Six days ago, SpaceX founder and CEO Elon Musk was atwitter with excitement over the next step in his plan to get humans off the planet. After successfully sending four of its Dragon capsules to resupply the ISS, SpaceX was launching yet another—but this time, with an added level of difficulty. The launcher that gets the capsules into orbit, the Falcon 9, would attempt to land its boost stage—that’s the part with the rocket—back on Earth after the delivery. Well, not exactly on Earth. On a drone spaceport barge. In the middle of the Atlantic ocean.
On the scale of targets that you’re trying to hit from space, this thing is tiny. Usually, space explorers feel lucky when they can target anything roughly the size of a vast body of water when they reenter the atmosphere; indeed, all of SpaceX’s Dragon capsules are designed to splashdown, aided by an impact-mitigating parachute. The Falcon booster has completed two soft landings in the ocean. But this time, it was aiming for a barge just 300 by 170 feet. Musk put the Falcon’s chances for successful landing at 50/50, but a day before the launch, he took it back in a reddit AMA: “I pretty much made that up. I have no idea :).”
All things considered, for the first try, the Falcon could’ve done worse:
Technically, Falcon did hit its target—just at the wrong angle, and a bit off-center. It’s dark, and a little hard to see, but Musk explained exactly what went wrong in a series of tweets today. The grid fins that he had described as crucial to the landing process “lose power and go hardover.” On their own, the rocket’s nitrogen thrusters aren’t powerful enough to deal with the aerodynamic forces at play here. So once the fins run out of hydraulic fluid during the booster’s descent, all bets are off. “Engines fights [sic] to restore, but…Rocket hits hard at ~45 deg angle, smashing legs and engine section.” Then, the leftover fuel and oxygen combine in a big ol’ explosion. The technical summary: “Full RUD (rapid unscheduled disassembly) event,” Musk quipped.
Musk seems pretty nonchalant about losing an asset like this—the booster looks pretty torn up, though the ship suffered only minor damage. (That’s one tough ship.) But Musk’s sanguinity makes sense in the context of his larger plans. At an MIT symposium in October, Musk broke down how important reusing the Falcon will be to getting humans off of Earth. “Reusability is the critical breakthrough needed in rocketry to take things to the next level,” he said. If you can reuse a rocket, each ship from Earth only costs you the fuel it takes to leave—not the $60 million or so it takes to build a Falcon. Landing on a floating platform is the first step to an even greater efficiency: Putting it right back at the launch site from whence it came. “But before we boost back to the launch site and try to land there,” Musk said, “we need to show that we can land with precision over and over again, otherwise something bad could happen.”
Which, you know, turns out to be true.
Luckily, we won’t have to wait long to see another test of the Falcon’s precision landing system: “Next rocket landing on drone ship in 2 to 3 weeks w way more hydraulic fluid,” Musk tweeted. “At least it shd explode for a diff reason.”
No comments:
Post a Comment