During flight, high-rate flight data is written to volatile RAM, and 1HZ data is telemetered to Perseverance. The high-rate data is not written to disk until la

During flight, high-rate flight data is written to volatile RAM, and 1HZ data is telemetered to Perseverance. The high-rate data is not written to disk until landing, because writing to disk is slow and CPU-intensive. There was a brownout during or just before landing, and sadly that meant the high-rate telemetry data was lost because it was never written to disk. And by "disk" I mean non-volatile flash memory.