Overview of a & R Within Japan's Space Programme

OVERVIEW OF A & R WITHIN JAPAN’S SPACE PROGRAMME

Mitsushige Oda

Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan,

e-mail: oda.mitsushige@jaxa.jp

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. A major lesson learned Space Telescope. Fig.11. depicts an artist’s image of from the ETS-VII rendezvous operations was that a robotic servicing of HST. Details of this study are flight operation assistance system that can show the shown in Reference 6. current status of the spacecraft and also show which contingency operation should occour next is higly required. In the case of ETS-VII, many contingency procedures depended on satellite situations. Identifying instantly which procedure to use is essential in such critical operations. In Figure 13, satellite design engineers are sitting behind the flight operation engineers to be reasy to assist them.

Fig.11. Concept of robotic servicing of the Hubble Space Telescope

4.2 Intelligent spacecraft operations

The ETS-VII conducted automated rendezvous Fig.12. ETS-VII Rendezvous operation docking three times during its mission life. The first one was the release of the target satellite up to 2m distance and subsequent re-docking. This operation was conducted smoothly. The second rendezvous docking operation was to place the target satellite up to 500m from the chaser satellite and then conduct the automated rendezvous docking from that position. The distance of 500m was the range that laser radar used on the chaser satellite to measure relative distance. If the relative distance exceeded 500m, GPS receivers on both satellites would be used to measure relative distance and relative velocity. However during this second flight operation, some gas jet thrusters on the chaser satellite malfunctioned. We tried to navigate the chaser satellite toward the target satellite several times, but each time, the faulty thrusters forced cancellation of the approach maneuvre. Since the stand-alone operation capability of the target satellite was limited mainly by the volume of the Fig.13. ETS-VII robot operation using GUI References Therefore we are investigating how to implement such 1. http://www.muses-c.isas.jaxa.jp/ capability in the ground rendezvous operation facility. 2. T.Yoshimitsu, T. Kubota, I.Nakatani, Mission and In investigating this capability, we have useful Technologies of MINERVA Asteroid Surface Explorer, experience in ETS-VII robot operations. Traditional IAF 54th International Astronautical Congress, satellite operation is still based on printed operation IAC-03-Q.5.07, (2003) procedures. However, ETS-VII robot operations, 3. M.Oda,, Experiences and lessons learned from including nominal and contingency cases, were all NASDA’s ETS-VII robot satellite, IAF 51th writen in electronic form. By clicking a mouse, a International Astronautical Congress, ground operator can select one of the suggested IAF-00-U.5.04 (2000) procedures displayed on a screen. The selected 4. JAXA’s web on JEM, operation procedures were verified using an onboard http://iss.sfo.jaxa.jp/iss/doc09_e.html robot system simulator built in the robot operation 5. JAXA’s web on HTV facility and sent to the satellite automatically. Reason http://www.jaxa.jp/missions/projects/rockets/htv/index why the rendezvous operation does not use an _e.html electronic operation system, while the robot operations 6. M.Oda, A feasibility study of robotic servicing for were based on the electronic one is partly because the the Hubble Space Telescope, International Symposium robot operation is not as time-critical as the rendezvous on AI, robotics and automation in space (i-SAIRAS), operation and the number of contingency cases of the Munich, Sept.2005 rendezvous operations was larger than the robot 7. S.Harauchi, T.Kojima, H.Koyama, N.Inaba, A operations. generation-based framework for spacecraft operation, 6th International Symposium on Reducing the Cost of In realizing this rendezvous operation assist system, the Spacecraft Ground System and Operations, ESA/ESOC, technical challenge is how to describe various June 2005 operations procedures including contingency cases. Traditional operation procedures were written by MS-Office like editor. This makes it difficult to revise procedures and keep procedures updated. We are studying an XML (eXtensible Mark-up Language) like language called SOML (Spacecraft Operations Mark-up Language) to describe the spacecraft operations. Procedures designed in SOML can be used and updated during the entire life cycle of a spacecraft as an entity of operation procedure. Once the operation procedures are ready, the selected procedures must be verified using a spacecraft simulation system. How to realize a realistic and effective simulation system is also a technical challenge. This operation assistance system can also be applied to various traditional satellites and this will lead to reduced mission operation cost while improving confidence of mission success. Preliminary results of the SOML study are introduced in Reference 7.

Conclusions This paper introduced ongoing A&R activities within Japan’s space program. Since JAXA is recovering from a series of problems that occurred at the time when JAXA was established, JAXA has to launch six satellites this year and four satellites next year. Most of these satellites would already hae been launched if there had not been problems with the launchers (H-IIA and M-V rockets). These satellite-launch backlogs are creating pressure to start new missions. However, JAXA is now trying to regain public confidence by conducting various missions involving the economical use of A&R technologies.