A Cannon for Shooting Supplies into Space

"John Hunter wants to shoot stuff into space
with a 3,600-foot gun. And he’s dead serious—
he’s done the math. Making deliveries to an
orbital outpost on a rocket costs $5,000 per
pound, but using a space gun would cost just
$250 per pound."

See:

http://www.popsci.com/technology/art...supplies-space