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Comment: Re:trial and error (Score 4, Informative) 248

by bledri (#48835065) Attached to: SpaceX Landing Attempt Video Released

It seems SpaceX is relying on a trial-and-error strategy during the development of the soft landing capability of their booster much more than they (or others in the industry) do for other components or capabilities of space launch or other aeronautical systems. I don't see (unmanned) rockets or drones being developed in this fashion. Even large rockets that can achieve orbit will normally be modeled, simulated and tested component-wise to the point that they will usually work at the first or second attempt when the entire system is integrated and tested for the first time. So why is this so different here? Is it just cheaper? Or is it actually that much harder to make the rocket land softly on its own exhaust jet than to make it go into orbit?

It's important to remember that the primary mission was a complete success. The Dragon delivered the cargo to the ISS and is awaiting trash and cargo to return to Earth. This was a post mission experiment meant to collect data. It's very common to completely loose a rocket in the early flights, but that's not what happened here.

SpaceX does what's called LEAN development, which is basically like agile software development. Really all development is incremental, the difference with lean/agile is you admit that instead of pretending that you can design the perfect solution from the start. SpaceX has a huge computer cluster and they model the hell out of everything they do. Then they try it to see how it works in the real world, measure the results and make improvements. The experiments are always done after stage separation in a way that collects important data without putting the mission as risk. You can call that trial and error, but that does the process a disservice.

There have been experimental rockets and landers that land vertically, most notably the DCX. But no one has reentered a first stage of an actual in service rocket, the previous vehicles have always been test platforms and never accelerating to launch vehicle velocities nor going to launch vehicle altitudes. NASA has flown aircraft to collect data from earlier SpaceX missions because no one else has EVER controlled a first stage's return to earth. (Shuttle SRBs were not controlled, just big steel tubes falling from lower and slower than the F9.) The first stage is a long cylinder with blunt ends and it reenters the atmosphere at hypersonic velocities. On top of that, it's a super light weight and fragile airframe. Just getting the thing down to terminal velocity in one piece is a big deal.

The LEAN development model is less expensive than the classic approach. It's also faster and yields really good results. You learn about problems sooner and don't bake them too deeply into your design. Look at it this way, the closest competitor to SpaceX in developing a reusable VTVL rocket is Blue Origin, started by Jeff Bezos. Blue Origin started with more money than SpaceX and before SpaceX. SpaceX is delivering cargo to the ISS, and about to test the Dragon V2 abort system in preparation of flying astronauts in 2017. They are also self funding the development of a much bigger reusable rocket (slightly bigger than the Saturn V). They are doing all of this while providing the least expensive launch prices in the world. Less expensive than Russia. Meanwhile Blue Origin hasn't even reached orbit. They aren't even trying to reach orbit, they are still developing a suborbital rocket, even though they have a number of experienced engineers that worked on the DCX. Oh, to be fair, Blue Origin is developing an engine for use by ULA (and Blue Origin) and doing some work on a man rated capsule. But nothing is anywhere close to flying.

Comment: Re:parachute (Score 4, Informative) 248

by bledri (#48834613) Attached to: SpaceX Landing Attempt Video Released

Remind me again, why doing this crazy rocket landing is better than using a parachute recovery like the shuttle boosters did?

SpaceX tried parachute recovery with the F9 v1 (the rocket flying now is the v1.1, though really is more like a version 2). After multiple attempts, they could not get the rocket to survive reentry. There are many reasons for this. First of all, the shuttle boasters were big heavy steal tubes. That's fine for a strap on booster, but not so good for the first stage. Rocket stages are very light weight, since the lighter the rocket the more payload it can carry (this is true for boosters too, but it's a different trade off when coupled to a "first stage".) Second the shuttle boosters separated at lower speed and a lower altitude than the first stage of an F9. So you have a much lighter, complex F9 reentering at much higher velocities. Third, the shuttle boosters were more "refurbished" than reused. The goal of SpaceX is to (ultimately) land the first stage and be able to refuel and relaunch it with a minimum of work. Shuttle boosters had to be fished out of the water, disassembled, cleaned, inspected, etc... SpaceX was hoping to use parachutes as a first step, but they always hoped to eventually land the boosters. Their timeline just got accelerated when uncontrolled reentries kept breaking up.

Comment: Re:The guy who defended Jeffrey Epstein? (Score 1) 227

by bledri (#48809671) Attached to: Lawrence Krauss On Scientists As Celebrities: Good For Science?

Really? Krause says he hasn't seen Epstein with underage girls and that means that his scientific papers are invalid? Are you implying that Krause has seen him with underage women? And what was the point of that video? Now I know that someone said that Epstein had an "egg shaped" penis. Does he? Hell if I know.

Here is what seems like a reasonable response from Krause to me:

I will add one remark here, as most people have not read my full set of comments, posted after the post appeared.. I am myself rather disappointed by the lack of skepticality of this community. As I said, I have read numerous reports of orgies on Jeffrey’s island involving me and other scientists during our meetings.. Orgies that never happened, I am VERY skeptical of other claims on his behavior. I am defending Jeffrey for 2 reasons: (1) Based on my knowledge and experience I am skeptical of the claims in the media and of those who have settled claims for money namely I don’t believe the published details just like I tend to be skeptical of many published details on the internet.. I don’t believe Jeffrey did what has been claimed, and unless I see hard evidence, I will trust my own judgement here, and (2) Jeffrey went to prison, and I happen to believe that having served time, even those who questioned his behavior should be willing to give him the benefit of the doubt, again until proved otherwise, that he is working hard to live a good life and do good things. I for one am disgusted that people eat up the salacious nonsense the read on the web and then jump to conclusions about things and people they do not know.. I do not jump to condemn people, especially when it concerns their sexual preferences. I DO NOT CONDONE sex with young girls, or young boys for that matter.. because there are real victims there.. Until I know all the facts however, I do not jump to conclusions, and I am sorry, having seen the media frenzy around Jeffrey, and having seen the shoddy behavior of those who have attacked him, I remain skeptical, and I support a man whose character I believe I know.. If you want to condemn me for that, so be it. L. Krauss

I don't know shit about Epstein, but discounting everything Kraus says because he was skeptical of charges brought against a friend, especially given that he's heard stories that include him that he knows are false? That seems pretty irrational to me.

Comment: Re:Your ignorance is complete!!!! (Score 1) 227

by bledri (#48809543) Attached to: Lawrence Krauss On Scientists As Celebrities: Good For Science?

That's twice you've gotten it wrong, now. "Star stuff". And, of course, we are. With the exception of the hydrongen atoms, almost every atom in our bodies was forged in the heart of an exploding star. Maybe you already knew that--but a lot of people don't, and many more never really stopped to think about. It really is amazing, you know.

Oh my GOODNESS. Do NOT correct someone if you're going to say something even less correct. Exploding stars - supernovae - produce everything on the periodic table after Iron (element 26). Carbon, Oxygen and Nitrogen happen as part of regular nuclear burning. They are certainly dispersed by a supernova but regular nuclear burning inside of a star.

I repeat: If you want to correct someone GET IT RIGHT.

Fuck sake. Yes, the elements from hydrogen up to iron are produced via nuclear processes in "normal" star. But none of it ended up in us unless the motherfucker exploded you pedantic fuck.

Comment: Re: Null hypothesis (Score 1) 556

Do you really want to spend eternity cooped up in a castle with a supreme being who would send you to eternal torment because you didn't believe in him, after being presented with no evidence?

Pascal's wager assumes belief gets you infinite gain. That seems highly unlikely.

I agree, I don't accept that assumption. I am just pointing out that it's not irrational thinking.

I think it's very sloppy thinking at best. It assumes that there are two possible beliefs: (Christian) God and no God. And it assumes that believing in God will get you into Heaven. But couldn't there be a God that sends people that believe in it for the wrong reason to Hell? Or that sends people to Heaven or Hell based on their acts? Maybe all Catholics go to Hell. Maybe only Protestants do, and everyone else goes to Heaven. If you follow Pascal's wager to it's logical conclusion, you'd have to spend your life in shear terror trying to figure out exactly what God wants so you don't go to Hell.

Comment: Re:Yawn (Score 1) 556

There is no leading voice in the scientific community on the issue. God has nothing to do with science, science only asks questions that have answers.

Athiesm is philosophy, not science.

Well, scientist keep finding out there is nothing for God to do. The God of the gaps has been shrinking for hundreds of years. And the first article claimed that science was making it more likely that there must be a God. It's perfectly reasonable for an actual scientist to counter that claim. Notice that Lawrence Krauss does not claim there is no God. Just that science is not finding any reason to claim there is one.

But you're right, atheism is not a science. I wouldn't call it a philosophy because it's really just a single belief. I'm an atheist because I don't believe there is a God. People that believe there is a God(s) are deists or theists. But that's as far as those labels go, they don't "mean" anything else. They don't even mean that you claim to "know" whether or not there is a God. Just what you believe. Many theists and atheists willingly admit they don't know whether there is a God, just as many in both camps claim they do know. My hunch is that more atheists are willing to admit the lack of knowledge, but I have no data to back that up.

Comment: Re: Yawn (Score 1) 556

Sorry, I misread your statement and Slashdot does not have an edit function. I guess we basically agree. I just prefer a quasi-baysian approach to navigate the world since there is not a lot we can know with complete certainty and I think a pragmatic approach is more useful than demanding absolutes. People have started using the "appeal to authority" as a sort of post modernist "all opinions are equal" woo.

For all I "know", the laws of physics are constantly changing and my memory and all the universe being recreated at the current point in time to make it seem like they are fairly constant. But other than an escape hatch to allow me to believe whatever the hell I want, I don't find that view useful in figuring stuff out.

Comment: Re: Yawn (Score 1) 556

As I've pointed out elsewhere, this stance is only true in formal logic. Opinion pieces are, at best, informal logic. In informal logical, an experts opinion is much more likely true than a non-expert's opinion. A scientist's opinion on science is much more valid than a theologian's opinion on science. Quoting the theologian on matters of science is an appeal to authority. Quoting a scientist's opinion on science they are an expert in is not.

Now Lawrence Krauss is not a biologist, so I guess that could be an appeal to authority. But on matters of cosmology, quantum mechanics, and a host of related topics, Lawrence Krauss is an actual expert and his opinion should be weighted as more likely true than a theologian with no expertise in those fields.

Comment: Re: Yawn (Score 1) 556

No it is not. A scientist's argument when dealing with science is more likely to be valid, yes. But it is no more valid based purely on their author's characteristics. To say that one argument is more valid because it was written by a scientist is a classic appeal to authority.

An expert is definitely more likely to be correct in their field than someone that is not an expert. Valuing the opinion of an expert in informal logic is not an appeal to authority, which people have twisted into some sort of post-modernist "all opinions are equal" absurdity. An appeal to authority is to appeal to someone that is not an expert in the field in question, but is in general considered an authority. Quoting Einstein (an authority on relatively) to support your political views is an appeal to authority.

It's true that it's a logical fallacy to consider an expert infallible, and therefore not sufficient for a deductive proof. But it is perfectly valid in informal logic to weigh expert opinion as more likely true than non-expert opinion. And opinion pieces are, at best, attempts at informal logic.

Now the original article was a non-expert making claims about science. Everyone that is quoting THAT article is making an appeal to authority by quoting a theologian's opinion of science.

Comment: Re:Re usability (Score 2) 151

by bledri (#48741161) Attached to: In Daring Plan, Tomorrow SpaceX To Land a Rocket On Floating Platform

That was the first thing that jumped to my mind. Kind of reminds me of retread tires -- a lot of the truck tire fragments you see by the side of the road are from retread tires that self destructed. A lot of companies buy them because they're cheaper, but the chances that they'll fail is far higher.

But the consequnces of your first stage failing are much worse than the consequences of your tire shredding on the freeway. And those are bad enough.

Yes, rockets go through more extreme forces and environments, but that does not mean that rockets can not be made to safely survive multiple fights.

It could be that due to the bathtub curve that some number of flights after the first flight are the most reliable. Right now every rocket flight is a maiden voyage (also known as a shakedown cruse). Brand new rockets fail on occasion.

Comment: Re:Tablets age well (Score 1) 328

by bledri (#48698247) Attached to: Is the Tablet Market In Outright Collapse? Data Suggests Yes

I have a tablet and use it all the time, but have no plans to buy a new one. I suppose if there are enough people like me, the tablet market is doomed.

Lesson learned: don't build a good product that is going to work well for a long time.

Me too. I still have an original iPad. Apple stopped upgrading it, and eventually no apps will upgrade (though surprisingly many still do get updates.) But it works great to watch movies and read books. The battery takes a long time to charge now but still lasts long enough.

Comment: Re:daytime crash? (Score 1) 132

by bledri (#48698153) Attached to: Debris, Bodies Recovered From AirAsia Flight 8501

What I find somewhat puzzling is how this happened in daylight. In AF447 and others where pilots lost control or were confused by conflicting instrument readings, it was during night or poor visibility and they lost reference to the horizon. This was at 7am Singapore time, and although there were storm clouds, I would have thought that at least for some portion of the incident, the horizon would have been visible? This of course assumes that the problem was a loss of attitude control due to instruments.

They were likely in clouds (remember they were trying to avoid a thunderstorm.) They probably had extremely poor visibility.

Comment: Re:Pilot Proof Airbus? (Score 1) 132

by bledri (#48698101) Attached to: Debris, Bodies Recovered From AirAsia Flight 8501

This, I watched a documentary about a crash a year ago. One instrument malfunctioned, the pilot then proceeded to ignore like 8 other instruments, and his cockpit window, and continue to slow down until he crashed and killed everyone. Pilot training has obvious gone way downhill, they are often less able to deal with instrument malfunctions than if we just put a simple non robust auto pilot in control.

Sounds a bit like Eastern Air Lines Flight 401. On that flight the auto-pilot was in the wrong mode. They thought the autopilot would maintain the current altitude, but it was in a mode that maintained whatever rate of climb/descent was input to the control yoke. The plane basically flew into the ground while everybody was trouble shooting a burned out light bulb.

Comment: Re:Why are we still fighting with this? (Score 5, Insightful) 105

by bledri (#48697935) Attached to: 10 Years In, Mars Rover Opportunity Suffers From Flash Memory Degradation

This was known, and should have been exploited:

Although subjecting the cells to high heat could return memory, the process was problematic; the entire memory chip would need heating for hours at around 250 C.

The rover is equipped with heaters. There is some possibility that simply placing the flash closer could have extended the life of the memory.

The rover's primary planned mission was 3 months and the extended mission plan was two years. It lasted 10 years and your upset they didn't design a way to bake the flash (offline) for four hours at 250C? Self heating flash did not exist, should they heat all the electronics? Invent a mechanism to remove the flash and put it in a little oven? Are you shutting down the rover's computer for this? How much complexity would that have added? How long would it take to develop?

There is such a thing as "good enough," and engineers that don't know that never ship usable product.

Comment: Re:Hmmm ... (Score 1) 180

by bledri (#48685373) Attached to: Sony Accused of Pirating Music In "The Interview"

True, you get some small "value" out of it, but you're not "making lots of money" from it. And the federal government treats these two scenarios very differently.

Relatively speaking, Sony's is not making "lots of money" off of The Interview. They made about 10-20% of their projected earnings. Does that make it OK not to compensate the artists? No?

She's not getting paid for her work. Just like when we pirate music the artist is not compensated for their work. It's *exactly* the same thing no matter what we tell ourselves to pretend it's OK.

The current laws are too draconian *and* pirating music is enjoying someone's effort without compensating them.

10 to the 12th power microphones = 1 Megaphone