Falcon... almost... Lands on Barge after boosting Dragon into orbit

Space X's new reusable version of the Falcon 9 first-stage booster made a very ambitious attempt yesterday to land on a barge 200 miles out in the Atlantic east of Cape Canaveral, after successfully boosting a Dragon supply capsule into orbit so as to dock with the International Space Station in a few days.

It almost worked. The booster located the barge and homed in on it, decelerating as it approached, but struck the barge too hard, resulting in the vehicle's disintegration.

All in all, that's a qualified success, I think. The biggest challenge in this test was performing the landing process above a 300 by 100 foot target far out at sea, and that part seems to have worked well enough. Earlier tests have demonstrated that the vehicles can slow down to safe landing speeds over the open ocean. Now they just have to put the two criteria together. Elon Musk seems to think that they will have a successful landing within a year.

To my knowledge this is the first time anyone has tried this with full-sized working satellite launchers.

 

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Impressive. Thanks for the update.

 

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Elon Musk tweeted (2:10 AM - 10 Jan 2015): "Ship itself is fine. Some of the support equipment on the deck will need to be replaced"
https://twitter.com/elonmusk/status/553856479590359040

 

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Yes, I was impressed with this. I was rather annoyed to see the BBC ran the story as being a "failure". It is clearly far from easy. I thought Musk's verdict of : "Close but no cigar." felt about right. Fingers crossed for the next one.

 

I agree... this is most certainly a success, not a failure. Granted, not a total-success... but a success none the less.

NASA, if memory serves, gave a "landing zone" of some 30km for where it's boosters would come down... so landing a booster in a 100x200 foot area is... well, damned impressive, even if it came down too fast!

 

Even the best baseball players drop the ball once in a while. We should be impressed that they can ever catch it at all.

 

There were impressive waterworks installed at Canaveral to accommodate the reusable boosters tow-ins. Why are the Xs insisting on a landing on a hard platform, rather than fishing the" empty" out of the water with a crane,-- after a fluid attenuated splash-down?
Congratulations for getting the supplies to the not leaking IST.

 

Because the booster is not designed for salt water immersion _or_ falling into the ocean. They have successfully brought the stage to a stop right above the ocean- but the resulting tilt over and impact destroyed it.

 

thanks billvon. I guess the two solid rocket boosters of the shuttle hanging from parachutes were more solid. That must be tricky with waves, the current of the nearby Gulf stream, and unpredictable winds to needlehole a soft landing.
---we do it because it is hard. --JFK.

 

Dramatic new video of the booster crashing on the barge has emerged.

http://www.space.com/28295-spacex-rocket-landing-crash-photos-video.html

It looks like the thing came in pretty fast, at about a 45 degree angle to the vertical. Elon Musk says that its control fins had lost power (due to a hydraulic fluid leak?) weren't working and that the rocket engine was fighting to correct the vehicle's attitude. When the booster struck the barge, the engines and landing legs were destroyed, and residual fuel exploded in a brilliant fireball resulting in what Musk called a 'RUD' (rapid unplanned disassembly) of the vehicle. He says that the conrol fin problem will be corrected in the next attempt, which means that the booster will have to find a different reason for exploding.

 

Yazata: "RUD" lol. Is spaceX developing a soft landing technology? the musk-ox: "The falcon has landed"? second only to the 'eagle' that landed?

 

Yeah, that's what this is, old 1950's science-fiction technology, where a rocket-ship lands vertically on a pillar of rocket exhaust. Coming in tilted at 45 degrees to the vertical obviously isn't going to work. SpaceX has performed successful vertical decelerations over the open ocean, this was the first time it was attempted over their recovery barge. It looks like the thing successfully located the barge, calculated a trajectory to it, decelerated from hypersonic velocity, but didn't have its attitude under control during final vertical approach.

 

Here is video of the "close but no cigar" Landing: https://mtc.cdn.vine.co/r/videos/78...p4?versionId=izhBdYPcHAJ3RhZJlBMG14kkGtFfvkpE

 

Most likely due to the depletion of whatever they were using to drive the hydraulic system, likely compressed gas. At that point they lost control of the gridfins and hence lost roll control, and the system will only have a limited ability to control pitch and yaw once roll control is lost.

 

I have to say, it did an admirable job trying to compensate for the loss of the control fins via (I would presume) vectored thrust. I'm interested to see the second attempt - so long as the fins function, I would imagine they might just nail it!

 

Quick note here -

They land via vectored thrust. That's what provides the impulse to slow their descent and also pitch and yaw control.

However, they have a problem with roll. Any launch vehicle that has at least two main engines can deal with this by differential vectoring - but with one engine running there is no way to use two engines to control roll.

The Falcon launches with nine engines, but upon landing, it is so light that even the thrust of one engine, throttled back to minimum, is almost too much. Thus they cannot fire up a second engine to achieve roll control.

This has been an ongoing problem. In early (water landing) tests they used cold-gas thrusters to control roll, but the aerodynamic forces exceeded the thruster's control authority. The stage began to spin, so fast that the propellant centrifuged away from the pickups and the engine shut down.

Thus they switched to grid fins, which can actually use aerodynamic forces to control roll. (Thrust vectoring still controls pitch and yaw.) To do that, of course, they have to work almost all the way down, which they did not in this case.

 

Oooh, alrighty - makes sense I guess - after all, those engines are meant to hoist something positively massive into space, and it comes back down with far less.

Would it be possible to use a variant of an RCS system at the top and bottom of the craft to handle roll control (or at least assist / fine tune it), as well as assist with attitude control? Or would aerodynamic forces be too great for such a system?

Not gonna lie - the physics of this is a bit over my head (though I had at one time dreamed of being an aerospace engineer heh)- it is fascinating though!

 

Well, they tried that (the cold-gas thrusters) but they didn't have enough authority (thrust) to overcome aerodynamic torque. They could switch to a different propellant or bigger thrusters, but all those come with a weight penalty, and they're already paying a pretty big penalty with the landing legs and the extra propellant. The fins were lighter/cheaper.

 

Ah... hm... yeah, I'm not sure what else would work well for this. Do they have a solid reason on why the fins failed (I know Musk said about the fins losing power but I meant more of a mechanical why) - or, for that matter, can they actually tell after the results of the impact and explosion?

 

Ran out of hydraulic fluid and hence actuator power. They were using an open hydraulic system for the sake of simplicity.