If I remember rightly (it's been a while since I read up on them), they proposed using tungsten rods initially. Not sure if they'd still go down that route, or

If I remember rightly (it's been a while since I read up on them), they proposed using tungsten rods initially. Not sure if they'd still go down that route, or whether they'd use something a bit more exotic (carbon nanotubes is always the go to answer for exotic-scifi style things).