If at first you don’t succeed, try, try again. And for SpaceX on Saturday afternoon, it paid off.
A Falcon 9 rocket, which flung an unmanned Dragon cargo ship to the international space station, landed vertically – without tipping or exploding – on a drone ship in the Atlantic Ocean minutes after take off.
In December, a Falcon 9 landed safely on land. But ocean landings are trickier. Not only must a rocket contend with choppy seas and high winds, it must also adjust for GPS errors – a big deal when its landing platform is only the size of a football field.
These historic touchdowns herald a new era of reusable rockets. Until now, rockets have been single-use, costing tens of millions of dollars per launch.
The road to success has not been a smooth one, though. The weekend’s launch was SpaceX’s fifth attempt at an ocean landing. Here’s what happened to the previous four.
Flight 14: 10 January 2015
Ocean platform landing attempt abandoned due to bad weather. Instead, the rocket landed in the water.
Flight 17: 14 April 2015
After a perfect liftoff into a blue sky, the Falcon 9 rocket made it to the drone ship and landed. But jubilation was short-lived. It tipped over due to what SpaceX called “excess lateral velocity“. In other words, it was moving sideways too fast when it touched down.
Flight 21: 17 January 2016
The rocket successfully popped a weather satellite into orbit, but as it landed on the platform, a landing leg failed to latch and the rocket toppled over in a spectacular explosion.
Flight 22: 4 March 2016
The video feed cut out in the final moments, but shortly afterwards SpaceX chief Elon Musk tweeted: “Rocket landed hard on the droneship. Didn’t expect this one to work (v hot reentry), but next flight has a good chance.”
Belinda Smith is a science and technology journalist in Melbourne, Australia.