[jcims]

Ramjet would still require atmosphere. If you look at the Japanese SS-520 or the RocketLab's Electron, you don't need a giant rocket to get a small payload to orbit from a standing start. If you give your payload a Mach 5 kick you can eliminate a lot of the propellant mass and get by with smaller rocket motors optimized for high altitude operation.

Elon Musk wants to put 12,000 satellites into orbit. It would be very strange to me if he doesn't have someone looking into the feasibility of a giant subterranean launch tube to do something similar. Get the payload up to Mach 10 on terrestrial power and complete the orbit with a small single stage.

[bboreham]

> Elon Musk ... giant subterranean launch tube

Hyperloop?

[manigandham]

The Hyperloop is a rehashed vacuum-train idea originally from the 1800s (reduce air and rolling resistance as the primary forces counteracting speed). [1]

A launch tube would be very different, if for no other reason then the fact that you need to actually jettison the payload at one end at high speed.

1. https://en.wikipedia.org/wiki/Vactrain

[skookumchuck]

We should just rename him Tom Swift:

"Tom Swift and his Subterranean Launch Tube"