In a comment below it is stated that they were archived on Laserdisc. I can imagine the images were written to a tape master first, then the tape used to write

In a comment below it is stated that they were archived on Laserdisc. I can imagine the images were written to a tape master first, then the tape used to write the (probably write-once) Laserdiscs. The tape could have been U-matic, but maybe it was digital video tape, https://en.wikipedia.org/wiki/D-2_(video) https://en.wikipedia.org/wiki/D-2_(video) which was released in 1989. If so, the whole project would have been at the very bleeding edge technology wise.