[Short Fiction] Error Budget

The incident report said the satellite had failed due to 'unrecoverable attitude control anomaly.' Priya had written that phrase herself, at 3 a.m., in the fluorescent calm of a mission control room where no one was speaking. What it meant was: the satellite had started spinning. It had kept spinning. And then it had kept spinning in a way that suggested something had gone wrong with the thing that was supposed to stop it spinning, and then the power had gone, and then the comms had gone, and now there was a very expensive piece of hardware in a 400-kilometer orbit doing something it had been specifically designed never to do. She had been on the team for eight months. The satellite had been in development for eleven years. Her manager had told her the incident report was very thorough. He'd said 'very thorough' three times, which she had understood to mean: you explained exactly why it wasn't your fault. She had tried to explain exactly what had happened, which in her mind was a different thing, but she had not said this. The error budget for the attitude control system had been forty milliseconds of latency over any thirty-second window. They had operated within this budget for four months in orbit. On the night of the failure, due to a ground software update that had not been fully validated before uplink, the latency had been forty-three milliseconds. Three milliseconds over budget, in a system that had worked perfectly for 124 days. She kept the incident report open on her laptop for a long time after it was filed. She wasn't revising it. She was just reading the phrase 'unrecoverable attitude control anomaly' and waiting for it to stop sounding like something that was her fault. It didn't stop.