I'm having some trouble with the opening salvo here: "Now imagine placing a marble somewhere on that slippery sheet -- it is guaranteed to fall into one of the funnels. " This holds for the case where there are two objects initially at rest, but I don't see it as obviously true if there are more than two objects in the universe.
This was lovely writing, and successfully enlightened me on a few points, but my mind immediately saw the marble deform the sheet. I'd suggest a ping-pong ball and a frictionless sheet for a less perplexing thought experiment.
> how much payload is sacrificed by the need to keep fuel > in reserve for the return to base? Simple answer: None. A more detailed answer is that building a system which can be reused is an economic proposition. So that the Falcon 9 can lift X Metric tons to orbit for $Y. The way in which they keep the value $Y low is by re-using the first stage. Every satellite project knows the throw weight of all the common launc…
SES already said that they're willing to be the first customer for a used booster[1]. Before they get that far, it'd be interesting to see if SpaceX flies a used engine, since they've got "one engine out" capability. Which has already been tested twice. 1: http://spacenews.com/spacex-early-adopter-ses-ready-to-reuse...
That article raises an interesting point I really hadn't considered, who owns the first stage? If you pay "full price" for a launch and SpaceX recovers the first stage to re-use, did the person who paid to launch it own it or does SpaceX? It was presumed lost of course. No doubt there is language in the contracts about that. Would be interesting to see a launch contract.
One thing I've not seen mentioned in the coverage so far: how much payload is sacrificed by the need to keep fuel in reserve for the return to base? I'm guessing the sacrifice is roughly equal to the mass of unburnt fuel in the booster at the point of booster separation, but don't much trust my intuition on these things.
> how much payload is sacrificed by the need to keep fuel > in reserve for the return to base? Simple answer: None. A more detailed answer is that building a system which can be reused is an economic proposition. So that the Falcon 9 can lift X Metric tons to orbit for $Y. The way in which they keep the value $Y low is by re-using the first stage. Every satellite project knows the throw weight of all the common launc…
"It worked at least once before" is more track record than any rocket fresh off the assembly line.
Clearly this man's intellect is through the roof. Reading this post and him explaining these concepts in such first-principle terms (despite not being a physicist/rocket engineer) indicates his in-depth understanding (nothing new there). I know he has a Bachelors in Physics but bear with me. But, I'm just in awe and I keep thinking 'how does he do it?'. He's running two intensely technical and risky companies. Yet he…
It's well written and I'm glad he takes the time to write things like this. But I think you might be a bit biased by hero worship. Don't you think the rocket engineers explained it to him in about the same way? And there's probably not a lot else for the boss to do while waiting for liftoff.
In his interviews with Tim Urban from Wait But Why, there's a bit of detail about what he read leading up to his founding of SpaceX. They're all hard science texts – Rocket Propulsion Elements (Sutton), Aerothermodynamics of Gas Turbine and Rocket Propulsion (Oates), Fundamentals of Astrodynamics (Bate). From everything I've heard, he's well-versed in the material in a way that not many CEOs are.
"[100Km altitude] is the equivalent of the starting line of a race. The race itself is the kinetic energy." Did you get that, Jeff? The truth is, they have both achieved an astonishing amount.
Blue Origin is cool but it's certainly not astonishing to me that a billionaire is able to send a rocket on a suborbital trajectory and recover it. It's certainly more than I've ever done by a long shot, but it's not a very interesting achievement unless you're interested in five-minute space tourism. I don't think BO's achievement here has many implications for space travel.
I wonder its implications for terrestrial travel, though? We are in a post-Concord era, after all, but suborbital flight could get you to any point on the planet pretty quickly if the price is right.
Clearly this man's intellect is through the roof. Reading this post and him explaining these concepts in such first-principle terms (despite not being a physicist/rocket engineer) indicates his in-depth understanding (nothing new there). I know he has a Bachelors in Physics but bear with me. But, I'm just in awe and I keep thinking 'how does he do it?'. He's running two intensely technical and risky companies. Yet he…
It's well written and I'm glad he takes the time to write things like this. But I think you might be a bit biased by hero worship. Don't you think the rocket engineers explained it to him in about the same way? And there's probably not a lot else for the boss to do while waiting for liftoff.
No, I think he is a rocket scientist himself (in knowledge, not degree). It is impressive.
The article mentions that the water landing requires less fuel to return the rocket because it doesn't have to spend fuel overcoming its initial ballistic trajectory. In the water landing scenario, how far away from the launchpad is the landing barge? I'm wondering about the economics of launching from a site where your first stage trajectory is entirely overland, to avoid the complications of landing on a barge that…
I found a reference that the barge was 320 km downrange in the earlier tests. The Bahamas look to be an appropriate distance from Florida, although to the southeast of Cape Canaveral. From SpaceX's planned Texas spaceport, there's nothing at that range but gulf.
Hypothetically, I imagine they could anchor a stable ocean platform out there if they find it's easier than the barge. No idea if it actually would be easier than the barge though.
I'm having some trouble with the opening salvo here: "Now imagine placing a marble somewhere on that slippery sheet -- it is guaranteed to fall into one of the funnels. " This holds for the case where there are two objects initially at rest, but I don't see it as obviously true if there are more than two objects in the universe.
Isn't the universe expanding? If you start in the right place couldn't everything be moving away from you faster than you'd be pulled in?
Yes. He's simplifying the description (though technically, he might still be correct; if only you and your pet existed in space and had no relative motion, it's entirely possible that dark energy would not exist, since we don't yet understand its origins or nature).
Clearly this man's intellect is through the roof. Reading this post and him explaining these concepts in such first-principle terms (despite not being a physicist/rocket engineer) indicates his in-depth understanding (nothing new there). I know he has a Bachelors in Physics but bear with me. But, I'm just in awe and I keep thinking 'how does he do it?'. He's running two intensely technical and risky companies. Yet he…
He's commented on this type of thing before and it seems like he thinks it isn't any great trick. The main thing is that if you're going to reason well from first principles, you have to learn from first principles. If you build your "tree of knowledge" efficiently, then adding on to it isn't so difficult because you have a good core. Contrast this with the hobbyist that tries to learn rocket science when they don't…