SpaceX is writing history with its gutsy rocket landing attempts that are unlike anything we’ve ever seen.
The company’s second attempt in history to land a rocket on a floating platform in the ocean on April 14 didn’t go exactly according to plan.
The good news is that this second landing attempt missed the mark for a different reason than the first attempt: Unlike the first try last January, where the problem concerned the fins at the top of the rocket, the problem this time around was the legs at its bottom, which means SpaceX fixed their grid issue from last time.
Although the rocket died in a fiery, explosive blaze, the latest attempt was still an improvement from the first: The rocket spent a total of 10 seconds on the platform before tipping over and disintegrating. Last January, the rocket exploded as soon as it contacted the barge.
Now, SpaceX has pinpointed the problem and is that much closer to successfully landing a rocket with the purpose of reusing it — a game-changing feat that would usher in a new era of cheap commercial spaceflight powered by reusable rockets.
The rocket did a great job slowing down as it landed on the platform, but as you can see in the GIF below, the rocket toppled over shortly after touch down instead of remaining upright:
The rocket fell on its side because the legs could not support its weight. The landing legs are designed to help keep the rocket upright, they aren’t strong enough to prevent it from tipping once that process has begun.
So, the big problem in this case was that the rocket started tipping in the first place. On Twitter, SpaceX CEO Elon Musk said the tipping was the result of a “slower than expected throttle valve response.”
In other words, the rocket descended too quickly. That’s what Musk meant in his tweet shortly after launch on April 14:
Ascent successful. Dragon enroute to Space Station. Rocket landed on droneship, but too hard for survival.
— Elon Musk (@elonmusk) April 14, 2015
The job of a rocket’s throttle valve is to regulate how much fluid reaches the engines and therefore how much fuel it has to power the rocket. As the first-stage Falcon 9 descended toward the platform, it fired its engines multiple times to slow it down to a walking pace in preparation for landing. But it appears that the throttle valve didn’t generate enough power to slow the rocket down for a successful landing.
At first, the rocket was right on target, coming in at a beautiful, completely vertical angle:
But the engines weren’t producing enough force between the rocket and the platform and, as a result, pushed the rocket off kilter, which led to the tragic toppling. Check out the video at the end of this post to see how much engine power it takes to get these colossal rockets to land upright. You can see thrusters at the top of the rocket firing to try and correct the angle, but to no avail.
Luckily, the landing platform survived the explosion and came back to port with obvious burn marks but in overall good condition. It will be used for the next landing attempt, scheduled for June 19.
Most of the rocket was lost in the explosion, but you can see some few surviving pieces strewn across the deck in the image above. Even one of the rocket’s legs survived the explosion, shown in the image below taken by George Worthington and colour-corrected by John Gardi.
Despite two misses, Musk is not deterred.
Shortly after confirming the throttle valve problem, he tweeted a video of a Falcon 9 rocket test flight and landing at SpaceX’s rocket development facility in Texas, uploaded to YouTube in April of 2014.
Although the rocket’s landing did not go according to plan, the other half of the launch mission was a success.
The Dragon spacecraft reached the International Space Station on April 17, supplying the astronauts on board with over 4,000 pounds of water, food, scientific experiments, technology, and even the first espresso machine ever to reach space.
In many ways, these landing attempts on a floating platform are more difficult than the ultimate goal of setting these rockets down on land because the platform is susceptible to the harsh winds and rocky waves of the Atlantic ocean. The floating platforms, however, are tens of miles from land and therefore a safer testing ground far away from any residential areas.
That’s why SpaceX will have to succeed in the ocean, first.
Check out a successful landing of a Falcon 9 rocket at SpaceX’s rocket development facility:
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