What caused the most sensitive X-ray satellite to fail

hitomi_fail_causeCredit: JAXA


The most sensitive X-ray satellite, Hitomi, was launched on February 17th from the Japanese Space Center. It was equipped with four telescopes and most importantly, on board was an X-ray microcalorimeter, an instrument designed to observe X-rays from space with the world’s largest capability. Unfortunately, on 26th of March, the satellite lost communication with Earth and space debris was tracked close to the satellite.

Further investigation from the Japan Aerospace Exploration Agency showed that a basic engineering error might be the cause of the failure. In an attempt to stop itself from spinning, the satellite’s control system commanded a thruster jet to fire in the wrong direction, accelerating, rather than slowing down its rotation. Ground-based telescopes have taken pictures of Hitomi spinning roughly once every 5.2 seconds.

Hitomi had been seen as the future of X-ray astronomy and its failure has been characterized as a scientific tragedy. A calorimeter, like the one Hitomi was equipped with, is scheduled to fly with European Space Agency’s Athena mission, but Athena will not launch until 2028. Nevertheless, the satellite managed to make an important measurement while it was still operating. It measured the speed of gas flowing from the Perseus cluster and that can help scientists study how the mass of galaxy clusters changes over time, a test of the crucial cosmological parameter known as dark energy.


Source: Nature