Watch: SpaceX Grasshopper Rocket Launch Reaches Record Height

October 15, 2013 6:52 AM

Grasshopper is an experimental rocket used by Space X to test returning the first stage of the Falcon 9 safely to the ground, for reuse on later flights. Last week, the latest test flight was filmed from a Hexacopter hovering near the launchpad and it's a minute and half of pure awesomeness.
posted by Brandon Blatcher (47 comments total)

I wish they could use a hexacopter on a real flight, but way too risky for that.
posted by smackfu at 7:02 AM on October 15, 2013

Amazing stuff. Every time I see that thing land, I expect to see Marvin the Martian come scuttling out.
posted by jquinby at 7:04 AM on October 15, 2013 [1 favorite]

So cool, but I still don't understand how the weight and expense of the fuel needed to return is better/cheaper than a parachute. I guess this way it's a much faster return to launch.

In any event, rockets returning to their pads being filmed by hexacopters is a good step towards The Future. I approve.
posted by bondcliff at 7:10 AM on October 15, 2013 [3 favorites]

Every time I see VTOL, I hope for SSTO, or even suborbital. I mean, I'd love to fly to Japan in an hour from the east coast. But it's gonna be a while, folks.
posted by rikschell at 7:15 AM on October 15, 2013

Wow. I've sorta been avoiding that video for the past day or so, 'cause "Elon Musk, feh," but that was a really, truly awesome display of elite Lunar Lander skills.
posted by notyou at 7:16 AM on October 15, 2013

So cool, but I still don't understand how the weight and expense of the fuel needed to return is better/cheaper than a parachute. I guess this way it's a much faster return to launch.

With a parachute you need to do a lot of strengthening so that the final landing into water doesn't destroy the stage. You also need to build it to resist salt water immersion and do substantial refurbishment work after you recover it (a non-trivial operation). Parachutes and their associated hardware can also be surprisingly heavy.

The idea here is that you don't actually need that much extra fuel. The first stage will fall at its terminal velocity and turn slightly so that it partially 'glides' back to the landing site. As it nears the ground, the engine fires up to kill the vertical velocity.

Of course, easier said than done. You still need to build landing legs that can survive a landing without weighing very much. The terminal velocity the stage reaches at altitude can be so high that as it falls back into the lower atmosphere the dynamic pressure tears it apart.

You have a very small margin of mass to play with in rocketry and I'm not sure whether SpaceX will be able to pull it off but in principle it can be done.
posted by atrazine at 7:18 AM on October 15, 2013 [11 favorites]

I think the Grasshopper tech is only designed for lighter loads at this point, say for the resupply missions to the ISS or lighter.
posted by Brandon Blatcher at 7:21 AM on October 15, 2013

Simulation for your home.
posted by Nanukthedog at 7:27 AM on October 15, 2013 [7 favorites]

Holy shit that was cool.
posted by Aizkolari at 7:36 AM on October 15, 2013

The idea here is that you don't actually need that much extra fuel.

Is there somewhere that will give me the numbers behind this? Because it sure doesn't look like a terminal velocity fall, and it seems like the extra fuel is going to cause an awfully big hit to the propellant mass fraction (where propellant here is only that used for going up, not down).
posted by kiltedtaco at 7:53 AM on October 15, 2013

OK, that was pretty damn awesome.

Musk really does think that he's the hero of a Heinlein novel, doesn't he?
posted by octothorpe at 7:54 AM on October 15, 2013 [4 favorites]

And for just a moment, that video returns the wonder of watching Saturn V launches when I was a kid.

Also, it's a shame the DC-X Delta Clipper didn't receive the development effort/focus it deserved 20 years ago; we'd probably have SSTO by now.
posted by CosmicRayCharles at 7:54 AM on October 15, 2013

I'm so sidetracked by how incredible it is that right now in 2013 we can watch the launch of a civilian spacecraft filmed by a flying robot minion that I can't even focus on the content of the video.
posted by elizardbits at 7:56 AM on October 15, 2013 [12 favorites]

I'm so sidetracked by how incredible it is that right now in 2013 we can watch the launch of a civilian spacecraft filmed by a flying robot minion that I can't even focus on the content of the video.

And they STILL can't get me a flying car!
posted by The 10th Regiment of Foot at 7:59 AM on October 15, 2013 [3 favorites]

I would much rather have flying robot minions to do my evil bidding.
posted by elizardbits at 8:01 AM on October 15, 2013

Yeah, that was fantastic. The whole idea of reusable launchers is awesome.

that landing was amazingly graceful

Did it stay standing? The video cuts off before that's clear; I'd love to see footage from the ground as well. I doubt it was graceful enough to be reused: "SpaceX has been explicit that they do not expect a successful recovery in the first several powered-descent tests." The source for that quote is this press conference last March where Musk said it'll be at least a year before they get the landing right.
posted by mediareport at 8:06 AM on October 15, 2013

I'm so sidetracked by how incredible it is that right now in 2013 we can watch the launch of a civilian spacecraft filmed by a flying robot minion that I can't even focus on the content of the video.

It's not a robot, it's remote controlled. It looks (based on the glimpse of the motor we see) to be a DJI S800 which has a bottom mounted gimballed camera. The gimbal cannot easily point above 0° and I think they just let the the hexacopter hover in place (to prevent any chance of getting too close to the rocket perhaps).

Of course if you can do better I'm sure they're hiring hotshot hexacopter pilots and camera operators.
posted by schwa at 8:06 AM on October 15, 2013

IIRC, the recovery procedure leads to a ~30% penalty on cargo. I believe Musk has said that 75% of the cost for the launch vehicle is in the first stage, so if they can successfully recover and refurbish for a fraction of new it should be a net gain to them.

This is some seriously impressive tech, and if we are to believe what he said about the recent Falcon launch where they tested some of the procedures for recovery (some successful, some not), they're much closer to making this a reality than not. And by "much closer" I'm thinking within the next 18 months.

The really big test will be getting the first stage to survive the fall and properly orient itself to re-ignite and control the terminal decent.
posted by tgrundke at 8:08 AM on October 15, 2013

metafilter: ruining your dreams of world domination with pesky facts
posted by elizardbits at 8:09 AM on October 15, 2013 [3 favorites]

And they STILL can't get me a flying car!

They've got two more years to get us hoverboards. I don't know who 'they' are though.
posted by TwoWordReview at 8:10 AM on October 15, 2013 [1 favorite]

Did it stay standing? The video cuts off before that's clear; I'd love to see footage from the ground as well. I doubt it was graceful enough to be reused

I think there's some confusion here. This Grasshopper vehicle is just to test the landing ability. This video is the last in a series of tests at higher and higher altitudes, so it has been reused several times.

The other tests that they are talking about that they do not expect a recover of are real launches of the Falcon. For instance, they did one recently that was one of those tests, where they were going to do a test landing at sea, and it didn't go very well. They didn't release the video of that one... one difference between NASA and a private company.
posted by smackfu at 8:12 AM on October 15, 2013 [5 favorites]

And they STILL can't get me a flying car!

You can ride the Hexacopter, just be careful where you put your feet.
posted by mittens at 8:14 AM on October 15, 2013

Did it stay standing? The video cuts off before that's clear; I'd love to see footage from the ground as well. I doubt it was graceful enough to be reused: "SpaceX has been explicit that they do not expect a successful recovery in the first several powered-descent tests." The source for that quote is this press conference last March where Musk said it'll be at least a year before they get the landing right.

That's for the tests on full-scale rockets that they do as part of their normal launch schedule. This is a test-bed for the terminal stage descent and landing.

Their recent test of the rocket re-ignition on the Falcon-9 failed because the stage was spinning so fast that the fuel centrifuged away from the fuel feeds.
posted by atrazine at 8:16 AM on October 15, 2013

smackfu -

They tried the recovery profile on the last launch without the landing legs. The legs are important because they help to stabilize the vehicle on decent.

What ended up happening is that the stage rolled more than the thrusters could counteract (due to the lack of legs). The engine re-ignited as scheduled, but because of the excessive roll the fuel centrifuged and starved the engine, causing it to flame out early.

Otherwise, the turn around procedure, re-ignition and decent profile worked as programmed. I imagine that once they fly one with the legs and figure out how to better control the roll rate the chances of at least getting back to vertical are substantially better.
posted by tgrundke at 8:17 AM on October 15, 2013 [5 favorites]

elizardbits: "I would much rather have flying robot minions to do my evil bidding."

Hmmm....
posted by jquinby at 8:26 AM on October 15, 2013

Because it sure doesn't look like a terminal velocity fall, and it seems like the extra fuel is going to cause an awfully big hit to the propellant mass fraction

Since this is a first stage, not SSTO, you're not carrying that fuel to orbit, but you are carrying that mass to SECO^* and then back down. You also have to null the velocity you gained, but you have an atmosphere, which makes it much cheaper to do so. You, however, are still boosting that mass to SECO velocity. Furthermore, since you're not burning that fuel to boost, velocity at SECO will be lower, which means your next stage will need to provide more ΔV to make a given orbit.

For recovery, you fall to terminal velocity, use a drogue to get to a velocity where you can deploy a chute, then just before landing, cut the chute and fire the engines to soft land. Better variants give you better control of where you land -- say, a parafoil to give you much more crossrange -- then again, if you have a parafoil, why not install skids and land on a runway?

You're not going to fire the engines to null the velocity you gained, fly back, and land while anything makes orbit. STS had an plan for this, it was called the RTLS abort -- Return To Launch Site -- and when they discussed trying it on STS-1, John Young said "Let's not practice Russian Roulette." Note that RTLS put zero kilograms into orbit and required a massive fuel tank.

Issues: Fuel you don't burn is delta-v you're not putting into your second stage or payload, which means you're making your mass fraction worse, which means less mass to orbit, which means your cost per kilogram on orbit just went up. How much more so remains to be seen, but almost everyone completely throws away the very expensive first stage for a reason.

The big exception was STS, which would recover the SRBs and refurbish. That wasn't cheap, but the SRBs were *very* powerful boosters -- a single SRB had 12MN of thrust at liftoff, increasing to 14MN shortly thereafter, compared to the 5.9MN of the current version of the Falcon 9 1st stage (with 9 engines.) They are, by far, the most powerful rocket engines ever flown.

^*Stage Engine Cutoff. At that point, the next stage would separate and any mass left on the first stage no longer affects the performance of the booster.
posted by eriko at 8:29 AM on October 15, 2013 [4 favorites]

What I found most strikingly weird about it was how fake it looked: Like I was watching a movie from one of the Civilization games or something.

I think it's the camera; I'm still not used to the idea that we can pretty much effortless put them anywhere nowadays.

Well, that and the whole rocket-landing-on-its-ass thing that still feels like Flash Gordon stuff to me.
posted by quin at 8:30 AM on October 15, 2013 [1 favorite]

THat was wild! An increasingly important reason for multi-use space vehicle components: The proliferation of low-orbiting junk that threatens to keep us planet-bound.
posted by Mister_A at 8:36 AM on October 15, 2013 [1 favorite]

Ah ok, I guess I under-appreciated the importance of staging in this scenario.
posted by kiltedtaco at 8:42 AM on October 15, 2013

The numbers SpaceX have put out are:

“If we do an ocean landing (for testing purposes), the performance hit is actually quite small, maybe in the order of 15 percent. If we do a return to launch site landing, it’s probably double that, it’s more like a 30 percent hit (i.e., 30 percent of payload lost).”

– Elon Musk

Losing 30% payload to recover 75% of your cost seems like a pretty good bargain (if those numbers match reality of course).
posted by Skorgu at 8:49 AM on October 15, 2013 [1 favorite]

Its OK. But the rocket really needs to emerge and return to a silo which is then covered by small cluster of palm trees. And it needs an orange flashing light on the top.
posted by rongorongo at 9:00 AM on October 15, 2013 [8 favorites]

I think parts of your request are achievable, rongorongo.
posted by Mister_A at 9:02 AM on October 15, 2013

The other tests that they are talking about that they do not expect a recover of are real launches of the Falcon.

Thanks, smackfu. I almost asked someone to articulate the differences between the Grasshopper, Falcon and Dragon, but thought I had it.
posted by mediareport at 9:44 AM on October 15, 2013

that video returns the wonder of watching Saturn V launches

...but with the added dimension of the return to launch pad., ready to refuel and go out again, like parking your car in the garage. So much more gratifying and logical than the Apollo-era retrieval from ocean splashdown.
posted by Rash at 9:45 AM on October 15, 2013

Still weirds me out that all this is happening in McGregor, which I generally associate with visiting my in-laws and avoiding head esplosions in the local diner that is absolutely plastered with GWBush memorabilia.
posted by kmz at 9:53 AM on October 15, 2013

I think it's the camera; I'm still not used to the idea that we can pretty much effortless put them anywhere nowadays.

that and the fact that the image was so steady - must be "steady-cam" or whatever it's called technology.
posted by bitteroldman at 10:01 AM on October 15, 2013

Musk really does think that he's the hero of a Heinlein novel, doesn't he?

Well it ain't bragging if you actually DO it...

and this is a new technology. The first part of a new technology (truly reusable launch vehicles) is always clunky and hacked together. The final days of steam power (the Stanley steamer cars say) were quite elegant and arguable better than the contemporary internal combustion cars of the era. However the internal combustion cars got better...
posted by bartonlong at 10:08 AM on October 15, 2013

Commander Cory :"Get the rocket refueled, Happy, while I find out where they've hidden the bartonium. We'll take off for Venus in an hour."

Cadet Happy: "Right Commander. Should I load the ray cannons, too?"

Commander Cory: "Good idea, Hap. We don't know what we'll find when we head into that Venusian swamp."
posted by mule98J at 10:09 AM on October 15, 2013 [1 favorite]

"that and the fact that the image was so steady"

Multicopter cameras are connected to the body via 2 or 3 axis gimbals with fast motors in them that can correct for movement. They use electronic accelerometers to detect movement and counteract that in real time. Warning self-link: example quadcopter 2 axis gimbal
posted by schwa at 10:34 AM on October 15, 2013

Dammit Jim, you left your phone at the launch pad again?
posted by prinado at 10:55 AM on October 15, 2013 [2 favorites]

Clearly these folks have never played Kerbal Space Program, where the solution is always more boosters. ALWAYS.
posted by fifteen schnitzengruben is my limit at 11:10 AM on October 15, 2013

octothorpe: "Musk really does think that he's the hero of a Heinlein novel, doesn't he?"

Is his lover a busty, genius, young redhead? (Googles "Musk Elon lover"...) Close enough. Except for the genius part.
posted by IAmBroom at 11:52 AM on October 15, 2013

I actually thought the earlier "Grasshopper Divert" video was more impressive, in terms of showing off just how thoroughly controlled that freakishly tall Lunar Lander thing really is. It looks so ungainly but it moves so perfectly.

The audio wasn't recorded from the hexacopter, was it? There's no speed-of-sound delay and you can't hear the (noisy!) hexacopter itself even before or after the rocket burn.
posted by Western Infidels at 12:43 PM on October 15, 2013

You can ride the Hexacopter, just be careful where you put your feet.

Indeed.
posted by figurant at 12:57 PM on October 15, 2013 [1 favorite]

That was really fun to watch for me since this isn't a project that I really follow and didn't know that the rocket wasn't going into orbit.

It got to the top of it's flight path and I thought, "Wow, once it gets high enough it doesn't really look like it's moving."

"Uh oh, sorry my penis shaped friend, you are not going to space today."

Awaits massive explosion from failed launch.

"n-no......no.....no way.....NO WAY!...HOLY CRAP THAT WAS SOOOO COOL!"
posted by VTX at 1:42 PM on October 15, 2013 [3 favorites]

Still weirds me out that all this is happening in McGregor, which I generally associate with visiting my in-laws and avoiding head esplosions in the local diner that is absolutely plastered with GWBush memorabilia.

But the locale probably does explain the cowboy passenger.
posted by rongorongo at 12:21 AM on October 16, 2013

Yesterday, they did actually release the launch video of the most recent Falcon 9 test. Mission Overview | Next Gen Falcon 9 Demonstration Flight Nice launch shots, kinda unclear what they are showing near the end though.
posted by smackfu at 8:46 AM on October 16, 2013