The Falcon 9's second stage is currently disposed of each flight. I know there have been some concepts by SpaceX on making it reusable, but evidently they have not yet done so. From my understanding, the difficulty in bringing this stage back comes from the much higher re-entry velocities and the higher payload penalty for adding weight (and saving extra fuel). That being said, I tried my hand at ideating a way in which this could be done:
Basically, the stage would do its normal de-orbit burn and point engine first as it re-enters. It would be protected by either a regeneratively cooled piece or a traditional heat shield. It could then conduct a series of burns and land similarly to the first stage, with grid fins and landing legs.
I wanted to know a couple of things.
- Is SpaceX still planning to recover their second stage?
- And if so, what would be the technical challenges in doing it this way?