[dwc]

This is the key passage:

    The spacecraft then automatically switched into a safe
    mode and, at about 4:10 a.m., fired thrusters to try to
    stop the rotation. But because the wrong command had
    been uploaded, the firing caused the spacecraft to
    accelerate further. (The improper command had been
    uploaded to the satellite weeks earlier without proper
    testing; JAXA says that it is investigating what
    happened.)

Going into safe mode is a thing. It happens with NASA stuff, ESA stuff, whatever. The spacecraft failed to stabilize and went into safe mode, and that's proper. Whatever glitch in the systems, this would have saved it and allowed for recovery.

But the uploaded command to shed rotational velocity was wrong. This is what caused the loss of the spacecraft. I'm sure there will be a pretty heavy postmortem on how this happened.

[azernik]

The more striking thing to me is the long failure cascade before that, mostly hardware failures: the star tracker that glitched over the South Atlantic Anomaly, the gyro that reported a nonexistent spin, and the reaction wheel that didn't spin down properly.

[ww520]

Isn't there a parallel simulator on the ground to try out the commands to see the effect before hand?

[rtkwe]

> The improper command had been uploaded to the satellite weeks earlier without proper testing

All the available testing programs in the world doesn't matter if the tests aren't run.

[quadrature]

I would not want to be in that PR.