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Merged SpaceX’s Starship Rocket Explodes After Launch/Starship hop

smartcooky said:
Two during space operations

24 April 1967: The astronaut aboard Soyuz 1m Vladimir Komarov dies when his parachute failed

30 June 1971: The crew of Soyuz 11, Georgy Dobrovolsky, Viktor Patsayev and Vladislav Volkov, died from lack of oxygen after a cabin vent valve opened during separation from the Salyut 1 space station

They also had numerous other fatal accidents including the massive explosion of a Vostok rocket that killed 48 people in 1980, and the earlier Nedelin Disaster in October 1960 where the second stage of an R-16 rocket ignited on the launch pad killing up to 300.
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Yikes. I had never heard of those launchpad deaths.

It all seems kind of dangerous to me.
 
Belz... said:
That's why it's generally -- but not always -- suggested to not stay on the launch pad when the rocket goes off.
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But being a passenger on the landing pad when the rocket lands is pretty much inevitable. My impression is that SpaceX soft landings pose much more of a danger than launchings. Why the recent stress on launch in this thread is baffling.
 
GlennB said:
But being a passenger on the landing pad when the rocket lands is pretty much inevitable. My impression is that SpaceX soft landings pose much more of a danger than launchings. Why the recent stress on launch in this thread is baffling.
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Sorry I can't hear you. I've been on the pad at too many launches.
 
Belz... said:
That's a very good point.
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Thanks! :)
But as I said, fundamentally, the last thing you want your rocket to do is explode. It's not a small matter. If I were the CEO of that company I wouldn't be happy with yesterday's events.
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Well, there's happy and then there's happy, I guess. You're definitely right that it would be better if the thing didn't explode. I think they're at the point now where they don't really know enough about what they're doing to expect them not to explode (Musk was saying as much at least before SN9, I think). Getting the thing to turn over for the bellyflop maneuver was already a big deal, as I understand it, so focusing on that and working on perfecting the other aspects of landing on later iterations makes sense to me.

But I definitely agree that everyone at SpaceX would have been a lot happier with an unmitigated success and no explosion. I would too! :D

I'm only saying that incremental progress is still progress, and as far as I can tell it seems like they're progressing about as fast as they expected to. I think the people at SpaceX out to be pretty happy about that, given the difficulty of what they're trying to achieve.
 
GlennB said:
But being a passenger on the landing pad when the rocket lands is pretty much inevitable. My impression is that SpaceX soft landings pose much more of a danger than launchings. Why the recent stress on launch in this thread is baffling.
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That's a good point. The difficultly of launching rockets safely enough for commercial passenger flights is pretty high, but landing them again in the way SpaceX does at least seems to be even harder.

Not to say they can't achieve it, but yeah it's a very difficult undertaking.

One thing that I think will help is if they can get enough rockets flying for other purposes first to really work out the issues with it. If you're launching hundreds of times/year (without passengers), you have plenty of chances to find the problems that might come up and fix them.
 
Roboramma said:
That's a good point. The difficultly of launching rockets safely enough for commercial passenger flights is pretty high, but landing them again in the way SpaceX does at least seems to be even harder.

Not to say they can't achieve it, but yeah it's a very difficult undertaking.
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Quite. The shuttles were amazingly cool, but they turned out to be not cost-effective. I'm not sure yet that reusable rockets will be better in that department.
 
GlennB said:
But being a passenger on the landing pad when the rocket lands is pretty much inevitable. My impression is that SpaceX soft landings pose much more of a danger than launchings. Why the recent stress on launch in this thread is baffling.
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Care to elaborate on why you think that?
 
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RecoveringYuppy said:
When would passengers experience this kind of landing?
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Isn't that the plan with Starship? Or is the idea still that Starship would launch with a Dragon capsule as payload which can then do reentry on its own?

That probably does make more sense, and even if it's not the plan now, it could be done that way if landing can't be made reliable enough for human safety.

(I apologize for not looking this up myself, my VPN subscription expired and I've yet to renew it, which means I'm currently stuck behind the Chinese firewall, so no google, or wikipedia...)
 
Roboramma said:
Isn't that the plan with Starship? Or is the idea still that Starship would launch with a Dragon capsule as payload which can then do reentry on its own?

That probably does make more sense, and even if it's not the plan now, it could be done that way if landing can't be made reliable enough for human safety.

(I apologize for not looking this up myself, my VPN subscription expired and I've yet to renew it, which means I'm currently stuck behind the Chinese firewall, so no google, or wikipedia...)
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Other than the Dragon capsule, I'm not sure of the details of what they have in mind for passengers.

I haven't been paying enough attention to this recently, so let me ask some stupid questions. SN10 was a test of the first stage, correct? I think there are only 3 Raptor engines in this vehicle and I think the full two stage configuration would have six. This was testing the recovery of the first stage, wasn't it? If this had been a real flight the passengers would have been on the second or third stage and it wouldn't matter that their first stage had exploded long after they were done with it.
 
RecoveringYuppy said:
Other than the Dragon capsule, I'm not sure of the details of what they have in mind for passengers.

I haven't been paying enough attention to this recently, so let me ask some stupid questions. SN10 was a test of the first stage, correct? I think there are only 3 Raptor engines in this vehicle and I think the full two stage configuration would have six. This was testing the recovery of the first stage, wasn't it? If this had been a real flight the passengers would have been on the second or third stage and it wouldn't matter that their first stage had exploded long after they were done with it.
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No - this was testing of the second stage of the two stage rocket. They've got a couple of first stage boosters under construction.
 
RecoveringYuppy said:
I haven't been paying enough attention to this recently, so let me ask some stupid questions. SN10 was a test of the first stage, correct?
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No, SN10 is not even remotely like any of the Starship stages, although it looks similar in shape to what the second stage is expected to look like. (The first stage is the superheavy booster, which will re-enter and land in much the same way as the Falcon 9 booster - tail first, with an "entry burn" and a "landing burn")

SN10 is a test article, nothing more. It has much the same sort of role that the SpaceX "Grasshopper" had, i.e. proving the concept that autonomously hovering and landing a rocket at a precise location was feasible. It is purely for testing the concept of free-falling towards a landing in which the second stage will flip from near horizontal to vertical, as we saw it doing. The reason for this is that the intention is for the Starship second stage to re-enter from orbit in that nose-up belly first attitude, shedding off orbital velocity until comes down to terminal velocity.

The reason for the two different methods is simple... the first stage only has to re-enter at speeds of around 6,000 kph - that is relatively low, so the engine bells and associated structure do not have to withstand a great amount of heating - the reason for the entry burn is to shed off speed to limit that heating. However, the second stage will be entering the earth's atmosphere at orbital velocity, about 28,000 kph - no entry burn, and the kicker is that convective heating isn't just proportional to velocity, its not even velocity squared, its velocity cubed!! - so double the entry speed from 6,000 to 12,000 kph, and the heating effect is eight times greater than at 6,000, double it again to 24,000 kph and the heating effect is 64 times greater than at 6,000 kph*. Obviously, the thrust structure would not be able to withstand this; any attempt to re-enter tail first at those speed would result in the destruction of the vehicle. SpaceX had to come up with a different way to re-enter and land the second stage.

* This is the simplified version. There is also radiative heating that needs to be considered, and it is proportional to the eighth power of velocity.
 
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smartcooky said:
Care to elaborate on why you think that?
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SN8/9/10 have all experienced disaster at or just after landing. In addition, launch technology is well established, while soft landings are novel. Musk said, of this very technology, something like "There will be some holes in the ground along the way", and he wasn't talking about launches.
 
GlennB said:
SN8/9/10 have all experienced disaster at or just after landing. In addition, launch technology is well established, while soft landings are novel. Musk said, of this very technology, something like "There will be some holes in the ground along the way", and he wasn't talking about launches.
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Ok, so you are specifically, talking only about these test article landings and not rocket landings in general.
 
smartcooky said:
No, SN10 is not even remotely like any of the Starship stages, although it looks similar in shape to what the second stage is expected to look like. (The first stage is the superheavy booster, which will re-enter and land in much the same way as the Falcon 9 booster - tail first, with an "entry burn" and a "landing burn")

SN10 is a test article, nothing more. It has much the same sort of role that the SpaceX "Grasshopper" had, i.e. proving the concept that autonomously hovering and landing a rocket at a precise location was feasible. It is purely for testing the concept of free-falling towards a landing in which the second stage will flip from near horizontal to vertical, as we saw it doing. The reason for this is that the intention is for the Starship second stage to re-enter from orbit in that nose-up belly first attitude, shedding off orbital velocity until comes down to terminal velocity.

The reason for the two different methods is simple... the first stage only has to re-enter at speeds of around 6,000 kph - that is relatively low, so the engine bells and associated structure do not have to withstand a great amount of heating - the reason for the entry burn is to shed off speed to limit that heating. However, the second stage will be entering the earth's atmosphere at orbital velocity, about 28,000 kph - no entry burn, and the kicker is that convective heating isn't just proportional to velocity, its not even velocity squared, its velocity cubed!! - so double the entry speed from 6,000 to 12,000 kph, and the heating effect is eight times greater than at 6,000, double it again to 24,000 kph and the heating effect is 64 times greater than at 6,000 kph*. Obviously, the thrust structure would not be able to withstand this; any attempt to re-enter tail first at those speed would result in the destruction of the vehicle. SpaceX had to come up with a different way to re-enter and land the second stage.

* This is the simplified version. There is also radiative heating that needs to be considered, and it is proportional to the eighth power of velocity.
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What do you mean by no entry burn? At that speed there has to be one, no?
 
Belz... said:
What do you mean by no entry burn? At that speed there has to be one, no?
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Just guessing, but in normal operations it probably detaches before the orbit is circularized so it's orbit still intersects the atmosphere. And probably pretty close to intersecting the surface of the Earth.


ETA: No, on reading the Wikipedia the current plan is for the second stage to make orbit, so I'm confused about the no burn comment too.
 
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