This URL (https://www.hou.usra.edu/meetings/newviews2018/pdf/6016.pdf) only shows a single page for me. Full paper at https://www.opsjournal.org/DocumentLibrary/Uploads/The_Lunar.... Skimming it, I can’t find how they arrive at that $2B number
They are proposing a tether that’s about 300,000 km long and 48,000 kg mass, so 0.16g/m
Which seems very small.
Density is about the same as water, so the diameter is about 0.12mm which (for fishing line) has a breaking strain of about 10N. UHMWPE’s strength is about 6 GPa, so (0.00012)^2 * 6e9 is about 100N.
Hmm.
At (about; adding cars to the tether changes things a bit) geostationary height (in this case I guess that could be called lunastationary), forces on the tether start going upwards, and tether size can go down as you go further up.