The suggestion to create RAID arrays is a good one. Doing so is only a matter of money, and this is money well spent. We can have it ready for the next experiment.
The data9 disk is only a few months old. It seems like the quality of disk hardware has decreased in the last two years. Older SCSI disks seem to last forever when treated right, but the newer ones die rather often, and if so without any apparent reason.
I think the potential for recovery of the data is nil unless you're willing to hire a company to do the job for a large junk of money.
The disk does not just have a "few bad blocks", but it simply doesn't respond at all. If it doesn't spin up, the motor is gone. No chance.