Space X nails it, except for this one part
January 18, 2016 1:31 PM Subscribe
On Sunday, Space X launched the JASON-3 satellite and also tried to land the first stage of the Falcon 9 rocket on a droneship barge. The satellite reached orbit successfully and the first stage landed perfectly. That's when a problem latched on to the mission (video in link).
According to Elon Musk, head of Space X:
"Falcon lands on droneship, but the lockout collet doesn't latch on one [of] the four legs, causing it to tip over post-landing. [The] root cause may have been ice buildup due to condensation from heavy fog at liftoff."
According to Elon Musk, head of Space X:
"Falcon lands on droneship, but the lockout collet doesn't latch on one [of] the four legs, causing it to tip over post-landing. [The] root cause may have been ice buildup due to condensation from heavy fog at liftoff."
At least the problem is of the fixable mechanical sort. The mission concept itself was proven, so a bit more tinkering with parts and protocols, and Elon should be good to go next time.
A successful mission, even if it blowed up real good. It didn't stick the dismount, is all.
posted by Capt. Renault at 1:42 PM on January 18, 2016 [7 favorites]
A successful mission, even if it blowed up real good. It didn't stick the dismount, is all.
posted by Capt. Renault at 1:42 PM on January 18, 2016 [7 favorites]
I realize that it's some SF reference, but as a technical writer who strives to write with some empathy I'm delighted that the obnoxiously named "Just Read the Instructions" keeps getting exploded on.
posted by ddbeck at 1:43 PM on January 18, 2016 [8 favorites]
posted by ddbeck at 1:43 PM on January 18, 2016 [8 favorites]
It was a great landing, apart from the final technical difficulties! Seriously, it seems that SpaceX has nailed the hardest part.
Watching the launch, for an exhilarating moment I felt a part of something bigger than life - a feeling to which I'm not really entitled. I was forcefully reminded of that when they cut the feed as soon as they saw what happened (it continued only until the moment when the camera starts to shake from the blast). Well, they're a commercial venture and have to mind the PR side of the business.
posted by hat_eater at 1:43 PM on January 18, 2016
Watching the launch, for an exhilarating moment I felt a part of something bigger than life - a feeling to which I'm not really entitled. I was forcefully reminded of that when they cut the feed as soon as they saw what happened (it continued only until the moment when the camera starts to shake from the blast). Well, they're a commercial venture and have to mind the PR side of the business.
posted by hat_eater at 1:43 PM on January 18, 2016
I've watched that video maybe a dozen times now, with the sound up. It is so satisfying, in the same way watching Wile E Coyote holding a slowly burning fuse is.
posted by Mei's lost sandal at 1:43 PM on January 18, 2016 [2 favorites]
posted by Mei's lost sandal at 1:43 PM on January 18, 2016 [2 favorites]
Space X Rocket? More like Ex Space Rocket, amirite?
But seriously, the accuracy on that touchdown was amazing.
posted by dazed_one at 1:46 PM on January 18, 2016 [3 favorites]
But seriously, the accuracy on that touchdown was amazing.
posted by dazed_one at 1:46 PM on January 18, 2016 [3 favorites]
Wouldn't adding legs make this less likely to happen?
posted by Splunge at 1:46 PM on January 18, 2016
posted by Splunge at 1:46 PM on January 18, 2016
That was the first time I'd watched the video. From a quick scan of some breathless headlines that popped up on my feed I thought the thing exploded on contact. I have to admit I was super-impressed with how precisely and almost gently it landed on the bullseye before tip-over-go-boom happened.
posted by TwoStride at 1:48 PM on January 18, 2016
posted by TwoStride at 1:48 PM on January 18, 2016
Wouldn't adding legs make this less likely to happen?
More latches to fail. :)
posted by Greg_Ace at 1:49 PM on January 18, 2016 [3 favorites]
More latches to fail. :)
posted by Greg_Ace at 1:49 PM on January 18, 2016 [3 favorites]
(not that I wish ill on SpaceX; their accomplishment is super-impressive)
posted by Mei's lost sandal at 1:50 PM on January 18, 2016
posted by Mei's lost sandal at 1:50 PM on January 18, 2016
Yeah, hitting the bullseye is great, so surely and gently. Then you notice the movement where there shouldn't be any and you're screaming "NOOOOOOOOOO," but gravity does its thing and that's that.
posted by Brandon Blatcher at 1:50 PM on January 18, 2016
posted by Brandon Blatcher at 1:50 PM on January 18, 2016
Wouldn't adding legs make this less likely to happen?
That's my Kerbal Space Program philosophy too!
posted by meinvt at 1:51 PM on January 18, 2016 [16 favorites]
That's my Kerbal Space Program philosophy too!
posted by meinvt at 1:51 PM on January 18, 2016 [16 favorites]
The best tweet: Well, at least the pieces were bigger this time!
posted by Dashy at 1:53 PM on January 18, 2016 [6 favorites]
posted by Dashy at 1:53 PM on January 18, 2016 [6 favorites]
More latches to fail. :)
But also more latches can fail without toppling the booster. eg In a five-point arrangement, you can lose up to two latches and potentially still stay upright. In a four-point arrangement, lose even a single latch and you're toast.
Bu yeah, when the device in question is a rocket, adding more stuff to it is usually less preferable to making a smaller amount of stuff work more reliably :)
posted by anonymisc at 1:55 PM on January 18, 2016
But also more latches can fail without toppling the booster. eg In a five-point arrangement, you can lose up to two latches and potentially still stay upright. In a four-point arrangement, lose even a single latch and you're toast.
Bu yeah, when the device in question is a rocket, adding more stuff to it is usually less preferable to making a smaller amount of stuff work more reliably :)
posted by anonymisc at 1:55 PM on January 18, 2016
It didn't stick the dismount, is all.
Fucking East German judge has it out for Team Elon.
posted by Cool Papa Bell at 1:57 PM on January 18, 2016 [4 favorites]
Fucking East German judge has it out for Team Elon.
posted by Cool Papa Bell at 1:57 PM on January 18, 2016 [4 favorites]
It is so satisfying, in the same way watching Wile E Coyote holding a slowly burning fuse is.
...
Wouldn't adding legs make this less likely to happen?
What they should do is put mattresses all around the landing area so that if the rocket tips over, it will just comically bounce off them with a boing-boing-boing...
posted by bitteroldman at 2:13 PM on January 18, 2016 [7 favorites]
...
Wouldn't adding legs make this less likely to happen?
What they should do is put mattresses all around the landing area so that if the rocket tips over, it will just comically bounce off them with a boing-boing-boing...
posted by bitteroldman at 2:13 PM on January 18, 2016 [7 favorites]
anonymisc: Bu yeah, when the device in question is a rocket, adding more stuff to it is usually less preferable to making a smaller amount of stuff work more reliably :)
For example, the N-1.
posted by traveler_ at 2:17 PM on January 18, 2016 [2 favorites]
For example, the N-1.
posted by traveler_ at 2:17 PM on January 18, 2016 [2 favorites]
You know, if the ASDS Just Read The Instructions really was a Culture ship, it would by now be petitioning to rename itself the ASDS Brace Yourselves, Here Comes Another One.
posted by Major Clanger at 2:31 PM on January 18, 2016 [24 favorites]
posted by Major Clanger at 2:31 PM on January 18, 2016 [24 favorites]
Metafilter seems not entirely aware that last month was the one where they made the landing and it didn't explode, which was probably more newsworthy.
posted by sfenders at 2:35 PM on January 18, 2016 [2 favorites]
posted by sfenders at 2:35 PM on January 18, 2016 [2 favorites]
There's a reason most office chairs have 5 legs instead of 4. It's significantly more stable.
posted by JackFlash at 2:39 PM on January 18, 2016 [3 favorites]
posted by JackFlash at 2:39 PM on January 18, 2016 [3 favorites]
Metafilter seems not entirely aware that last month was the one where they made the landing and it didn't explode , which was probably more newsworthy.
There was a meta thread about that one too. Yes, the ground success was more newsworthy than another ocean failure, but the next step forward after that big success on the ground is a successful ocean-barge landing (because this allows much more cargo into space). So watching this near-success is part of the same narrative. It's like watching sports - the last innings was record-breaking and super exciting, and this one was looking good until the last second, which is also exciting but not as much, and now we're eagerly awaiting the next innings. :)
posted by anonymisc at 2:41 PM on January 18, 2016
There was a meta thread about that one too. Yes, the ground success was more newsworthy than another ocean failure, but the next step forward after that big success on the ground is a successful ocean-barge landing (because this allows much more cargo into space). So watching this near-success is part of the same narrative. It's like watching sports - the last innings was record-breaking and super exciting, and this one was looking good until the last second, which is also exciting but not as much, and now we're eagerly awaiting the next innings. :)
posted by anonymisc at 2:41 PM on January 18, 2016
They just have to stop making them so goddamn tall and skinny.
posted by bonobothegreat at 2:42 PM on January 18, 2016 [2 favorites]
posted by bonobothegreat at 2:42 PM on January 18, 2016 [2 favorites]
What they should do is put mattresses all around the landing area
Which they should attach with velcro. Which they should also put on the bottom of the rocket and this would never have happened to begin with.
posted by 7segment at 2:48 PM on January 18, 2016 [1 favorite]
Which they should attach with velcro. Which they should also put on the bottom of the rocket and this would never have happened to begin with.
posted by 7segment at 2:48 PM on January 18, 2016 [1 favorite]
Well, at least the pieces were bigger this time!
*Carson opens envelope and reads* "What's the least reassuring thing to say to an astronaut?"
posted by dephlogisticated at 3:02 PM on January 18, 2016 [10 favorites]
*Carson opens envelope and reads* "What's the least reassuring thing to say to an astronaut?"
posted by dephlogisticated at 3:02 PM on January 18, 2016 [10 favorites]
There was a meta thread about that one too.
None that I can find. I'd have made one myself except that holidays meant I didn't hear about it until a week afterwards.
posted by sfenders at 3:05 PM on January 18, 2016
None that I can find. I'd have made one myself except that holidays meant I didn't hear about it until a week afterwards.
posted by sfenders at 3:05 PM on January 18, 2016
If they can put them down so on target, maybe the barge should have a rocket grabbing device that grasps the rocket at 45% of its height. Then the whole contraption would be more stable anyway, with the barge holding on to the rocket, rather than the rocket balanced on the barge.
posted by Oyéah at 3:12 PM on January 18, 2016 [3 favorites]
posted by Oyéah at 3:12 PM on January 18, 2016 [3 favorites]
Successful landing! Less successful with the standing. As I understand, the next Falcon revision has a different landing leg mechanism, though I can't remember where I saw that.
My favorite comments on SpaceX videos are from the people suggesting design changes, based on their extensive KSP knowledge.
posted by HighLife at 3:25 PM on January 18, 2016
My favorite comments on SpaceX videos are from the people suggesting design changes, based on their extensive KSP knowledge.
posted by HighLife at 3:25 PM on January 18, 2016
It's not like it's brain surgery.
posted by peeedro at 3:30 PM on January 18, 2016 [4 favorites]
posted by peeedro at 3:30 PM on January 18, 2016 [4 favorites]
They are landing on a barge because apparently there are endangered nesting birds at Vandenberg. The barge is not entirely stable so that adds to the landing difficulty. It's puzzling that with that challenge, they don't make the legs bigger, and add a few more. With six legs instead of three, if one breaks it's not a big deal.
posted by beagle at 3:33 PM on January 18, 2016
posted by beagle at 3:33 PM on January 18, 2016
I think this is all really a trick to one-up Amazon's delivery drones. Your package, from Vandenberg to anywhere on Earth. Please ensure the landing area is free of flammable material.
posted by ctmf at 3:50 PM on January 18, 2016 [1 favorite]
posted by ctmf at 3:50 PM on January 18, 2016 [1 favorite]
the barge is not entirely stable so that adds to the landing difficulty.
That's putting it mildly. It was in 10 to 15 foot seas which isn't a storm, but it's not nothing either. There are a lot more winds at sea too.
That it got down in one piece and only fell over because of a locked joint is really amazing.
posted by bonehead at 3:52 PM on January 18, 2016 [1 favorite]
That's putting it mildly. It was in 10 to 15 foot seas which isn't a storm, but it's not nothing either. There are a lot more winds at sea too.
That it got down in one piece and only fell over because of a locked joint is really amazing.
posted by bonehead at 3:52 PM on January 18, 2016 [1 favorite]
That is a strangely mesmerizing video to watch repeatedly.
posted by gottabefunky at 4:00 PM on January 18, 2016 [2 favorites]
posted by gottabefunky at 4:00 PM on January 18, 2016 [2 favorites]
The figure I've seen in a few recent articles about SpaceX-- that refuel and refurbish will cost around $200,000 as opposed to $60 million for each non-reusable launch vehicle -- excites the hell out of me for the next few decades of spaceflight, if they get things sorted out. That's a world-changing cost reduction right there.
More power to them!
posted by stavrosthewonderchicken at 4:02 PM on January 18, 2016 [5 favorites]
More power to them!
posted by stavrosthewonderchicken at 4:02 PM on January 18, 2016 [5 favorites]
It didn't stick the dismount, is all.
Fucking East German judge has it out for Team Elon.
How long until Mckayla Maroney watching the rocket fall over?
posted by Ray Walston, Luck Dragon at 4:17 PM on January 18, 2016
Fucking East German judge has it out for Team Elon.
How long until Mckayla Maroney watching the rocket fall over?
posted by Ray Walston, Luck Dragon at 4:17 PM on January 18, 2016
There's a reason most office chairs have 5 legs instead of 4. It's significantly more stable.
I had two five-leg office chairs from Big Lots. The legs were plastic, and one of them broke. It instantly put me on the floor. I used the other chair until the same thing happened to it. This experiment proved to me that five legs are not significantly more stable than four, when one of them fails.
posted by Kirth Gerson at 5:12 PM on January 18, 2016 [2 favorites]
I had two five-leg office chairs from Big Lots. The legs were plastic, and one of them broke. It instantly put me on the floor. I used the other chair until the same thing happened to it. This experiment proved to me that five legs are not significantly more stable than four, when one of them fails.
posted by Kirth Gerson at 5:12 PM on January 18, 2016 [2 favorites]
I wish they had a reaction cam on the SpaceX mission control or whatever, because the jubilation as the rocket touches down beautifully right where it's supposed to...and then the spreading consternation as they start to see that sideways movement...
It would be just like in a basketball game when you're absolutely sure the ball is going to whiff right into the net and it finds unlikely way to bounce back out.
posted by not that girl at 5:42 PM on January 18, 2016
It would be just like in a basketball game when you're absolutely sure the ball is going to whiff right into the net and it finds unlikely way to bounce back out.
posted by not that girl at 5:42 PM on January 18, 2016
That it got down in one piece and only fell over because of a locked joint is really amazing.
Yeah, it looks like they've got the gist down, now there's just ironing out the details.
This really wasn't an optimal day to try this landing. But the main mission was to launch the Jason-3, and conditions were going for doing that, so they launched. But the sea was rough and it sounded like the landing wasn't going to be successful. BUT IT WAS. And not just successful but seemingly perfect, as the stage came down pretty much down on center. Then that damn latch failed.
But I got goosebumps looking at the stage come in. It reminded me that Space X is testing Mars landings with this and it's looking good!
posted by Brandon Blatcher at 5:59 PM on January 18, 2016
Yeah, it looks like they've got the gist down, now there's just ironing out the details.
This really wasn't an optimal day to try this landing. But the main mission was to launch the Jason-3, and conditions were going for doing that, so they launched. But the sea was rough and it sounded like the landing wasn't going to be successful. BUT IT WAS. And not just successful but seemingly perfect, as the stage came down pretty much down on center. Then that damn latch failed.
But I got goosebumps looking at the stage come in. It reminded me that Space X is testing Mars landings with this and it's looking good!
posted by Brandon Blatcher at 5:59 PM on January 18, 2016
and then the spreading consternation as they start to see that sideways movement...
I expect someone in their mission control has a button that plays sadtrombone over the PA.
posted by ROU_Xenophobe at 6:01 PM on January 18, 2016 [1 favorite]
I expect someone in their mission control has a button that plays sadtrombone over the PA.
posted by ROU_Xenophobe at 6:01 PM on January 18, 2016 [1 favorite]
There is no such button. :-P
posted by Feantari at 6:43 PM on January 18, 2016 [3 favorites]
posted by Feantari at 6:43 PM on January 18, 2016 [3 favorites]
Feantari, you're with Space X? Any insights to add (other than that sad button lackage)?
posted by brundlefly at 7:15 PM on January 18, 2016
posted by brundlefly at 7:15 PM on January 18, 2016
I'm a little curious why there was so violent an explosion. Was there a lot of unspent fuel in there? If so, why?
posted by kafziel at 10:49 PM on January 18, 2016
posted by kafziel at 10:49 PM on January 18, 2016
For rocketry, that was a very mild, gentle explosion. The reason for the fuel left as it lands is that there is inevitably a small amount of uncertainty in the amount of fuel needed, and if you run out early, the mission fails. Rocket fuel is very reactive. In addition, a design requirement of all elements is to be as light as possible to save fuel, so they are only as strong as needed to function correctly.
posted by sanedragon at 11:55 PM on January 18, 2016
posted by sanedragon at 11:55 PM on January 18, 2016
How painful financially is the loss of that rocket?
posted by eugenen at 12:26 AM on January 19, 2016
posted by eugenen at 12:26 AM on January 19, 2016
It's the third one they've lost trying to get barge landings right in the last 12 months (or so)... obviously they'd have preferred to stick the landing the first time and every time thereafter, but I'm pretty sure it's all budgeted for. Like they say, space is hard (and expensive).
The $60 million per vehicle I quoted upthread (as opposed to a $200,000 refuel and refit) is also a very substantially cheaper replacement price for similar rockets than has been customary for decades, thanks to their efforts to make everything at every stage cheaper and more efficient.
The $60 million per vehicle I quoted upthread (as opposed to a $200,000 refuel and refit) is also a very substantially cheaper replacement price for similar rockets than has been customary for decades, thanks to their efforts to make everything at every stage cheaper and more efficient.
United Launch Alliance, the consortium of Boeing and Lockheed Martin that produces both the Delta and the Atlas, does not make its prices public. But budget documents show that in 2010 the EELV program received $1.14 billion for three rockets—an average of $380 million per launch.posted by stavrosthewonderchicken at 12:42 AM on January 19, 2016 [2 favorites]
If my numbers are off, please do correct them. I hadn't actually realized until this moment -- assuming that they are right -- that SpaceX is already running at something like 6x cheaper launch costs even before they get reusability perfected!
posted by stavrosthewonderchicken at 12:47 AM on January 19, 2016
posted by stavrosthewonderchicken at 12:47 AM on January 19, 2016
Stolen from elsewhere: what we have here is a successful landing, but a failed standing.
posted by generichuman at 1:09 AM on January 19, 2016
posted by generichuman at 1:09 AM on January 19, 2016
Those winds look pretty strong, I'm not convinced it could have remained standing even if the leg had held. I like this solution.
posted by sophist at 1:40 AM on January 19, 2016
posted by sophist at 1:40 AM on January 19, 2016
You all know that they successfully landed one at Cape Canaveral - a world first - on Dec 21st, right?
The video is amazing.
posted by memebake at 2:42 AM on January 19, 2016
The video is amazing.
posted by memebake at 2:42 AM on January 19, 2016
I had two five-leg office chairs from Big Lots. The legs were plastic, and one of them broke. It instantly put me on the floor. I used the other chair until the same thing happened to it. This experiment proved to me that five legs are not significantly more stable than four, when one of them fails.
While most people would coach you to get the six-leg office chair, I recommend the greatly superior seven-leg office chair, which, when one leg breaks, still has a spare leg in reserve.
The eight-leg office chair is simply over-egging it. Although if you find someone selling one with a broken leg it's a reasonable investment compared to a stock seven-legger.
posted by sebastienbailard at 3:01 AM on January 19, 2016 [1 favorite]
While most people would coach you to get the six-leg office chair, I recommend the greatly superior seven-leg office chair, which, when one leg breaks, still has a spare leg in reserve.
The eight-leg office chair is simply over-egging it. Although if you find someone selling one with a broken leg it's a reasonable investment compared to a stock seven-legger.
posted by sebastienbailard at 3:01 AM on January 19, 2016 [1 favorite]
Sure, but the problem with the "more legs = more stability" argument, at least at lower numbers of legs, is that when one leg fails, the other legs do not relocate to share the load equally; there's still an unsupported segment. That segment also happens to be more heavily-loaded than the supported ones, which is why that leg failed instead of another one. When you get up to seven or eight legs, the unsupported segment may be small enough that your chair or rocket stays vertical. With that many supports, you might as well have one big conical support member instead of legs.
posted by Kirth Gerson at 3:26 AM on January 19, 2016
posted by Kirth Gerson at 3:26 AM on January 19, 2016
I am smugly sitting pretty right now because I am seated upon a cost-plus government contract specified platinum-plated Herman Miller chair with two stage propulsion, not one of your ropey edge-of-the-performance-envelope single seat to orbit designs.
Also, it has five legs.
posted by cstross at 3:47 AM on January 19, 2016
Also, it has five legs.
posted by cstross at 3:47 AM on January 19, 2016
Can anyone explain why landing on a floating platform is desirable?
posted by trif at 3:56 AM on January 19, 2016
posted by trif at 3:56 AM on January 19, 2016
Can anyone explain why landing on a floating platform is desirable?
Elon said this was a high velocity mission and so its not possible to get the first stage back to the launch site (1) (2). So landing on a floating barge is the next best option. On Dec 21st they got their first stage back to Cape Canaveral because it was a low orbit mission.
posted by memebake at 4:20 AM on January 19, 2016
Elon said this was a high velocity mission and so its not possible to get the first stage back to the launch site (1) (2). So landing on a floating barge is the next best option. On Dec 21st they got their first stage back to Cape Canaveral because it was a low orbit mission.
posted by memebake at 4:20 AM on January 19, 2016
Ah, OK. There's no particular operational benefit then?
posted by trif at 4:38 AM on January 19, 2016
posted by trif at 4:38 AM on January 19, 2016
You have 70% of the Earth's surface available to land on (within reason).
posted by EndsOfInvention at 4:50 AM on January 19, 2016 [1 favorite]
posted by EndsOfInvention at 4:50 AM on January 19, 2016 [1 favorite]
Can anyone explain why landing on a floating platform is desirable?
Same reason it doesn't have six legs, to save fuel and leave more room for payload. The landing gear adds a substantial amount of weight. They want it as light as possible, and they want it to go as short a distance out of its way as possible. To get into orbit, the rocket heads east, really fast. Must be there's no convenient land a suitable distance east of where they launch.
posted by sfenders at 5:13 AM on January 19, 2016 [1 favorite]
Same reason it doesn't have six legs, to save fuel and leave more room for payload. The landing gear adds a substantial amount of weight. They want it as light as possible, and they want it to go as short a distance out of its way as possible. To get into orbit, the rocket heads east, really fast. Must be there's no convenient land a suitable distance east of where they launch.
posted by sfenders at 5:13 AM on January 19, 2016 [1 favorite]
The $60 million per vehicle I quoted upthread (as opposed to a $200,000 refuel and refit) is also a very substantially cheaper replacement price for similar rockets
I think you're right on all of that except the $200k refit, or the extent to which it's equivalent to the entire launch cost. Poking around looking for other info I saw that wikipedia has $200,000 as the price of fuel alone, which seems more reasonable in light of what Musk has said elsewhere about the low price at which he expects to be able to launch stuff into orbit. It'll still be in the tens of millions.
posted by sfenders at 5:17 AM on January 19, 2016
I think you're right on all of that except the $200k refit, or the extent to which it's equivalent to the entire launch cost. Poking around looking for other info I saw that wikipedia has $200,000 as the price of fuel alone, which seems more reasonable in light of what Musk has said elsewhere about the low price at which he expects to be able to launch stuff into orbit. It'll still be in the tens of millions.
posted by sfenders at 5:17 AM on January 19, 2016
trif: the operational benefit is that if they can land on a barge offshore they can use more of the first stage fuel for adding velocity to the payload and less for turning round and flying back to the pad. So it improves their payload capacity.
posted by cstross at 5:24 AM on January 19, 2016 [2 favorites]
posted by cstross at 5:24 AM on January 19, 2016 [2 favorites]
Sure, but the problem with the "more legs = more stability" argument, at least at lower numbers of legs, is that when one leg fails, the other legs do not relocate to share the load equally; there's still an unsupported segment.
If it was a static environment and a perfectly vertical landing, you'd want exact three legs.
But it's not -- there's wind and stuff, which means you have those loads to deal with as well. Four legs is badly unstable in 180° since two of the remaining legs are directly opposite each other and on the centerline. Five legs gives you a triangle, with the load's CoM inside the triangle, even if you lose a leg.
trif: the operational benefit is that if they can land on a barge offshore they can use more of the first stage fuel for adding velocity to the payload and less for turning round and flying back to the pad.
Yes. But they're still wasting a ton of ΔV in A) carrying the fuel needed to correct to make sure the fall end very near the barge, and 2) actually brake from terminal velocity to 0 and maneuver to *exactly on* the barge, and 3) the mass of the landing legs. Controller mass is basically none anymore, you already needed a controller, adding another program to it costs, well, maybe a couple of grams if you have to add another memory chip to the controller.
Tsiolkovsky's rocket equation is very, very, very clear on this. Every pound in the first stage that remains in the first stage is a huge hit on the final payload to target velocity. Worse, a vertical landing on thrusters is the absolute worst way to do it when you landing in a dense fluid, you know, like our atmosphere. The atmosphere SUCKS when you're trying to get to orbital velocity, but while physics is hard, physics is also fair, the atmosphere is great at slowing things down and generating lift.
Does it look as cool to parachute down and either splash or be caught by a chopper mid-air? No. But this is real life, not Thunderbirds. The single most expensive thing you can do in spaceflight is bring things back, and the single most expensive way to do that is to point the motor down and fight gravity again. You do this when you don't have an atmosphere, yes, but man, the Moon would have been vastly easier to get to if it had one, and Mars landers would be *vastly* harder if Mars didn't have the tenuous atmosphere that it has.
I'm getting ranty. I'd better stop, but I'm honestly not that impressed. The landing vertically on rocket thing from terminal velocity has been done before, see the DC-X in the early 1990s, and the New Shepard earlier this year, which, despite certain CEO's mocking statements, would have ended up falling at the same basic velocity for landing, because that's how terminal velocity works. Doesn't matter exactly how high or how fast you were when you started, you end up slowing as you land because atmosphere, and as long as you fall long enough, you end up at terminal velocity. And falling from 100km is *more* that far enough.
posted by eriko at 7:24 AM on January 19, 2016 [1 favorite]
If it was a static environment and a perfectly vertical landing, you'd want exact three legs.
But it's not -- there's wind and stuff, which means you have those loads to deal with as well. Four legs is badly unstable in 180° since two of the remaining legs are directly opposite each other and on the centerline. Five legs gives you a triangle, with the load's CoM inside the triangle, even if you lose a leg.
trif: the operational benefit is that if they can land on a barge offshore they can use more of the first stage fuel for adding velocity to the payload and less for turning round and flying back to the pad.
Yes. But they're still wasting a ton of ΔV in A) carrying the fuel needed to correct to make sure the fall end very near the barge, and 2) actually brake from terminal velocity to 0 and maneuver to *exactly on* the barge, and 3) the mass of the landing legs. Controller mass is basically none anymore, you already needed a controller, adding another program to it costs, well, maybe a couple of grams if you have to add another memory chip to the controller.
Tsiolkovsky's rocket equation is very, very, very clear on this. Every pound in the first stage that remains in the first stage is a huge hit on the final payload to target velocity. Worse, a vertical landing on thrusters is the absolute worst way to do it when you landing in a dense fluid, you know, like our atmosphere. The atmosphere SUCKS when you're trying to get to orbital velocity, but while physics is hard, physics is also fair, the atmosphere is great at slowing things down and generating lift.
Does it look as cool to parachute down and either splash or be caught by a chopper mid-air? No. But this is real life, not Thunderbirds. The single most expensive thing you can do in spaceflight is bring things back, and the single most expensive way to do that is to point the motor down and fight gravity again. You do this when you don't have an atmosphere, yes, but man, the Moon would have been vastly easier to get to if it had one, and Mars landers would be *vastly* harder if Mars didn't have the tenuous atmosphere that it has.
I'm getting ranty. I'd better stop, but I'm honestly not that impressed. The landing vertically on rocket thing from terminal velocity has been done before, see the DC-X in the early 1990s, and the New Shepard earlier this year, which, despite certain CEO's mocking statements, would have ended up falling at the same basic velocity for landing, because that's how terminal velocity works. Doesn't matter exactly how high or how fast you were when you started, you end up slowing as you land because atmosphere, and as long as you fall long enough, you end up at terminal velocity. And falling from 100km is *more* that far enough.
posted by eriko at 7:24 AM on January 19, 2016 [1 favorite]
I disagree that the parachute choice is as obvious as some make it out to be. From what I've read, parachutes are quite nearly as heavy as the extra fuel and systems needed for landing. Even parachute options need extra fuel for breaking and adjustments.
This quora answer goes into a lot of detail. It looks to me like an informed engineering trade-off between simplicity, cost and capability. The cost to retrieve the unit is significant here too. Being able to control landing does help both make this more certain and cheaper.
posted by bonehead at 8:03 AM on January 19, 2016
This quora answer goes into a lot of detail. It looks to me like an informed engineering trade-off between simplicity, cost and capability. The cost to retrieve the unit is significant here too. Being able to control landing does help both make this more certain and cheaper.
posted by bonehead at 8:03 AM on January 19, 2016
Mars landers would be *vastly* harder if Mars didn't have the tenuous atmosphere that it has
I can't find it out now, but ahead of Curiosity's landing, I saw an interview with an engineer who said that Mars's atmosphere might be more hindrance than help. It was suggested that the Martian atmosphere is, on the one hand, too thick to ignore, prohibiting the construction of a fragile, but lightweight powered lander (like the Apollo Lunar Module). On the other hand, the Martian atmosphere is too thin to allow the use of wings, lifting bodies, or parachutes to the surface (as on Earth).
Anyway, I'm pretty skeptical of reusability. There's a interesting book from the '90s, LEO on the Cheap , that puts forward the idea that rockets should be designed to be big and cheap, at the cost of poor payload fractions. First stages in particular seem to be the least desirable part to have back, given the increasing value of things further up the stack. For that reason, I wish the Air Force was more forthcoming about about the X-37B, which has to be the least-talked about reusability project going on right now.
posted by ddbeck at 8:37 AM on January 19, 2016
I can't find it out now, but ahead of Curiosity's landing, I saw an interview with an engineer who said that Mars's atmosphere might be more hindrance than help. It was suggested that the Martian atmosphere is, on the one hand, too thick to ignore, prohibiting the construction of a fragile, but lightweight powered lander (like the Apollo Lunar Module). On the other hand, the Martian atmosphere is too thin to allow the use of wings, lifting bodies, or parachutes to the surface (as on Earth).
Anyway, I'm pretty skeptical of reusability. There's a interesting book from the '90s, LEO on the Cheap , that puts forward the idea that rockets should be designed to be big and cheap, at the cost of poor payload fractions. First stages in particular seem to be the least desirable part to have back, given the increasing value of things further up the stack. For that reason, I wish the Air Force was more forthcoming about about the X-37B, which has to be the least-talked about reusability project going on right now.
posted by ddbeck at 8:37 AM on January 19, 2016
Does it look as cool to parachute down and either splash or be caught by a chopper mid-air? No.
I think this question of exactly how cool it looks to catch a descending space rocket mid-air with a chopper deserves further research and experimentation.
posted by sfenders at 8:56 AM on January 19, 2016
I think this question of exactly how cool it looks to catch a descending space rocket mid-air with a chopper deserves further research and experimentation.
posted by sfenders at 8:56 AM on January 19, 2016
Has anyone asked Elon Musk if they have any plans to solve the icing problem?
posted by caphector at 10:46 AM on January 19, 2016 [1 favorite]
posted by caphector at 10:46 AM on January 19, 2016 [1 favorite]
Can anyone explain why landing on a floating platform is desirable?
It probably isn't desirable, but just the best solution to recovering a first stage. Although eriko's implied ability for said stage to glide to a runway sounds very intriguing.
Has anyone asked Elon Musk if they have any plans to solve the icing problem?
I'm willing to bet that they're looking into solving the problem that causes a good landing to fail.
posted by Brandon Blatcher at 10:48 AM on January 19, 2016
It probably isn't desirable, but just the best solution to recovering a first stage. Although eriko's implied ability for said stage to glide to a runway sounds very intriguing.
Has anyone asked Elon Musk if they have any plans to solve the icing problem?
I'm willing to bet that they're looking into solving the problem that causes a good landing to fail.
posted by Brandon Blatcher at 10:48 AM on January 19, 2016
As the space shuttle proved though, you've got to haul those dead-weight wings up with you, again at the cost of payload.
What the barge landing really gives them is the ability to drop the first stage way down-range and not have to pay for the fuel to return it to Florida. This means they can put up heavier payloads and/or payloads into higher orbits.
posted by bonehead at 10:59 AM on January 19, 2016
What the barge landing really gives them is the ability to drop the first stage way down-range and not have to pay for the fuel to return it to Florida. This means they can put up heavier payloads and/or payloads into higher orbits.
posted by bonehead at 10:59 AM on January 19, 2016
Yeah, it's not a perfect solution, everything costs, in some way. The tall skinny rocket on a barge landing just seems to be the best solution for Space X at this point.
In other news, Sierra Nevada won a contract to use an unmanned version of their Dream Chaser craft for supply runs to the ISS, so that should be interesting to see in the early 2020s.
posted by Brandon Blatcher at 11:08 AM on January 19, 2016
In other news, Sierra Nevada won a contract to use an unmanned version of their Dream Chaser craft for supply runs to the ISS, so that should be interesting to see in the early 2020s.
posted by Brandon Blatcher at 11:08 AM on January 19, 2016
I think this question of exactly how cool it looks to catch a descending space rocket mid-air with a chopper deserves further research and experimentation.
It has certainly been done. Maybe mid air recovery is a problem because of airspace exclusion zones? Or just the mass of the booster?
posted by Chuckles at 11:14 AM on January 19, 2016
It has certainly been done. Maybe mid air recovery is a problem because of airspace exclusion zones? Or just the mass of the booster?
posted by Chuckles at 11:14 AM on January 19, 2016
Mid-air retrieval is the preferred option for the Vulcan, the Open Launch Alliance's reusable rocket. This is Space-X's main domestic competition.
posted by bonehead at 11:26 AM on January 19, 2016
posted by bonehead at 11:26 AM on January 19, 2016
They also use a "hypercone" drag with secondary parachute design as well, btw.
posted by bonehead at 11:28 AM on January 19, 2016
posted by bonehead at 11:28 AM on January 19, 2016
What the barge landing really gives them is the ability to drop the first stage way down-range and not have to pay for the fuel to return it to Florida. This means they can put up heavier payloads and/or payloads into higher orbits.
It also changes your viable mission dates - if you need to put up supplies for a particular satellite, or drop some satellite in some particular orbit, there are only so many viable injection maneuvers to get them there, and your launch needs to match those. If you have major re-entry requirements like "nothing over water", that's effectively a significant filter function on when your schedule is viable. If you have both options, you get to use any rendezvous point available, not just the ones whose arc ends the right way. And that means more viable launch dates you can match up with your other logistical needs.
There's politics to handle (what, we can't land our rocket in Beijing? Why not?), and there's already some extra flexibility from not being purely ballistic on the way down, but having water landings as an option still adds a lot of schedule flexibility in many cases.
posted by atbash at 11:46 AM on January 19, 2016 [1 favorite]
It also changes your viable mission dates - if you need to put up supplies for a particular satellite, or drop some satellite in some particular orbit, there are only so many viable injection maneuvers to get them there, and your launch needs to match those. If you have major re-entry requirements like "nothing over water", that's effectively a significant filter function on when your schedule is viable. If you have both options, you get to use any rendezvous point available, not just the ones whose arc ends the right way. And that means more viable launch dates you can match up with your other logistical needs.
There's politics to handle (what, we can't land our rocket in Beijing? Why not?), and there's already some extra flexibility from not being purely ballistic on the way down, but having water landings as an option still adds a lot of schedule flexibility in many cases.
posted by atbash at 11:46 AM on January 19, 2016 [1 favorite]
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