Comment by joha4270
17 hours ago
LOX halfway to orbit is significantly more expensive than the same LOX delivered to the launchpad.
Its not the cost, its the mass you're trying to reduce. So far, the engineering challenges have made it unfeasible, but its not a surprise that people look at the hundred tons of LOX on a rocket and imagine exchanging it for payload (or aircraft style re-usability).
A gram of oxygen that you carried to orbit is more valuable than a gram of oxygen you collect at that location: oxygen that you carried is moving at the same velocity as you.