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Cool video! Just what we've been waiting to see. I wonder what actually exploded there? Part of the argument for why the landing was supposed to be relatively

by ufmace 12y ago

Cool video! Just what we've been waiting to see. I wonder what actually exploded there? Part of the argument for why the landing was supposed to be relatively safe was that the stage would be mostly empty of fuel by the time that it landed, so there wouldn't be much to explode if something went wrong. So is that an explosion of the remaining fuel in the rocket, or something on deck?

delinka 12y ago
I figured it was just the automatic aperture on the camera causing the flame to simply appear bigger. I'd point out that the sound didn't change (no boom) but then maybe the mic was already clipping. Still, I'd like more detail to be certain whether something exploded. Edit: no, you're right. I just mis-remembered. When I reviewed the video, it looks like the thing breaks open and I'd suspect the last remnants of fuel are spilling out.
geerlingguy 12y ago
It doesn't take much to make the kind of explosion you see in the video (those chemicals are quite volatile). I think the safety comes from that being the extent of the explosion. Compare that to a fully-fueled stage, which would have 90x more fuel, a 90x larger fireball, shock wave, etc. The deck of the ship almost looked undamaged!
- Sammi 12y ago
  Images of the barge post explosion here: http://spaceflightnow.com/2015/01/11/photos-spacexs-rocket-landing-platform-back-in-port/ http://spaceflightnow.com/2015/01/11/photos-spacexs-rocket-l...
TheLoneWolfling 12y ago
"Mostly" != "entirely". Also, don't forget the rocket engine itself My guess would be the explosion was of the remaining fuel in the rocket engine and tank. Either that or it wasn't actually an explosion, just burning fuel-air mix spewing about after the rocket nozzle deformed too much.
terravion 12y ago
That was pretty small and safe as rocket explosions go. Launch pad explosions with a full load of fuel and oxidizer are huge and would have engulfed the whole ship in flames.
ramidarigaz 12y ago
From this tweet, it looks like it was the residual fuel: https://twitter.com/elonmusk/status/555980855537975296 https://twitter.com/elonmusk/status/555980855537975296
gizmo686 12y ago
You need some margin for error to assure that you have enough fuel during the last fuel seconds to hit the marge at a safe speed, this means that there will likely be some fuel left over. In terms of a rocket exploding, that explosion seemed tiny. Compare it to the Antares [1], which exploded just a few seconds after launch. [1] https://www.youtube.com/watch?v=jHMmMgdcOSU https://www.youtube.com/watch?v=jHMmMgdcOSU
- johntb86 12y ago
  Another example is https://www.youtube.com/watch?v=a3BB8SsIEtA https://www.youtube.com/watch?v=a3BB8SsIEtA , though even in that case the launch ship wasn't too damaged.
ChuckMcM 12y ago
Not easy to do with Vine's crappy interface but if you step through it and stop you will see that the rocket is decelerating and when it gets close to the platform it adds thrust which then increases its pitch over (which would be expected without anything on the top to control pitch) and then it increases thrust still more (presumably to right itself) but the back end of the stage is already below deck level at that point. It comes across the back of the barge and clips the engine section which separates the engines from the fuel supply. The fuel and oxidizer continues coming out and burns rapidly. That ends up tossing the remains of the rocket off the screen to the left. We can't tell of course from the video if the barge was moving (by virtue of the camera being fixed to the barge it makes it appear to be unmoving in the video). If you are reading this SpaceX, here is my suggestion for capturing more data in future flights. Install quad copters on the barge which launch once the barge detects the landing stage is inbound, have them position themselves using the GPS from the barge 100 yards out in four directions. Then have four reference lights on the corners of the barge (can be LEDs) to give you the ability to back compute angles from the video. Stream video from the quad copters back to a secure video storage facility in the barge which is designed to withstand rapid disassembly of the barge and float. Could make for some awesome videos too.
- Florin_Andrei 12y ago
  > If you are reading this SpaceX, here is my suggestion for capturing more data in future flights. Install quad copters on the barge which launch once the barge detects the landing stage is inbound I'm sure they will do that - once the landings become predictably successful.
- narag 12y ago
  I've been watching an old scifi series this days, called Starhunter. They had that obvious (but unusual) concept of drones that gripped on prey and delivered it to the mothership.
jccooper 12y ago
That's not much of an explosion; you can tell by the barge still being there. For a real exploding rocket (of a similar class), see: http://www.youtube.com/watch?v=BSr4hUcROwo&t=3m42s http://www.youtube.com/watch?v=BSr4hUcROwo&t=3m42s A landing stage will still have some fuel and oxidizer on board, to keep burning all the way to the deck, though not much compared to when full. But 1% of ~385,000kg of propellant is still enough to go bang. There's also a fair bit of energy in the pressurized tanks. (It's a turbo-pump engine, so the tanks are not kept at high pressure, but they still have 3-5 bar/40-70 psi and it's 70m tall structure.) That's what tears the stage apart. Looks like it hit the fuel tank, so the pressurized kerosene was exposed to the atmosphere and a burning engine. Thus fireball. It would have been worse were the LOX tank ruptured at the same time. But it's not a very big explosion; doesn't even overexpose the camera for more than a frame.
Florin_Andrei 12y ago
> I wonder what actually exploded there? The last few teaspoons of fuel it had left.
ggonweb 12y ago
This is the tweets by Elon Musk on this "Tks. Turns out we recovered some impact video frames from drone ship. It's kinda begging to be released…" " Before impact, fins lose power and go hardover. Engines fights to restore, but …" "Rocket hits hard at ~45 deg angle, smashing legs and engine section" "Residual fuel and oxygen combine " "Full RUD (rapid unscheduled disassembly) event. Ship is fine minor repairs. Exciting day!" "Next rocket landing on drone ship in 2 to 3 weeks w way more hydraulic fluid. At least it shd explode for a diff reason." https://twitter.com/sacca/status/556107612396457984 https://twitter.com/sacca/status/556107612396457984 https://twitter.com/elonmusk/status/555980855537975296 https://twitter.com/elonmusk/status/555980855537975296
- grecy 12y ago
  I love the acronym RUD (Rapid Unscheduled disassembly) Is there ever a RSD (Rapid Scheduled disassembly) ?
  - Gravityloss 12y ago
    Staging.

by ufmace 12y ago

delinka 12y ago

I figured it was just the automatic aperture on the camera causing the flame to simply appear bigger. I'd point out that the sound didn't change (no boom) but then maybe the mic was already clipping. Still, I'd like more detail to be certain whether something exploded. Edit: no, you're right. I just mis-remembered. When I reviewed the video, it looks like the thing breaks open and I'd suspect the last remnants of fuel are spilling out.

geerlingguy 12y ago

It doesn't take much to make the kind of explosion you see in the video (those chemicals are quite volatile). I think the safety comes from that being the extent of the explosion. Compare that to a fully-fueled stage, which would have 90x more fuel, a 90x larger fireball, shock wave, etc. The deck of the ship almost looked undamaged!

Sammi 12y ago
Images of the barge post explosion here: http://spaceflightnow.com/2015/01/11/photos-spacexs-rocket-landing-platform-back-in-port/ http://spaceflightnow.com/2015/01/11/photos-spacexs-rocket-l...

TheLoneWolfling 12y ago

"Mostly" != "entirely". Also, don't forget the rocket engine itself My guess would be the explosion was of the remaining fuel in the rocket engine and tank. Either that or it wasn't actually an explosion, just burning fuel-air mix spewing about after the rocket nozzle deformed too much.

terravion 12y ago

That was pretty small and safe as rocket explosions go. Launch pad explosions with a full load of fuel and oxidizer are huge and would have engulfed the whole ship in flames.

ramidarigaz 12y ago

From this tweet, it looks like it was the residual fuel: https://twitter.com/elonmusk/status/555980855537975296 https://twitter.com/elonmusk/status/555980855537975296

gizmo686 12y ago

You need some margin for error to assure that you have enough fuel during the last fuel seconds to hit the marge at a safe speed, this means that there will likely be some fuel left over. In terms of a rocket exploding, that explosion seemed tiny. Compare it to the Antares [1], which exploded just a few seconds after launch. [1] https://www.youtube.com/watch?v=jHMmMgdcOSU https://www.youtube.com/watch?v=jHMmMgdcOSU

johntb86 12y ago
Another example is https://www.youtube.com/watch?v=a3BB8SsIEtA https://www.youtube.com/watch?v=a3BB8SsIEtA , though even in that case the launch ship wasn't too damaged.

ChuckMcM 12y ago

Not easy to do with Vine's crappy interface but if you step through it and stop you will see that the rocket is decelerating and when it gets close to the platform it adds thrust which then increases its pitch over (which would be expected without anything on the top to control pitch) and then it increases thrust still more (presumably to right itself) but the back end of the stage is already below deck level at that point. It comes across the back of the barge and clips the engine section which separates the engines from the fuel supply. The fuel and oxidizer continues coming out and burns rapidly. That ends up tossing the remains of the rocket off the screen to the left. We can't tell of course from the video if the barge was moving (by virtue of the camera being fixed to the barge it makes it appear to be unmoving in the video). If you are reading this SpaceX, here is my suggestion for capturing more data in future flights. Install quad copters on the barge which launch once the barge detects the landing stage is inbound, have them position themselves using the GPS from the barge 100 yards out in four directions. Then have four reference lights on the corners of the barge (can be LEDs) to give you the ability to back compute angles from the video. Stream video from the quad copters back to a secure video storage facility in the barge which is designed to withstand rapid disassembly of the barge and float. Could make for some awesome videos too.

Florin_Andrei 12y ago
> If you are reading this SpaceX, here is my suggestion for capturing more data in future flights. Install quad copters on the barge which launch once the barge detects the landing stage is inbound I'm sure they will do that - once the landings become predictably successful.
narag 12y ago
I've been watching an old scifi series this days, called Starhunter. They had that obvious (but unusual) concept of drones that gripped on prey and delivered it to the mothership.

jccooper 12y ago

That's not much of an explosion; you can tell by the barge still being there. For a real exploding rocket (of a similar class), see: http://www.youtube.com/watch?v=BSr4hUcROwo&t=3m42s http://www.youtube.com/watch?v=BSr4hUcROwo&t=3m42s A landing stage will still have some fuel and oxidizer on board, to keep burning all the way to the deck, though not much compared to when full. But 1% of ~385,000kg of propellant is still enough to go bang. There's also a fair bit of energy in the pressurized tanks. (It's a turbo-pump engine, so the tanks are not kept at high pressure, but they still have 3-5 bar/40-70 psi and it's 70m tall structure.) That's what tears the stage apart. Looks like it hit the fuel tank, so the pressurized kerosene was exposed to the atmosphere and a burning engine. Thus fireball. It would have been worse were the LOX tank ruptured at the same time. But it's not a very big explosion; doesn't even overexpose the camera for more than a frame.

Florin_Andrei 12y ago

> I wonder what actually exploded there? The last few teaspoons of fuel it had left.

ggonweb 12y ago

This is the tweets by Elon Musk on this "Tks. Turns out we recovered some impact video frames from drone ship. It's kinda begging to be released…" " Before impact, fins lose power and go hardover. Engines fights to restore, but …" "Rocket hits hard at ~45 deg angle, smashing legs and engine section" "Residual fuel and oxygen combine " "Full RUD (rapid unscheduled disassembly) event. Ship is fine minor repairs. Exciting day!" "Next rocket landing on drone ship in 2 to 3 weeks w way more hydraulic fluid. At least it shd explode for a diff reason." https://twitter.com/sacca/status/556107612396457984 https://twitter.com/sacca/status/556107612396457984 https://twitter.com/elonmusk/status/555980855537975296 https://twitter.com/elonmusk/status/555980855537975296

grecy 12y ago
I love the acronym RUD (Rapid Unscheduled disassembly) Is there ever a RSD (Rapid Scheduled disassembly) ?
- Gravityloss 12y ago
  Staging.