The 'regular' Hasselblad 70 mm backs take cassettes that hold approximately 4.7 meters.
They are called "70", not after the film, but in Hasselblad style after the approximate number of exposures a load yields.
There are also Hasselblad 70 mm backs that use spools, no cassettes, that hold more film: approximately 6 - 7 meters. They are called "100/200", indicating the number of exposures.
How much exactly depends on how thick the base of the film, and how tight you load the thingies. They are called "500" again the number of exposures.
And there were huge Hasselblad 70 mm back that took full 30 meters rolls.
You need not go to the moon for anyone of those. And they are not free, though with 70 film being rather scarce, you can get any of those for next to nothing.
(Besides: they left the cameras on the moon, not the film backs.
The backs used on lunar surface cameras are of the "100/200" type.)