''HIBARI'' is a space mission by

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

for a

microsatellite A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome. ...

that would test a new

attitude control Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc. Controlling vehicle ...

(orientation) method to achieve high accuracy pointing for its small telescope, and was launched on 9 November 2021 by an

Epsilon Epsilon (, ; uppercase , lowercase or lunate ; el, έψιλον) is the fifth letter of the Greek alphabet, corresponding phonetically to a mid front unrounded vowel or . In the system of Greek numerals it also has the value five. It was der ...

launch vehicle as part of the

Innovative Satellite Technology Demonstration Program The Innovative Satellite Technology Demonstration Program is a series of spacecraft missions for testing technology and ideas put forward by universities and private companies. The program demonstrates various experimental devices and technology ...

-2 mission. The key technology to be tested on ''HIBARI'' is called "Variable Shape Attitude Control" (VSAC), and it is based on reaction torque by rotating its four solar array paddles.

Conceptual design

''HIBARI'' is a space mission by the Japanese scientists from the

Tokyo Institute of Technology is a national research university located in Greater Tokyo Area, Japan. Tokyo Tech is the largest institution for higher education in Japan dedicated to science and technology, one of first five Designated National University and selected as ...

to develop high pointing stability and agile maneuvering of a small satellite by using reaction torque of the satellite's structure.Variable Shape Attitude Control Demonstration with Microsat "HIBARI"
(Slide presentation) Kenichi Sasaki, Yuhei Kikuya, ShoKoizumi, YutoMasuda, ToshikiOzawa, Yusuke Shintani, Tsubasa Tsunemitsu, Yuichiro Takeuchi, Yoichi Yatsu, Saburo Matunaga Tokyo Institute of Technology 4 August 2018 This technology, first presented in 2016,A Study of Rest-to-Rest Three-Axis Attitude Maneuver with Shape Variable Function
Watanabe Fuuta Tokyo Institute of Technology January 2016 is hoped to substitute the use of

reaction wheels A reaction wheel (RW) is used primarily by spacecraft for three-axis attitude control, and does not require rockets or external applicators of torque. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be ...

and

control moment gyroscope A control moment gyroscope (CMG) is an attitude control device generally used in spacecraft attitude control systems. A CMG consists of a spinning rotor and one or more motorized gimbals that tilt the rotor’s angular momentum. As the rotor tilts ...

s (CMG), which arguably have difficulty achieving both agility and stability simultaneously. This capability would be useful for a very fast response to observe in the direction of gravitational waves or other transient astrophysical phenomena. The spacecraft is a microsatellite configured in a cube, where half of it would carry a small

ultraviolet telescope Ultraviolet astronomy is the observation of electromagnetic radiation at ultraviolet wavelengths between approximately 10 and 320 nanometres; shorter wavelengths—higher energy photons—are studied by X-ray astronomy and gamma-ray ast ...

to verify the pointing stability (< 10 𝑎𝑟𝑐𝑠𝑒𝑐²) and accuracy of the VSAC system. The orientation high accuracy would be achieved by rotating the arms of its four solar arrays in an orthogonal axis.

Solar cell A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.

s would be mounted on both sides of each of four solar array paddles.

References

Satellites of Japan Space telescopes Ultraviolet telescopes 2021 in Japan Spacecraft launched in 2021 {{Japan-spacecraft-stub