Optimization of Return Trajectories for Orbital Transfer Vehicle between Earth and Moon

In this paper, optimum trajectories in Earth Transfer Orbit (ETO) for a lunar transportation system are proposed. This paper aims at improving the payload ratio of the reusable orbital transfer vehicle (OTV), which transports the payload from Low Earth Orbit (LEO) to Lunar Low Orbit (LLO) and returns to LEO. In ETO, we discuss ballistic flight using chemical propulsion, multi-impulse flight using electrical propulsion, and aero-assisted flight using aero-brake. The feasibility of the OTV is considered

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

Initial Operation Results of a 50kg-class Deep Space Exploration Micro-Spacecraft PROCYON

This paper presents the development and initial operation results of 50kg-class deep space exploration microspacecraft PROCYON (Proximate Object Close flYby with Optical Navigation), which was jointly developed by the University of Tokyo and Japan Aerospace Exploration Agency (JAXA). The primary mission of PROCYON is the world’s first demonstration of 50kg-class deep space exploration bus system which includes the demonstration of high-efficiency GaN-based SSPA (Solid State Power Amplifier) for communication and high-precision navigation by a novel method of DDOR (Delta Differential One-way Range) observation. PROCYON also has some secondary advanced missions, which are deep space flight to a Near-earth asteroid and high resolution observation of the asteroid during close and fast flyby, and the wide view scientific observation of geocorona by a Lyman alpha imager from a vantage point outside of the Earth’s geocoronal distribution. PROCYON was developed at very low cost (a few million dollars) and within very short period (about 1 year), taking advantage of the heritage from Japanese Earth-orbiting micro satellite missions. PROCYON was launched into an Earth departure trajectory together with Japanese second asteroid sample return spacecraft Hayabusa-2 on December 3, 2014, and it has achieved its primary mission and some of the secondary missions

On-Orbit Operation Results of the World\u27s First CubeSat XI-IV – Lessons Learned from Its Successful 15-years Space Flight

In recent years, the size and cost of satellites have been reduced, and the frequent launch of satellites have been realized even by small private companies and universities. The first step of this big wave was the first successful launch of CubeSats, 1kg nano-satellites, in June 2003. One of the CubeSats was XI-IV, which was developed by Intelligent Space Systems Laboratory (ISSL) of the University of Tokyo. Its mission was the world’s first on-orbit demonstration of the CubeSat bus system. Due to the spatial, power and cost constraints, most of the bus system was composed of low-cost COTS parts, and a “cross-check” type fault redundancy system against the radiation effects was implemented to achieve as better reliability as possible within the resource constraints. Since the successful launch by the ROCKOT launch vehicle from Russia, the satellite has been in normal operation for over fifteen years since the launch (as of June 2019). The operation has been jointly conducted by the University of Tokyo and amateur radio operators in Japan. This paper reports its more-than-15-years world\u27s longest CubeSat operation results and the lessons learned from it

Optimal Design Methodology Emphasizing Surface Equipment Placement Applied to 6U CubeSats

In recent years, the number of launches of nano-satellites, which have the advantage of being developed in a short period of time, has increased rapidly. However, several issues need to be addressed to maximize the benefits of nano-satellites. One of them is that theoretical methods have not been widely applied to the placement of equipment on satellites. Therefore, this paper proposes an Optimal Design Methodology Emphasizing Surface Equipment Placement Applied to 6U CubeSats . It details the design and development of two 6U CubeSats using this method, along with the results and lessons learned

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

Development of the Water Resistojet Propulsion System for Deep Space Exploration by the CubeSat: EQUULEUS

In this study, Water micro-propulsion system AQUARIUS (AQUA ResIstojet propUlsion System) is proposed for 6U CubeSat: EQUULEUS to explore the deep space. AQUARIUS uses storable, safe and non-toxic propellant: water, which allows for downsizing of whole propulsion system to 2U and storing 1.2 kg water. Liquid propellant storage allows design of all propulsion systems below 100 kPa. The waste heat of communication components is reused to cover high latent heat of water. AQUARIUS has 4.0 mN and specific impulse of 70 s by less than 20 W power consumption. Breadboard model was designed and tested successfully. Engineering model is under developments and operations by using whole systems of EQUULEUS. AQUARIUS will be equipped with EQUULEUS scheduled to be launched in 2019 by SLS (Space Launch System)

Thermal Operation for the 6U Deep Space CubeSat EQUULEUS in the Initial Critical Phase

EQUULEUS (EQUilibriUm Lunar-Earth point 6U Spacecraft) was launched to deep space by NASA\u27s SLS (Space Launch System) on November 16, 2022. It has an engineering mission to demonstrate low-energy orbit maneuvering to EML2, a libration orbit around the second Earth-Moon Lagrange Point using the water propulsion system “AQUARIUS” (AQUA ResIstojet propUlsion System). The initial critical phase in EQUULEUS refers to a series of operational procedures associated with the first delta-V(DV1), which generated the largest thrust throughout the entire mission, taking place about 38 hours after separation for entering the transfer orbit to EML2. Thisorbit control was followed by several Thrust Correction Maneuver (TCM) operations to compensate for thrust errors