Nine weeks after its launch, Japan’s flagship astronomical satellite Hitomi has been declared lost by the country’s national space agency. The satellite had been launched on February 17 but had started to tumble out of control on March 26. At the same time, other space agencies around the world began to notice debris in the vicinity of the satellite, although it couldn’t be confirmed until recently if the pieces belonged to Hitomi.
In a notice published on April 28, the Japanese Aerospace Exploration Agency (JAXA) said it was giving up on efforts to restore the satellite, whose scientific payload was designed to survey a broad range of cosmic phenomena, especially high-energy events that emitted X-rays. Some of its instruments were three decades in the building. The satellite itself cost $286 million to put together and launch.
According to various reports, Hitomi was in trouble at all after its computer miscalculated that the satellite was spinning (when it was not) in orbit. After an initial attempt to stabilise the craft failed, Hitomi was left actually spinning. About 70 minutes after the miscalculation, it entered safe-mode and fired a thruster to resolve the problem once and for all, but because it fired the wrong thruster, it started to tumble out of orbit.
At this point, according to the JAXA notice, “Most of our analyses including simulations on the mechanisms of object separation, it is highly likely that both solar array paddles had broken off at their bases where they are vulnerable to rotation.” Moreover, communications between ground-control and Hitomi were complicated because Hitomi was then somewhere over South America, on the other side of Earth from Japan.
Before the tragedy, however, Hitomi had made some observations, especially of the motion of gases in a galactic cluster in the constellation Perseus. Astronomers believe measuring the rate of such flows could yield clues about the nature of dark energy, and Hitomi‘s observations could result in a few papers. It had also been making observations of the Crab Nebula.
The satellite’s marks the third failure for JAXA in launching space-borne instruments. The Suzaku mission, to which NASA had contributed, failed a few weeks after launching in 2005 while the ASTRO-E mission had to be abandoned after the M-V rocket carrying it veered off course on launch. Both, like Hitomi, had been slated to study the universe in X-rays. Now, the space agency has said it “will carefully review all phases from design, manufacturing, verification, and operations to identify the causes that may have led to this anomaly including background factors”.