This isn't the first such experiment (with tethers in space) but previous ones (such as the Shuttle tether experiments from 1996 onwards: https://www-istp.gsfc.

This isn't the first such experiment (with tethers in space) but previous ones (such as the Shuttle tether experiments from 1996 onwards: https://www-istp.gsfc.nasa.gov/Education/wtether.html https://www-istp.gsfc.nasa.gov/Education/wtether.html ) discovered some unanticipated and terminal problems ... and as they flew aboard a time-limited Shuttle mission there wasn't really any scope for attempting repairs/fixes on orbit. Also, it's arguably obvious with 20/20 hindsight that trying for a 20km long tether on the first experiment was maybe slightly over-ambitious ...