Progress on the tether is incremental. Much more challenging imo is getting the popular and financial support needed. I have a hunch that FF and the SE are both going to reach the public awareness about the same time. By public awareneness, I mean when most people believe it can be done and then start asking why it hasn’t been done yet.
Now If W had directed NASA to develop the SE as the most cost-effective road to Mars and beyond, $50G would be no major problem.
