Hacker News new | comments | show | ask | jobs | submit login
SpaceX's Falcon Heavy center booster lacked ignition fluid to re-light engines (latimes.com)
251 points by jacquesm 9 months ago | hide | past | web | favorite | 175 comments

They’ll learn and move on. All told it was a very successful mission and they got the money shot of the two other boosters landing back at the space center + putting the car in orbit. Very impressed with everything they’ve accomplished and can’t wait to see what’s next.

I bet it didn't randomly lack fluid due to some stupid miscalculation. It's probably more like: "Due to unforeseen circumstances it needed more fluid than expected. But we adjust our numbers and next time we expect more (in the hopes that it will be enough, which it will probably be)."

It says right there in the article that it used up the fuel while attempting to re-lights the engines (without success).

> Musk said Monday that there wasn't enough ignition fluid to light the outer two engines of the booster "after several three engine relights."

I don't see a mention of whether the previous relights succeeded or not. I'm guessing they did succeed, but the center booster had to perform a higher number of relights than a Falcon 9 booster due to its higher speed.

It's the same amount of relights - boostback burn, re-entry burn, and landing burn. It's possible the re-entry burn used more TEA-TEB than usual because of the high speed, but it's also possible that non-boostback GTO missions re-entered at higher speeds (this is the case at least in flightclub.io's model of the mission). Remember that this wasn't a particularly challenging flight profile for Falcon Heavy, which allowed it to boost back to reduce speed and landing distance from shore.

The excessive TEA-TEB use may have been caused by an unrelated engine issue. In any case, Musk reported the fix is 'obvious'.

By my reading, the center core was using three engine burns for more efficient boost-back and re-entry burns. The side cores and typical F9 boosters (afaik) always use single engines for those and occasionally three-engine burns at landing, so three engine-ing all three burns would be 4 more relights than any previous core.

So, an equal number of "relights" of the entire rocket but more engine relights, and engine relights are the relevant unit for ignition fluid consumption.

Boostback and reentry burns are always 3 engines. Landing burns are often 2 engine and often 1-3-1, usually on the drone ship.

The unique part of the GovSat "failed to expend" mission a few weeks ago was not cutting off the outer two engines some time before hitting the surface, not that it used three engines at all.

No, three engine burns are typical for boostback/re-entry. In many of the webcasts you can see the initial round plume turn into a rectangle as the two outboard engines ignite.

This was the original tweet: https://twitter.com/elonmusk/status/963107229523038211 that the article referenced but not linked.

Sure, but that system was in place for all the Falcon 9 relights as well. Presumably there's something different about the FH - minor architectural differences, flight profile, etc. - that caused this previously reliable system to run out.

The center core has a different structural design than the side boosters, which are stock F9 stages AFAIK.

Both of the side boosters were re-used for the Falcon Heavy launch. So stock F9s to some extent.

Core booster reaches higher hypersonic velocities.

Elon mentioned that it’s heavier in the post launch press conference. But of course they would have used that information in their calculations...

Yeah. I guess in space flight you can't just double the calculated requirement. That would be expensive.

Probably not as expensive as losing the entire booster, though.

Expensive as in, if you apply it to everything, the booster doesn't work.


From what I understand, the problem was because the second burn was when the rocket was going tail-first through the atmosphere at hypersonic speed, and much faster than a Falcon 9 booster.

That's a problem because the amount of igniter fluid depends on the air pressure in the rocket chamber, and it was not possible to determine this exactly beforehand through either testing or modeling. So they took a guess and it turned out wrong, but they got lots of data on the rocket chamber pressures, and will adjust accordingly in the future.

Two big aerospace companies ran out of fluid recently. Southwest airlines cancelled basically all their flights from Chicago yesterday because they ran out of Deicing fluid. They can use your same excuse! Something tells me Southwest failed at a much easier task, though.

"Southwest has 'multiple glycol deliveries' scheduled for Monday and expects to resume 'close to normal operations' at Midway, she said."


Interesting, I would have assumed that was a service they just paid the airport for, rather than one the airline handles itself.

Well, it's probably a lot easier to store fluid at an airport than on a rocket

SpaceX fluid issue is likely a calculation / estimation error.

Southwest fluid issue is likely a logistics failure.

I don't see them as related.

I like hearing that the problem is something as (relatively) trivial to solve as this. I know carrying more fuel with the rocket isn't exactly an easy thing to do, but far easier than finding out there's something fundamentally wrong with the design.

SpaceX is amazing and I'm glad they're doing the hard stuff.

It apparently ran out of TEA-TEB ignition fluid, not fuel:


I can't find any info on how much TEA-TEB is carried on-board, only that it's ground supplied for initial launch with the on-board TEA-TEB being used only for restarts.

(I'm not even an amateur rocket scientist: I just googled all this.)

If I'm not mistaken, the SR-71 and A12 had enough TEB for 15 restarts. After doing an aerial refueling, they had to use TEB to get back to afterburner.

They also had to use TEB to re-light after an unstart [1]. I think 15 is abount right but it seems like a very small margin to deal with considering how common unstarts were.

[1]: https://en.wikipedia.org/wiki/Unstart

Once they learned about that they worked around unstarts with software to control the engine spikes to keep the shockwave inside.

Yes, unstarts became less common but they still happened.

I've read about unstarts before and never got the impression that the engine in question stopped. It was the shockwave configuration at the inlet that had to be "restarted"?

Yes I believe that is correct but one consequence of an intake unstart in a J58 is that the afterburner will also stop functioning. I'm not sure what the proper term is when an afterburner stops producing thrust. Maybe flame out?

Regardless, this was the cause of the violent yaw/roll action associated with an unstart (loss of thrust). When the intake was reconfigured the afterburner had to be re-lit and in a J58 this requires TEB. So while TEB was not used to correct the unstart it still had to be used after an unstart.

Which was like a pint and a half. Pretty powerful stuff.

Will it work, though? Is the center-core restart happening under the same conditions as the heretofore successful ones? Is it really a matter of adding more lighter fluid? (That's like The Cable Guy's BBQ advice.) How fast is the wind those rocket nozzles are pointed into?

Supersonic, for a start.

I was under the impression that the center core's re-entry was faster than the previous Falcoln 1st stages.

> about 328 feet from the floating platform

Someone doesn't understand precision.

(That's 100 meters, so "about 300 feet".)

I think it's not exactly 328 feet, so it's about 328 feet.

Equally well could have said "about 328.084 feet".

Hm, I don't know of a rule that specifies how to use the word "about".

To me at least, "about 328 feet" seems okay. It gives you more precision than "about 300 feet" while still letting you know that it's not exactly 328 feet.

The point is that extra precision is unwarranted. We only know that it missed by somewhere between 50 and 149 meters, so it's not appropriate to imply that we know it more precisely.

Ah, didn't notice that. Thanks for clarifying.

328 feet is a unit conversion after already rounding to one significant figure

This discussion reminds me of the time Apple quoted surprisingly precise weights for how much material they recovered through recycling[1]. It turned out the figures were converted from heavily rounded metric numbers.

The best part was that in the websites for some some markets they converted the very precise imperial figure back to metric and claimed something that was close to the original rounded number number but off enough to be extra weird (like 2,999 kg of silver).

[1] https://news.ycombinator.com/item?id=11514106

He also announced the 3rd drone ship's name on twitter as "A Shortfall of Gravitas".

Going all in on the Culture ship names. I'd be happy if he just made 100(ish) more just to name them after every ship that Iain M. Banks named. They don't need to catch rockets, they can just link up and make a floating utopia.

Mistake Not My Current State Of Joshing Gentle Peevishness For The Awesome And Terrible Majesty Of The Towering Seas Of Ire That Are Themselves The Mere Milquetoast Shallows Fringing My Vast Oceans Of Wrath

They don't need to catch rockets, they can just link up and make a floating utopia.

Well for that, you'd want to change the hull type from a barge to a spar buoy. Given that, there's no reason why they couldn't do both.


(Permanent structures in the ocean need to be spar buoys, or some other architecture that are largely immune to Rogue Waves.)

Got any more cool info on permanent ocean structures. Or large ocean structure engineering in general?

That's a great name to add to the stable of Autonomous Spaceport Drone Ships:

- Of Course I Still Love You

- Just Read the Instructions

- A Shortfall of Gravitas

(and doubly great for you, u/ZeroGravitas)

Here's the whole list:


My all-time favorite is "Ultimate Ship the Second".

Minor spoilers, don't read below if you care:

I'm biased by my love for 'The Hydrogen Sonata,' but my favorite will always go to the Mistake Not...

Which is short for Mistake Not My Current State Of Joshing Gentle Peevishness For The Awesome And Terrible Majesty Of The Towering Seas Of Ire That Are Themselves The Mere Milquetoast Shallows Fringing My Vast Oceans Of Wrath.

If they ever start doing regular military missions (or we end up fighting bug-eyed aliens) I hope they add Falling Outside The Normal Moral Constraints. (Edit: Falling, not Operating.)

The 'Gravitas' thing is a running gag across the series. I'm glad they picked up on it.

For those unaware, the name came about when a competing civilization to the Culture complained that the Culture's powerful warships "ought to have names with more gravitas", and the Minds made a joke out of it.

I wonder if the same thing happened here. Maybe Elon saw someone complaining about his irreverent ship naming (both the ASDS and the "BFR") and decided to respond with this.

This is why we compare hard problems to rocket science. It's so hard to recover from failure of even the smallest sources.

but the hip programming tips these days are to move fast and break things!

a rocket certainly moves fast...

It's not like SpaceX didn't break things either: https://www.youtube.com/watch?v=bvim4rsNHkQ.

The real trick is knowing when it's OK to break things in experimentation and the acquisition of knowledge, and when everything needs to run smoothly.

It would have broken a bunch of things if it weren't "about 328 feet" off target, too.

When they said they lost the core, I've been envisioning a barge with a big, round hole in the center...

They intentionally aim off-target, and have the final engine burn steer them back into the landing.

If an engine relight doesn't happen, they won't hit the barge.

I think the biggest danger to the barge is a final engine relight without enough fuel, or with a guidance and nav systems failure or error.

-OT, but related - for the same reason, offshore vessels set their autopilot targets say, half a mile off the oil rig/whatever they are headed for - just in case someone doesn't pay attention as they approach.

I once saw a nice enamelled sign on a bridge stating 'Whoever programs a target on target will be promoted to figurehead prior to arrival at said target.'

(And, in that position, being the first to regret their sloppiness. Plus, they will somewhat soften the impact. Cough.)

Super interesting. Something I wouldn't have ever thought about, but makes perfect sense.

The world is just frighteningly complex, sometimes.

SpaceX have been moving fast and breaking things. It's worked out pretty well for them, even in non-software.

Obviously one of the things you don't want "too much of" is a pyrophoric fluid that you need to dump before you can let people near :-). Have they ever published their safeing procedure? I'm wondering if they recover more volattiles than the old shuttle did after it landed.

It doesn't have as much nasty as Shuttle. The TEA-TEB takes care of itself by combusting when vented, but that's the only hazardous material. Shuttle had hypergolics on board which F9 doesn't use (just kerosene, oxygen, nitrogen, and helium.)

The rest of the passivation will mostly be purging the engines, closing valves, and releasing pressure in the various tanks and vessels. LOX venting might take a while as it all boils off.

Man, TEA-TEB is a hypergolic pair

No, it is not. It's a pyrophoric mixture. It is hypergolic with oxygen.

> The fix, he said, was "pretty obvious."

I've said the same before many software bugs or family computer problems that ended up being all nighters on :P

But I'm sure SpaceX will get through this,,,

Perhaps some rocket scientist can explain why this seemingly-obvious error even happened? Shouldn't it be possible to calculate the precise amount of fuel used, and therefore required?

It's because there are very high penalties for carrying excess weight in aerospace, and the environment is uncontrolled. Imagine trying to calculate how much gasoline you need to drive from A to B which is 1,000 miles away, but for every extra fluid ounce of fuel you have at the end, you have to pay $10,000. You have to deal with varying weather, wind speeds, traffic and so on. How would you do this "precisely"? Let's remind ourselves that this rocket did 99% of its mission successfully, but didn't seal the deal.

They probably used a simple model (and experience) to determine the needed amount. But the model was wrong because, well, it encountered the real world. So they'll adjust in the future. Probably they could have analyzed the heck out of it for years, and gotten it right, but then that would take years and cost buckets.

This reminds me of a phrase: “All models are wrong; Some models are useful”. https://en.m.wikipedia.org/wiki/All_models_are_wrong

Or to quote a Prussian general:

"No plan of operations extends with any certainty beyond the first contact with the main hostile force."

I’m not a rocket scientist, but the Navier-Stokes equations are nasty; the best we can do is model what happens, assuming that we can exactly predict what will happen, which we can’t. Temperature, pressure and humidity of the air the rockets will fall through will not be exactly known, and all will affect how the rocket moves.

And even the best of modeling will not guarantee that reality will behave as predicted. Suspension bridges, for example, often need some ‘tuning’ to remove resonance after construction.

Bridge engineers, knowing that, often won’t even try to spend time and money to exactly predict bridge behavior. This may be similar: they may just have thought it would be faster or easier, maybe even cheaper to do the experiment than to work on exactly modeling their engine.

(The center engine is different from the others, but it also could just be statistics, with the amount they used giving a probability slightly below 1 of igniting one of these engines, and this being their unlucky day (given that they already have quite a bit of data from earlier launches, that is not too likely, but it is something I would let an engineer look at)

I'm not a rocket scientist, but I think I can explain why this happened in a more general probabilistic sense. This error may have been "obvious", but successfully landing a supersonic rocket onto a floating platform probably requires hundreds or thousands of "obvious" things to go exactly right, and if any one of them doesn't, then it explodes. Even assigning a very small probability to each obvious failure mode, compounded together it gives a non-trivial chance that the landing will fail, especially in the maiden launch when there are still lots of "unknown unknowns". If it hadn't been the igniter fluid, it could just as easily have some other "obvious" thing.

Anyway, that's why they do these tests: to make the "unknown unknowns" known.

It's not "fuel" in this case, it's the highly reactive compounds that are used to ignite the engines (TEA/TEB are pyrophoric, so they ignite spontaneously when exposed to air).

The precise amount they'll need depends on how quickly and reliably the engines restart. If the engines take a couple extra shots to light, then you may run out.

In this case they ran out because they were relighting three times as many engines.

No, they have used this profile several times in the past. The past couple droneship landing have used three engines for the landing burn (the outer engines shut down before landing).

The recent "stage that lived" was testing three engines all the way to "0" (which worked fine, apparently).

My guess is the hotter than normal reentry meant the engines were a bit tougher to relight, and they burned through more starter loads than they expected.

Hm, I thought they were doing 1-1-3 in previous situations and 3-3-3 in this one?

I'm not sure what your sequences mean there, almost every boostback and re-entry burn has used three engines (they always light the center engine first, then the outer two).

Most recent droneship landings recently have used three engines for the 'middle' part of the burn, shutting down the other two before actually landing.

The recent GovSat launch tested a three engine burn all the way down (the first time they have tried that, AFAIK).

There was nothing unusual about the number of relights. My guess is the issue was with the difficulty of the relights.

Ah, I thought the outer two were optional and not always used for every landing. Ok, thank you for correcting that.

But didn't put in 3 times as much fuel? Seems like a simple oversight.

It's not quite that simple. So many factors, as well as random chance, affect the quantity of TEA/TEB used that it's virtually impossible to create an accurate prediction. Other comments in this thread mention that they could probably have modeled and tested on the ground until they had a better idea, but that takes a long time and is expensive. Actually launching the thing and learning from that is a much more effective usage of time and money. As someone else ITT quoted George Box "all models are wrong, but some are useful.".

It's traveling at hypersonic velocities when it's first relit. It's also far too large to fit in any wind tunnel to test that situation.

Has anyone seen any updates on how their fairing recovery attempt went?

They had the ship done and seemingly ready back in December - https://imgur.com/gallery/MQcEE

Fairing recovery was asked in the press conference afterward - here's a transcription from r/spacex

Fairing recovery has proven surprisingly difficult. I'm still fairly sure we can do it in the next six months, but the fairing is [not aerodynamic], messes with the parachute... we also have a fairing version 2, much more important than version 1 fairings.... my guess is next six months for fairing recovery. We have the special boat. .....we might even be able to catch the dragon too, if nasa wants to


Based on https://space.stackexchange.com/questions/24990/did-the-fair... it looks like they didn't get it this time.

Isn't the fairing just a simple pair of metal casings. Why bother to recover it?

They're actually huge expensive carbon fiber things. Think "racing yacht hulls", and cost several millions of dollars each. A significant portion of the cost of the whole vehicle.

Plus they're slow to manufacture, so they can increase tempo if they can get them back intact.

I think they cost on the order of magnitude of $1M each.

As I've heard it been put - "Imagine if there was a pallet of $1M in cash falling from the sky. And you knew where and when it would fall. And you'd expect the rate of 'cashfall' to increase to tens, even hundreds of times a year. Would you try to develop a system to catch it?"

Only if the total operational cost of that system would be lower than the amount of cash falling from the sky.

The profit equation is a little bit more complex. Consider that recovered fairings would be used multiple times, not just once each; and the long time to manufacture each new one adds an unwanted scheduling delay.

They look a little more complicated than just a sheet of metal.


Imagine building a shell big enough to hold a school bus, capable of withstanding hypersonic flight through the upper atmosphere, and protecting an extremely delicate payload from outside noise so loud it causes the waveform to clip because the troughs become vacuum.

They’re not quite simple.

No, they are carbon composite.

The fairings are troublesome for several reasons. They have to be very large because they have to be larger than the payload, they have to be very strong because they have to protect the payload through the atmosphere at supersonic speeds, and they have to be very light because they ride on the upper stage, and their weight takes away from payload weight (not quite at a 1:1 ratio but not too far from it). So they are expensive because expensive fairings allow you to launch even more expensive payloads.

And in principle they are not terribly difficult to recover. The re-entry speeds are fairly low since they are only ever sub-orbital, and they are very light for their size so re-entry heating isn't a major challenge. But aerodynamically controlling them in a reliably manner to a precise location seems to be a problem.

In addition to the several million dollar cost of the fairings they represent a production bottleneck - they're carbon composites which take a long time to make and require very expensive tooling. No matter how many reflyable first (and maybe in future, second) stages spacex has in stock, if they can't produce fairings fast enough they cannot go to space.

Aside from the actual costs involved in (lengthy) labour and materials, manufacturing fairings also takes up vast amounts of factory real estate.

The numbers are small compared to the rest of the game, but it's one of those things that would make life so much easier if they could just catch the damned thing.

It's carbon composites, slow to build and about 10% of the total launch cost.

Even being a seemingly simple structure it would still be expensive to build. I'm sure it also contains latching hardware, etc. used to release it. Seeing as it's mostly a static piece if they can get it down in one piece it's probably "trivial" (compared to a full core) to re use it, but it saves money (and junk in the ocean)

Wonder why they dont just leave them in space, could make a good chassis or building block for building bigger space stations

The fairing doesn't get carried to orbit. It's dumped as soon as aerodynamic loads are negligible.

Since the fairing has the same energy requirement as the payload (in energy/kg), it's important to get rid of it the moment it's unnecessary. If they took it to orbit (so they could leave in space), it would drastically cut down payload mass.

First off, they aren't lifted to a stable orbit, that'd cost additional fuel (which'd need more fuel again). They're detached once the air is thin enough that the resistance doesn't cause problems. Secondly, it'd also clutter space further.

About $5 million and long production time.

Musk mentioned that they are about 2 mil each.

They had the Air Force bomb it instead

I thought they bombed the booster, not the fairing.

Oh, my mistake :-)

So, I wonder why the side boosters won't be used again? Was that explained. I'm curious, but I barely have internet on this hill.

I believe the two boosters were previously flown and were of an older block/generation (block 3 and 4 if memory serves me) where they are focusing on block 5 as the final revision and all future Falcon rockets would be this same standard. https://en.wikipedia.org/wiki/Falcon_9#Block_5

So, from that reasoning it might be less that they couldn't fly those rockets again, but that maintaining multiple versions of the rockets might not be in their financial interest. Thanks for the input.

Whoa, so not only were the boosters landed, they were actually reused from previous launches! That's doubly awesome.

Yeah. I'd say even more than double awesome. The falcon heavy launch was super important for Space-X, PR and investment wise. Trusting two used rockets for THAT launch shows real confidence in the re-usability of their rocket tech. Bravo.

They are the older version, so not useful when there are a lot of block 5 versions available.

Is that also why the video feed was not working? SpaceX commentators said it was possibly due to vibration.

The video feed didn't stop working, or if it did, it was only for a brief moment.

If you watch this part of the YouTube stream, after it cuts back to the two hosts there is a monitor at the far right center of the video that shows the continuing camera feed of the drone ship landing pad. Only part of the monitor is visible, but after the smoke clears over the next few minutes you can see the empty pad:


You can also see the surprised reactions of the hosts during these few minutes, and how relieved they were when John Insprucker joined them to wrap things up. It would have been interesting to be a fly buzzing around their earpieces to hear what the producers were telling them!

People have speculated that with everything else in the mission being so spectacularly successful, they wanted the initial news reports to be about that success instead of the one core that failed to land.

Knowing how the news works - "Here's what's wrong with the world today!" - I can sympathize with that.

Although I understand why they would have done that for click-bait news outlets, it did really bother me that they were so slow in revealing what happened. What I like about SpaceX is that they're always been very open about their failures, even compiling that great video of their failures. Being able to seeing the full result would have been nice, and I spent a fair bit of time for the following hours refreshing Twitter.

They weren't only slow about revealing it, they straight-up lied.

Smoke on deck clears, no core visible, deck empty. Both go "oh." and after a pause, while looking at the empty deck: "we're waiting to hear what happens. [...] we'll let you know as soon as we find out" and "we'll [...] know [...] whether it's standing". All while looking at the empty pad.

They saw it didn't land, they found out immediately and didn't let "us" know. Instead they claimed it might be possible it is standing despite seeing the empty deck.

The aftermath of this was the most confusing thing ever. In the screen in the background that they forgot about, right when the smoke clears the crowd started cheering. We also could only see the left half of the barge. It certainly left everyone wondering until the official confirmation.

I don't think any of the boat landings have ever worked live -- only the ones on land.

They've had successful Falcon 9 boat landings....

The rocket plume plays havoc with the data uplink. It happens all the time.

I'm someone who doesn't follow a lot about current aerospace capabilities and technologies. Can someone explain why the work SpaceX is doing is so much more exciting than that of United Launch Alliance or Khrunichev or similar systems?

SpaceX can reliably deliver payloads to orbit at far lower cost than their competition; as they start to re-use vehicles in earnest, that cost will fall even further. Falcon Heavy is now the most powerful rocket in commercial service by a factor of two. Two years ago they were a highly promising competitor; today, they're the market leader.

Khrunichev are out of the game. The old Proton vehicles are cheap, but they're very unreliable due to a barely-modernised 1960s design and poor construction. They flew four launches in 2017, versus SpaceX's eighteen; by all accounts their order book is looking very sparse indeed. Their new Angara vehicle hasn't flown since the first orbital test flight in 2014 and has attracted no real commercial interest.

ULA can't even begin to compete on cost. Without the capability and readiness contract from the US government, they'd be out of the game entirely. They didn't even bother to bid for the GPS-III contract. The SLS won't be ready until next year, it'll only have about 10% more payload capacity to LEO than Falcon Heavy and it'll cost at least three times as much, with no possibility of reuse.

EADS are attracting a good amount of commercial launches, but their competitive advantage is fading rapidly. Ariane 5 is reportedly 3-4x more expensive than Falcon 9 and has less payload capacity to LEO. The planned Ariane 6 will be considerably cheaper than Ariane 5, but it'll have less payload capacity and still won't be price-competitive with Falcon 9. EADS have not announced plans for a heavy launch vehicle.

Blue Origin are chasing SpaceX's tail. The New Glenn vehicle won't begin test flights until 2020, it has less payload capacity than Falcon Heavy, shows no signs of being cheaper and isn't as reusable. Even if everything goes to plan, they'll still be badly trailing behind SpaceX.

Over and above the rocket technology itself, they're pushing the boundaries of what they (SpaceX) and others are capable of constantly - this is because they have a grand vision that they're all working towards that isn't primarily shareholder profits.

I think a lot of the excitement, for myself anyway, is that SpaceX represents the only tangible effort to bring us kicking and screaming into the space exploration age.

All my other "real" points have been covered by other users, but one other thing that SpaceX is doing is making space cool again. I've always found it interesting, and the launch vehicles technically incredible, but (as a university student) it's the first time in my life that current space-related events have been at the front of my mind. Various news outlets called the Falcon Heavy launch the most anticipated launch of the last decade, and I'd agree. In the lecture I was in during the launch, everyone was either watching it on their laptop, or looking over the shoulder of the person in front of them. People were shaking from excitement, and nearly tearing up as the FH lifted off.

SpaceX is putting a huge focus on pricing.

Despite having prices reportedly[1] lower than any newly manufactured rockets[2], they are rapidly approaching parity or superiority on a number of other measurements of quality with other launch organizations.

Basically in the 1960s, it was envisioned that space launches would become routine, but they did not (the "Space Shuttle" was so named as an analogy to shuttle buses that have regular round-trip service). SpaceX is the most successful attempt since then to make it routine.

1: most other launch companies don't advertise prices

2: repurposed ICBMs are historically the cheapest way to space, but see also #1

SpaceX is still the only company to land a real first-stage booster, and the Falcon Heavy was the largest rocket (in terms of payload capacity) to fly since the Saturn V.

false! The energia and the N-1 flow before and they was more powerful that the Falcon Heavy.

From the N-1's wikipedia page:

Each of the four attempts to launch an N1 failed; during the second launch attempt the N1 rocket crashed back onto its launch pad shortly after liftoff and exploded, resulting in one of the largest artificial non-nuclear explosions in human history.

Energia's a more interesting comparison, since it's hard to know if its advertised payload was at all accurate, but it did fly. I'd say that if it could have delivered its advertised payload reliably, the design probably would have flown more than twice and would have survived the fall of the Soviet Union. I have no idea what a half-finished Buran weighs...

Did the N-1 rocket really "fly"?

It flew all the way to the scene of the crash.

Ah, the Chuck Yeager school of flying:

"If you can walk away from a landing, it's a good landing. If you use the airplane the next day, it's an outstanding landing"

The N-1 never worked properly though. And even one of the two Energia launches was not without issues.

Partially it's the new hotness, but also the landings are pretty spectacular and if the economics work out long term (ie SpaceX isn't just burning cash to break into the market with subsidies like Uber does) will significantly reduce the cost of launches compared to the expendable rockets produced by ULA, Khrunichev, et al. Their launches are already significantly cheaper than the others on a per kg basis to LEO and GTO.

Perhaps the most important reason people are so excited about SpaceX is they are planning to colonize Mars, and are busy working on the BFR to to make it possible. NASA also wants to go to Mars, but their plans are way smaller and they many years behind SpaceX.

The exciting innovation that SpaceX promises is lower flight costs by making reusable rockets. This is motivated by the desire to land on mars (which factors into their marketing and recruitment). Many people who work there have issues with work life balance and to work there and the pay is lower than other similar aerospace companies.

In contrast ULA is higher cost but is more reliable. A great deal of their technology is older than SpaceX because they are the incumbent launch platform. They don’t really market themselves the same way due to the fact that they are profitable. The pay I believe is average and has better work life balance than SpaceX.

> Many people who work there have issues with work life balance and to work there and the pay is lower than other similar aerospace companies.

which is really saying something, as a lot of aerospace employers prey on the cool factor of doing space stuff to keep folks working absurd hours, for well under what they'd make doing similarly difficult work elsewhere.

SpaceX is making progress to their goal of airline style reusable rocket.

That engine uses tetraethyl borane (TEB), right? Do they have to first ignite the turbopump and then ignite the main engine?

This is not a definitive answer (a quick googling failed to turn up a solid source), but presumably they have to ignite both the gas generator (that powers the turbopump) as well as the main combustion chamber. You certainly see the green flash of TEA/TEB lighting underneath the rocket (inside the combustion chambers) just before liftoff.

> Those two boosters, which were used in previous launches of SpaceX's workhorse Falcon 9 rocket, will not be reused again, Musk said in a post-launch news conference last week.

Why did SpaceX spend resources to get them to safe landing then? I presume, they rather maintain their routine and maintain the success of landing the booster. It would probably be expensive to change their standard procedure.

Does any know how many times a booster can be resued? What dictates its lifetime?

Titanium grid fins is a big reason they recovered the 2 side boosters. This launch and landing will be used to fine tune their simulation parameters.

The block 5 variant is designed for 10 launches in a row with 24hr turnaround. With service, over 100 launches is the goal.

Wow! that's impressive!

SpaceX has a fairly large collection of graphics cards for simulation purposes see https://www.youtube.com/watch?v=vYA0f6R5KAI and https://www.youtube.com/watch?v=xNqs_S-zEBY

The current version of the rocket is called "block 5". Those two boosters weren't block 5 boosters. Presumably the reason to spend resources to get them to safe landing was to learn things that will be useful in future launches; for example, those two boosters had enough ignition fluid to land successfully this time, but the main first stage did not.

Precisely. "We can afford to lose these ones on a test flight."

That make sense. In that case, wouldn't these boosters be useful in future Falcon Heavy launches? Why can't they be resued?

At this point they're historic artifacts worthy of preservation. Retire them to a museum.

During the news conference after the launch, Elon commented on being really happy to get the upgraded titanium grid fins back from the side boosters:


These are the first two boosters used to launch a Falcon Heavy. They are modified Falcon 9's. They already know much of the wear and tear that Falcon 9's endure in flight from previous launches. They didn't yet know how their boosters are affected by the modifications required, and the stresses involved in launching a Heavy. Now they have two pristine pieces of data they can tear down and analyse for potential improvements.


That, and the best equipment to test out is equipment you know you won't need again in the future.

Case in point: It's much cheaper and less disruptive for them to lose this rocket and fix the issue than to lose a future rocket slated for reuse.

Demonstrating that the system can work as intended is the point of the test, and that includes recovery. The boosters in particular have different aero. Even though these won't be reused, they serve to demonstrate that future vehicles can be.

Probably worth having done just for that beautiful video of the two of them landing together... You want credibility in the marketplace? You just can't buy the things that imagery says about your business/capability.

They are older versions of the boosters, the new Block 5 versions are designed to be re-used many more times.

> Why did SpaceX spend resources to get them to safe landing then?

collect data + parts of the booster can be reused

Recovering the boosters on land is practically free. Landing at sea is less so, but they want to ensure they can recover the center booster in the future, so they probably want to start testing right away so they can find problems like this one before they start losing boosters they actually want to reuse.

They might have plans for them, like they did with this booster: https://en.wikipedia.org/wiki/Falcon_9_booster_B1019

To analyze/test the used boosters, or to put them on display, probably

Probably both, particularly with the main booster now lost.

"This was the pair of boosters used on the historic first flight of X to Y" looks good on a museum plaque.


The good news is it seems like a fairly easy thing to fix going forward. Not really an engineering problem as such, but rather a miscalculation

What is ignition fluid, exactly?

  The fix, he said, was "pretty obvious."
I mean, it's not rocket science, is it? >_>

This is one of the reasons why space travel will never be 'routine'.

A million and one things can go wrong, and any one of them can destroy the spacecraft. Compare that to commercial air travel - where a number of unlikely events have to happen, to down an airplane.

Some time ago, there was a HN discussion about traveling from continent to continent in minutes, using a sub-orbital hop. I don't know about anyone else, but I'll pass on being strapped to a skyscraper filled with LOX and RP-1.

An airliner is on a building scale and carries a slightly less refined petroleum fuel. RP-1 and Jet Fuel are both refined petroleum fuels. Rockets only carry LOX because they go into space where there is no atmospheric oxygen to burn the fuel.

Airliners are fully capable of turning themselves into fireballs. It doesn't happen often because we have a lot of experience operating them. The same safety levels are possible with rockets over time.

> An airliner is on a building scale and carries a slightly less refined petroleum fuel. RP-1 and Jet Fuel are both refined petroleum fuels. Rockets only carry LOX because they go into space where there is no atmospheric oxygen to burn the fuel.

That's true, but a 747 does not burn its weight in fuel in 397 seconds. A Falcon 9 does. It's the difference between igniting a gas barbecue in your back yard, and igniting the propane tank that feeds it. One of those things is something I do on the 4th of July. For the other, I'd prefer to be taking cover in a foxhole.

> Airliners are fully capable of turning themselves into fireballs. It doesn't happen often because we have a lot of experience operating them. The same safety levels are possible with rockets over time.

It's also because the possible margins for safety with airplanes are much higher. You can engineer redundant systems, and overbuild, because you aren't fighting the tyrrany of the rocket equation.

There is no one thing that can go wrong on a 747 that will down the aircraft. The dozen SpaceX launch/landing failures were almost all due to 'one thing went wrong, there went $60-100m USD.'

Incidentally, most other catastrophic launch failures (Including ones that claimed lives) were also due to 'one particular thing went wrong, everyone died.'

Rocket engineers aren't stupid, there's a reason that rockets don't have the amount of rendunancy and capability for failure recovery that a commercial airliner does.

> There is no one thing that can go wrong on a 747 that will down the aircraft.

C'mon, that's demonstrably false.

https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981 involved a poorly sealing latch.

https://en.wikipedia.org/wiki/Japan_Airlines_Flight_123 involved a single poorly repaired bulkhead.

https://en.wikipedia.org/wiki/TWA_Flight_800 may have been a spark in the fuel tank.

Plenty of other examples on https://en.wikipedia.org/wiki/Category:Airliner_accidents_an...

> the tyrrany of the rocket equation

It's actually not that bad for suborbital flights. You can overbuild by a lot.

One big flaw in your argument is that the payload was delivered safely and successfully. They're making great strides towards making components reusable when they never really were before. That they're not perfect right out of the gate isn't reason to give up hope it ever could be.

Actually...the payload was put on the wrong trajectory, so OP's argument still stands.

"Elon Musk’s cherry red Tesla sports car and its dummy test pilot Starman were on a new course hurtling towards the asteroid belt on Wednesday after overshooting their planned trajectory."


The mission was not intended to get the Tesla to Mars. It was to get it into an orbit that showed that they could get it to Mars. Getting it to Mars itself would have required more careful scheduling of the mission, and would have run the risk of needlessly polluting the planet with debris and earth bacteria. The actual results however showed they could get a mass that size into a heliocentric orbit with Mars.

If Earth and Mars were in the right places then with the right payload they could have gotten to Mars itself.


That is bad reporting. SpaceX always planned to burn the 2nd stage until it ran out of fuel.

Elon always said they weren't sure exactly what the final trajectory was, just that the roadster would be sent out as far as possible.

They weren't sure how much O2 would boil off during the 6-hour coast after launch before it departed orbit. That was part of the test.

Also, they weren't heading towards mars - just outwards towards mars orbit. When the roadster crosses mars orbit mars itself will not be nearby. If they wanted to actually reach mars they would have had to launch during a specific launch window when earth and mars lined up at the correct angle. This happens once every couple of years.

That's not at all a mistake. Any sort of overshoot is extremely unlikely to occur with these situations. The public plan was to put it into an orbit around the sun with the perihelion near Earth's orbit and its aphelion near Mars's. Using the additional remaining fuel, they decided to burn until the aphelion reached well past mars towards the asteroid belt.

Guardian is wrong to use "overshoot" as though it was a mistake - it was a burn to exhaustion, the exact limits of which was unknown beforehand (because it was unknown how well the fuel in the second stage would survive the time in higher orbit. Kerosene starts turning to sludge in cryo). Mars-orbit-distance was the lower end of what was expected.

There were plenty of accidents in the the first couple decades and first couple thousand plane flights. Even in the 1970s, airliner crashes were a fairly regular occurrence - they've been made extremely safe by a robust culture of crew training and safety regulation, plus a hundred thousand flights PER DAY worth of practice.

A million and one things can happen to airplanes as well. We have learned about them, sometimes at the cost of lives. This is how we arrived at the current level of redundancy and maturity in safety procedures. Not to mention regulation and enforcement.

The energies involved are much greater, that's for sure. This will require more engineering effort.

But "never" is too strong a word. There is no good reason why we can't master this.

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact