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A Look At Orion's Launch Abort System

gman003 Re:Would this kind of system have saved Challenger (43 comments)

You basically described Orion on top of SLS. SLS takes the Shuttle launch system, scales it up a bit (adds another fuel "segment" to the boosters, and a fourth SSME), and puts it into a regular stack.

This would probably have saved the Challenger crew. The scariest thing about Challenger is that the crew actually did survive the explosion - they died when they hit the water, possibly unconscious from the lack of air pressure at altitude. The crew compartment also remained mostly-intact.

In a similar failure on SLS, it's likely the capsule would also have survived. Even if LES doesn't get them away from the explosion, they could probably survive the fireball (particularly since they're now above it, rather than beside it). The parachutes can then bring them down safely.

In an emergency like this, the LES might be triggered by computer. In that case, the LES would be able to safely pull them away from the explosion. If it relies on crew or ground-control to abort, it would need someone that can instantly tell the problem is dire enough to abort.

yesterday
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A Look At Orion's Launch Abort System

gman003 Re:Would this kind of system have saved Challenger (43 comments)

Possibly. Probably not.

The failure modes for the Shuttle are unlike any other spacecraft's - even the near-clone of it, Buran. And any theoretical abort mode for it has to account for that weirdness.

First, the Shuttle has to remain intact. You can't just eject the "pilot area", because the whole thing is really monolithic. You might be able to get away with ejection seats, but that works only for a very small period of spaceflight (probably not Challenger - they'd have ejected into a fireball and coasted up to 60,000ft). They did, in fact, have some ejection seats on the early test flights, with partial crews, but they did away with them in use (letting some escape while leaving others to die was inhumane, and making all seats eject was far too heavy for the marginal benefit).

Second, the boosters cannot be shut off. That's the big safety drawback of solid rockets - you light them, and they aren't going out until they're out of fuel. This means detaching the boosters isn't going to work, because (without the drag and mass of the Shuttle holding them back) they'll just blow past the Shuttle, bathing it in hot exhaust. If my memory is correct, the Shuttle is the only manned rocket in history to use solid engines, in no small part because of this sort of problem. Even the Soviet shuttle clone, Buran, used all-liquid engines.

Third, the Main engines are nearly useless in-atmosphere. They're lit mainly because they sometimes fail to light, and having that failure occur halfway to orbit would suck. The "boosters" provide about 80% of the thrust, if memory serves. The SSMEs aren't even at full throttle for much of the flight - Challenger had just set them to full when the stack exploded. So any idea of "just floor the main engines to outrun the boosters" is ludicrous.

Fourth, these sorts of disasters happen with very little notice. Rocket fuels are generally extremely volatile - even the least exotic combo, LOX+RP1, is still liquid oxygen and high-grade kerosene. LH2 is safer than some things (ClF3 was, and still is, considered for rocket use), but it's still pretty dangerous, and when a tank of LH2 and LOX decides to explode, it's not going to give you even a second's warning. So the escape systems they did add after Challenger probably wouldn't have been usable, because it literally involved jumping out of the Shuttle.

Fifth, the Shuttle is HEAVY. Really goddamn heavy, especially since you're not going to be able to dump the payload during an abort. So you've got the crew, all their supplies, whatever they were carrying to orbit, and all the vehicle mass. Any rocket that could accelerate the Shuttle away from an exploding stack would be itself enormous, not something you could really justify launching into orbit every mission.

Because of these peculiarities, the Shuttle abort modes are along the lines of "pick where to crash" instead of "run away from the explosion". The four post-launch modes are "return to launch site", "trans-atlantic landing", "abort to once-around" and "abort to orbit" - all of which require a mostly-working Shuttle and must be used after the boosters are exhausted.

An LES like this could not have saved them, because you couldn't really use an LES such as this on the Shuttle. Modifying the Shuttle enough that an LES like this makes sense would basically require making it not a Shuttle - in fact, you'd basically end up with an Orion-like capsule on top of an SLS-like stack, because they're literally reusing that much of the technology.

yesterday
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An Algorithm to End the Lines for Ice at Burning Man

gman003 Re:An algorithm to end BH posting (325 comments)

Since DICE obviously isn't going to stop him from blogging here, can we at least make him an editor so he can post them himself and we can block him specifically?

yesterday
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IBM Pays GlobalFoundries $1.5 Billion To Shed Its Chip Division

gman003 How on earth? (81 comments)

How on earth do they find "pay someone a billion and a half to take this business" to be cheaper than just shutting the entire thing down? Even if the division is losing more money than that, I think you could do better by just firing everyone and burning any physical assets to the ground. The only way I think it could be otherwise is if it costs more than $1.5 billion just to shut down the division. Unless IBM is running a nuclear reactor somewhere and I just never heard of it, that just doesn't seem plausible.

2 days ago
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Oracle Database Certifications Are No Longer Permanent

gman003 Re:Not a great loss... (108 comments)

Yes. That's why they haven't bothered implementing right joins, you can do every join using just inner joins, left outer joins and unions, like how any logical gate can be implemented with NAND gates.

I've never had need for a right join, and only rarely do I use a full outer join.

about a week ago
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Oracle Database Certifications Are No Longer Permanent

gman003 Re:Not a great loss... (108 comments)

Left joins only, no right joins.

about a week ago
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Positive Ebola Test In Second Texas Health Worker

gman003 Re:Just tell me (463 comments)

Don't panic.

about a week ago
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When will the first successful manned Mars mission happen?

gman003 Re:oil discovery = terraforming (218 comments)

Since when has any reasonable person given a single flying fuck what PETA thinks?

about a week ago
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When will the first successful manned Mars mission happen?

gman003 Look at the orbital mechanics (218 comments)

The way the orbits work, there's a period every sixteen years or so where the journey between Earth and Mars is shortest. There's a similar cycle for the longest path, eight years offset. Using this close approach is crucial - it means less fuel is needed (very important in rockets), and it shortens the crew's exposure to radiation.

The next close approach is in 2018 (it's still a two-year journey, so you'd actually want to launch in 2017). Barring a massive undertaking, bigger than Apollo, we will not be ready in time. I'd like it to happen, but it just isn't.

After that, missions become harder up to 2026, then become easier until the next close approach in 2035. That's when I think we will be ready. So my money is on a 2030's Martian mission.

about a week ago
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PETA Is Not Happy That Google Used a Camel To Get a Desert "StreetView"

gman003 Re:And? (367 comments)

Several of their "animal shelters" were closed because the government was going to force them to call themselves "euthanasia clinics" because they killed so many animals. PETA closed them rather than accept the more accurate name.

about a week ago
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Texas Health Worker Tests Positive For Ebola

gman003 Re:No worse than AIDS, are you kidding? (419 comments)

Ebola is weird.

It doesn't spread easily. The virus is basically content to sit in a corpse and multiply. It doesn't spread through air, or aerosol, or even a lot of fluids. Just blood and bile - which, granted, it does like to make you spew out, but it's not too hard to avoid unless you're trying to treat infected people or lugging corpses around.

On the other hand, just a small initial infection can be lethal. Most diseases don't spread from one particle of the virus or bacterium entering your body - most need quite a lot, otherwise they get smashed by your immune system before you even show symptoms. Ebola doesn't need much of an initial infection to turn into a full-blown case.

Given those two things, there's no surprise that Ebola so often infects the doctors who are treating it. But that's on outlier on its infectiousness - it's still not going to be a massive plague, because outside medical and funeral services, it just doesn't spread well.

about two weeks ago
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Four Dutch Uberpop Taxi Drivers Arrested, Fined

gman003 Re:Getting tired of this shit (281 comments)

The line is when the payment goes from "covering expenses" to "generating profit".

about two weeks ago
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Four Dutch Uberpop Taxi Drivers Arrested, Fined

gman003 Getting tired of this shit (281 comments)

The level of astroturfing for Uber is getting ridiculous. I was sympathetic at first, because I can see how the existing monopolies are bad, but:
a) They aren't even trying to change the laws, they're just ignoring them. There are some laws that are so bad civil disobedience is a valid tactic. This is not one of those laws, and even then, when you do civil disobedience you're supposed to *accept* the legal punishment, because you *did* break the law.
b) They're astroturfing like crazy to frame the debate as "the common man versus the big bad taxi monopolies" when it's really "big international web-based corporation versus big local corporations". I don't care how many times you make sockpuppet comments about it, nobody's getting arrested for driving their grandma to the grocery store. People are getting arrested for running unlicensed taxicabs.

Licensing taxis is a good thing. The current laws may be overly-restrictive to protect existing businesses, but the spirit of the law is good. Uber? You're not. Any sympathy I once had is gone, purely because of your PR tactics. I was already unlikely to be a customer (I *have* my own car), but now I'm definitely not going to.

about two weeks ago
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Ubisoft Claims CPU Specs a Limiting Factor In Assassin's Creed Unity On Consoles

gman003 Re:Cell (337 comments)

The SPARC processors are still doing some interesting things, and there's been some shakeups in the GPU architecture space.

about two weeks ago
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Test-Driving a $35 Firefox OS Smartphone

gman003 Actually thinking of getting one (132 comments)

Not as a main phone, hell no. But there are times when I might not want to carry my expensive, fragile phone - going to a metal show, or a bad neighborhood, or whatever.

For that, being able to pop my SIM out of my Nexus 5 into something literally a tenth the price would save a lot of hassle and cash if it gets broken or stolen, and as long as it can still make calls and texts, it will work for most purposes. There isn't a single app I rely on, even email, but I do rely on being able to make phone calls and send texts. I briefly looked into buying a second-hand phone to see if it was cheaper, and it still can't beat the price of $35.

That said, who the hell said "let's make a dirt-cheap phone OS so the entire planet can enjoy the web!" and then decided to do everything in HTML and Javascript? Even Android is better than that. That's one of the areas where you would really want the speed and efficiency of a low-level language.

about two weeks ago
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Why Military Personnel Make the Best IT Pros

gman003 Re:Some would be well suited. (299 comments)

Spray-and-pray is a gangster or rebel tactic. Actual soldiers use actual tactics.

Most infantry don't use automatic fire except as suppressing fire - making the enemy keep their heads down while your guys move in close enough for a kill-shot. For a while our main rifle didn't even have full-auto - late-era M16s were single or three-round-burst only. There's some exceptions for urban combat, but for the most part, if they're shooting full-auto, they don't expect to hit you, they're just making it unsafe for you to pop out of cover.

about two weeks ago
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Why Military Personnel Make the Best IT Pros

gman003 Re:Good attitude but rarely much aptitude (299 comments)

I work with several IT guys that are former military. I DM a D&D game including two of them, and one is also a massive Warhammer geek. They also had basically zero formal IT training (we all went to the same shitty night school, and taught ourselves the actual skills on our own) and yet are fully capable, so they're also big enough computer nerds to teach themselves programming at a professional level.

about two weeks ago
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Linux 3.17 Kernel Released With Xbox One Controller Support

gman003 Re:Linux games (114 comments)

How many games does a platform have to have so it doesn't have "no games to play" ?

The PS3 was (and sometimes still is) widely ridiculed in gaming circles for having "no games", despite a launch lineup of 6-23 games (6JP/14US/23EU) and a current library of 796 retail games.

As no similar critiques were lobbed against the Xb360 (1,125) or Wii (1,222), we can conclude that the number of games necessary is somewhere in the range of 800-1100, most likely 1000.

However, your link only shows 702 games for me. Also, the above counts are of retail releases, which excludes a lot of the small indie stuff that makes up most of that list. And so we can conclude that Linux has "no games", and will continue to have "no games" for quite some time.

about two weeks ago
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Linux 3.17 Kernel Released With Xbox One Controller Support

gman003 Re:Systemd should replace the kernel. (114 comments)

Look, if it's not running straight LISP at the hardware level, it's not a real computer. Who needs firmware when you have CONS?

about two weeks ago

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