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> not aim for a perfectly mid-point landing That was a perfect landing. As far as not aiming for the center. Of course it is aiming for the center. That's w

> not aim for a perfectly mid-point landing That was a perfect landing. As far as not aiming for the center. Of course it is aiming for the center. That's where you have the greatest margins. Yet, this is nothing like what Blue Origin has been doing. The comparison is simply not warranted. Rather than go into a long explanation I'll just give you this data point: Blue Origin is FALLING down from zero velocity. It reaches a terminal velocity of around 300 to 400 miles per hour. It uses fins to navigate down to a spot that, for all intents and purposes, is almost straight down. Falcon 9 is FLYING down from somewhere around 17,000 miles per hour. During that time it has to flip around and use three of it's engines to slow down enough not to burn-up on re-entry. The grid fins also need to fly the rocket to a ship, in the middle of the ocean, about 600 miles from the coast...and then use a precisely timed single engine burn to land it. Here are a couple of pictures to further illustrate the point: http://goo.gl/BT92J8 http://goo.gl/BT92J8 https://goo.gl/9Vttob https://goo.gl/9Vttob Like I said. Perfect landing.

mikeash 11y ago
BO also gets to wait for perfect weather (for now, eventually they won't) while SpaceX has paying customers to satisfy. Worse, SpaceX's customers don't care in the slightest about the landing, they just want their payload shot into space. That means that if weather is good at the launch site, but bad at the landing site, the customer will get annoyed with you if you cancel on them. In this particular case, they were dealing with winds of something like 25MPH. Dealing with that in a vehicle this clumsy to control has to be tough. SpaceX also aims next to the ship first, then corrects at the last moment to land on the ship. This is so they don't make a big hole in the ship if the engine fails to restart. I believe BO does this too, but BO's rocket can hover and take its time with this maneuver. The Falcon 9 first stage has too much thrust to hover, even with only one engine running at minimum throttle, so it has to do everything at once.
dyarosla 11y ago
Yes, it's clearly nothing like what Blue Origin is doing and the landing was perfect. You're arguing against something I never said. My question was specifically about the centering, which up until this point, SpaceX had always seemed to land (and aimed to land) right on target. This time it was not centered, and I wanted to know if anything had changed.
- rebootthesystem 11y ago
  This ain't software. Contact with the real world with physical things introduces, among other things, variability. They didn't aim to land 25 feet from the edge of the ship, it just happened. Can they do better. Probably. Give them time. Just don't expect perfection. A perfect landing is one where you get to recover and reuse the rocket. It was perfect.
Malice 11y ago
> somewhere around 17,000 miles per hour. Much less than that. Closer to 4,000mph (from memory). You're thinking about 2nd stage.
- rebootthesystem 11y ago
  Yes, yes, you are right. At MECO it's about 4,000 mph.

mikeash 11y ago

BO also gets to wait for perfect weather (for now, eventually they won't) while SpaceX has paying customers to satisfy. Worse, SpaceX's customers don't care in the slightest about the landing, they just want their payload shot into space. That means that if weather is good at the launch site, but bad at the landing site, the customer will get annoyed with you if you cancel on them. In this particular case, they were dealing with winds of something like 25MPH. Dealing with that in a vehicle this clumsy to control has to be tough. SpaceX also aims next to the ship first, then corrects at the last moment to land on the ship. This is so they don't make a big hole in the ship if the engine fails to restart. I believe BO does this too, but BO's rocket can hover and take its time with this maneuver. The Falcon 9 first stage has too much thrust to hover, even with only one engine running at minimum throttle, so it has to do everything at once.

dyarosla 11y ago

Yes, it's clearly nothing like what Blue Origin is doing and the landing was perfect. You're arguing against something I never said. My question was specifically about the centering, which up until this point, SpaceX had always seemed to land (and aimed to land) right on target. This time it was not centered, and I wanted to know if anything had changed.

rebootthesystem 11y ago
This ain't software. Contact with the real world with physical things introduces, among other things, variability. They didn't aim to land 25 feet from the edge of the ship, it just happened. Can they do better. Probably. Give them time. Just don't expect perfection. A perfect landing is one where you get to recover and reuse the rocket. It was perfect.

Malice 11y ago

> somewhere around 17,000 miles per hour. Much less than that. Closer to 4,000mph (from memory). You're thinking about 2nd stage.

rebootthesystem 11y ago
Yes, yes, you are right. At MECO it's about 4,000 mph.