A droneship landing recovers a rocket booster at sea: the returning stage steers itself to an autonomous floating platform positioned downrange and lands vertically on its deck. It exists because flying the booster back to the launch site costs propellant that high-energy missions can't spare.
Understanding Droneship Landing
The hoverslam: landing without the ability to hover
A nearly empty booster is so light that even one engine throttled to minimum produces more thrust than the stage weighs — hovering is impossible. The landing burn is therefore a "hoverslam" (suicide burn, in the vernacular): ignite at precisely the altitude where maximum deceleration brings velocity to zero exactly at deck height, with no margin to pause or retry. Guidance software solves this continuously during descent against wind, engine performance and deck position, steering with grid fins until the final seconds. At sea the target complicates further: the deck heaves with the swell, so the last metres are a moving-target problem — and the ocean provides both the vast safety buffer that makes failed attempts consequence-free and the weather constraint that scrubs recoveries a rocket could otherwise fly.
How the recovery choice is made
| Profile | Propellant cost | Used when |
|---|---|---|
| Return to launch site (RTLS) | Highest — full boostback | Light payloads, low orbits |
| Droneship landing | Moderate — no boostback | GTO, heavy LEO, most missions |
| Expendable | None — all propellant to payload | Maximum-performance missions |
| (Parachute/catch concepts) | Varies | Other vehicles' recovery experiments |