“We can give everybody a computer that can access all the world’s knowledge, has a built-in still and video camera, receives signals from outer space to pinpoint its location anywhere on Earth, makes and receives telephone calls as well as text messages, and fits in your shirt pocket; but we can’t even land a rocket on a barge!”
I kind of like it…
Sure as hell beats having to explain “car clock” for friggin’ ever…
The clock would get about 12.8 volts when the engine is running, charging the battery, and 12.0v when the engine isn’t running.
p.s.: the “car clock” gag predates both 12v AND regulators AND alternators.
See Watchismo Times: Time On The Road - A Dash of Dashboard Clock History
Overhead pic of debris on the landing barge.
Punched a pretty good hole in the upper left corner! Not a whole lot of identifiable stuff in the pic, though. Is it the octaweb under the tarp? Seems likely, since that’s the strongest part of the vehicle and seems to be the largest surviving piece (other than the flattened skin). I figure they just ran out of fuel. Nevertheless, it’s impressive that they yet again managed to hit their ocean target.
In his tweets, Elon Musk calls such events “RUD” - Rapid Unscheduled Disassembly.
It’s an old term, dating back to at least the early days of jet turbines (where it referred to the turbine breaking apart under load and destroying the engine) and later used in rocket engine testing. I’ve seen the terms “rapid unscheduled disassembly” and “singular non-causal mishap” as euphemisms for catastrophic structural failures and non-reproduceable failures without a defined root cause in documentation going back to the 'Sixties.
Stranger
In all my years in the jet engine world, I never came across it. Thanks for the background.
It’s an engineer’s typical wry understatement, like “suboptimal” for “sucks”, or “rapid oxidation event” (an actual formal term at one enginemaker) for “titanium fire”.
Bump for the next launch:
SpaceX is set to launch their next cargo mission to the ISS. This launch is scheduled for Friday, April 8 at 4:43 PM Eastern time (20:43 UTC), and will be followed by another barge landing attempt for the first stage. By all estimates the first stage should have the capability to return to the landing site. However, current speculation is that SpaceX wants to perfect the barge landing since it will be necessary for many landings in the future.
I haven’t seen full details on the payload so far, but presumably it will include the usual mix of supplies and new experiments to be conducted onboard the ISS. Notably, however, it will also include the BEAM inflatable module, as a test bed and proof of concept for future inflatable space stations. While it will be attached to the ISS and inflated, for the most part it will remain isolated in case it fails. If it proves safe it might end up being used for extra interior storage. There was a brief discussion of the module in this thread.
The launch and landing will be streamed by SpaceX.
OK, I give - the Falcon-9 is on the pad.
Around the rocket and its gantry are at least 4 towers. They look like antenna towers, but:
See this pic.
What are those horizontal wires doing?
The towers are for lightning protection, and the wires act as you might expect–as conductors to carry away the electrical discharge. Basically giant lightning rods.
Thanks!
Maybe trying to land on the same pad might just be a bit tricky…
But I really, really want to know how the rocket and barge do that dance - the barge can’t be perfectly level at touch down - does the rocket “hover” until the pitch is within some tolerance?
They have a separate pad for landing that doesn’t have the towers–in fact it’s well away from any large structure. You don’t want to take out your gantry/propellant tanks/etc. if something goes wrong! On the occasions where rockets explode close to the pad, the fact that you lose the pad is as much a problem as the loss of the rocket itself. They don’t want the same exposure for their landings as well, especially since they’re still experimental.
As far as the barge landing goes–they definitely do not hover, because they literally can’t. The rocket has too much thrust to hover in place, and in any case not enough fuel.
The legs can absorb a certain amount of shock, so there’s a bit of wiggle room, but if the barge is rocking too much, they’ll abort and dump it in the drink. The landing slope is such that they can abort very close to the last few seconds. If they get unlucky and a big wave comes up… well, them’s the risks in rocketry.
Perhaps one day they’ll have a large, stable platform, like an oil rig. It’s probably not worth the effort today, but maybe someday.
nm
As Dr. Strangelove noted, the towers are part of the lightning protection system. Rockets are prone to lightning strikes both on pad and in flight (Apollo 12 was hit by a strike that temporarily disabled the primary power distribution system and forced a reboot of the CSM during ascent) and most launch facilities are oceanside where storms and hurricanes are not uncommon.
A large ocean barge is very stable in WMO Sea State 4 or less, to the point that you really won’t feel motion unless you are looking at thr horizon. It’s not that different from landing on a land-based pad. The bigger challenge is navigation. The position of a land-based landing site is known to high precision and can be arbitrary in size. A barge, on the other hand (or rather, the water it sits in) is moving and its position needs to be constantly transmitted to the landing vehicle so that it can navigate to the landing site. It you watch the videos of landing attempts, the vehicle doesn’t hover at all (which would waste fuel which they want to minimize in order to gain greatest performance upon ascent); it just comes in arse first, throttles up to slow for the final approach, and then plops down on the deck and shuts down the engines. There is no real opportunity to recover from any misalignment; they do have ACS thrusters up top, but they’re really intented to reorient the stage during initial reentry and don’t have enough thrust or control authority to correct for a gross failure upon final approach, and in fact if the vehicle had a significant yaw or pitch rate they would likely limit cycle and use up all of the gas before landing was complete.
Stranger
Thanks for the bump lazybratsche.
Note that due to the ISS payload, NASA TV is carrying today’s launch in addition to the usual SpaceX webcast.
I’ve got a good feeling about today’s barge landing. I think they’ll nail it.
It’s gotten so exciting lately - all these launches to watch and look forward to.
Fuck yeah! They stuck the landing. That was gorgeous.
And it worked! And almost right on the bulls-eye.