Did we actually get 480,000,000 dipole antennae into space? This seems utterly impossible.

If I'm calculating right, all of the dipole antennas could have been packed into a box the size of an old-fashioned toaster (a 15cm or 6-inch cube).

Calculation: Volume of cylinder (πr²h) x 480M antennas (assume half were of each diameter) = 3.14x(0.00254/2)^2x1.78x240000000 + 3.14x(0.00178/2)^2x1.78x240000000 = 3225cm^3; cube root of 3225 is about 15cm or 6 inches

Yup. Even smaller than an old fashioned, toaster, even - although this is assuming perfect packing density, which wouldn't be the case, and would add about 10% to the needed volume.

https://www.wolframalpha.com/input/?i=the+volume+of+a+cylind...

Yes. They are referring to each individual copper needle as a dipole antenna.

Since Mythbusters proved that finding a needle in a haystack isn't that difficult, I propose that the term be changed to "finding a needle in the ionosphere." [Not applicable to orbital debris trackers...]

Given that the ones still up there are in large clumps, I feel this analogy is flawed, much as I enjoy the mental image.

Define large...