A SpaceX Falcon 9 rocket has exploded at Cape Canaveral • Hacker News Board

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#371

Post by exDM69 » Thu, Sep 01, 2016, 7:58 PM UTC

Animats wrote: post #324

trothamel wrote: post #228

Here's good video of the test/failure: https://www.youtube.com/watch?v=_BgJEXQkjNQ#t=1m10s

No sign of a fire extinguishing or pad deluge system, such as NASA had for the shuttle. Maybe Space-X needs that. Fire crews can't approach until the fire burns itself out - too toxic.

> Fire crews can't approach until the fire burns itself out - too toxic.

You're thinking of hypergolic propellants like hydrazine and nitric acid. This is kerosene (RP-1) and liquid oxygen. Not particularly toxic, just hot as hell.

The deluge system in shuttle launches was for the flame trench and sound dampening to avoid the air pressure from the noise damaging the vehicle, not fire extinguishing.

You can see the launch tower get charred black, that's the fire protective paint.

It's not really possible to fight rocket fuel fires, just mitigate the damage.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#372

Post by TrevorJ » Thu, Sep 01, 2016, 7:59 PM UTC

angryspacesheep wrote: post #343

Tuna-Fish wrote: post #148

Earlier quoted context omitted.

They chill the fuel and oxidizer to slush, just above their freezing point, to fit more of it into the same volume and save on structure.

How many Falcon 9s have been launched using this fueling method?

At least the last two launches, off the top of my head.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#373

Post by npiazza83 » Thu, Sep 01, 2016, 8:01 PM UTC

stcredzero wrote: post #216

rattray wrote: post #210

Earlier quoted context omitted.

> Even if somehow your crackpot theory had merit We try to avoid that kind of tone here, regardless of the merits of anyone's comments.

However, the adjective is an accurate measure of the theory's merit.

Don't like it? Send an email to hn@ycombinator.com

"Tone" policing on HN is getting a bit ridiculous.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#374

Post by TrevorJ » Thu, Sep 01, 2016, 8:01 PM UTC

dogma1138 wrote: post #222

dandelany wrote: post #205

Earlier quoted context omitted.

On the contrary, venting LOX is very common and easily visible in the lead-up to nearly every Falcon 9 launch. Google "falcon 9 lox vent" for plenty of videos/photos.

The "venting" you usually see isn't LOX, it's condensed water vapor, there are small bleeder valves in the LOX tanks and the fuel line but they are not designed or used for emergency pressure relief.

They definitely do vent LOX boiloff.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#375

Post by jhayward » Thu, Sep 01, 2016, 8:02 PM UTC

rst wrote: post #334

Animats wrote: post #324

Earlier quoted context omitted.

No sign of a fire extinguishing or pad deluge system, such as NASA had for the shuttle. Maybe Space-X needs that. Fire crews can't approach until the fire burns itself out - too toxic.

The point of those systems was to limit damage from vibration and rocket exhaust on a normal launch, not to allow the pad to withstand an explosion. (And SpaceX does have them as well; the pad deluge system is more visible than usual in this video of the Dragon pad-abort test, which was conducted at the same launch pad they use for Falcon 9s, though without the rocket itself or any of its mobile support equipment: ht…

> The point of those systems was to limit damage from vibration and rocket exhaust

It is important to note that the deluge functioned to protect the launch vehicle from sound vibrational damage, not the pad.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#376

Post by TrevorJ » Thu, Sep 01, 2016, 8:04 PM UTC

mikeknoop wrote: post #306

ygra wrote: post #56

Earlier quoted context omitted.

About the same as you debug an issue from having just a tracelog. The rocket and pad equipment have quite a few sensors that record information, so you have quite a lot of data afterwards to spot anomalies (you could also compare to previous successful launches / static fires to spot them). Admittedly, that doesn't really explain how they figure out some stuff, e.g. with CRS-7 the problem was with a strut holding a h…

I don't recall the source, but they identified the CRS-7 strut by using several mechanical vibration sensors placed on various parts of the rocket. The deflection / explosion reaches the sensors at different times, and with precision timing, it enables you to reverse pinpoint where it must have originated: the failing strut.

they also have pressure sensors in the tanks so the timing of pressure differences allowed them to determine that the tank came loose before it burst.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#377

Post by Florin_Andrei » Thu, Sep 01, 2016, 8:04 PM UTC

anigbrowl wrote: post #272

Florin_Andrei wrote: post #270

Earlier quoted context omitted.

It's pretty easy to mate an interchangeable lens camera (DSLR, Micro Four Thirds, etc) with a small telescope. There are standard adapters for it. That basically gives you the telephoto lens to rule all telephoto lenses.

I know, I've done it. It's beautifully clear for a 5km throw though.

Seeing conditions must cooperate also.

The shot is totally within the capabilities of a 200 mm Schmidt–Cassegrain in good seeing, which is not very bulky and could sit comfortably on a medium-to-large size tripod.

The theoretical linear resolving power of that aperture at 5 km is 12 mm. But in practice it will be several times worse.

This is all napkin-based math, I've no clue what optics were used for the shot. Might have been a compact 150 mm apochromat refractor - still capable of enough theoretical resolution, and possibly a more popular option (though more expensive) in practice.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#378

Post by dpcx » Thu, Sep 01, 2016, 8:04 PM UTC

0xffff2 wrote: post #115

627467 wrote: post #104

For those overthinking about the loss of the payload: Contact (1997): "First rule in government spending: why build one when you can have two at twice the price?" I'd argue: at less than twice the price.

I don't understand what the quote has to do with this at all. It's neither a government payload, nor AFAIK do they have a second satellite. Maybe I'm overthinking your comment.

You are. :)

The comment was essentially stating that Facebook should have built two of the satellites, as a contingency plan. Rocket science is hard. Having a backup is easier.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#379

Post by riboflava » Thu, Sep 01, 2016, 8:04 PM UTC

psahabu wrote: post #245

matt-attack wrote: post #191

Earlier quoted context omitted.

> using a fallacy does not make them automatically wrong I thought that is precisely what using a fallacy makes you. It's what the word fallacy means. It essentially means a "false statement".

This line of reasoning is itself a fallacy. http://www.fallacyfiles.org/fallfall.html

Furthermore there are other forms of reasoning than pure deduction. If you allow probabilistic inference, which is how humans generally operate intuitively, many deductive fallacies turn into probabilistic theorems.

Re: A SpaceX Falcon 9 rocket has exploded at Cape Canaveral

#380

Post by Nelson69 » Thu, Sep 01, 2016, 8:06 PM UTC

phonon wrote: post #277

dogma1138 wrote: post #199

Earlier quoted context omitted.

The design might be the "easy" part, these are 6 tons of one off highly specialized components with a huge lead time. Each component is custom and built for order by a contractor the lead time on some of them can be years simply because there aren't that many companies that design and build space systems. That combined with the fact that they need to go to each subcontractor and ask them to bid again after Spacecom f…

> there is no way the insurance payout is anywhere near the actual cost of the satellite Why not?

I'm 15 years removed from the TV biz, but I vaguely remember 'birds' costing like $350m to launch, something like $200m + for the hardware, then $150m for launch fees and misc pre-launch insurances. In some cases, I want to say they insured them before taking possession of them, like if some guy at Lockheed has a bad day and drops a wrench on exactly the wrong part, you're looking at a substantial delay which could substantially impact business. Companies would talk up these satellites to investors for years before they launched, hard to imagine them not being completely insured up in to space. Then there was launch insurance and I think it included operations in many cases, TV birds had a lifetime of like 7 years and the operational insurance paid out if they had a certain amount of failure before the lifetime was up, transponders die and they need to spend fuel periodically to keep them in place when the fuel is gone the bird is done. I want to say the launch and ops insurances were like another $100m to $150m. All told you were in for half a billion to get in in to place and that's not including the lease on the slot of sky... I'm pretty sure Echostar was involved in some lawsuits about it and there are probably some public details that came out of that; maybe they wanted to claim more damages than the insurer wanted to cover or something like that and then no insurers wanted to sell them operational insurance.

It's not cheap but if that's your business you absolutely insure it. It's not cheap though. Would investors let you get away not insuring one? Rockets not making it in to space isn't uncommon.