How SpaceX lands the Falcon 9: Grid Fins, Thrusters and Engines!

Everyday Astronaut · June 3, 2017 · 7:14 · English · Documentary

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Video from the channel Everyday Astronaut about Falcon 9, linked on its Above Ten Thousand entry. Duration: 7:14. Language: English. Video type: Documentary.

What it's about

An educational video about how SpaceX guides the Falcon 9 first stage back to land or to a drone ship. It explains the three control systems involved in the descent and ends with a recreation of the landing in the video game Kerbal Space Program, which only illustrates the explanation.

Historical context

Most first stages are destroyed when they fall into the ground or the sea. To recover it, the stage must land without exploding and hit a precise target, often a ship the size of a football field. The video recalls that grid fins were developed in the Soviet Union in the 1950s, mainly for missiles, and that the Soyuz and the N1 already carried them before SpaceX.

Key facts

Using footage from the NROL-76 mission on May 1, 2017, it describes the full sequence: a flip using cold-gas nitrogen thrusters, a boostback burn with 3 of the 9 engines, deployment of the grid fins, a reentry burn, and a final landing burn with 1 to 3 engines before deploying the legs. The Falcon 9 has two sets of four nitrogen thrusters on the interstage, and its engines can gimbal several degrees. All of this allows it to hit a target after falling from more than 70 miles of altitude and at speeds of up to 5,000 miles per hour.