I just read about yo-yo de-spin as a measure to reduce the spin of objects. The basic idea is simple and makes sense, but then I read this:
As an example of yo-yo de-spin, on the Dawn Mission […] reduced the initial spin rate of the 1420 kg spacecraft from 36 RPM down to 3 RPM in the opposite direction.
The linked source also mentions this:
Even with a 204-kilogram ([…]) third stage […] and a 1218-kilogram ([…]) spacecraft, the small yo-yo system halts the spin and even reverses it, leaving Dawn rotating at 3 rpm in the opposite direction from its original spin.
How does extending the cables / weights actually cause a reversal of the rotation? What is missing from the explanation?
My gut tells me that this technique should only be able to reduce spin to zero as the extension goes towards infinity. If at some point it were to reverse the spin direction, there'd have to be a point of no spin at all which would violate the conservation of momentum, no?