[rguzman]

From the XKCD:

> This leads us to the central problem of getting into orbit: Reaching orbital speed takes much more fuel than reaching orbital height. Getting a ship up to 8 km/s takes a lot of booster rockets. Reaching orbital speed is hard enough; reaching to orbital speed while carrying enough fuel to slow back down would be completely impractical.[5]

Did SpaceX just solve this problem and rendered this paragraph obsolete? Or is that Falcon 9 reached space and turned around without achieving orbital velocity?

[ekimekim]

That paragraph was in reference to zeroing out your velocity before re-entry. The Falcon 9, iiuc, uses a combination of thrust and aerodynamic forces to slow itself down / put itself on the correct trajectory.

It's also worth noting that they only land the first stage, there's an entire next stage which isn't reusable which adds further speed to achieve full orbital velocity.