System) Artemis-1 on November 16, 2022, the spacecraft successfully performed a first Delta-V and a trajectory correction maneuver. This enabled a precise lunar flyby and successful insertion into the orbit toward EML2. Although the size of EQUULEUS is only 6U CubeSat, the spacecraft carries three different science instruments. The spacecraft can effectively demonstrate science missions during and after the flight to EML2 by using these instruments; the plasmasphere observation around the Earth by PHOENIX, the space dust flux detection in the cis-lunar region by CLOTH, and the lunar impact flash (LIF) observation at the far side of the moon by DELPHINUS. All instruments have already completed its checkout. During the cruising phase, PHOENIX conducted Earth observations and successfully identified the Earth\u27s plasmashere. CLOTH has started regular standby operations. DELPHINUS obtained impressive images such as the far side of the Moon at lunar closest approach and long-period comet, Comet ZTF. This poster presents the details of these scientific missions and the initial checkout and observation results of the science instruments

Solar System Exploration Sciences by EQUULEUS on SLS EM-1 and Science Instruments Development Status

EQUULEUS is a spacecraft to explore the cislunar region including the Earth-Moon Lagrange point L2 (EML2) and will be launched by NASA’s SLS EM-1 rocket. Although the size of EQUULEUS is only 6U, the spacecraft carries three different science instruments. By using these instruments, the spacecraft will demonstrate three missions for solar system exploration science during and after the flight to EML2; imaging of the plasmasphere around the earth, observation of space dust flux in the cislunar region, and observation of lunar impact flashes at the far side of the moon. The developments and verifications of the flight models of these science instruments were completed by the end of 2018, and we started flight model integration and testing. This paper introduces the details of the scientific objectives, design results and development statuses of the instruments. In addition, results of the integration and pre-flight tests are also described

Compression Stockings Suppressed Reduced Muscle Blood Volume and Oxygenation Levels Induced by Persistent Sitting

This study quantitatively analyzed the effects of 3 h of constant sitting on skeletal muscle oxygenation in the lower extremities, using near-infrared time-resolved spectroscopy (NIRTRS). The effects of compression stockings were also evaluated. Eleven healthy men (age, 30.0 ± 6.7 years) maintained their knee joints at 90° flexion during 3 h of constant sitting and wore a compression stocking on either the right or left leg. The side the stocking was worn was chosen randomly. Subsequently, leg circumference and extracellular water were measured. After 3 h of sitting, both factors increased significantly in uncompressed limbs. Furthermore, intracellular water and muscle oxygenation had significantly decreased. In contrast, extracellular water had not increased in the limbs wearing compression stockings. Furthermore, the increased circumference of compressed limbs was significantly smaller than that of uncompressed limbs. Decreases in oxygenated hemoglobin and total hemoglobin were significantly smaller in compressed limbs than in uncompressed limbs (oxy-Hb; p = 0.021, total-Hb; p = 0.013). Three hours of sitting resulted in decreased intracellular water and increased extracellular water in the lower extremities, leading to reduced blood volume and oxygenation levels in skeletal muscle. Compression stockings successfully suppressed these negative effects

Low dispersion spectra of lunar impact flashes in 2018 Geminids

International audienceLunar impact flashes have been observed at collisions of meteoroids against the non-sunlit lunar surface at speeds exceeding 10 km s À1. We detected 13 flash candidates between 6.2 and 9.9 in R-magnitude on December 15, 2018 during the Geminids meteor activity. Two or three observatories confirmed eleven of them. We obtained their spectra in the wavelength range between 400 and 870 nm. They are continuous and red, with best-fitted single blackbody spectra indicating the temperatures of about 2000-4000 K. The temperatures for a few successive movie frames at 16 ms or 25 ms intervals decrease with time. Incandescent ejecta, consisting of melt droplets or dust, and the radiant floor of an impact crater could be the source of these flashes, except for the initial stages. At the beginning of some flashes, we found an excess of fluxes at short wavelengths of less than about 600 nm. The composites of two blackbody spectra may fit the spectra better where their temperatures are about 2000 K and 6000 K. The contribution of a high-temperature vapor plume, generated at the very beginnings of the impact phenomena, could be important