[cookingmyserver]

Correct, hence the need for the probe to unroll the cable as it goes down. If you had the roll on the surface, you would need to heat the whole cable to allow it to slip down.

[knodi123]

Or design the cable along the same principles as one of these,

https://www.walmart.com/c/kp/water-wiggler-toy

So it can "slip down" by a continuous unrolling process!

[protomolecule]

Which would require much more power than a single RITEG.

[arethuza]

Why - 25km of fibre isn't that large?