Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

SpaceX Falcon rocket explodes on landing after delivering satellite to space

bbc.com

Post reply on HN
Print view View original

21–30 of 216 posts

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#21

Post by mabbo »

jaffee wrote: post #11

I want to know what exploded - I wouldn't have expected it to have very much leftover fuel at that point...

If you put a spark inside a full gas/petrol can, not much happens. Not enough oxygen. Half full? Still not such a big deal.

But empty the can, leaving behind just the fumes and the oxygen, and you have yourself a bomb.

My understanding is that the rocket here is a similar problem. It's a giant tube of explosive material. I wouldn't want to tap it with a hammer. And they've got it falling to earth at supersonic speeds, then calmly setting itself down on a barge at sea in 3m waves.

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#22

Post by mikeash »

jaffee wrote: post #11

I want to know what exploded - I wouldn't have expected it to have very much leftover fuel at that point...

Here's a couple of examples of what it looks like when a rocket explodes when it's still full of fuel:

https://youtu.be/NCWunnJXdm0?t=180

https://youtu.be/Zl12dXYcUTo?t=32

Then compare to this dinky little explosion.

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#23

Post by mrfusion »

mabbo wrote: post #21
jaffee wrote: post #11

I want to know what exploded - I wouldn't have expected it to have very much leftover fuel at that point...

If you put a spark inside a full gas/petrol can, not much happens. Not enough oxygen. Half full? Still not such a big deal. But empty the can, leaving behind just the fumes and the oxygen, and you have yourself a bomb. My understanding is that the rocket here is a similar problem. It's a giant tube of explosive material. I wouldn't want to tap it with a hammer. And they've got it falling to earth at supersonic speeds…

It fills with helium as it empties out the fuel.

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#24

Post by mikeash »

NikolaeVarius wrote: post #7
madaxe_again wrote: post #4

a) isn't this from last year? IIRC they had two failed barge landings. This looks like the first one. b) The headline makes this sound like a miserable failure - still beats "fell into the ocean never to be found again", as all other current first stages do.

Its a failure because it didn't do what it is supposed to do. Current first stages do exactly what they are supposed to do extremely well.

It did exactly what it was supposed to do: deliver the second stage to the right place and velocity, and attempt a landing.

The landing failed, but it's part of a test program, failures are supposed to happen.

They got paid ~$90 million for this flight, and the customer is happy because they got exactly what they paid for.

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#25

Post by bantunes »

Could someone explain to me why they attempt this? Wouldn't inflating a set of floating devices when it goes down the ocean an easier way of retrieving it? Or something other than this REALLY HARD TO PULL OFF maneuver? Genuinely interested.

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#26

Post by kardos »

JoeAltmaier wrote: post #10

Speaks volumes for Mr. Musk's character that they're being completely open and honest about this problem. Turns the conversation from "What happened? What are they hiding?" to "Interesting Engineering problem. How can it be addressed?"

They don't have much in the way of competition to keep 'trade secrets' from

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#27

Post by CarolineW »

jaffee wrote: post #11

I want to know what exploded - I wouldn't have expected it to have very much leftover fuel at that point...

    ... the first stage of Falcon 9 v1.1 is
    capable of holding 119,100 Kilograms of
    Rocket Propellant 1 and 276,600 kg of
    Liquid Oxygen.
(From http://spaceflight101.com/spacerockets/falcon-9-v1-1-f9r/ )

So even if it's 99.9% empty, it still can have 120 kgs of rocket fuel. That'll go with a bang.

And it's unlikely to land with only 0.1% of its fuel left - that margin is too small to be attempting a soft landing, so I'd expect it to be a lot more. Then compare with just 5 gallons (probably US gallons, about 19 liters, close to 17 or 19 kgs) of ordinary gasoline:

* https://www.youtube.com/watch?v=C72bv2YhZ6A

* https://news.ycombinator.com/item?id=10924521

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#28

Post by dchesterton »

bantunes wrote: post #25

Could someone explain to me why they attempt this? Wouldn't inflating a set of floating devices when it goes down the ocean an easier way of retrieving it? Or something other than this REALLY HARD TO PULL OFF maneuver? Genuinely interested.

They want to use this tech to eventually land rockets on other planets so the rocket needs to be able to land upright. Short term it might be easier to land on inflatables but they're looking at the bigger picture.

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#29

Post by Medox »

The landing could be made safer by something like cushioned walls that deploy towards the rocket after touchdown, to avoid such explosions. Think of a giant Christmas Tree stand like this: http://www.christmastreeland.co.uk/product_images/v/428/761_.... but with cushioned hooks on the barge. You can't always hope for all 4 legs to be in perfect condition, or that there aren't high waves in the ocean. That rocket is huge and seems to fall too easily, while a stand with hooks can't be too expensive, unlike a complete new rocket...

Re: SpaceX Falcon rocket explodes on landing after delivering satellite to space

#30

Post by Grue3 »

bantunes wrote: post #25

Could someone explain to me why they attempt this? Wouldn't inflating a set of floating devices when it goes down the ocean an easier way of retrieving it? Or something other than this REALLY HARD TO PULL OFF maneuver? Genuinely interested.

Yeah, I don't understand why they won't keep landing them on the ground like everyone else does. It's not like there's not enough space on Earth.
Post reply on HN