[Elsie]

HELLO!!!

It ain't SPACE travel to suck up OXYGEN from the ATMOSPHERE to run the engine!!!

[thoughtomator]

Perhaps, but to get to space in the first place, one has to cross the atmosphere, and at our current level of technology, efficient atmospheric travel that can achieve escape velocity is our major obstacle to further space exploration.

[r9etb]

It ain't SPACE travel to suck up OXYGEN from the ATMOSPHERE to run the engine!!!

Yes it is. In order to get into space, you need to go through the atmosphere.

Conventional rockets carry along liquid oxygen and a fuel (typically liquid hydrogen or kerosene) and hose it out through a big rocket engine.

The nice part of using oxygen out of the atmosphere is that you don't have to use precious launch mass carrying oxidizer (and associated tanks, lines, and pumps) for that stage of the mission. Further, the beauty of this particular approach is that you also don't have to lug around a complicated rocket or turbine engine.

This is potentially a very big deal, as long as: a) it's possible to scale this thing up; and b) it can be done relatively cheaply.