The SpaceX Falcon rocket that landed on an ocean platform after catapulting a communications satellite toward orbit sustained heavy damage due to its extremely high speed, says company founder and chief executive Elon Musk.
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Before the May 6 launch, SpaceX downplayed chances the rocket's first-stage would even be able to repeat the successful ocean landing of the previous mission, a cargo run to the International Space Station for NASA.
The May 6 mission delivered a hefty TV broadcasting satellite into an orbit about 22,000 miles above Earth. The space station's altitude is about 250 miles.
The extra speed required for the satellite-delivery flight meant the returning rocket experienced five times more heating than the previous booster.
"Most recent rocket took max damage, due to (very) high entry velocity," Musk posted on Twitter.
When the rocket's primary stage separated from the second-stage about 2.5 minutes after liftoff, it was zipping along at 5,220 mph, or about 1.5 miles per second.
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After coasting to an altitude 76 miles above Earth, the rocket slammed into the atmosphere at Mach 5.7. With a half-mile left to go, the rocket ignited three of its nine engines to shave its speed from 441 mph to 134 mph in three seconds.
With one engine still burning and running out of fuel, the rocket, now traveling at about 2.5 mph, settled itself onto a platform floating in the Atlantic Ocean east of its Cape Canaveral, Florida, launch site.
The scorched booster likely won't be flying again.
Instead, it "will be our life leader for ground tests to confirm others are good," Musk wrote on Twitter.