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Comment: Re:Landing vs splashdown (Score 1) 342

All the engines on the Falcon 9 (and just about every other multiengine* rocket stage) are fed from the same propellant and oxidizer tanks. Giving them separate tankage just adds weight and plumbing complexity.

In the Falcon Heavy, there is a cross-feed mechanism from the outrigger 9s to the core so that the core can keep burning when the outriggers jettison (saving weight).

*(except multiengine solids, where the engine is the fuel tank.)

Comment: Re:Landing vs splashdown (Score 1) 342

DC-X also did it, several times -- but then DC-X wasn't trying to make even a fraction of orbit, it was proving the vertical takeoff and landing principle. Its engines (modified Pratt & Whitney RL-10s) could be more deeply throttled than the Falcon's Merlin, and it (the DC-X) was built fairly heavy to start with, since was designed as a test vehicle rather than a launcher (fully-fueled the legs couldn't hold its weight, it needed a support structure for takeoff -- and in an abort (happened once) it had to hover until it had burned off enough fuel to land).

Since then a number of small-company-built test vehicles have done the same, although not (afaik) to the tens of thousands of feet altitudes that the latter DC-X flights made.

Comment: Re:Landing vs splashdown (Score 2) 342

One would think that if they didn't know that the shuttle's boosters are made of inch-or-more-thick steel, while the Falcon's tanks are millimeter thick aluminum-lithium. And that the booster splashdown still tended to leave the boosters slightly out of round (which contributed to the problem Challenger had).

The extra fuel almost certainly weighs less than the necessary parachutes would.

Comment: Re:Refactoring done right happens as you go (Score 2) 247

by AJWM (#49178245) Attached to: Study: Refactoring Doesn't Improve Code Quality

"Memory architecture" -- you mean data structures?

As the title of my old intro CS text put it, "Algorithms + Data Structures = Programs". Yep, one is clearly going to influence the other, and sometimes a minor tweak in one will vastly simplify (or complicate, if you do it wrong) the other.

Refactoring isn't merely reformatting -- a prettyprinter can do that -- but it can help give you insight into the code. After getting the code right I like to refactor to see how much code or useless variables I can get rid of, but that's partly a hangover from my old APL one-liner days. (grin)

Comment: Re:This should not be on the front page (Score 1) 247

by AJWM (#49178203) Attached to: Study: Refactoring Doesn't Improve Code Quality

I could believe 10 kloc (kilo lines of code) functions being created by some front-end automated code generator (like a gui builder or parser generator, etc). If anyone is hand-coding 10 kloc functions they should be taken out and shot, or at least have their fingers broken so they don't do it again.

And while a multi-million-line class certainly seems excessive, that says nothing about how it's broken down into members and methods and inner classes.

Comment: Re:Roads are now illegal (Score 2) 199

You don't have to be actually breaking the law, the cop just has to have a reasonable suspicion that you might be.

Many, many years ago as a teenager I got stopped by an on-foot cop (I was pulling out of a fast food place). Turns out he recognized the license plate because the car (my mom's) had been stolen (for joy rides) several times before (easy to hotwire, and predating ignition locks in the steering column). I wasn't breaking any law, but the stop was justified on suspicion. Since the last name and address on my license matched the registration, of course he waved me on as soon as I'd shown them to him.

Comment: Re:so not only and ancient disease? (Score 4, Interesting) 65

by AJWM (#49124761) Attached to: Giant Asian Gerbils May Have Caused the Black Death

Plague is endemic to the prairie dogs of the Four Corners area of the US (where NM, Arizona, Utah and Colorado meet). Every year it gets transmitted to a few people. Presumably early diagnosis and antibiotics will take care of it, but occasionally it will go missed until too late.

Of bigger concern in that area is hantavirus.

Comment: Re:Nuclear fission has higher carbon than measured (Score 1) 309

by AJWM (#49107743) Attached to: The IPCC's Shifting Position On Nuclear Energy

Considering that I gave a paper on (in part) the use of a beanstalk on Mars in the 1991 Space Manufacturing Conference, and a similar one at the Case For Mars IV (or whichever) conference, I do know a bit about orbital tethers and doing a Mars version.

Since you were the one who mentioned running a mono (greek root, means "single" or "alone") filament to orbital satellites, you were the one implying a single stage version from the surface to (geostationary, unless you're planning on wrapping the planet like a ball of yarn).

Sure, there are other ways to do it. As you suggest, none of them are elegant.

Comment: Re:Yes we should but... (Score 1) 291

by AJWM (#49056637) Attached to: Should We Really Try To Teach Everyone To Code?

Troubleshooting is a skill applicable to, and learned in, far more than the narrow domain of coding. Your experience is biased by the crowd you hang out with in your chosen profession.

But any good mechanic (taking that as a generic term for electrician, plumber, etc also) is a good troubleshooter/problem solver, ditto any other expert in their chosen field (doctors, lawyers, salespeople, etc). It's a skill you need to be a good programmer, but it's a skill you need to be good at anything. How do I isolate the symptom? What is the real problem? What can I do to fix it? What can I substitute or change if I don't have the right part (library, API) to fix it as is?

I've seen plenty of coders who weren't that hot at troubleshooting (especially if it required some out-of-the-box thinking). I don't think coding teaches that skill, but it may well exercise it and make it stronger if it's already there.

Comment: Teach? No. Play? Yes. (Score 1) 291

by AJWM (#49056559) Attached to: Should We Really Try To Teach Everyone To Code?

First step is to get kids to have fun developing critical thinking and logical analysis skills. Some of those will go on to want to learn coding and related topics, while the fundamentals will help anyone faced with that sort of problem.

Give grade school kids games like The Logical Journey of the Zoombinis to play, don't force them to memorize the particulars of a programming language that will be obsolete by the time they graduate high school.

More toppings!

Comment: Re:Nuclear fission has higher carbon than measured (Score 1) 309

by AJWM (#49022077) Attached to: The IPCC's Shifting Position On Nuclear Energy

You can run monofilament cables to orbital satellites

No we can't. The technology to manufacture mile-long monofilament (I assume you're talking something like buckytubes, nothing else has the strength) cables isn't available yet, let alone manufacturing 23,000+ mile cables.

Now, people might argue about risks, but until the technology is actually availabe -- which it is not -- the point is moot.

Come back when they're building suspension bridges out of the stuff.

Evolution is a million line computer program falling into place by accident.