SpaceX breaks a leg and misses chance at a successful rocket landing

After a successful mission on Sunday afternoon out of Vandenberg Air Force Base in California, SpaceX attempted to land the first stage of its un-crewed two-stage Falcon 9 rocket for a second time in a row, but the attempt was unsuccessful.

"Unfortunately we are not standing upright on a drone ship," a SpaceX spokesperson announced during a live broadcast of the event.

Click here for the first footage of the aftermath.

While the landing attempt was not successful, SpaceX achieved its primary goal, which was to deploy its cargo into orbit — the Jason-3 weather satellite, designed to measure ocean height across the globe and track sea level rise.

The problem with the landing was a technical issue concerning one of the landing legs: 

SpaceX Falcon 9 rockets are equipped with four landing legs that deploy seconds before touch down and are what keep the rocket stable and upright after landing. Here's what that looked like during SpaceX's last, successful, rocket landing in December:

Seconds before the rocket was to reach the ship's platform on Sunday, the camera on the drone ship froze, which means footage of the landing is pending at the moment.

After successfully boosting the second stage and its cargo off the planet, the first stage booster turned itself around for re-entry, performing a series of engine burns to slow down. Upon descent grid fins and GPS tracking helped guide the rocket to a drone ship floating 186 miles south of the launch site in the middle of the Pacific.

It sounds like everything was working well — the engine burns, the descent, and the navigation — up until the rocket landed on the platform. One of the legs didn't lock into place. Without all four legs working, the 14-story-tall rocket wasn't stable, and after touch down, it tipped over.

One of the earlier suspicions was that the rocket was coming in too fast (see SpaceX founder Elon Musk's tweet below from right after touch down was expected), but upon further investigations it looks like touch down was good. If the leg had locked as it was supposed to, the landing might have been a success.

This second attempt at two landings in a row would have proven that SpaceX's first rocket landing — performed on Dec. 21 of last year — wasn't a one-and-done deal. Now, it's back to the drawing board.

To be fair, Sunday's landing attempt is more difficult than last month's because it happened on a floating target: One of SpaceX's un-crewed autonomous drone ships.

Last year, SpaceX attempted this same landing twice, and did not succeed in retrieving the rocket. Both times the first stage exploded after reaching the platform, shown below:

Musk said that landing rockets on drone ships is critical for high-velocity missions, which refer to mainly commercial satellite missions, wherein the Falcon 9 has to transport its payload higher above Earth's surface than it would on a cargo transport mission to the International Space Station, for example.

Commercial satellite missions make up a substantial amount of SpaceX launches, therefore, we can likely expect to see more rocket landing attempts like this in the future.

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