2:18 PM EDT (-0400 GMT): Issue resolved. A hard drive failure was experienced in Helios on a hardware RAID10 arrangement. RAID10 is built to be durable, able to sustain multiple drive failures without compromising system stability. For reasons still under further research, the drive failure created an anomaly on the RAID10-backed swap partition that in turn induced a kernel panic.
4:12 PM EDT: subsystem dropped again. Appears to be a bad RAID controller.