This success was unexpected. That means that they can recover a stage from a higher speed than previously thought. Does that mean that the recovery of the second stage from LEO may actually be feasible?
SpaceX lands rocket at sea second time after satellite launch
281–290 of 497 posts
Re: SpaceX lands rocket at sea second time after satellite launch
#282Earlier quoted context omitted.
> the barge outweighs the rocket by orders of magnitude The energy amount the rocket impacts with is dominated by its speed, not its mass. A small, fast-travelling projectile can make a hole in just about any kind of armour. The terminal velocity is quite low, but that's in part because of the way it is engineered — an ICBM would probably be able to put a hole through a ship deck with ease. There is a lot of reasonin…
f = ma.
No, you're looking for
1/2m * v^2
Re: SpaceX lands rocket at sea second time after satellite launch
#283For those wondering, this isn't a simple repeat of CRS8 which landed on a drone ship about a month ago. CRS8 was a mission to low earth orbit which left the first stage with plenty of fuel to effect a landing. The landing was made as slow as possible and limited only by how low a single engine could be throttled. The re-entry burn which slows the rocket down before the landing burn was also more agressive. This missi…
From the video it looks like it lands on a ship in rough seas and they do nothing to secure it. Won't it just fall over if the seas are rough enough, and if so, why don't they have some sort of robotic system that locks it down tight the moment it lands?
From the last landing, Elon said (on twitter), that the ASDS can list up to 8% and the rocket can still land or stay upright.
Re: SpaceX lands rocket at sea second time after satellite launch
#284Earlier quoted context omitted.
Securing is purely a safety precaution, it's not actually required. https://twitter.com/elonmusk/status/726218218109444096
With respect to Musk, that is total bunk. Any structure like this will have to be secured to the deck. The fact that it is a rocket doesn't matter. He may think that it is safe from falling over, but the insurance company and/or the health and safety people will tell him that cargo that tall needs to be secured. Ropes, chains, welding ... it cannot just sit there. A Volvo station wagon, on that deck at sea, would be…
I suspect he is in a unique situation to know the numbers for this much better than you do, because he runs the company that has successfully done this.
Bonus points that the overwhelming majority of ships lack the giant oil rig thrusters that all of the ASDS armada contain to keep them as stable as feasible and prevent listing too much in normal ocean condiditons.
Re: SpaceX lands rocket at sea second time after satellite launch
#285Earlier quoted context omitted.
> But all non-Americans who are watching and also feeling a lot of pride in what the company has achieved instantly feel alienated when the chant gets going because it's exclusionary. Yes, it is, and yes, as an non-American I feel alienated. But I suck it up. Because I'm just a supporter. A fanboy, for a lack of better world. In reality, this is not my success, but the success of men and women working there, almost e…
I didn't really look it up but it would be hard to believe SpaceX being a strictly American company with 100% American workforce. Hell, even if it were, it would still be troublesome if the company didn't position itself as an American nationalistic company - think about all the stakeholders. Maybe some supporters wouldn't be so passionate and some suppliers wouldn't be so perfectionist if they felt they were there f…
SpaceX's rockets are basically intercontinental ballistic missiles being used for benign purposes. So there are legal regulations that make it difficult for them to hire foreigners. So...
> I didn't really look it up but it would be hard to believe SpaceX being a strictly American company with 100% American workforce.
They're pretty close to that, actually.
Disclaimer: I used to work there
Re: SpaceX lands rocket at sea second time after satellite launch
#286I always try to watch the webcasts and I can't help but cringe so hard when they start chanting 'USA USA USA', every single time. What is up with that?
It's tribalism, which is never good, no matter how common or accepted it might be in certain regions or cultures. Much the same as sports fans cheering for their teams or extreme nationalists at a political rally, chanting such as this is symtomatic of an "us versus them" and/or a "we are better than them" mentality. I feel pride in SpaceX accomplishments even though I have in no way contributed to their success beca…
[deleted]
Re: SpaceX lands rocket at sea second time after satellite launch
#287Here's the landing from the webcast video on youtube https://youtu.be/L0bMeDj76ig?t=2300
Re: SpaceX lands rocket at sea second time after satellite launch
#288Earlier quoted context omitted.
Wikipedia says Ariane 6's first test flight is scheduled for 2020, and Adeline will arrive between 2025 and 2030. Meanwhile, SpaceX plans to launch a Mars mission in 2018.
Say what you want about SpaceX's plans for re-usability, nobody can deny they are making progress at an incredible pace. I've just checked on Wikipedia and apparently the first flight of the Falcon was in 2010. That's six years ago. Compared to that, Arianeespace's target of 2025 (in nine years!) for Adeline is almost ridiculous. Just checked: Stephane Israël just raised concerned after SpaceX's latest success: http:…
Could you copy-paste his comments? Google translate worked OK, but the site has a paywall.
Re: SpaceX lands rocket at sea second time after satellite launch
#289Re: SpaceX lands rocket at sea second time after satellite launch
#290What's notable about this attempt (as opposed to the last) is that the first stage rocket was traveling twice as fast (4x the energy to overcome on landing), and didn't have enough propellant to do a 'boostback' burn. Instead, coming in very hot, the rocket had to use three engines (instead of one) to slow for landing. The last time this was attempted, the first stage put a nice hole in the deck of the drone ship. Se…
One of my favorite facts is that merely relighting the engine provides enough thrust to lift the rocket (at its minimum throttle of 60%). This means that it must slow to a standstill, cut the engines and hit the platform at exactly the same time or it will either start going up again or be dropped onto the platform from a less than ideal height.
Slow to a standstill and cut the engines at the exact point where it pushes enough on the platform that when the engine stops thursting, the platform bumps back exactly to the bottom of the rocket.