OVERVIEW OF A & R WITHIN JAPAN’S SPACE PROGRAMME Mitsushige Oda Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan, e-mail: [email protected] Abstract asteroid ITOKAWA. The mass of the satellite is about 500kg, including fuel. It has a pair of solar cells panels, 2 the total area of which is 12m . Figure1 presents an This paper introduces activities in the field of artist’s image of Hayabusa heading to an asteroid. automation and robotics (A&R) within Japan’s space program. Major ongoing projects in the automation and robotics area are an asteroid sample return mission (HAYABUSA / MUSES-C), a remote manipulator system for the international space station Japanese Experiment Module (JEMRMS), and an H-II transfer vehicle (HTV). Various research studies are also in progress, aiming at future missions. 1. Introduction This paper introduces activities in the field of automation and robotics within Japan’s space program. Japan’s governmental space program is mostly conducted by JAXA. JAXA was created on October 1, Fig.1 An artist’s image of spacecraft Hayabusa heading 2003, by merging former NASDA, ISAS, and NAL. to an asteroid Other ministries, national institutes, and national laboratories are also conducting space projects in their Hayabusa arrived at ITOKAWA on September 12, 2005 own areas. Additionally, private sectors are conducting and will spend several months in close proximity to space activities either in their own activities or as part this target asteroid, observing the surface, and taking of governmental activities. asteroid surface samples. Figure 2 shows a picture of Major ongoing projects in the automation and robotics ITOKAWA taken by Hayabusa’s onboard camera from area are an asteroid sample return mission 20km distance. Asteroid surface sampling will be (HAYABUSA / MUSES-C), a remote manipulator conducted by injecting a small bullet into the asteroid system for the international space station Japanese and collecting fragments of the impact by horn-like Experiment Module (JEMRMS), and an H-II transfer equipment. The collected samples will be stored inside vehicle (HTV). Various research studies are also in a separate re-entry capsule for return to Earth. The progress, aiming at future space missions. capsule and the collected samples will return to Earth in 2007. Figure 3 presents an artist’s image of surface sampling by Hayabusa and Figure-4 illustrates the 2. Asteroid Sample Return Mission, Hayabusa sampler. Hayabusa (called MUSES-C before launch) is a sample return mission to an asteroid. Its primary goal is to acquire and verify technology that is necessary to retrieve samples from a small body in the solar system and to bring them back to Earth. The Hayabusa spacecraft is equipped with a solar-powered electrical propulsion system, and an autonomous navigation and guidance system. The spacecraft will rendezvous with asteroid 1998 SF36 (ITOKAWA), touch down, and take some samples. The samples will be stored inside an Earth re-entry capsule and will be brought back to scientists on Earth. The Hayabusa spacecraft was launched on May 9, 2003 Fig.2. Image of asteroid 1998 SF36 (ITOKAWA) taken using an M-V rocket and is now heading to the target by Hayabusa’s onboard camera from 20km distance Fig.5 Micro-rover MINERVA of Hayabusa Fig.3 An artist’s image of Hayabusa conducting surface sampling 3. Japanese Experiment Module of the International Space Station JAXA has developed the Japanese Experiment Module (JEM) for the International Space Station. JEM consists of a pressurized module, an exposed platform, a logistic module and a remote manipulator system. JEM’s flight hardware is built and is awaiting launch at NASA Kennedy Space Center. JEM’s remote manipulator system (JEMRMS) consists of a main arm and a small fine arm. The main arm is 9.9m long and has 6 degrees-of-freedom. It can handle up to 780kg of payloads. The small fine arm is 1.9m long and has 6 degrees-of-freedom. It can handle up to 300kg of payloads. The main arm is primarily used to handle the logistic module and experiment units on the exposed facility. The small fine arm is mainly used to handle orbital replacement units (ORU) on the exposed facility. Fig.5. depicts an artist’s image of the Japanese Experiment Module and its Remote Manipulator Fig.4. Sampler of Hayabusa System on the International Space Station. The JEM system, including JEMRMS, is designed The A&R of Hayabusa is not limitted to surface assuming six to seven astronauts are on the sampling. New technologies adopted by the Hayabusa international space station. Japan has the right to use spacecraft include interplanetary cruise via ion engines 12.8% of the onboard resources, including astronauts’ as the primary propulsion system, autonomous working hours. The original ISS utilization scenario navigation and guidance using optical measurement, assumed many users, enough logistic flights, and and direct re-entry for sample recovery from enough crew time to operate JEM’s facility and users’ interplanetary orbit. Among these, the most interesting equipment. However, recent incidents have indicated A&R technology is a tiny rover named MINERVA the possibility of operating the international space (MIcro/Nano Experimental Robot Vehicle for Asteroid). station with fewer astronauts and fewer logistic flights. The mass of the rover is just 591g. This rover does not Aware of this issue, JAXA is studying options for have a wheel for locomotion; however it can move better use of the ISS with fewer astronauts and fewer around using a hopping system that uses reaction force logistic flights. The current JEM utilization scenario, and friction between the robot and the surface. The especially utilization of the exposed facility assumes rover has CCD cameras and a temperature sensor to that each JEM/EF user will prepare a standard-size observe the surface of the asteroid. Figure 5 illustrates experiment unit of 0.8m X 1m X 1.8m. JEM/EF can this micro rover and its holding/release mechanism. accommodate up to 10 experiment units. However, After the successful launch of Hayabusa, we are now limited logistic flights mean only a limited number of trying to identify the next moon/planetary mission on JEM/EF users. This problem can be solved by sharing which A&R technology can be applied. limited resources (space and crew time) for experiments using A&R technologies. the existing robot arm (JEMRMS) or the introduction of a small but capable robot system will be needed. We are currently evaluating this option. 4. H-II Transfer Vehicle (HTV) The H-II Transfer Vehicle (HTV) is the upper stage of the H-IIA rocket and also a payload carrier for the International Space Station. The HTV consists of a propulsion module, an avionics module, and payload carriers as illustrated in Figure 9. The HTV will be launched by the H-IIA rocket and will conduct an automated rendezvous with the international space station. After the HTV arrives beneath of the ISS, the Fig.7. Japanese Experiment Module and its Remote space station remote manipulator system will capture Manipulator System (JEMRMS) the HTV and then move it to an ISS node. Cargo of HTV will then be moved to the JEM. After all cargo is delivered, the HTV will be filled with discarded goods and then conduct an atmospheric controlled re-entry. Propulsion Module Avionics Module Payload Carrier Fig.7. JEM Remote Manipulator System (JEMRMS) Fig.9. H-II Transfer Vehicle (HTV) The HTV’s rendezvous technologies are based on experience gained through the ETS-VII project. The ETS-VII chaser and the target satellites were launched together on November 28, 1997 using an H-II rocket. The ETS-VII chaser satellite (HIKOBOSHI) conducted three automated rendezvous dockings with the ETS-VII target satellite. Figure 10 depicts the ETS-VII chaser and the target satellites. Fig.8. Concept of a multi-access test and observation platform The basic concept of this platform is that many users will share limited resources (especially the facility port on the exposed facility and space for logistic flights). Each user will prepare a relatively small experiment unit instead of a large standard-size unit (0.8m X 1m X 1.8m). Such small equipment can be carried in various ways. Each experiment unit will be located on the platform using a robotic system. Some improvement of Fig.10. ETS-VII chaser satellite (HIKOBOSHI) and the ETS-VII target satellite (ORIHIME) 4.1 Utilization of HTV propellant, we quickly modified the onboard thrusters’ control software to generate the required thrust using Since the HTV is a capable spacecraft that can carry only healthy thrusters. This software modification went cargo, conduct automated rendezvous, and conduct smoothly and the chaser satellite accomplished docking controlled re-entry into the ocean, we are studying its with the target satellite three weeks after the separation utilization. An example of this utilization concept is of the satellites. on-orbit satellite servicing. Many satellites are delivered to a Geo-stationary Earth Orbit. However Figure 12 illustrates the ETS-VII rendezvous operation some are occasionally left on a useless intermediate room when the contingency operations were in altitude orbit because of difficulty with the propulsion progress. During this flight operation, many satellite system of the rocket or satellite. If the satellite is an design engineers involved in the development of the expensive one, such as a technology demonstration ETS-VII were gathered in the operation room to satellite, the rescue mission can be economically identify the source of troubles and to find corrective feasible if economical rescue vehicle can be used. The measures. HTV has such potential. The results of this study were utilized when NASA publicly requested a robotic However we cannot repeat such operations each time service mission to save or dispose of the aging Hubble when the HTV is launched.