SpaceX makes rocket science look easy: Falcon 9 passes tests

The first SpaceX rocket to land after launching a payload into orbit has been checked out and is ready for a test burn, according to boss Elon Musk. Youtube Video Last month, SpaceX successfully landed its upgraded Falcon 9 rocket after depositing 11 Orbcomm satellites into low-Earth orbit, and has spent the Christmas break …

[Ian Michael Gumby]

How many times?

Ok, so the rocket came back down in one piece.

But how many times could it be reused?

For materials... sure. But if you're going to be sitting on top of it... do you trust it?

I for one would love to know...

Don't get me wrong its a start and a step in the right direction.

[Dave 126]

Re: How many times?

At this stage of the game, I would still be apprehensive about sitting atop a rocket on its very first trip to orbit. SpaceX themselves have had a rocket explode before it reached orbit, though their recent success strongly suggests they correctly identified the issue (a dodgy strut IIRC).

There will come, I hope, a point at which the risk is low enough that I would decide it is worth it to experience being in orbit... even if my first minutes in microgravity include me vomiting whilst a crewmate (or rather, flight attendant) pulls down my trousers and injects a syringe of anti-nausea medication into my buttock.

[hplasm]

Re: How many times?

" me vomiting whilst a crewmate (or rather, flight attendant) pulls down my trousers and injects a syringe of anti-nausea medication into my buttock."

And people think a vegetarian option on air flights is progress.

How much extra would you pay for this service?

[Ian Michael Gumby]

@Dave Re: How many times?

So, I get 6 down votes for saying the tech is neat and its a good start, but questioning how many times could it be reused ???

;-)

To your point, yes sitting on top of a rocket is still a risky endeavor. I get that and while I'd do it, my wife would kill me for even thinking about it.

However my point was that even if they could constantly land it... we have a strengths and materials problem where components will eventually fail after so many uses.

How could they test this? I mean, depending on the payload, even insured, there's going to be a cost for Space X and that has to be balanced out against the manufacturing costs and the savings from reuse.

That's not rocket science but strictly bean counting and risk assessment. One would have to have a bunch of these being reused, and even after examining them for stress fractures and failures... extrapolate their life and then divide by 2 for a safety factor. (e.g. if its safe to use up to 10 times, limit its reuse to 5 and then melt it for scrap...)

You bring up another issue.

While I don't know you... but you do realize that you could get the shot in the arm or anywhere. Most likely the flight attendant will be male so if you want to pull your shorts off and get a long needle in the buttox... who am I to judge? ;-)

Personally, I'd skip breakfast and travel on an empty stomach.

[Dave 126]

Re: @Dave How many times?

@Ian Michael Gumby

Sorry mate, I didn't down vote you.

However, I am guilty of 'replying' to your post, and then failing to write what i originally meant to... mainly because I would have been mostly musing on the state-of-the-art of non-destructive-testing of used rockets as regards quality control of new units. I apologise for straying off your topic. Genuinely.

As for the first moments in orbit details, those came from the autobiography of a NASA astronaut. Apparently, all those terrestrial centrifuges give no idea whatsoever as to who will succumb to nausea in microgravity, and a jab in the arse is standard procedure (it's a larger target than the arm for the 'stabees', who are themselves floating around the gaff) for those who feel sick. The rest of the book was a reminder of how ridiculously qualified this guy was - IIRC, a full medical doctor, pilot, and he completed special forces physical training. Being jabbed in the backside was amongst the least of the physical discomforts he endured to attain his dream.

Hope you get to get to enjoy some awe-inspiring views in 2016, be them in orbit, atop a mountain or under the sea. Without the blisters, altitude sickness or odd jellyfish sting, it wouldn't feel the same!

[Ian Michael Gumby]

Re: @Dave How many times?

Dave, no worries... I think we're in violent agreement. :-)

The only time I was stuck in the arse was with 500cc of Pen VK. (One in each cheek)

That my friend was not fun. (At least I had enough sense to call the nurse a sadist before the shots. )

One of the best ways to limit nausea is to have an empty stomach. As to who will succumb? No idea. The best test would be to be on a small fishing boat that spews a lot of diesel smoke out on rough seas.

[Alan Brown]

Re: @Dave How many times?

"a jab in the arse is standard procedure"

A buccostem under the top lip prior to launch would surely be a better option.

[greatnesslostislegend]

Re: How many times?

Note the Dragon capsule survived the accident, but was not programmed to deal with failure and simply followed a ballistic trajectory hitting the Atlantic at 600 MPH or so. Another RUD.

With no doubt Space X engineers spent thousands of hours going over this rocket. X raying parts, sending probes into the combustion chamber, fuel tanks, turbo pumps and so on. Every bolt and screw tested as well. They know where weak point, and strong points are, and will adjust manufacture of ongoing F-9's accordingly.

I'd keep this one, and fire the next one landed, and checked out for 200 seconds, full on. See if something breaks. If not its power systems are proven robust enough for another run. Tanks and structure another question. You can only test this with another go. This is just a step. I figure ten recoveries, and half a dozen flight tests will have to occur before trying to commercially sell a used rocket flight. First using a Dragon programmed to save itself in case of an accident. The second stage will be brand new. In addition I would not try and recover the first re-use flight. Just put up a payload made up of experiments put forward by college and university engineering students. See what they can cook up. For one I'd love to put my much dreamed about satellite that incorporates a magnetic propulsion system on board. Hall thrusters to orientate. A small 400 pound thing that can be built in the garage. I bet there are thousands of students who'd jump at this chance. Paying for it? The students pony up fuel and range costs though university, grant, and crowd funding. Space X the second stage and its staff. Just a Doc Brown moment.

This was a big deal. Blue Origin doing it proves landing is more than possible. When the next F-9 lands it will be a ULA and ESA shattering moment...

[Anonymous Coward]

Re: How many times?

> "But how many times could it be reused?"

Its been bruited about that 20-25 reuses is not unreasonable. That remains to be seen, since no one has ever tried to design a big engine specifically to be reused a lot. Typically there was no point, until now.

[Anonymous Coward]

Re: How many times?

> "...since no one has ever tried to design a big engine specifically to be reused a lot."

Well, except for the shuttle engines. Oops.

[Alastair Dodd 1]

Re: How many times?

Well the shuttle engines themselves NEVER failed - the shitty DISPOSABLE solid rocket boosters did and so did the heat shield.

So thats a big tick for positive success. They needed major maintenance, more than expected but that is still not bad.. NASA has had more wins than failures remember and has returned 100x when it has cost in value.

[Nigel 11]

Re: How many times?

Weren't there some major issues with the Shuttle's fuel pumps, which meant that the cost of rebuilding the engines for the next launch approached the cost of just scrapping them after one use? Or did they manage to fix that?

[TitterYeNot]

Re: How many times?

"Weren't there some major issues with the Shuttle's fuel pumps, which meant that the cost of rebuilding the engines for the next launch approached the cost of just scrapping them after one use? Or did they manage to fix that?"

Yes, the Shuttle main engine turbopumps were replaced with a new design in the Block 2 upgrades in the late 90's / early 00's. Prior to this, engine maintenance required a nearly full engine strip down after each launch, which is one of the reasons that the turnaround time between launches for an individual vehicle was several months rather than the 2-3 weeks envisaged by the original designers (it was still economically viable to re-use engines even with this maintenance work as new main engines cost around $40 million each.)

[cray74]

Re: How many times?

Well the shuttle engines themselves NEVER failed

Yes, they did. STS-51-F had to abort-to-orbit because of an SSME shut down. STS-93 lost a small pin that was violently ejected into the engine nozzle and punctured the cooling lines, which led to a below-target orbit, and almost lost two engines with a separate digital control unit failure. There were also five pad aborts because of SSME misbehavior.

[John Stoffel]

Re: How many times?

Actually, as I recall the shuttle main engines did have at least one failure where they had an abort to orbit happen. They ended up lower than planned, which caused some problems. A quick google shows it was STS-51F which was the failure.

John

[Alan Brown]

Re: How many times?

"Well the shuttle engines themselves NEVER failed "

Not in flight, at any rate.

On the test stand was an entirely different (and often spectacular) matter.

[Weapon]

Re: How many times?

It is hard to call shuttle engines fully reusable when they were exposed to salt water. Salt water is corrosive.

[JeffyPoooh]

Re: How many times?

@Weapon

Are you confusing the Solid Rocket Boosters (which splashed down in the ocean) and the Shuttle Main Engines (which usually didn't) ?

[Alan Brown]

Re: How many times?

"Well, except for the shuttle engines. Oops."

Shuttle engines were so highly stressed that they pretty much had to be completely rebuilt before reuse.

That's why they're being treated as disposable when used in NASA's current projects.

Elon's engines are designed to be reused without being rebuilt. Big difference...

[mathew42]

Re: How many times?

> For materials... sure. But if you're going to be sitting on top of it... do you trust it?

I hope we are all familiar with the failure bell curve. If SpaceX can reach 20+ flights from a single rocket, then it might make sense to take the third to tenth flights. For example none of the shuttles were lost on their first flights. However you do need to consider that with success, management may relax the tolerances.

As for costs, Quartz reported that Falcon 9 rocket costs $54 million and the fuel it burns is $200,000. This does suggest an order of magnitude reduction in launch costs is achievable. i'll drink to that.

If you are launching 100+ satellites into LEO you might well consider taking a punt on the later launches if SpaceX provide sufficient discounts.

[Destroy All Monsters]

Re: How many times?

I hope we are all familiar with the failure bell curve.

The idea that there is a bell curve in the failurerate/launchcount graph (for any given subset of devices) is an unwarranted assumption. Time will tell - if SpaceX takes off.

[Destroy All Monsters]

Re: How many times?

> Not bell curve

> Thumb down

Looks like some NASA engineer from the STS booster design team is here

[Voland's right hand]

Re: How many times?

The idea that there is a bell curve in the failurerate/launchcount graph (for any given subset of devices) is an unwarranted assumption

Dunno which moron mod-ed this down. It is spot on. Material fatigue does not follow bell curve. It goes nice and low up to a point, then shoots up. Erosion, corrosion, etc follow similar curves, etc.

Bell curve as a failure distribution is as rare as a white swallow.

[Voland's right hand]

Re: How many times?

The rocket - probably zero times. It is likely to be cheaper to scrap the structural components instead of reusing them. They are not that expensive.

The engine (that is the really expensive bit) - target is 40 times or thereabouts.

This is according to Musk himself from one of his interviews. It will be interesting to see what they do.

[John Robson]

Re: How many times?

"But if you're going to be sitting on top of it... do you trust it?

I for one would love to know..."

As opposed to:

"sitting on top of two million parts -- all built by the lowest bidder on a government contract."

I don't know - but I'm probably not cut out to sit atop an experimental firework...

(Yes, this is a repeated response, to a repeated question in a different thread)

[jabuzz]

Re: How many times?

The target is around 20-25 times. The engines have had extensive testing and have been through 40 full burns on the test stand with minimal maintenance between burns.

[Martin Budden]

Re: How many times?

It's worth mentioning that even if a Merlin engine fails it doesn't really matter. The Falcon 9 is designed to be able to continue with eight engines if one does conk out. (Presumably that would mean the Falcon Heavy could cope with up to three engine failures?)

We've already seen this happen: on one earlier launch an engine conked out mid-flight, and the Falcon 9 continued and successfully put the primary payload in the correct orbit. Extra fuel was used which meant the chances of getting the secondary payload to its correct orbit dropped from 99% to 95%. NASA decided that 95% wasn't good enough and refused permission for SpaceX to continue with the secondary payload... I still count that as a solid success for the Falcon 9's ability to handle an engine failure.

[Anonymous Coward]

Needs a name

If the heavy lifter works out, there will be a group of flying boosters flocking back to their designated landing pads along the sand bar, all at once. :-)

This is a new class of Things In A Group (flying boosters). Got to have a catchy group name.

My vote goes for a "rumble" of boosters.

[Preston Munchensonton]

Re: Needs a name

My vote goes for a "rumble" of boosters.

Given the obvious, phallic shape of the things, the only sensible thing to call them would be an erection of boosters.

[Sweep]

Re: Needs a name

Sausage-fest?

Bukkake?

[Ian Michael Gumby]

@Sweep Re: Needs a name

Bukkake?

Only if they explode.

[Skilty]

Re: Needs a name

Lets hope they don't suffer from dysfunction or there will be some unsatisfied astronauts...

[allthecoolshortnamesweretaken]

Re: Needs a name

"Given the obvious, phallic shape of the things, the only sensible thing to call them would be an erection of boosters."

Naughty boy. But this is about the going-down-phase, that's like the opposite of erection...

[Preston Munchensonton]

Re: Needs a name

"Naughty boy. But this is about the going-down-phase, that's like the opposite of erection..."

Come now. Do I really have to point out the obvious link between erections and going down?

Obviously, Paris.

[phuzz]

Re: Needs a name

I've heard of a "salvo" of rockets before, but that's more if you're trying to blow stuff up, so yes, I like your idea of a Rumble of Returning Re-useable Rockets.

(I'm not sure what you did to deserve a downvote)

[Martin Budden]

Re: Needs a name

I've heard of a "salvo" of rockets before, but that's more if you're trying to blow stuff up

A salvo is when they are going up, so on the way back are they an ovlas?

[Destroy All Monsters]

Re: Needs a name

Wolfpack sounds nicer

[Hero Protagonist]

Re: Needs a name

A musk of boosters

[MyffyW]

Re: Needs a name

Adding a feminine touch because it is, after all, a space ship, how about a handful of boosters?

As in the well know imperial derived unit a standard British handful

[PJF]

x? up, one down.

How many times did Musk try to re-land a first-stage rocket? (not being a prick)

Is this the first one re-landing on solid ground rather than a bobbing-barge?

If so, hats-off. Just re-using the engine is cost-savings enough (if all checks out). Then launching, and hopefully reclaiming a "heavy" will be leaps-n-bounds ahead of anyone else.

[oldcoder]

Re: x? up, one down.

Quite a few.

The first one only went up 1000 feet or so, and there were a couple of those.

The Falcon 9 had some 8 landing tests (https://en.wikipedia.org/wiki/Falcon_9_booster_landing_tests and https://en.wikipedia.org/wiki/SpaceX_reusable_launch_system_development_program )

[Sorry that handle is already taken.]

Re: x? up, one down.

All of the barge landing attempts were failures, although there was a successful simulation without a barge in place prior to the barge landing attempts.

That said, this one is perhaps the most impressive of all landing attempts since the booster returned to the launch site rather than follow a (largely) ballistic trajectory to a downrange landing site.

[Gene Cash]

F9 Heavy

I just went to SpaceX.com where they list $90M for a Falcon 9 Heavy.

I don't see how they can do that when a standard F9 is $60M, unless all 3 boosters are recovered and reused at least twice.

That'd explain why F9H has not had any movement recently... they're waiting for the recoverable stages.

At that price, it'll kill Delta IV Heavy, which is about 5x that cost as far as I can find out. (nearly $400 million according to http://spaceflightnow.com/2015/04/22/ula-needs-commercial-business-to-close-vulcan-rocket-business-case/)

[Mark 85]

Re: F9 Heavy

The biggest cost is the engines and engine management devices, from what I've read. The rocket body and tanks are considered expendable in the long term.

[Vulch]

Re: F9 Heavy

How much of that is for the hardware and how much goes to things like paying for the Air Force range tracking and rent on the pads though? There will be a fixed cost per launch that is independent of the number of first stages involved. Still sounds like a bit of a bargain mind you.

[Grimzod]

Cost

Musk stated his F9 costs 16 million to build. The COST of a launch on one is 60 million (90 if you are NASA or AF for Mission Assurnace - meaning they dont do insurance they do Mission Assurance). FH cost is stated to be 90 million (120 ish million if you are NASA or AF for Mission Assurance).

16 million per stick. Musk indicated the cost of going to space might come down more than a factor of 100. That is not revolutionary - it is a tectonic shift. A dino killing asteroid if you will.

[Vulch]

Re: Cost

Replying a week later but at least I'll be able to find it next time...

Actually, if that 16 million is for the first stage rather than the whole F9 it does fit with advertised rates. A standard launch is being priced at 60 million, a Heavy launch 90. It has been suggested that the first stage makes up two thirds of the hardware cost so with a fixed cost per launch (y) plus a hardware unit cost (x) we have F9R as 3x + y = 60 and F9H as 7x + y = 90. Solving that gives x = 7.5 making each first stage 15 million, 22.5 million (15 + 7.5) for a complete F9R and 52.5 million (3 * 15 + 7.5) for the F9H. It also means there's an overhead of 37.5 million for each launch going into range payments, pad rent, payload integration and company profits.

[Winkypop]

Pretty soon....

....LEO pizza delivery boys!

Imagine the tip.

[Anonymous Coward]

They better hope to make delivery within 30 minutes.

Otherwise the pizza will be free.

[Graham Marsden]

Re: Pretty soon....

No, I ordered the Hawaiian, not the Pepperoni...

[Anonymous Blowhard]

Re: Pretty soon....

Pineapple on pizza is just wrong; see the instructional video:

Futurama - Pineapple pizza

[Fatman]

Re: Pretty soon....

<quote>....LEO pizza delivery boys!

Imagine the tip.</quote>

Me: "Man, I ordered DIET soda!!!! And, no, I won't take """credit""" on the bill. Go back and get me my soda!!!!"

"""Delivery Driver""": "SHIT!!!!! I have to waste all of that """gas""" just to deliver a 2-liter!!!!!"

</snark>

[Anonymous Coward]

Re: Pretty soon....

All pizzas guaranteed to arrive hot and fast.

Freshly cooked during re-entry and at about mach 4.

[Martin Budden]

Re: Pretty soon....

"Imagine the tip."

Most rockets are either pointy or rounded.

[Filthysock]

"The next stage is to convince a company to entrust some highly expensive satellites to a second-hand rocket."

Orbcomm is already on board to fly used rockets.

https://twitter.com/marc944marc/status/682247411289305088

[I ain't Spartacus]

I'm not using a second hand rocket unless it wore a condom the first time...

[Anonymous Coward]

I use my second hand rocket all the time.

OK I admit, more than second.

[dotdavid]

Second-hand Rockets

I dunno if people would be more apprehensive about using second-hand rockets rather than brand new ones. There is a lot of value in live testing - I'd prefer to use an aeroplane that had had at least one successful flight before I got on it than a brand new one out of the factory :-)

[Nigel 11]

Re: Second-hand Rockets

I'd prefer to use an aeroplane that had had at least one successful flight before I got on it than a brand new one out of the factory

Need a bit of experience on re-launches to tell how it works for rockets. On the one hand the engines will have been mission tested and won't contain any fatal manufacturing flaws the second time around. On the other hand they'll have been stressed by use and recovery which may have caused some damage that escape the re-use inspection and revalidation procedures. Some of the wear and tear will be cumulative.

Seems a shame to put this one in a museum. Isn't there more to be gained by re-launching it a good few times as soon as possible, knowing that it is exploring unknown territory and will probably blow up at some point? A static firing next so it can be more closely observed is sensible, but can't cover all the stresses of a real re-launch. So after a successful static firing, another overhaul and launch again would be the most informative step.

[Ironclad]

Re: Second-hand Rockets

That was my first thought too, why not re-launch this rocket empty or with a nominal payload to see how it performs?

[NotBob]

Re: Second-hand Rockets

One possibility is comprehensiveness. We launched x rockets and then tore them apart. These are the things we found. Compare to: it didn't mess up this time, so it never will. Hopefully they are quite thorough about checking everything anyway.

Another possibility is redundancy. If you launch another one and then make it your first re-used one and something does fail (and they will try very hard to avoid that), you have that first one to look at and see what you might've missed.

It is also likely that it will take some time to tear it apart and check every bloody component. Time that could be spent launching another rocket while the checking is underway. You don't learn as much sitting still in a game like this.

[Anonymous Coward]

Re: Second-hand Rockets

"Seems a shame to put this one in a museum. " ...

One of the great things about the Space X approach to this is that the ongoing commercial launches will supply them with a wealth of used first stages to experiment with.

[Destroy All Monsters]

Why ar they so sooty and what is that hairy stuff?

Ok, so they are burning kerosene, but temperatures are rather high, so why so much deposits? Plus, there are patches of material looking like Andromeda Strain on the engine bells. Doesn't most of that come from after the landing when the rocket cools down with lots of gases swirling around?

[cray74]

Re: Why ar they so sooty and what is that hairy stuff?

Ok, so they are burning kerosene, but temperatures are rather high, so why so much deposits?

Rocket designers tend to prefer fuel-rich designs because superheated excess oxygen is hell on the engines. The Rooskies have made oxygen-rich turbopumps for some kerosene designs, and SpaceX is working on some oxygen-rich pumps for the Raptor engines, but you can identify the engineers behind such engines by the way they walk around with wheelbarrels to carry their enormous brass gonads.

Fuel-rich kerosene combustion produces soot. The Falcon 9 first stage fell backward into the exhaust plume of a Merlin 1D for several minutes, so it got covered in soot.

Plus, there are patches of material looking like Andromeda Strain on the engine bells.

Also soot. I've seen soot peel off metal surfaces in patterns like that before.

[Sorry that handle is already taken.]

Re: Why ar they so sooty and what is that hairy stuff?

They also run rich because leaving significant diatomic hydrogen and carbon monoxide in the exhaust stream is more beneficial for efficiency than burning all the way to water and carbon dioxide. Running rich also allows you to control the combustion chamber temperature, which in the case of reusable engines is also beneficial.

According to this information, LOX/RP-1 engines run an oxidiser:fuel ratio of ~2.3:1 by mass. Based on the average molecular formula given, ~3.4 kg of O₂ will completely burn 1 kg of RP-1 to H₂O and CO₂, so assuming I haven't made a mess of the calculations, almost a third of the fuel is incompletely combusted, leading to lots of H₂, CO and a bit of free carbon in the exhaust.

[Sorry that handle is already taken.]

Re: Why ar they so sooty and what is that hairy stuff?

Whoops! "A third is incompletely combusted" is incorrect, since what I mean is "there's enough oxygen to completely combust two thirds of the fuel" and they're not the same.

Anyway at an O:F of 2.3:1, the stoichiometry of C:H:O is 1:2:2, so (again, assuming no mistake in the calculations) under ideal circumstances you can go completely to H₂O + CO, or completely to CO₂ + H₂. Or, as we see, several species (probably even some O₂) including free carbon to complicate matters.

[JDX]

Where did it land?

I thought they were still doing the barge-landings but that looked more like terra firma?

[Destroy All Monsters]

Re: Where did it land?

Yes that baby landed on Earth.

Webcast here

[Martin Budden]

Re: Where did it land?

More specifically, it landed on a pad next (ish) to the one it launched from.

[Hopalong]

I have seen reports that SES are up for using a pre-used first stage on one of their flights.

They are the customer for the next launch out of the cape, but it will not be that flight.

The next Falcon 9 going up will be the last v1.1 and that will be out of Vandenberg - currently scheduled for the 17th

[cray74]

For materials... sure. But if you're going to be sitting on top of it... do you trust it?

More than an expendable rocket. If I'm sitting on a reusable launcher like the shuttle or Falcon 9 that's flown once or more, then I'm sitting on a proven rocket. It's an individual vehicle that the support and maintenance personnel are familiar with, and has an engineering history of tests, tags, telemetry, and flight performance.

On another, fresh, never-used rocket, you don't have that confidence building data. Yes, it's sisters have flown, but every new vehicle comes with its own manufacturing flaws and quirks (like badly made struts that might fail despite a safety factor of five.)

The Falcon 9 reusable first stage will have a learning curve of its own. I'm sure there are overlooked issues from reusing the stages that will only be found through more flights - it does appear to get beat up, but did the engineers look for the correct issues? Did their broader tests check the correct variables? More tests needed.

Unfortunately, rockets can't be tested like cars and airplanes: many prototypes made and put through thousands of hours of road and flight testing. But SpaceX is taking the right approach of flight testing as many reusable first stages as possible, and then testing them further when they're back.

[Marvin O'Gravel Balloon Face]

Ironic

Big, sooty, reusable. Could almost have been designed by Volkswagen.

[Anonymous Coward]

The Moon Rises

I hope Studio Ghibli proceeds to make an not-entirely-historically-accurate anime out of this

[Anonymous Coward]

wormhole's and stuff

instead of big time charlie wormhole's to the other side of the universe why dont they start with one from nasa to earth orbit to see how it goes.

[annodomini2]

"This is basically three Falcon 9 rockets strapped side-by-side, making it the most powerful rocket in the world by far,"

...Operational...

Saturn V was way more powerful.

[Ugotta B. Kiddingme]

would be thrilled to see

all three segments of a Falcon 9 Heavy land in formation. Now THAT would be cool!

[cray74]

Re: would be thrilled to see

all three segments of a Falcon 9 Heavy land in formation. Now THAT would be cool!

It would be, but with current plans you'll only see two land in formation. Per the SpaceX Falcon 9 Heavy animation, the boosters drop off earlier and return together. The core returns later, from a greater distance.

This stems from the SpaceX plan to use "cross feeding." The boosters will supply the core with fuel, leaving the core fully fueled when they separate. It does its thing to heave the second stage to higher altitude and velocity, then heads home after the boosters are already well on their way back. Per the animation, SpaceX seems to want them to land in a neat row, but it won't happen in triple formation.

I'd assume that the core might also land on a barge rather than trying to return to launch site, leaving more fuel for launching a heavier payload, but that's speculating.

[greatnesslostislegend]

Re: would be thrilled to see

Side boosters land first. Fuel is cross fed to the center core. Outer two only run for 120 seconds or so. Center core fires for around 180 seconds longer. Here I suspect a modified oil platform landing makes a lot more sense. A Merlin Vacuum powers the second stage, later perhaps a Raptor variant will take up this job.

[John Robson]

Re: would be thrilled to see

Cross feeding is also called Asparagus staging in KSP - and is a remarkably good way of getting stuff off the ground.

[Matthew Taylor]

Tried and tested

SpaceX's only recent failure was on a rocket's maiden flight, and was due to a faulty component (a strut, I think) that failed way below spec.

Given this, is it possible that flying on a rocket that has flown once already could actually be a safer bet than a new one. At least it's proven that it can go up there once already, and that the components are sound. I suppose it depends on whether failures are more likely to come from flight fatigue, or from consistency of manufacture.

[Charlie van Becelaere]

SpaceX makes rocket science look easy

Rocket science IS easy - it's rocket engineering that's difficult.