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Design, Hardware, Software Errors Doomed Japanese Hitomi Spacecraft (scientificamerican.com)
Reader Required Snark writes: The Japanese space agency JAXA said its recently launched X-Ray observation satellite Hitomi has been destroyed. After a successful launch on February 17, contact with the satellite was lost on March 28. Off the 10-year expected life span, only three days of observations were collected. Preliminary inquiry points to multiple failures in design, hardware and software. After the launch it was discovered that the star tracker stabilization didn't work in a low magnetic flux area over the South Atlantic. When the backup gyroscopic spin stabilization took control, the spin increased instead of stopping. An internal magnetic limit feature in the gyroscope failed, causing the spin get worse. Finally, a thruster based control started, but because of a software failure the spin increased further. The solar panels broke off, leaving the satellite without a long-term power supply. It seems that untested software had been uploaded for thrust control just before the breakup. This is a major loss for astronomical research. Two previous attempts by Japan to launch a high-resolution X-ray calorimeter had also failed, and the next planned sensor of this type is not scheduled until 2028 by the ESA. Just building a replacement unit would take 3 to 5 years and cost $50 million, without the cost of a satellite or launch.
From the TFA
Dan McCammon, an astronomer at the University of Wisconsin–Madison, helped to design and build Hitomi’s premiere scientific instrument, an X-ray calorimeter that measures the energy of X-ray photons with exquisite precision. He has been working on the technology for more than three decades, flying versions of it on the ASTRO-E mission, which failed on launch in 2000, and the Suzaku spacecraft, in which a helium leak rendered the instrument useless weeks after its 2005 launch.
On the first launch of the Ariane 5 rocket, it used parts of the control software of the Ariane 4, a very reliable rocket with a success rate of more than 97%. The launch ended with the destruction of the rocket 37 seconds into the flight due to an arithmetic overflow. It had not been taken into account that the bigger rocket would cause bigger values in the control software.