Hironori Sahara

Space Demonstration of Bare Electrodynamic Tape-Tether Technology on the Sounding Rocket S520-25

A spaceflight validation of bare electro dynamic tape tether technology was conducted. A S520-25 sounding rocket was launched successfully at 05:00am on 31 August 2010 and successfully deployed 132.6m of tape tether over 120 seconds in a ballistic flight. The electrodynamic performance of the bare tape tether employed as an atmospheric probe was measured. Flight results are introduced through the present progressive report of the demonstration and the results of flight experiment are examined as the premier report of the international cooperation between Japan, Europe, USA and Australia. Future plans for maturing space tether technology, which will play an important role for future space activities, are also discussed.

Propulsion System for Panel ExTension SATellite (PETSAT)

We are promoting SOHLA series PETSAT microsatellites and developing a propulsion system based on a new concept as part of the SOHLA project, in order that microsatellites will be capable of orbit transfers by equipping with propulsion system for orbit correction, compensation, and EFELDO. We found a good combination of fuel and oxidizer with a higher performance catalyst, and they are the most promising candidate for the propulsion system because of propulsion performance and their safety. We estimated the propulsion system attained 200 seconds of specific impulse in an appropriate thrust magnitude range, and designed and manufactured a breadboard model of the propulsion system for PETSAT.

Propulsion System on Hydrogen Peroxide Mono-Propellant for Panel ExTension SATellite (PETSAT)

[Abstract] An innovative microsatellite, PETSAT, and propulsion system for PETSAT are presented in this paper. First, we outline what PETSAT is and why propulsion is installed into the PETSAT. Based of the PETSAT ethos, design policy of the propulsion system is also provided. According to the policy, we designed propulsion system and concretely estimated and assembled monopropellant system and preliminary thruster, which indicated that monopropellant propulsion with 50 sec of specific impulse and 100 mN-class of thrust is probable even based on the design policy. Catalyst performance tests were conducted for efficient decomposition of propellant and captive tests via the preliminary thruster were conducted. We have also been investigating bipropellant propulsion for PETSAT based on the design policy, and 100 sec of specific impulse and 1 N-class of thrust is probable. We are reporting on the present situation in their developments.

Generalized Mono/Bi-Propellant Propulsion System for Microsatellite Based on Non-Toxic Propellant Technology

Propulsion system for microsatellites is required to realize practical and complicated mission, such as formation flight and constellation with a number of microsatellites. However, traditional or typical propulsion can not install in microsatellite because of its volume, mass, and too many elements. In addition, propulsion system for microsatellite will be chemical propulsion, and hydrazine is treated as the most principal propellant. It is too difficult to handle a hydrazine thruster in universities and compernies, because of its high toxic. Therefore, we started to developed propulsion system for 50kg-class microsatellite based on green propellant from 2004, and continue to develop the propulsion system that has safty, good handleability, and decent performance. In this paper, we present the innovative propulsion system and its captive test.

Ignition Test of Bi-Propellant Propulsion System Based on Green Propellants for Microsatellite

Purpose of microsatellites under 50kg-class development, is now becoming to practical and more complicated mission. At the same time, propulsion system for the microsatellites tends to be eagerly desired for their missions with orbit transfer. Therefore, we considered chemical propulsion is very suitable for the microsatellites and started to develop an innovative propulsion system for the microsatellites based on our policy of SAFETY FIRST and EFFECTIVE COTS from 2004. In this paper, we present an ignition test of bipropellant and its consideration, and future works and report on progress of a monopropellant propulsion system.

Generalized Propulsion System for Panel ExTension SATellite (PETSAT)

An innovative Panel ExTension SATellite (PETSAT) and propulsion system for PETSAT, are presented in this paper. Based on PETSAT ethos, design policy of the propulsion system is provided. According to the policy, we designed propulsion system and concretely estimated and assembled mono-propellant and bi-propellant systems, and it indicated that mono-propellant propulsion with 50-60 seconds of specific impulse and 1 N of thrust is probable. In the case of bi-propellant, 120-150 seconds of specific impulse is valid even based on the design policy. We conducted captive tests of mono-propellant and bi-propellant propulsions with a breadboard model and flight model of propulsion system for PETSAT, and obtained good operations and performances. Now we are proceeding with its further improvements.

Development of Mono-Propellant Propulsion System for A Japanese Microsatellite "Hodoyoshi-1"

As the development of microsatellite is recently increasing in the world, miniaturization of elements for space use is strongly desired to make efficient use of microsatellite with respect to its dimensions, cost, and capability of space mission. As for propulsion, chemical propulsion is the most suitable to microsatellite with progress in miniaturization because of its high thrust density, short term injection, and easiness to handle. However, the conventional propulsion for satellite is difficult to handle the propellant, hydrazine, due to its toxicity and high cost, so that universities and non-governmental associations developing their microsatellites have not installed such propulsion so far. Accordingly, we have been developing a propulsion system for microsatellites based on Hydrogen Peroxide because of its little toxicity, low cost, and handling properties compared to the conventional propulsion system. Thus, we completed a mono-propellant propulsion system for microsatellite with the policies of SAFTY FIRST and EFFECTIVE COTS. Now we are planning to demonstrate our propulsion system in a Japanese microsatellite, Hodoyoshi-1, to execute its phase shift in orbit. The propulsion system has a mono-propellant thruster with 500mN of thrust and 80 seconds of specific impulse. We already evaluated its performance in injection tests on ground and in vacuum, and are planning to conduct the detailed vacuum test and mechanical environment test such as vibration test for its launch. In this paper, we present the innovative propulsion system and its injection test.

LARGE “FUROSHIKI” NET EXTENSION IN SPACE – SOUNDING ROCKET EXPERIMENT RESULTS

Abstract University of Tokyo and Kobe University conducted a sounding rocket experiment to deploy large “Furoshiki” net in space, which is a promising candidate for the future large antenna or solar power satellites. The experimental system consisting of mother and three daughter satellites as well as a folded net was separated from S-310 sounding rocket of JAXA/ISAS at the altitude of 110km, where the daughter satellites, after separated from mother satellite with 1.2 m/s velocity, deployed a large net of 14m-sized triangle. The deployment was quire successful without any tangling and the dynamics during deployment has been captured by cameras, INS and radar distance measurement system. Retro-directive antenna micro wave transmission experiment using 4 antennae on the bottom of satellites were conducted also successfully.

Development of focal plane x-ray detector aboard a microsatellite for monitoring supermassive blackholes

We describe the development of the focal plane detector onboard a micro-satellite aimed for observing cosmic Xray emission. Combined with an X-ray optics with focal length of approximately 40 mm, an X-ray CCD camera realizes low and stable background thanks to its capability of event classification by pulse height distribution of a event. The mission will intensively monitor a specific binary black hole to investigate periodic time variability owing to its possible binary motion. The focal plane detector adopts P-channel back-illumination type CCD. It is a miniature version of the sensors utilized in the CCD camera aboard Hitomi satellite but is upgraded in terms of the energy resolution and the prevention of visible light transmittance. We have built up an equipment for cooling and driving the device. Dark current as a function of device temperature is investigated. We see clear difference of the amount of the dark current between the imaging area and frame store area, which is probably due to the difference of the pixel size. The result indicates sufficiently low dark current can be achieved with temperature lower or equal to -80 °C. Number of pinholes in a surface aluminium layer is significantly different between devices. We identified a process with which we decrease the number of pinholes. To realize a whole instrument, we develop communication board and compact analog board.

Small satellites with MEMS x-ray telescopes for x-ray astronomy and solar system exploration

Toward a new era of X-ray astronomy, next generation X-ray optics are indispensable. To meet a demand for telescopes lighter than the foil optics but with a better angular resolution less than 1 arcmin, we are developing micropore X-ray optics based on micromaching technologies. Using sidewalls of micropores through a thin silicon wafer, this type can be the lightest X-ray telescope ever achieved. Two new Japanese missions ORBIS and GEOX will carry this optics. ORBIS is a small X-ray astronomy mission to monitor supermassive blackholes, while GEO-X is a small exploration mission of the Earth’s magnetosphere. Both missions need a ultra light-weight (<1 kg) telescope with moderately good angular resolution (<10 arcmin) at an extremely short focal length (<30 cm). We plan to demonstrate this optics in these two missions around 2020, aiming at future other astronomy and exploration missions.