In the 70's one summer I skied on a demo track an inventor (forgot his
name) set up on the Hanover, NH golf course. The track was made from
two foot wide white packing foam. A long roll (200' ?) of it was
stretched out and staked on the ground. And then heavily sprayed with
silicone. Skiers would use waxless skis (Trak's) and stride and glide
on this summer skiing miracle. Looks like it took the Russians 30
years to catch up with the New Englanders in this case.