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Editorial: Clarify cause of 'Hitomi' satellite's failure

The Japan Aerospace Exploration Agency (JAXA) has abandoned operating the "Hitomi" X-ray astronomical satellite, with which it had lost radio contact. The space agency has deemed it impossible to restore the observation spacecraft to working order after confirming that all solar panels that supply electric power to the satellite had broken off.

Japan's X-ray astronomy community has so far made numerous achievements, such as the discovery of the possibility of a huge black hole existing in the center of the Milky Way. It is extremely regrettable that the Hitomi satellite has broken since the spacecraft had drawn worldwide attention.

JAXA says a series of errors in controlling the satellite's attitude caused the spacecraft to spin at abnormal speeds, which put an unexpectedly strong force on the joints of the solar panels, causing the spacecraft to fall apart. JAXA should thoroughly investigate the trouble to confirm why the series of errors occurred in order to prevent a recurrence.

The Hitomi satellite was launched on an H-IIA rocket in February this year. Approximately 31 billion yen was spent on Hitomi.

JAXA lost radio contact with the Hitomi satellite on March 26. According to the space agency, a system to control the satellite malfunctioned, causing the spacecraft to be unable to grasp its own attitude and it began to spin. Hitomi fired its small engine in an attempt to stop itself from spinning, but data on burning the engine contained errors, causing the spacecraft to spin even faster. This apparently caused the satellite to fall apart.

JAXA has not yet clarified why the control system malfunctioned and why mistakes in the data were not detected in advance. The space agency needs to examine other spacecraft and their data to prevent a similar accident.

In February 2000, Japan unsuccessfully launched the ASTRO-E X-ray astronomical satellite. An ASTRO-EII satellite named, "Suzaku," which was launched in July 2005, was unable to conduct observations as initially planned because of problems involving its observation equipment. The trouble with Hitomi marks the third consecutive failure of Japan's X-ray astronomical satellite, which could shake confidence in Japan's operations of satellites.

Hitomi's failure is expected to have a huge impact on researchers around the world. More than 200 global researchers, including those at the U.S. National Aeronautics and Space Administration, participated in the development of Hitomi, which is equipped with a cutting-edge X-ray telescope and X-ray detector. The developers had planned to operate the satellite while soliciting researchers from other countries to propose observations themes.

During experimental observations until March, the Hitomi satellite had sent unprecedentedly high-resolution observation data to Earth, raising hopes among researchers.

Following the unsuccessful operation of Hitomi, the European Space Agency intends to launch an X-ray astronomical satellite in 2028, possibly leaving a 12-year blank in research using such a spacecraft. Calls may arise for the development of a successor to Hitomi. If the successor is based on the design of Hitomi, it will not take a long time to develop it and could reduce development expenses.

However, priority should be placed on clarifying the cause of the trouble involving Hitomi over the development of its successor.

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