SpaceX Successfully Lands Its Rocket On A Floating Drone Ship For The First Time (theverge.com)

An anonymous reader quotes a report from The Verge: SpaceX has finally landed its Falcon 9 rocket on a drone ship at sea, after launching the vehicle into space this afternoon. It's the first time the company has been able to pull off an ocean landing, after four previous attempts ended in failure. This is the second time SpaceX has successfully landed one of its rockets post-launch; the first time was in December, when the company's Falcon 9 rocket touched down at a ground-based landing site in Cape Canaveral, Florida, after putting a satellite into space. Now that SpaceX has demonstrated it can do both types of landings, the company can potentially recover and reuse even more rockets in the future. And that could mean much greater cost savings for SpaceX.

Comments

Igneous acceleration?

[FrankSchwab]

SpaceX Successfully Lands Its Rock On A Floating Drone Ship For The First Time

Its Rock?

Re:Igneous acceleration?

[Sven-Erik]

Maybe it got classified as a meteorite since it fell from the sky and survived... ;-)

Re:Igneous acceleration?

[bryanandaimee]

A rock is a larger more masculine form of a rockette.

https://en.wikipedia.org/wiki/...

I can't wait for this movie, I love The Rock

[Anonymous Coward]

Can you smell what SpaceX is cookin?

Economics of that stunt are dodgy

[HuguesT]

To pull that off they have to leave unburned fuel in the stage rocket, going all the way up and all the way down. This means the stage engine is not as efficient as it could be. It is not obvious that doing this risky vertical landing is going to result in any savings at all.

For any larger rockets, multi-stage rockets this is going to look worse and worse. later stages actually orbit the Earth for a while. Pulling something out of orbit requires a lot of fuel, making the endeavour even less economic.

This is interesting but looks like a stunt.

Re:Economics of that stunt are dodgy

[jamesborr]

The smallest launch cost is fuel -- the largest is hardware. The majority of the hardware cost is for the 1st stage. So if the hardware of the 1st stage can be re-used, how is this not a win?

Re: Economics of that stunt are dodgy

[sp4ni3l]

Somehow your logic does not add up. Fuel is nowadays a lot cheaper then a whole stage. Even if the payload goes down by a lot, it makes sense.

Re:Economics of that stunt are dodgy

[belrick]

You are simplifying it to such an extent that you completely miss the point. The cost of the fuel is a small fraction of the cost of the launch - the cost of building the 1st stage dominates. When that stage is destroyed, it is an operational expense for that launch. When it is recovered, it is a capital expense with an additional smaller operational expense to refurbish and another expense to account for the reduced efficiency of the launch (some fuel held in reserve as you say).

Since converting the huge operating expense into a a huge capital expense that results in an asset that can continue delivering value minus some small additional operating expense, the net result is a more economic system.

Re:Economics of that stunt are dodgy

[werepants]

All rockets fly with lots of margin (read: extra fuel) in case of unexpected anomalies during flight. The difference with SpaceX is, when the flight goes as planned, they can use that extra margin to recover an immensely expensive piece of hardware. What's more, not all payloads are using every last pound of capacity in the vehicle. If you can launch 90% of the weight at half the cost thanks to reuse, you've fundamentally changed the market.

This is like getting to reuse a Boeing 747 instead of scrapping it after a single flight. If you think that's just a stunt, you don't have much of an imagination. This is a game changer.

Re: Economics of that stunt are dodgy

[ArmoredDragon]

If that was the case, then why have their competitors shown interest instead of mocking it?

Re:Economics of that stunt are dodgy

[Anonymous Coward]

True, and a jetliner could probably be considered more efficient if they cut out the landing too. If you filled every last kg on a payload to the max to get the most per dollar you argument makes sense, but once you have a payload that is less than the theoretically max then you argument breaks down rather quickly lets ignore the fact the rocket is purposely over engineered so it can land. Multi stage I would agree but when you just recovered %70 of your equipment costs, I would say thats a little more than a stunt.

Re:Economics of that stunt are dodgy

[zwede]

1st stage is $60M. Fuel is $250K. You do the math.

Re:Economics of that stunt are dodgy

[Gavagai80]

The only accurate point in your post is that second stage landings may not prove practical, which is why there are no current plans to attempt that. Fortunately the second stage is a lot cheaper than the first stage, in this case the second stage is just one engine compared to 9 in the first stage.

Re:Economics of that stunt are dodgy

[DerekLyons]

This means the stage engine is not as efficient as it could be.

There are other goals than fuel efficiency. And really, given how dirt cheap kerolox is, optimizing for extreme fuel efficiency (especially on a first stage) is something of a fool's errand.
 

It is not obvious that doing this risky vertical landing is going to result in any savings at all.

o.0
 
Reflying/reusing something is, with rare exceptions, always going to be cheaper than building a new something. The only real question is, how much cheaper?

Re:Economics of that stunt are dodgy

[OzPeter]

. . It is not obvious that doing this risky vertical landing is going to result in any savings at all. . . This is interesting but looks like a stunt.

I'll bet on the SpaceX engineers anytime over a random commenter on /. (regardless of the UID)

Do you really think that they haven't run the sums before spending all that time and effort perfecting something that you call "a stunt"?

Re:Economics of that stunt are dodgy

[Anonymous Coward]

Efficiency is overblown as a performance metric for launch vehicles. Back in the 1950s it may have made some sense, especially if you could only make your payloads (nuclear bombs, in those days) so small, but other metrics (reliability, ease of manufacture, etc) replace that a long time ago.

You design your stage for the required orbital payload plus a few percent, which gives you margin to either (1) land and reuse the first stage, (2) launch a heavier payload and discard the stage, or (3) successfully continue to orbit even if you lose an engine or something.

Efficiency is for race cars, not cargo vans.

Or do you work for ULA?

Re:Economics of that stunt are dodgy

[Anonymous Coward]

Fuel is cheap. Relatively speaking.

The only expensive part is a minor, albeit important part.
But the bulk is pretty cheap.

The rocket tech itself is the expensive part. Those are some high-quality materials needed to withstand immense forces and temperatures.
Those prices have dropped considerably in the past 3 decades, but fuel has gotten cheaper much faster.

Re: Economics of that stunt are dodgy

[Anonymous Coward]

Read the articles of the last ten years, no one thought they'd succeed. Cost of fueling 200k for one launch. Roughly Fifteen percent of the total fuel is saved for landing.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

From another article it stated that refurbishing the first stage so it can be launched again would most likely cost about half a million dollars. Building a new first stage costs about $60 million and the fuel for a whole launch is only around $200k. So not using all the fuel so they can land the first stage to allow it to be refurbished and reused is more than a stunt. It makes a lot of economic sense.

Re: Economics of that stunt are dodgy

[MichaelSmith]

Yes but the unused fuel represents payload mass which can't be delivered to orbit, which reduces revenue.

Re:Economics of that stunt are dodgy

[dsmatthews9379]

It is a potential Mars landing technology, it makes "cents" if it enables a future contract to get people to Mars, and back. Not that sending flesh-bags to Mars 20 years from now is good economics when AI and robotics can do the job better and cheaper, but that would not be SpaceX's problem they would still get paid to deliver the tax payer funded package.

Re: Economics of that stunt are dodgy

[Guspaz]

Most of their launches don't require the full payload capabilities of the rocket. If they're not going to use the extra payload mass anyhow, how does that reduce revenue?

Re:Economics of that stunt are dodgy

[JoshuaZ]

A lot of good points have already been made, so I'd like to make one more note: they aren't doing second stage reuse here. There is a second stage but they are only reusing the first stage. Everyone knows second and third stage reuse has a lot of problems (more fuel required is only one of them). First stages cost more than other stages since the have the highest variability in what conditions they need to be able to function in (from near sea level pressures to near vacuum) and they are larger because they need to lift more total material. So just focusing on saving first stages already helps a lot.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

Quite true, although it should also be noted that the ratio you provide isn't going to be the ratio of savings they get. There are fixed costs associated with turning the stage around, so the cost of re-use isn't just the fuel, but it's also the labor to haul the stage back, pay the boat crews, re-inspect the engines, etc.

It's still a major win even considering those fixed costs. Many predictions are coming in around the 1/4 to 1/2 mark relative to a brand new stage. That's SpaceX's savings: they have the option to price used stages anywhere between there and full price. E.g, just to make numbers up, say their costs end up dropping to 1/3 given the number of times they launch each state. They could price used stages at 2/3 to the customer, which both gets SpaceX more profit, and gives the customer cost savings.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

... not to mention that the 2nd stage isn't re-usable, so that's also a per-mission cost. S2 is much cheaper than S1, but still a significant per-mission non-recoverable cost.

Re:Economics of that stunt are dodgy

[ncohafmuta]

which is why they're now saying it will cost 30% less, which is still disappointingly low, compared to elon's previous $60M minus $250K statements. and which is why you have to take what people say with a grain of salt (like launch timeframes!).

Re: Economics of that stunt are dodgy

[Anonymous Coward]

In a way, they (Orbital ATK, ULA) have been mocking it from day one. Whether it is whispers to Congress critters being one way, questioning NASA and Dept of Defense about opening up launch contracts to include SpaceX, etc.

Blue Origin has tried mocking it, too, after their baby steps. but that's like the teenager still at the kid's table trying to mock the adults at the grown ups table during Thanksgiving dinner...

Re: Economics of that stunt are dodgy

[MichaelSmith]

Then they have an operational problem at the outset. They should be selling all the capacity they have available.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

60M is their entire rocket..... There are 3 parts to the rocket and their original (and still current) goal was for FULL re-usability. Since 33% of the rocket = 1/3, that completely matches up what they originally stated since you have to account for recovery, refurbish/inspection, and relaunch cost.

It's a long process and even SpaceX acknowledge early on the 2nd stage was more complex to recover and may not be possible. That said, the dragon capsule is slowly on it's way to re-usability so even if they don't accomplish that, a 50-60% cost reduction is still big considering they are currently the cheapest on the market.

Re:Economics of that stunt are dodgy

[bmo]

Since converting the huge operating expense into a a huge capital expense that results in an asset that can continue delivering value minus some small additional operating expense

And since capital equipment /always/ has a depreciation, you can write off the depreciation instead of watching it burn up in the atmosphere.

And then you can sell the capital equipment to some other sucker.

--
BMO

Re:Economics of that stunt are dodgy

[Kjella]

The only accurate point in your post is that second stage landings may not prove practical, which is why there are no current plans to attempt that. Fortunately the second stage is a lot cheaper than the first stage, in this case the second stage is just one engine compared to 9 in the first stage.

Even if they can't recover the second stage, if they can get reliable recovery/refurbishing/reuse of the first stage that'll completely change the economic equation. Say you can reduce the second stage cost by $1m by increasing the first stage cost by $1.2 million, today you won't do that because it's a net $200k loss. If you can reuse the first stage once for neglible fuel costs it becomes a (2*$1m - $1.2m)/2 = $400k profit per launch. If they can do it five or ten times, it's even more profitable. So I think there's a lot of potential improvements just redesigning to take maximum advantage of first stage reuse by making the second stage do less and cost less.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

NASA and ESA are both mocking SpaceX.

Re:Economics of that stunt are dodgy

[rmdingler]

You can talk money til you're blue in the face, but watch this little spine tingler.

Re: Economics of that stunt are dodgy

[Anonymous Coward]

Look, I love to mock SpaceX myself. I think it's a bunch of over inflated egos reinventing things their grandparents invented without acknowledging anything that came before that they rely on. Like all of the basic research, all of the lessons learned of things that do and don't work, and of course they don't have to invent the machines that make the machines that make the rockets, and invent the materials. Oh, and invent portable computers too. And the language to program them. And a user interface that works. . A little less ego would go a long way in other words.

Even the vertical landing concept is not new, but back then they lacked the fine control to pull it off.

Still, engineering something like that is hard even with all the modern advantages, and those who actually did the work (as opposed to their cheerleaders) should be applauded.

Re: Economics of that stunt are dodgy

[Megane]

Blue Origin has been mocking them in the other way. "Hey, look at what we just did! What took you so long?" Sure, you had a sub-orbital launch profile (almost no horizontal velocity), popping off a tin can that came straight back down. Boy Scouts recover their Estes rockets all the time. SpaceX already did the landing thing with their Grasshopper rocket (and DC-X long before either of them), and the only reason they didn't take it higher was because they didn't have clearance to go higher at McGregor.

Falcon 9 has been on an orbital launch profile every time, sometimes even GTO, which is a lot harder to come back from. Even hitting the drone ship and falling over was harder than what Blue Origin did. A side-effect of having an actual useful launch profile is engines that can't throttle down to hover (Blue Origin can), so they have to do the much harder "hoverslam" maneuver. (zero vertical velocity at the same moment as zero altitude)

I will, however, give Blue Origin a few points for doing quick turnarounds. Their short-term objective is space tourism, and they're doing exactly what they need. It's just not nearly as hard as what SpaceX is trying to do.

Re:Economics of that stunt are dodgy

[Jeremi]

And since capital equipment /always/ has a depreciation, you can write off the depreciation instead of watching it burn up in the atmosphere.

Surely the burning-up-in-the-atmosphere approach qualifies as accelerated depreciation?

Re: Economics of that stunt are dodgy

[Guspaz]

That's not really how rockets work. Sometimes a launch profile is compatible with secondary payloads, and so they sometimes do that. But often they're not, and so you can only launch to the one orbit. SpaceX doesn't control the satellite manufacturers operators: if the payload doesn't need the full payload, they can't just stick another satellite in there or tell them to make it bigger. If they could be putting additional payloads in the rocket to derive additional revenue, they would be. When they do the Orbcomm launches, they're launching lots of satellites at the same time, but then, those satellites all launch into very similar orbits.

Reusability on the first stage doesn't add terribly much weight anyhow: it takes a lot less fuel to decelerate a mostly empty stage than it does to accelerate the whole thing up to speed in the first place. It's also not a 1:1 relationship: 1 kilo of extra fuel does not subtract 1 kilo of mass from the potential payload. That would be true of the second stage, but not the first stage.

Since they can't really use that extra capacity anyhow, they might as well use it for cost savings, because reducing your costs is even better than increasing your revenue.

Re:Economics of that stunt are dodgy

[Bruce Perens]

Elon said today in the post-launch press-conference that recovery meant a potential of 1/100 in present operating cost but that fixed cost would not change from recovery. He is trying to reduce fixed cost with additional automation and of course there are economies of scale. 30% is what they can start with and make a profit, which they have to do now. I believe they can achieve a significantly larger reduction over the long term.

Re:Economics of that stunt are dodgy

[waimate]

Even if they can't recover the second stage, if they can get reliable recovery/refurbishing/reuse of the first stage that'll completely change the economic equation. Say you can reduce the second stage cost by $1m by increasing the first stage cost by $1.2 million, today you won't do that because it's a net $200k loss. If you can reuse the first stage once for neglible fuel costs it becomes a (2*$1m - $1.2m)/2 = $400k profit per launch. If they can do it five or ten times, it's even more profitable. So I think there's a lot of potential improvements just redesigning to take maximum advantage of first stage reuse by making the second stage do less and cost less.

Also worth pointing out that those first-stage engines will have a limited number of flights they're good for. So on it's last flight, you stick the engine in a second stage. After all, you've got to get rid of your expired engines somewhere, so they may as well go in a second stage as a junkyard somewhere.

Each "time's up minus one" first stage yields nine expendable second stage engines, sorta kinda for free.

Re: Economics of that stunt are dodgy

[haruchai]

While he did not mention Blue Origin by name, Elon made a point of mentioning how difficult it is to cope with high speed horizontal velocity.
Blue Origin just isn't playing in the same league yet.

Re: Economics of that stunt are dodgy

[Anonymous Coward]

Bitch, please; stop bitching. Nobody thanks the 1st lumberjack or the 1st carpenter or dedicates to Newton, Euler, Kepler.
Get over it.

Re: Economics of that stunt are dodgy

[khallow]

Two obvious things here. First, who are they going to sell that capacity to? A bunch of cubesats? The income isn't necessarily there.

Second, by this particular compromise in capacity they're trying to get both lower costs per launch and higher reliability of operation. There are some very significant benefits to this, if they can get it to consistently work.

Re:Economics of that stunt are dodgy

[religionofpeas]

Also worth pointing out that those first-stage engines will have a limited number of flights they're good for. So on it's last flight, you stick the engine in a second stage

The second stage engine has a different design, because it's optimized for operating in vacuum. I think a better plan would be to launch the first stage as disposable when the engines are getting near the end of their life, and use that disposable launch for a heavy payload.

Re:Economics of that stunt are dodgy

[waimate]

For the Merlin 1C, the only difference with the vacuum (second stage) version is the nozzle - a much larger expansion ratio. Other than the nozzle, they're the same engine.

The Merlin 1D variant is more deeply throttleable on the second stage, but it's unclear whether this is just a configuration setting or substantive hardware differences. I would imagine the former as much as possible.

But in any event, we concur -- lots of useful things to do with engines on their last flight.

Re: Economics of that stunt are dodgy

[Anonymous Coward]

For serious Mars travel, even unmanned, you want to get a big rocket into Earth orbit, then top-up the fuel tanks before accelerating towards Mars. Running fuel trips to low-Earth-orbit is going to be a large "customer", and the weight of the delivered fuel can be matched to whatever the rocket is capable off. Anything to space stations can be filled up to max payload by adding water (for drinking, oxygen extraction, and shielding). So many payloads can be adjusted to match the max payload. Satellites are a big portion of launches right now, but that will change.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

It is not obvious that doing this risky vertical landing is going to result in any savings at all.

It is not obvious to you, because you haven't thought the whole thing through properly.

Spend more time thinking and less time posting, and you'll be better off.

Good luck.

Re: Economics of that stunt are dodgy

[K. S. Kyosuke]

I think you're looking at it from the wrong perspective. Given some regular size of payload you need to launch, building one first stage that is 30% bigger and using it ten times, even at the cost of needing 30% more propellant, simply can't be less advantageous than building ten normal-sized stages for single use.

Re: Economics of that stunt are dodgy

[K. S. Kyosuke]

Assuming that SpaceX can eventually deliver on their vision of 40 launches per year, cutting off another 30% out of the already quite low figure of 60M means that Ariane is getting off the market and Proton barely survives.

Re: Economics of that stunt are dodgy

[khallow]

For serious Mars travel, even unmanned, you want to get a big rocket into Earth orbit, then top-up the fuel tanks before accelerating towards Mars.

No, you wouldn't. Because now that big rocket launch is a single point of failure for your mission. Further, thrust per mass is not that important once you have a vehicle in orbit. What took a lot of thrust to lift off of Earth can be moved with a much smaller rocket engine in space, even considering the Oberth effect and crossing of the Van Allen belts.

So many payloads can be adjusted to match the max payload.

Those payloads can also be adjusted to cheapest cost per unit mass too.

Re: Economics of that stunt are dodgy

[K. S. Kyosuke]

I would think that even considering all the differences, at least quite a few of the parts could still be reused to rebuild an upper state engine.

Re:Economics of that stunt are dodgy

[RealGene]

How about we put the end-of-life first stages into orbit, and lash them together into orbital fuel depots?

Re: Economics of that stunt are dodgy

[Agripa]

Even the vertical landing concept is not new, but back then they lacked the fine control to pull it off.

What part of fine control did they lack? Processing? Sensors? Engines?

Re:Economics of that stunt are dodgy

[Immerman]

Actually, pulling something out of orbit takes a *lot* less fuel than putting it there in the first place - you don't have to stop, you only have to include a heat shield and slow down just enough so that the opposite side of your now-elliptical orbit intersects the Earth's atmosphere. Air resistance is your friend. After a pass or two you're pretty much at first-stage velocities, and your craft is a lot lighter than the first stage as well.

Also, reentry is pretty much already standard for orbital vehicles, though not all are designed to reach the ground in one piece. The alternative is leaving huge chunks of trash in orbit to hit things you care about.

Re: Economics of that stunt are dodgy

[Anonymous Coward]

Then they should just land it with parachutes and just pay more in this supposedly cheap fuel to make up for the extra mass needed to make the structure strong enough to new forces applied to it.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

It's actually saving more like 70% of the rocket (the first stage is much larger and more expensive than the second stage). It's only a 30% reduction right now to account for the fact that recovery is not guaranteed yet, plus refurbishment costs and fixed infrastructure/launch costs, and of course R&D and profit.

Re:Economics of that stunt are dodgy

[tibit]

Consumables for the whole thing are around $200k-$250k. By "whole thing" I mean the F9+Dragon stack, which consumes LOX, kerosene, helium, nitrogen, hydraulic fluid, Draco hypergolics, and TEA-TEB for Merlin start-ups.

Re: Economics of that stunt are dodgy

[tibit]

So, when you get to your car to drive to work in the morning, you load up every last pound of unused capacity with trash and dump it at the dumpster behind your office? If you don't, you have an operational problem at the outset. You should have bought a much smaller car, and kept your weight tightly controlled.

Re: Economics of that stunt are dodgy

[oobayly]

I'm beginning to view any suggestion of splashing down reusable [non-SRB] stages with parachutes to be a troll nowadays.

Re:Economics of that stunt are dodgy

[godefroi]

Storing cryogenic liquids is a hard problem. Even in space, they boil off.

Re: Economics of that stunt are dodgy

[ArmoredDragon]

Yes but the unused fuel represents payload mass which can't be delivered to orbit, which reduces revenue.

I really think you don't know what the word revenue means.

Re:Economics of that stunt are dodgy

[HuguesT]

How is this not a win?

Because this assume that the hardware will actually be reusable. Rocket engines are not like jet engines. All the data on the space shuttle has shown that its engines basically needed to be rebuilt every time, over periods of several months. This was not correctly anticipated by NASA and as far as I know, it was never solved over the entire life of the Space Shuttle. This fact was also the main reason the Space Shuttle was not able to launch sufficiently often.

This also assume that the hardware will be retrieved every time. Perhaps SpaceX will improve, but it looks as if a vertical landing is actually harder than an vertical launch, and we know those are not 100% reliable.

SpaceX believes that reusing the 1st stage could lower its launch costs by 30% ; I'm just being highly skeptical of this claim. Fortunately, it doesn't matter all that much.

What I find highly annoying is the belief that because SpaceX is a private enterprise, they will necessarily do better than a large governmental agency like NASA.

Re: Economics of that stunt are dodgy

[HuguesT]

The rocket equation is highly non-linear. If you leave 30% of the fuel in the rocket for the return trip, you may lose a large proportion your final impulse and so final speed before separation with the second stage. I don't see how that could be economical.

The thing is that reusable engines have existed for a while. Solid Rocket Boosters are the simplest. They use 100% of their fuel every time, and they are retrieved by parachutes. Even under these conditions, they need significant rebuilding. SRB Rebuilding issues were a significant factor in the Challenger disaster. How economical was that?

Re: Economics of that stunt are dodgy

[HuguesT]

Depends on many factor, like reliability, and how much of the retrieved engines they can actually reuse.

Re:Economics of that stunt are dodgy

[HuguesT]

So you have to send to orbit a heat shield. This is not free.

Re:Economics of that stunt are dodgy

[HuguesT]

Mocking is not the right term. They are skeptical because both ESA and NASA have looked at the economics and practicalities of doing the same thing, and rejected the idea.

Now if SpaceX do it, all power to them.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

Not a bad comparison. Passenger planes do sometimes fly "home" empty (except for the pilots of course), and spending tons of fuel doing that is still a lot cheaper than scrapping the plane and buying a new one at the airport where it's needed.

Re: Economics of that stunt are dodgy

[Anonymous Coward]

Processing, presumably.

The engines can't throttle down to hover, so they have to come down at speed, brake at exactly the last moment, and then cut off just as the rocket would otherwise start lifting off again.

Re:Economics of that stunt are dodgy

[Immerman]

Nope, but it's a hell of a lot lighter than the amount of fuel it replaces, which is all that's important.

As others have pointed out in regards to the first stage recovery - the point is not necessarily to eliminate as much mass as possible from every launch, but to maximize the economic return on the launch - because right now the cost of a launch is basically fixed at slightly more than the cost of the vehicle, regardless of payload size. The rocket is also built to the most extreme payloads it can service, resulting in lots of excess capacity for the average launch, and it's unlikely that that excess capacity can be sold effectively since that would require that other payloads need to be delivered to basically the same narrow range of orbits AND be capable of being physically squeezed into the remaining cowling volume without throwing off the center of gravity or risking damage to the primary payload.

Fuel is typically less than 5% of the launch cost, with 90+% being the vehicle itself. I've heard numbers in the 60-70% range for the cost recovery of the Falcon 9R first stage, so maybe 20-30% for the second stage. A launch currently costs $61.2M, so we could conservatively say that landing the first stage for reuse is worth about $36M, and the second stage about $12M, leaving an extra 10% for refitting costs. Those costs may prove higher than that, especially before reuse is mastered, but even if you're only recovering 70%or even only 50% of your launch costs, it's extremely unlikely that you could arrange for secondary payloads that are anywhere near as lucrative.

As others have probably pointed out - the current state of affairs is akin to requiring 747s to be completely scrapped after every flight. It's incredibly wasteful, and causes the ticket price to be so high that only the most economically valuable payloads are even considered.

Re:Economics of that stunt are dodgy

[s13g3]

$60 million to build a rocket, vs. $200k to fuel it. Even if (and I do stress IF) half the fuel cost was to account for inefficiency in carrying extra fuel and landing the rocket, that's still a heck of a lot cheaper than a 1-shot $60m rocket every time you launch.

Even if they reuse the rocket only once before having to scrap it, that halves the mission cost of each launch.

I might suck at math, but even I'm not that bad at it. And de-orbiting something isn't remotely as costly in terms of fuel as you imply, but that's also why the first and primary stage don't actually achieve orbit in a multi-stage vehicle, which, in the history of rocketry, is not something that happens... pretty much ever. As for the later stages, either leave them in orbit, or leave them with just enough fuel to deorbit, but since those upper stages are insignificant in terms of cost as compared to the main launch vehicle, you don't bother landing them, and just let them burn up on re-entry, if you're that concerned about creating space junk.

Re:Economics of that stunt are dodgy

[torkus]

Before you lecture, research.

SSME is staged combustion vs gas-generator on the Merlin 1D which is a world of difference.

SpaceX has done quite a bit endurance testing on it's engines and they are absolutely able to fly multiple missions without complete rebuilding. Their design lifetime is 25 missions if memory serves. Maintenance? Yes. Rebuild? Certainly not.

Be ask skeptical as you like but even if they stick 50% of launches, it's a major savings. I'd venture to guess the reason they aren't showing more than 30% savings is to not set investor expectations too high. New rocket = $60mil, refuel = $200K. Do the math even if you factor in maintenance.

SpaceX will (and is) doing far better privately than NASA has publicly. They're not rife with corruption, bribery, and general governmental BS that NASA was and is.

Re:Economics of that stunt are dodgy

[HuguesT]

What you claim as research is simply company communication. They have no duty of public disclosure unlike NASA. There are many other cost factors in engine reuse than fuel cost, like others have said on this very thread.

SpaceX will (and is) doing far better privately than NASA has publicly.

Right now SpaceX is riding off the back of NASA. We'll see how this pan out in the long run. Private enterprise is not able to rewrite the laws of physics. NASA may be rife with corruption and top-heavy with management, its engineers are still top-notch, and they are skeptical as well.

Re:Economics of that stunt are dodgy

[Anonymous Coward]

There was a proposal to do this with the shuttle's main fuel tank. Vented, scrubbed, and repressurized they would have made massive space habitats, far larger than the ISS. The downside was that they weren't designed for it, and a bunch of stuff would have been a PITA with them.

I wish this had been pursued. The dregs from a single launch could have kept MIR in orbit for another decade. That was a lot of kit to drop into the ocean.

Thats just impressive....

[sp4ni3l]

Elon and crew: Congrats! Can we now go to Mars?

Drone ship

[Anonymous Coward]

Only on Slashdot is a landing platform a "drone ship".

Re:Drone ship

[werepants]

It's automated. No humans aboard. That fits the commonly accepted definition of drone.

Re:Drone ship

[zwede]

SpaceX calls it a drone ship as well.

Re:Drone ship

[Sowelu]

That's the term SpaceX uses.

Re:Drone ship

[Anonymous Coward]

So is an assembly-line robot a "drone hand."

And the Hubble Space Telescope a "drone probe."

My printer is also a "drone press."

Re:Drone ship

[Anonymous Coward]

Drones are vehicles.

Assembly line robots are not vehicles.
The HST is a "vehicle", but a probe is already a drone, so that term is redundant.
Printers are not vehicles.

Re:Drone ship

[zero_out]

To be a drone it has to be remotely piloted without requiring line of sight by the operator. Your three examples fail the "remotely piloted" requirement because they are in a fixed location.

Dear lazy web

[BlackPignouf]

Dear lazy web, any higher quality video out there?
Congrats SpaceX, this looks really impressive.

Re:Dear lazy web

[zwede]

Dear lazy web, any higher quality video out there? Congrats SpaceX, this looks really impressive.

https://www.youtube.com/watch?...

Re:Dear lazy web

[BlackPignouf]

Thanks a lot.

Re:Dear lazy web

[Sperbels]

And in rough seas

Re:Dear lazy web

[Anonymous Coward]

Fuck you space ex. Go die in a fire musk.

Slashdot is slipping.

[Nutria]

It didn't even mention that SpaceX was launching today.

Re:Slashdot is slipping.

[Anonymous Coward]

With their upcoming launch schedule? With some luck they hope to launch well over a dozen rockets THIS YEAR. That would get a bit repetitive.

"Now that I got a strike, I can win at bowling!"

[neminem]

After a couple hundred tries (yes, I suck), I finally got a strike! Now that I did it, I can go on to win all the bowling trophies ever!... said no sane person ever.

Sure, that's pretty impressive already, I'm not knocking them. SpaceX is awesome - I really want to see leaving earth becoming reasonably affordable in my lifetime, and SpaceX is doing a huge amount to make that a reality... but just landing a rocket once (after failing a few times), while news enough already, isn't really going to *change* anything until they can prove they can do it *consistently*. Did they actually change the *process* they use, such that they'll be able to pull it off every time by following that new process? Or are they just getting better at the process they already had, due to practice?

Do the math.....

[tekrat]

The first stage costs $60 million to build.
The fuel costs $200,000 -- do the math.

I mean, if you don't mind $60 mil coming out of your pocket. The point is, re-use of the first stage enormously decreases costs per pound to orbit. If you can't figure that out, then I'm sorry, but, what are you doing on Slashdot?

Re: Do the math.....

[Anonymous Coward]

The first stage costs 60 million to 'buy' a launch on. It cost spacex less to build it.

Re: Do the math.....

[Anonymous Coward]

It cost spacex less to build it.

Does it cost $59,800,000 less?

Re: Do the math.....

[jimtheowl]

Not only the cost for building the first stage would have to be less than $200,000, it would have to be less than the price of the remaining fuel to make 'fuel efficiency' a consideration.

Re:"Now that I got a strike, I can win at bowling!

[zwede]

During the webcast they mentioned several times that they collect tons of data for each landing attempt, so yes, I expect them to successfully land a very high number of 1st stages going forward.

Re:"Now that I got a strike, I can win at bowling!

[Anonymous Coward]

They've been fixing technical problems that appeared in prior attempts so those problems would not re-occur. It's possible there are other lurking demons of course, but every time one occurs and they fix it, the whole endeavor becomes more reliable for the next time.

Even if they never achieve 100% stage recovery, it is still plenty worthwhile to do, and will meaningfully reduce the cost/kg to orbit. It won't reduce it as much as the ratio of stage to fuel costs, because there are fixed costs to turn the stage around for another flight (labor, etc), but even so, it might drive costs down to somewhere between 1/4 and 1/2 of what they are right now, which is significant.

Whoo-hoo...

[the_skywise]

Now we just order the drone ship back to port! ...

Uhh... that wasn't a story in the epic

Re:Whoo-hoo...

[Ksevio]

Actually the weld the rocket to the barge and tow it back over a few days. The drone ship can really only stay in one spot autonomously.

Video Here. Starting at 35:30 for Real Joy

[boley1]

https://www.youtube.com/watch?...

Re:Video Here. Starting at 35:30 for Real Joy

[haruchai]

At some point, about 8 mins got trimmed from the start of the video so you need to back up to about 27:15 for the beginning of the magical moment

https://youtu.be/7pUAydjne5M?t...

From "we do these things because they are hard..."

[Anonymous Coward]

..to, "We do these things because in the short term they appear to save money, just like Boeing did half a century ago, and Reagan's capitalistic NASA was pushed into fucking up Challenger so they've lost street cred." Thanks, 1980s.

Developing countries actually interested in an efficient landing system are exploring such revolutionary ideas as parachute+airbags. Musk is still cuckoo about suicide mission to Mars (of course, he's not going himself), and this is all part of the bullshit.

Oh well, 1/5 ain't bad for an investment of taxpayer's money, I guess - better than 1/6!

Re:"Now that I got a strike, I can win at bowling!

[Anonymous Coward]

debugging complex systems doesn't really work like that

Re:Economics of that stunt are amazing

[kwerle]

I was gonna mark the parent as a troll, but really it's just uninformed.

https://science.slashdot.org/s...

Elon Musk says it takes $60 million to build the Falcon 9, and $200,000 to fuel it.

Steve Poulus, a former NASA project manager, suspects final costs could be driven below a million dollars.

So it's looking like a stunt that could be worth more than 95% of the first stage's $60M. That seems like a big deal.

Re:"Now that I got a strike, I can win at bowling!

[Anonymous Coward]

They've actually landed successfully on land prior, this was their first success on a ship at sea. The last attempt it landed, then tipped over when a support leg broke, so i'd guess they reinforced that or something. I'm sure they'll have a few more fireballs, but my money is on them getting the landing down consistently very soon.

Re:"Now that I got a strike, I can win at bowling!

[Anonymous Coward]

They change the process after every flight, if the telemetry tells them they could have done something better. Just like they enabled the Dragon's parachutes during ascent on this flight, in case the rocket blew up. (The previous flight the 'chutes were disabled on ascent because it was assumed an explosion would be non-survivable, so when the Dragon capsude did survive the explosion, it was destroyed when it hit the water.) The odds of that making a real difference on any upcoming flight is minuscule, but it was a no-weight software change so why not? (Of course, they put considerable effort into making any software change reliable and predictable, unlike the vast majority of software out there.)

Continuous improvement. They may well change the process after this successful landing depending on telemetry, or may decide that it is good enough (for now).

That came in at a pretty steep angle

[drew_kime]

Anyone know why they would come in at an angle and straighten up at the last moment? Is it actually easier to control that way, or is it to protect the landing pad in case of a list-second abort?

Re:That came in at a pretty steep angle

[fgodfrey]

There are two reasons that I've seen.

Because the rocket is almost out of fuel, even burning only one engine at minimum throttle, the thrust to weight ratio is more than one (ie, the rocket would fly, not land). So, they can't hover, they have to hit the ship and shut the engine off at the exact moment that the velocity is zero (or very close to it). So, to help with that problem, they come in at an angle which helps consume at least some of the thrust in a direction that isn't upward.

The second reason is, as you say, to protect the landing platform. If they run out of fuel (or the engine fails or....), the stage just drops into the ocean rather than crashing into the barge at a very high speed. That said, based on their last several failed landing attempts, that barge can take quite a hit and stay in one piece....

Re:That came in at a pretty steep angle

[Anonymous Coward]

The stage has a lot of horizontal velocity as it enters the atmosphere. By the time it gets to sea level it still hasn't lost all of it, so comes in at an angle

Re:That came in at a pretty steep angle

[Anonymous Coward]

The latter. If the engine fails to re-ignite for the final landing burn the stage will hit the ocean going several 100mph. Why you don't want that "landing" location right on top of the barge should be fairly obvious.

Re:That came in at a pretty steep angle

[Sowelu]

As a universal rule, on your way back down to a planet, you want to to apply maximum force for a short of a time as possible and at the last second possible. Anything you do to slow your descent before that means that you're fighting gravity for a longer time, and that wastes fuel. They don't have the resources to change their approach angle--and even if they did, shallow means it's hitting more air resistance on the way down, which means you slow down for free.

Re:That came in at a pretty steep angle

[Anonymous Coward]

They're reentering from orbit so they're moving sideways at a speed relative to the ground. Also from the manoeuvring to aim for the platform. If they were vertical but moving sideways the resulting drag would likely cause the stage to rotate and flip, so it's angled slightly in the direction it's travelling to make its flight more stable. The tilting is also to adjust the direction in which it's directing the thrust which allows the manoeuvring.

Re:That came in at a pretty steep angle

[wildsurf]

There are two reasons that I've seen.

Third reason: Wind. In the post-launch press conference, Elon mentioned that the wind was significant during landing. (And may reach up to 50mph tomorrow on the way back to port.) So the rocket had to tilt somewhat into the wind to avoid being blown sideways relative to the landing pad, and only went vertical at the last moment. It also explains why the droneship maintains a slight tilt in some of the post-landing footage; this is to cancel out the considerable force of the prevailing wind.

Re:That came in at a pretty steep angle

[Anonymous Coward]

It was tilted because of a 50 mile per hour wind.

Re:That came in at a pretty steep angle

[DerekLyons]

Anyone know why they would come in at an angle and straighten up at the last moment?

Because they have to control vertical *and* horizontal velocity. Simple as that.

Re:That came in at a pretty steep angle

[Bruce Perens]

It looked like pretty rough seas, too. The next step is that someone goes on the barge and welds shoes over the landing gear to hold it to the deck. There may also be something that fastens to the "octoweb", the frame that holds the engines at the bottom of the first stage.

Believe it or not, welding something to the steel is fast, and easy to un-do. You just cut it off with the same welding equipment, and use an angle grinder to remove the bead.

Re:That came in at a pretty steep angle

[Megane]

Ditto for landing on shore. I remember seeing a landing profile for the successful pad landing. It aimed for a point away from the landing site during the re-entry burn, then restarted the engines and zigged over when it was almost down. That ensures a failure to restart the engines results in a splash a few miles away, not a boom at your landing site.

Re:That came in at a pretty steep angle

[Anonymous Coward]

In the press conference Musk stated it clearly. It was tilting into the wind, which was blowing at 50 mph at the time. That's a pretty strong wind, by any standard. Landing a plane in 50 mph wind would be something to tell your friends about at the cocktail party, let alone for landing a rocket that was going almost 10,000 mph just a few moments earlier.

He also said the ship was pitching 2 degrees in the seas, which he described as not too bad. But for a ship that size, 2 degrees sounds like pretty heavy seas. He said the rocket could handle twice that, maybe three times.

Re:That came in at a pretty steep angle

[Sivaraj]

The reason is simpler, actually. The stage has significant horizontal velocity because it is coming back from too far away. There is a boost back burn right after MECO which reverses the direction the stage is going. It is not practical to move it horizontally at that speed while keeping it vertically straight (too much wind resistance can break the stage). So it has to lose both horizontal and vertical velocity at the exact moment of touch down, while straightening up at the same time. Straightening and stabilization of the rocket is done by a combination of reaction control thrusters, grid fins, and the landing burn of the central engine. The points you raise are also valid of course.

Re:That came in at a pretty steep angle

[goodmanj]

I think I can answer that based on my extensive training with Kerbal Space Program. And okay some stuff I read about the moon landings too. If you come straight down and find you're going to land off-target, you have to swivel the engine sideways, burn to build up some horizontal velocity, and then swivel in the other direction to cancel it out again. But if you keep some sideways velocity as you descend, it's easy to adjust your final landing point in that direction by starting your final deceleration burn a little early or late. It's still tricky in the other horizontal direction, of course.

Re:That came in at a pretty steep angle

[tibit]

It's harder, because not only the linear velocity must be zero, but angular velocities too, and the orientation in two axes out of three must be correct too. It's actually a fairly hard optimal control problem, and they hired the guy who came up with the math to facilitate that. What they are doing is ground-breaking not only in terms of reusability, but also in terms of engineering challenges, even at the level of basic science of control theory.

Re:"Now that I got a strike, I can win at bowling!

[Lab Rat Jason]

Uh... yes. They've changed the volume of on-board hydraulic fluid, they changed the leg lock-out mechanisms, they changed the landing approach angle, and probably a billion other things. Do you even follow SpaceX bro?

I'd go out on a limb and say they will probably stick 8 out of the next 10 sea landings, and no less than 9 out of 10 RTL landings.

Why Better than Parachute?

[Anonymous Coward]

Honest question. Can someone explain the benefit of this vs deploying a parachute and some inflatable bumpers to protect the rocket for reuse? This seams more expensive and much more complicated. Does a controlled landing outweigh the cost of retrieval of an uncontrolled but safe landing?

Re:Why Better than Parachute?

[Geordish]

Ditching it in the sea and recovering it causes too much damage to make it viable to refit. This was intended for the boosters on the space shuttle, but it ended up being cheaper to make new ones than fix the old ones.

Of course they could bring them down over land, but I think the unpredictability of exactly where they would land could be marginally terrifying.

Re:Why Better than Parachute?

[Geordish]

The damage is caused by the salt in the water. Missed that out!

Re:Why Better than Parachute?

[Lab Rat Jason]

Seawater and final impact speed are two good ones.

Seawater inside a booster makes refurbishing it MUCH harder. With parachutes, you can't control the attitude at which the booster hits the surface, and those rockets are designed to be very strong for vertical loading, but horizontal loading would destroy it... like a beer can, it can support a load at it's top, but not it's side.

Keep in mind that they have to fly with that fuel anyways... they need the margin in case of engine failure or other recoverable scenario. So all they've really done is add the weight of some landing legs, fins, a few other sundries, and some intelligent flight computers to relight the engine and bring it back down... it's not as inefficient as people are making it out to be.

Re:Why Better than Parachute?

[G-forze]

We're talking about some extremely sensitive equipment here. This approach allows the landing to be highly predictable as it comes to mechanical stresses on the components, contrary to the high randomness of a parachute + airbag landing. Add to that the fact that many of these missions cannot be returned to land, and soaking the engines in atlantic salt water is a good way to make sure they never fly again.

Re:Why Better than Parachute?

[zwede]

Of course they could bring them down over land, but I think the unpredictability of exactly where they would land could be marginally terrifying.

They already did a landing on land back in December. The landing site (ocean or land) depends on where the rocket is going. If it needs to reach high orbit like the ISS the 1st stage does not have enough fuel to go back to shore and they do an ocean landing.

Re:Why Better than Parachute?

[Geordish]

I meant bringing them back with parachutes. A burn back is much more controlled.

Re:Why Better than Parachute?

[Anonymous Coward]

Somewhat counterintuitively, it requires far less mass to do it this way. Parachutes are heavy, and have lots of other issues: you don't get to land the stage upright, and it isn't stressed for unpressurized loads that aren't aligned with the long axis, so it would require even more mass to re-enforce it. Then too, you could only land it on land that way, not on the ship, and landing on land requires much more fuel (even if you used chutes) because you have to boost further back from whence you came to get back to land. You can't drop it in the ocean with chutes and re-use it because of all the damage done by the salt water, water-incursion into places not meant to have water, etc. Fixing all that would require yet more mass.

(They can boost back to land with the powered landing scheme, but the fuel to do so comes out of their mass budget to orbit, so they can only do it for lighter payloads).

This is a much more efficient way to go about it, than to use parachutes. It's a little odd, but that's how it works out. Surely there's much more the SpaceX engineers considered beyond the troubles above, too.

Re:Why Better than Parachute?

[quicks0rt]

Because parachuting will work only on earth and similarly dense atmospheric planets. Places like Mars and others where atmosphere is very little to non-existent, you will have to land by propulsion with something as heavy as this. As Elon Musk puts it, the ultimate goal is to create a technology capable of multi-planetary traveling.

Re:Why Better than Parachute?

[sconeu]

I thought they did refurb the SRBs.

Re: Why Better than Parachute?

[Anonymous Coward]

If anything, a parachute will slow down the decent much more and protect the sensitive equipement - thrusters would only need to be fired horizontally to steer to landing position and maybe a vertical thrust for super smooth landing

Re: Why Better than Parachute?

[Anonymous Coward]

Parts not entire thing

Re:Why Better than Parachute?

[Michael Woodhams]

The payload cost of reusability is much more that you are saying. From wikipedia:

In order to make the Falcon 9 reusable and return to the launch site, extra propellant and landing gear must be carried on the first stage, requiring around a 30 percent reduction of the maximum payload to orbit in comparison with the expendable Falcon 9."

(That is a return-to-launch-site cost, not a land-on-barge cost, which I didn't find a value for and must be a fair bit lower.)

And from here:

SpaceX has indicated that the Falcon Heavy payload performance to geosynchronous transfer orbit (GTO) will be reduced due to the addition of the reusable technology, but would fly at much lower launch price. With full reusability on all three booster cores, GTO payload will be 7,000 kg (15,000 lb). If only the two outside cores fly as reusable cores while the center core is expendable, GTO payload would be approximately 14,000 kg (31,000 lb).[39] "Falcon 9 will do satellites up to roughly 3.5 tonnes, with full reusability of the boost stage, and Falcon Heavy will do satellites up to 7 tonnes with full reusability of the all three boost stages," [Musk] said, referring to the three Falcon 9 booster cores that will comprise the Falcon Heavy's first stage. He also said Falcon Heavy could double its payload performance to GTO "if, for example, we went expendable on the center core."

(Not clear if this is return to launch site or land on barge.)

Note that I'm not saying this makes it uneconomic. If you have a source to show that contingency fuel (e.g. to accommodate a failure of one engine during launch) is of the same order as fuel requirement to land the stage, please share it. (Also, I agree with your comments about salt water and horizontal loading.)

Re: Why Better than Parachute?

[Anonymous Coward]

Guess how much parachutes for a fourteen story first stage weigh?

Re: Why Better than Parachute?

[Anonymous Coward]

>> This seams more expensive and much more complicated.

It's true, the seams on reentry chutes are incredibly difficult to stitch and can add up to 20 million to the cost of an average launch.

Re:Why Better than Parachute?

[frank249]

Also because you cannot use parachutes on Mars. SpaceX plans to eventually land on Mars, refuel and then take off to return to Earth.

Re: Why Better than Parachute?

[Anonymous Coward]

About the same as the fuel required to slow down a fourteen story stage weight?

Re: Why Better than Parachute?

[Anonymous Coward]

Because the best implementation used to land on earth will the same on mars - that makes sense

Re:Why Better than Parachute?

[Anonymous Coward]

is the seawater issue massively better than just being near seawater? I work for a university near the sea that loans media equipment. if anybody goes near the water (let alone start a rocket engine anywhere near it) we have immense problems.screws blow out, lens connections fail. we've recently had a freefly movi die after being near the water.

Re:Why Better than Parachute?

[Michael Woodhams]

For the Dragon capsule, they're still intending propulsive landing. To me this seems a less clear cut decision than for stage I.

When manned, the Dragon needs both parachutes and rockets whatever landing scenario you have in mind, because you need to allow for abort on launch (rockets to get away from misbehaving lower stages, parachutes to land safely.) A parachute landing is likely to have a sideways velocity component, but this is much less critical for the short Dragon than the very tall stage I.

I'd have imagined a landing scenario where you use the chutes, and just a little bit of rocket right at the end to cushion the impact. (Chutes get released either shortly before or immediately after landing, so as to not get dragged sideways by the wind.)

Perhaps it is a matter of precision: my scenario works fine if you have lots of empty tundra to land in, not so well if you have a hundred metre landing pad to aim for.

Re:Why Better than Parachute?

[Michael Woodhams]

All the following is speculation.

They'll have people on the barge within perhaps 30 minutes of landing. They can hose stuff down with fresh water, then put a tarpaulin over the engines. All the delicate stuff already has to be protected from hypersonic travel through atmosphere, so is probably pretty well protected.

Re:Why Better than Parachute?

[Megane]

The SSRBs were little more than empty pipe after all the fuel burned. They had a lot less parts to damage than a liquid-fuel engine.

Re:Why Better than Parachute?

[KGIII]

I'm sure they've already thought of this and declined to try it for good reasons but nobody has explained the reasons to me why they don't use a chute for part of their decent, drop it at a certain altitude, and then use the remaining fuel for the controlled burn during the landing stage.

Re:Why Better than Parachute?

[KGIII]

I thought they *did* use a chute on Mars to put the rovers down? That and bouncy balls.

Re:Why Better than Parachute?

[Anonymous Coward]

Musk explained that this could have been a landing back at Canaveral, but they wanted to try a sea landing with a larger margin for error so they could have a better chance to succeed. The point of the test was to learn how to do sea landings. He said that he expects over 50% of future launches to require a sea landing, so this is something they need to perfect.

Re:Why Better than Parachute?

[Anonymous Coward]

Yes, they did and can use chutes (or fancier versions like the Low Density Supersonic Decelerator) and bouncy balls, but there's an upper limit to the amount of mass you can safely land using those systems. The limit is too low to be practical for anything except small-ish rovers.

Re:Why Better than Parachute?

[harperska]

Generally correct, except that this launch was to the ISS, which happens to be in a very low orbit to make it easy to rendezvous with it. But yes, it takes a lot more fuel to launch to something like GTO, so less fuel left to turn around and get back to the cape, so they have to land on a ship in the ocean.

Re:Why Better than Parachute?

[Anonymous Coward]

SpaceX actually did make all engine and rocket parts slat-water proof when they where experimenting with parachute landings in the ocean. The problem was that the waves crumbled the rocket and caused it to sink before they could get to it. For this reason, I don't think a bit of salt spray is a problem for the current landing procedure.

Re:Why Better than Parachute?

[hackertourist]

The Shuttle SRB casings were 8mm thick steel in order to withstand crashing into the ocean. The F9 skin is in the region of 0.4 mm aluminium. The Shuttle SRB had a fuel fraction of only 80%.

Re:Why Better than Parachute?

[Anonymous Coward]

Because it's unnecessary, it's a needless complication with more things that can go wrong, for practically no gain. The amount of energy a parachute can "absorb" equals very little rocket fuel, especially when you have such a crazy power to weight ratio.

Re:Why Better than Parachute?

[Anonymous Coward]

I'd have imagined a landing scenario where you use the chutes, and just a little bit of rocket right at the end to cushion the impact.

That's exactly how the Soyuz capsule lands.

Pretty sure that's the same plan for the Dragon v2, mostly as a backup method in case one of the chutes doesn't open.

Re: Why Better than Parachute?

[Anonymous Coward]

Nope. And carrying both us just stupid. Stop humping old space ideas. Chutes didn't work , rocket landing does.

Re:Why Better than Parachute?

[frank249]

The atmosphere on Mars is roughly 100 times thinner than on Earth so you can use a parachute to slow you down but only to a limited extent. The largest supersonic parachute ever used was foe the Curiosity rover mission. Good video here. Not practical for a manned mission due to the snap of the parachute opening at that speed(9 Gs) would break necks. It only slowed the rover to 320 kph and needed a rocket to land.

Re:Why Better than Parachute?

[thrich81]

Chutes were used on all the missions for some of the deceleration but rockets were also needed after the chutes for final deceleration. Mars Pathfinder also had bouncy balls (airbags) for the very end. Mars is tough to get anything heavy onto (in one piece) because the atmosphere is too thin to use a parachute all the way down, but it is thick enough to cause problems with lighting landing rockets at supersonic entry speeds (that last, about the rockets, I was told and don't have a handy reference).

Re:Why Better than Parachute?

[stevelinton]

EIther the parachute opens at high speed in which case it needs to be very strong and well anchored, which makes it complicated and heavy, or it doesn't, in which case it doesn't do you much good. SpaceX don't seem to have much problem getting the stage to just above the pad at reasonably low velocity anyway, using air resistance and rockets.

Re:Why Better than Parachute?

[Anonymous Coward]

Yes they do refurbish the SRBs, at great expense. There are no numbers straight from NASA/Thiokol but they are almost certainly in the $10 Million each ballpark, possibly as high as $23 Million each. They also have operational limits (no throttling), safety issues (no shutdown, thrust variations, etc) & environmental impacts (they basically burn rubber).

Re:Why Better than Parachute?

[Anonymous Coward]

They also stated that, even before the reusable rockets work, they are still putting payloads in orbit for 70% less than their competitors.

Re:Why Better than Parachute?

[Anonymous Coward]

The primary damage is caused by hitting the water and subsequent wave action. The Shuttle SRBs were heavy steel tubes that were still sometimes banged up beyond repair. The Falcon 9 first stage is a bunch of precision hardware attached to ultra-lightweight lithium-aluminum tanks. Every attempt they made to splash down in the water resulted in a few bits of floating debris even after the gentlest of touchdowns.

If you could somehow keep it intact, *then* you would encounter the very-significant problems resulting from immersing aerospace hardware in salt water, but getting to that point's harder to do than attaching some airbags.

Re:Why Better than Parachute?

[Anonymous Coward]

Current plan for Dragon v2 is actually fully propulsive landing, with chutes only as a backup, once they get the kinks worked out. Initially it'll be a water landing solely with chutes.

Re:Why Better than Parachute?

[KGIII]

I figure that if they were going to then they'd do a combination of the two. They will be landing multiple things on Mars, if any of the current plans are to be believed, so having multiple methods might be good. They'll be sending supply missions ahead of time in any of the existing plans that I've read about. Those won't have human necks on them. Above, you stated that they can't use parachutes which struck me as odd as I recollected that they'd done just that.

Re: Why Better than Parachute?

[oobayly]

"Parachutes will slow down the descent..." - only in relation to the speed it was previously doing. The shuttle's SRBs splashed down at speeds in the region of 50mph. Soyuz capsules descend at about 24 ft/s (16mph) and use retro rockets to reduce the speed further.

"...thrusters would only need to be fired horizontally..." - thrusters that the 1st stage doesn't have. It has some cold RCS thrusters at the top for attitude control, but the amount of fuel needed for horizontal translation against a modest 10kt breeze would be massive. This stage landed on a rotating and vertically translating ship in a 40-50kt gale.

"...vertical thrust for super smooth landing" - which is exactly what SpaceX are doing. Remember, a single Merlin engine provides too much thrust to hover, so it'll have to fire at exactly at the right time anyway.

Put simply, explain how to slow a stage from 7,000 + km/h using just parachutes so it lands within a previously designated area of 300x170 ft in gale force winds. If you can, ESA, ULA & Roscosmos have a job for you.

Re:Why Better than Parachute?

[Anonymous Coward]

Because the parachute will hold the capsule to some terminal velocity. Drop the parachute, and it will resume accelerating, meaning, it would need more fuel to stop at the end with no advantage.

Re:Why Better than Parachute?

[Anonymous Coward]

They did, because they promised congress re-usability. The dirty secret was that you could make new ones for less than the cost of the refurb.

that's history, get the details right.

[Thud457]

Hey, that's "ASDS Of Course I Still Love You" to you, bud!

Re: that's history, get the details right.

[Anonymous Coward]

That ship name is from an Iain Banks novel.

Re:"Now that I got a strike, I can win at bowling!

[slew]

I'd go out on a limb and say they will probably stick 8 out of the next 10 sea landings, and no less than 9 out of 10 RTL landings.

Spoken like a pointy haired boss in training...

FWIW, I'll go out on a limb and say that that given the percentage of recovered first stages is integral to SpaceX profitability, Elon Musk probably would know better than most and he apparently has stated publicly that last time when he predicted a 50-50 chance of sticking the landing, that he pretty much made it up and he had no idea...

Re:"Now that I got a strike, I can win at bowling!

[Kjella]

First of all, they don't have to do it consistently just enough to matter. Every success is a win, every failure a cost of doing business. The real question now is, how big is the refurb effort. After all they've landed... twice. They've relaunched... zero. And if they can keep doing that, I mean once is nice but... if they can do it five times, ten times that's when you really start to spread the initial cost across lots of launches. It'll be interesting to see what's possible, also hopefully by the end of the year we'll see the Falcon Heavy launch.

To save even more - work with ISRO

[Anonymous Coward]

Indian Space Research Organisation - http://www.isro.gov.in/ - has made its mark on its ability to launch really cheap rockets

Their Mars orbiter flight - http://www.isro.gov.in/pslv-c2... - only cost $74 million, roughly 11% of the cost of Nasa space launch

If SpaceX can work with ISRO they can lower their cost even more, much more !

Re:To save even more - work with ISRO

[Anonymous Coward]

The US launch industry is terrified of ISRO, because they know ISRO can and will beat them on price. They've been lobbying for protectionist measures to avoid competition with India's fast-expanding space industry.

http://www.indiatimes.com/news/india/us-launch-companies-are-so-scared-of-india-s-space-success-they-re-trying-to-ban-isro-rockets-252968.html

Re:To save even more - work with ISRO

[Anonymous Coward]

Do ISRO charge 1/3 as much and deliver buggy crap that blows up on launch like all the H1B shops?

Re:"Now that I got a strike, I can win at bowling!

[ColdWetDog]

They've actually landed successfully on land prior, this was their first success on a ship at sea. The last attempt it landed, then tipped over when a support leg broke, so i'd guess they reinforced that or something. I'm sure they'll have a few more fireballs, but my money is on them getting the landing down consistently very soon.

When I first started SpaceX I wanted to land a booster in the ocean. Everyone said I was daft to try to land a booster in the ocean, but I built in all the same, just to show them. First time, it crashed into the ocean. So I built a second and third one. They sank into the ocean as well. So I built a fourth. That landed, fell over, then sank into the ocean. But the fifth one stayed up. And that's what you're going to get folks, first stages that land on autonomous barges with weird names in the middle of the ocean.

Re:"Now that I got a strike, I can win at bowling!

[MichaelSmith]

About half their issues have been fixable engineering problems, and the other half have been bad luck, so their success rate from here on should be about 50%.

This is a Really Big Deal, And More to Come

[Bruce Perens]

Obviously now we have to see the recovery percentage that SpaceX can achieve, especially when they start landing Falcon Heavy on three barges, the one for the center booster being much farther downrange than the others. Seeing three land, two of them simultaneously, is going to be pretty amazing. If they can recover a lot of them, this completely changes the economics of space flight beyond the 30% discount SpaceX is quoting in the short term.

And don't forget that they are getting the Dragon back too, and Dragon 2 with its eventual ground-landing capability is expected to be reusable. Currently Dragon 1 lands in sea water, and the reuse they have so far is only of the pressure vessel, the capsule is stripped down to that and rebuilt.

Recovering the second stage is possible although not currently on the SpaceX roadmap. They would need to fly it with a heat shield.

Now, consider what it would take to land a Dragon on the moon and return. Not inconceivable, given Falcon Heavy and a few launches.

Re:This is a Really Big Deal, And More to Come

[cbhacking]

From what I've read, the side booster stages of Falcon Heavy will always be able to make ground landings; they don't go nearly as far or fast as the central stage. I'm sure it still costs some payload to go for the ground landing with the side boosters, but not nearly so much. The central stage, though... that burns for a considerable while after the side boosters detach (it spends much of the flight at low throttle, plus there's the whole propellant crossfeed thing, assuming they ever get that working), and it doesn't ramp back up to full thrust until the rocket is already pretty far and moving pretty fast. By the time it separates, it's going to be way too far to get back to the launch site.

Re:This is a Really Big Deal, And More to Come

[Bruce Perens]

SpaceX has stated that about 30% of rockets launched overall will be able to RTLS. That's why the barge is so critical. F9 Heavy will only be able to RTLS depending on the total delta-V demanded for the mission. There is a delta-V cost for RTLS, you can't just do it on the grid fins.

Re:This is a Really Big Deal, And More to Come

[edxwelch]

More importantly, we have yet to see them reuse a returned rocket. After all, the entire exercise is just a cool way to waste money unless you are actually launching with returned rockets.

Re: This is a Really Big Deal, And More to Come

[Bruce Perens]

They did a test burn of the first one, which showed some engine damage, maybe debris in it. It will be interesting to see if they get a clean burn this time.

Re:Economics of that stunt are amazing

[Anonymous Coward]

SpaceX hopes to sell used Falcon 9 boosters for as low as $40 million

https://spaceflightnow.com/2016/03/31/spacex-hopes-to-sell-used-falcon-9-boosters-for-40-million/

mod do3N

[Anonymous Coward]

WASTE OF BITS AND ultimately, we Let's kk3p to Of challenges that Were taken over and I probably

A Very Stupid Question -

[Anonymous Coward]

Okay. We've seen NASA working with inflatable heat shields for probes and what have you. Making airbags pop out of things is old-hat. If this rocket can right itself, decelerate, and land on a solid surface already, wouldn't it be easier and safer to just have it deploy balloons and land directly in the water?

I'm assuming that corrosion protection has something to do with this.

Re: A Very Stupid Question -

[Anonymous Coward]

A very stupid question that was just asked

Re:A Very Stupid Question -

[MichaelSmith]

Yeah once it has been in the water it has to be rebuilt, rather than fueling it up again and lighting the fuse.

Re:A Very Stupid Question -

[Gavagai80]

Car analogy: instead of hitting the brakes to stop before you crash into the brick wall, why not inflate an air bag and swerve into the nearby lake instead? Because the air bag doesn't really protect very sensitive parts and once you get water in the engine you can't trust it ever again.

Re:"Now that I got a strike, I can win at bowling!

[wonkey_monkey]

After a couple hundred tries (yes, I suck), I finally got a strike! Now that I did it, I can go on to win all the bowling trophies ever!... said no sane person ever.

Yeah. Those are totally the same thing.

This is more like lining up the ball rolling thing that kids use, seeing where the ball goes, then adjusting your aim based on the result until you get a strike, at which point you screw the ball rolling thing into the floor.

Did they actually change the *process* they use

Yes. You think they just watched the others explode, shrugged, and said, "Huh. Okay, do exactly the same thing again, it might work this time"?

Or are they just getting better at the process they already had, due to practice?

Uh... I'm not sure what you think is going on here. Do you imagine there's some guy called Steve guiding the rockets in with a joystick, and he's only now got the hang of it?

Re:"Now that I got a strike, I can win at bowling!

[ericloewe]

She's got huge.... tracts of land, perfect for landing rockets.

Re:"Now that I got a strike, I can win at bowling!

[fnj]

Chutulu

Are you trying to spell Cthulhu? If so, back to the drawing board.

Ignore the economics

[Anonymous Coward]

Ignore the economics and appreciate the engineering marvel of this reusable rocket booster. Once they prove this feat can be reproduced reliably the process of designing a version 2.0 that improves the economics can begin. The fact that they are able to deliver useful payloads doing this kind of R&D is absolutely fantastic.

Re:"Now that I got a strike, I can win at bowling!

[petermgreen]

Afaict they have attempted landings* on 6 flights of those two were successful.

Flight 14, failure due to grid fins ran out of hydralic fluid.
Flight 17, failure due to stuck valve
Flight 20, successful landing at the cape
Flight 21, failure due to landing leg issue
Flight 22, failure (and was expected to fail) due to coming in too fast due to a large payload.
Flight 23, successful landing on

So basically the devil is in the details. Each time a failure happens i'm sure they put a lot of effort into working out the details of what went wrong but what is not clear is how many iterations of failure they will have to go through before they get a reliable result.

One thing I would note is that they don't need 100% reliability. They just need sufficient reliablity to make the savings from reuse greater than the cost (payload reduction, landing location operations and repairs etc) of the landing,

* Defined here as attempting to land etiher a landing pad on land or a droneship. I don't count the drop in water tests as landing attempts.

4k

[Anonymous Coward]

SpaceX has uploaded there 4K original as well: https://www.youtube.com/watch?v=sYmQQn_ZSys
And a zoom-in of the landing "hop" https://www.youtube.com/watch?v=j3B9QElpoCk for which the jury is going to subtract points.

More physics than economics, and it checks out

[goodmanj]

SpaceX, and the people in this thread, are comparing the vehicle cost to fuel cost, which is kinda cheating. It's not the cost of the fuel that matters, it's the cost of building the vehicle larger to hold that fuel -- and the fuel needed to launch that fuel -- that matters. So let's do the math!

Most data taken from http://spaceflight101.com/spac...
Basic info:
Stage 1: 23 tonnes structure, 400 tonnes fuel
Stage 2: 4 tonnes structure, 93 tonnes fuel
Payload: 13 tonnes

When launching, the first stage burns all 9 engines at full thrust for two and a half minutes. The re-entry burn and landing happen on a single engine, and from eyeballing the videos (including this one that shows the re-entry burn) appear to take about 30 seconds total. Assuming all burns are near full thrust (which is the best way to do it), that means the landing burn takes about (1/9) * (0:30 / 2:30) = 2% of the first stage fuel. Let's double that to 4% to provide a generous safety margin: that works out to about 400 * 0.04 = 16 tons more fuel.

This fuel is carried up to the moment that the second stage separates, so it subtracts from the mass of the second stage. Second stage plus payload weighs 110 tonnes: without the landing fuel, you could have scaled that up to 126 tonnes, a 15% increase.

So, landing the first stage reduces the payload SpaceX can launch, and thus the money they earn, by about 15%. In exchange, they recover about 75% of the cost of the launch hardware. So it's worth doing, even after you subtract off the cost of recovery and refurbishing. Maybe not the game-changer Elon Musk wants it to be, but it's a win.

Re: More physics than economics, and it checks out

[sp4ni3l]

I agree with the math right to the point where you made the money you earn equal to the amount of mass you launch. There is a base cost per launch and that makes the first "kilo" very expensive, but the last kilo very cheap. Its like saying a truck which can carry 40 tons will earn 2 times more money then a truck which carries only 20 tons. It all depends ( basic logistics ) on the size of the shipments you have and then a truck of 20 tons could be just perfect.

Re: More physics than economics, and it checks out

[goodmanj]

You make a very good point for, say, satellite delivery, where being in space at all is much more valuable than how many pounds the satellite weighs. But for ISS resupply, what NASA cares about for its COTS program is total tonnage reliably delivered. And SpaceX's stated goal has always been reducing the cost of bulk cargo delivery, with "dollars per pound" as the metric of success.

Re:More physics than economics, and it checks out

[Insanity Defense]

This fuel is carried up to the moment that the second stage separates, so it subtracts from the mass of the second stage. Second stage plus payload weighs 110 tonnes: without the landing fuel, you could have scaled that up to 126 tonnes, a 15% increase.

Among the assumptions you make is that every payload is at maximum mass and requires maximum thrust to make the appropriate orbit. Most will be below those values. Therefore most missions will have excess unneeded fuel capacity which can be used to save the first stage for reuse. Those that don't have the excess can use reused first stages at lower cost compared to a new 1st stage as it will have used up some number of its possible launches.

Re:More physics than economics, and it checks out

[Anonymous Coward]

If I remember correctly, there is already fuel in excess for the case when one of the engines malfunction during launch - the launch happens on 8 instead of nine engines, the acceleration takes longer and uses a bit more fuel.
      If this is the case, the extra fuel is "free" if all the engines work (and might not be there at all in case one of the engine malfunction, but you still manage to launch the payload).

Re:More physics than economics, and it checks out

[hackertourist]

There are three burns: boostback, reentry and landing. The boostback and reentry burns use 3 engines, IIRC. Only the landing burn uses a single engine.
Most estimates of fuel needed for landing are in the 35-40 ton range.

Big push to engine improvement too!

[DeltaQH]

Being able to inspect intact engines after a real mission would improve its development and refinement.

Re:Big push to engine improvement too!

[tarpitcod]

Exactly - not throwing everything away has advantages. SpaceX deserves to be congratulated for pulling this off. There's lots to be said for incremental improvement.

Re: More physics than economics, and it checks ou

[K. S. Kyosuke]

Since the Dragon is volume-limited already, the only thing you gain by expending the first stage with it is more scrap at the bottom of the ocean.

Re:"Now that I got a strike, I can win at bowling!

[Anonymous Coward]

They have at least done a test firing on the previously landed first stage. And the refurbished first stage will probably launch in Fall 2016.

Plus, now they have two to play with!

Artillery versus Airplanes

[tarpitcod]

That's the analogy to think about with this. When is it best to use the artillery approach, and when is it best to use an airplane approach. An airplane approach implies refueling and re-use. You can amortize investments to improve capabilities over time. Artillery is all about cheap getting payload up there.

If you really want to get pure mass to LEO cheaply - it's hard to beat big artillery with a rocket stage. It has a few issues though.
Your payload has to be able to handle the G's from firing. The payload is probably fairly small unless you build a really big gun. If you are interested - google Gerald Bull.

Another cheapish way to get lots of mass to orbit that is mostly politically acceptable would be *really* big rockets. Some of the plans for humungous solid rocket boosters etc. Big diameter solid rockets are hard to beat for cost if you are going to throw it all away.

The truth is it's a continuum. You can plot this stuff on a graph and it's very informative. You discover the above. Artillery to LEO is very cheap - but limits you to tiny payloads. Massive throw away solids are cheap too, but if the launch vehicle fails you lose a lot. For things you value a lot (like people) you may not want to use a huge solid.

If you want to launch truly huge amounts of stuff to orbit it's very difficult to beat Orion and nuclear pulse propulsion. Politically the only way you'd see that happen would be to save the planet.

Re:Artillery versus Airplanes

[stevelinton]

If you want to launch truly huge amounts of stuff to orbit it's very difficult to beat Orion and nuclear pulse propulsion. Politically the only way you'd see that happen would be to save the planet.

Wang bullet is cheaper -- dig a deep hole into hard rock. put a nuke at the bottom, then some padding, (sand say) then a very tough payload.

Re:Artillery versus Airplanes

[tarpitcod]

Thanks for sending that. I was thinking a little about Plumbbob and the steel-plate as I typed the Orion comment, but hadn't heard of Wang Bullet. It has all the advantages of artillery and NPP combined. Plus the reaction mass (steam) reduces the acceleration. It's awesome.

 

Very sweet, now...

[Khyber]

...let me know when I can ride that first stage up and back, and do so reliably, so I can have fun watching payloads going into orbit first-hand.

Cross Wind Landing

[catchblue22]

And in rough seas

Based (1) on some quick calculations on the video based on the speed of the exhaust traveling across the deck, (2) on the word of an experienced blue water sailor who looked at the sea state in the video, and (3) what Elon Musk said during a press conference, the cross winds for that landing were about 40 knots. That's intense!

Re:"Now that I got a strike, I can win at bowling!

[tibit]

It was even better: both the Dragon and the 1st stage survived the breakup of the 2nd stage. That was a sight to behold. If it wasn't for the flight termination system, the 1st stage and Dragon could have been recovered intact. If the CRS-8 kind of S2 failure happened today, and the flight rules were such that neither the range nor the automated termination system would have blown up what's left, we would have had a Dragon and S1 recovery. That's pretty amazing capability if you ask me. Sure other things could always go wrong, but I think it's quite reassuring that we have now experience with a S2 failure that leaves S1 and the payload intact!

Re:"Now that I got a strike, I can win at bowling!

[Anonymous Coward]

All hail Cthulhu, may his tentacleness embrace us and usher in a thousand years of darkness!

Re:"Now that I got a strike, I can win at bowling!

[Talderas]

I'm not expecting a relaunch until they've recovered three. That would give them one for destructive analysis and one to preserve.