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Everything posted by DerekL1963
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ComNet Ideas for maximum coverage and minimum upkeep
DerekL1963 replied to Leafbaron's topic in KSP1 Discussion
As someone with extensive experience with RT.. the problem within Kerbin's SOI isn't generally north-south, it's east-west. That's why relay birds at the (simulated) L points are so popular, they allow the network to "see" behind the Mun. (Which was Leafbaron's original question - "I just feel that this would give you optimal coverage on the fariside of Kerbin's Moons with the least amount of infrastructure design".) North-south birds are useful for longer (Kerbol system) range relays in RT because (with an equatorial belt of shorter ranged relays) they avoid the problem of KSC being occluded. However, with CommNet's equatorial ground stations you no longer have that problem, if you can see Kerbin and have an antenna with sufficient range, you always have a connection to KSC. CommNet has some significant differences from RT, and because of that you need to rethink the logic behind your network design from the ground up. -
Stopping an ICBM with an orbital interceptor
DerekL1963 replied to SomeGuy123's topic in Science & Spaceflight
[[Citation Needed]] As far as is publicly known, nobody has ever tested a depressed trajectory system. And the limits I described are fundamental problems, and are going to be difficult to solve at best. -
It's not entirely clear, but it appears the fault wasn't entirely caused by lack of isolation (though they certainly wouldn't have helped), but was contributed to by the emergency operations team continuing to pump water to pad 40.
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Your ideas for extracting water from other planets
DerekL1963 replied to Waseemq1235's topic in Science & Spaceflight
It also depends on there being no volatiles or contaminants that can be vaporized and/or captured and/or entrained in the condensing water. And that's the real show-stopper in the whole thread, the methods of collecting and processing water from the environment is going to be heavily influenced by the environment itself. -
A detached object mission for New Frontiers 4
DerekL1963 replied to _Augustus_'s topic in Science & Spaceflight
Mostly (as in 98-99%) of the wrong kind of plutonium. Reactors produce mostly Pu-239 (which is used in nuclear bombs), along with a good proportion of -240 (which is a messy contaminant useless to everyone). Only a very small proportion is the -238 that's wanted for RTG's. It's much cheaper and easier to produce -238 directly than it is to haul those fuel rods around and process them. -
Huh? No. Did you read the story? "Placed in jeopardy" means "the launch complex suffered a complete loss of cooling water, threatening the loss of the payload and requiring emergency corrective action".
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One of the downsides of having billionaires run space programs is that their egos drive the process as much as engineering or the market.
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An interesting look at the accident from the POV of the emergency management team - and a fun tidbit, the accident placed OSIRIS-REx in jeopardy. http://www.patrick.af.mil/News/Commentaries/Display/Article/938481/emergency-management-a-behind-the-scenes-look-on-the-eastern-range
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Stopping an ICBM with an orbital interceptor
DerekL1963 replied to SomeGuy123's topic in Science & Spaceflight
At the cost of considerably less accuracy (due to a longer time and shallower trajectory during the re-entry phase), and heavier RV's (because of the longer heat pulse and the higher peak heating). Really, both sides of this debate are making the same classic error - assigning all the advantages to their 'side' and presuming that there are no disadvantages. -
Re-reading the message... They're not relying on amateur footage. The message called for assistance from three professional organizations and "everyone else". It's still odd, but not as odd and desperate as it's being made out here.
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"Not telling us anything" != " they don't the slightest clue about what happened".
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Simulation of life using chemistry?
DerekL1963 replied to Findthepin1's topic in Science & Spaceflight
No. -
Mars Colonial Transporter: What will it look like?
DerekL1963 replied to NSEP's topic in Science & Spaceflight
That's mostly because you've handwaved away all the problems Nibb31 pointed out. To take just one example of your ludicrous handwaving: "Long duration life support - I suspect anyone supporting the ISS (i.e. the Dragon flights) has a pretty good understanding of this." Huh? They didn't design the ECLSS, didn't build the ECLSS (they didn't even exist when it was built), and don't operate the ECLSS. Their only connection to the ECLSS is that of being a FedEx driver. They have precisely zero experience with long duration ECLSS. Heck, their flight experience with any duration of life support is essentially zero. Why? Because the ion engines and the requisite power supplies sufficient for cargo of any significant quantity (heck, any quantity over thirty or forty pounds) simply doesn't exist. -
Could you Make a Billboard in Space?
DerekL1963 replied to AtomicSnails's topic in Science & Spaceflight
No, it's not vacuum that makes inflatable things pop - differential pressure being too high for the burst strength of the material makes things pop. And there's no reason an inflated structure on orbit (especially one meant to have a limited lifetime) needs have an internal pressure over a few grams per square meter.- 37 replies
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Like wumpus I find it very hard to believe that an expensive satellite wasn't covered by somebody's insurance (SpaceX, IAI, Spacecom, any banks or financiers involved, etc... etc...) at every step of the process from exiting the factory doors through end-of-life. Speculating over which insurance did or did not, will or won't pay out strikes me as just meaningless jaw flapping. As to whether or not SpaceX owes a 'free' launch, that depends on the terms of the contracts involved, the terms of the insurance coverage, etc... etc...
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If you're planning on using the coordinates stored on the laptop to find safety... How are you going to navigate from where you are (heck, how are you going to find where you are?) to safety? You're going to need more than just a quick (temporary) recharge to "quickly check something". That being said, I'd carry at least a sat phone and my trusty 60CSx handheld GPS if I were headed out into the jungle.
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Unless they have a contract with SpaceX - neither.
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The space island group
DerekL1963 replied to Emperor of the Titan Squid's topic in Science & Spaceflight
VASMIR doesn't have sufficient thrust to even put itself (let alone it's power supply, fuel, plus any cargo) on a trajectory that won't spends weeks or months in the Van Allen belts.- 38 replies
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And I quote Mr Boisjoly from Chapter V of the Rogers Comission Report (I only have the webbed edition available): "The conclusion was we should not fly outside of our data base, which was 53 degrees. Those were the conclusions. And we were quite pleased because we knew in advance, having participated in the preparation, what the conclusions were, and we felt very comfortable with that." Where in giving the OK to launch if the temperature is "within the database" is he taking a stand? And the only dated remarks in chapter VI are from 1985 and all Boisjoly does is "express concern" and recommends setting up a team to study the problem. From volume IV of the report (testimony before the Commission on February 14,1986: "I guess, in all honesty, the data that we ran in resiliency showed on that chart at room temperature showed that in a normal ambient environment, that we did not have a problem, and we had a very sufficient erosion margin." And again, the dated notes are from 1985. And the same pattern continues in volume V - "concerns" and the dated material comes from 1985. So no, there's no evidence that I can find that they took any significant action at any time, let alone 'as far back as 79'. (Which would be difficult since Boisjoly didn't come to work until 1980.) For all intents and purposes they stood silent and hid behind a web of bureaucratese. If, as they claimed afterwards, they knew the joint was dangerous, there is no evidence that they took any significant action to inform anyone of these dangers. In fact, as quoted above, the flat out stated that it was safe to launch if the temperature conditions were met. . Give me actual cites proving I'm wrong, and read the material I mentioned in my previous reply, otherwise all you're doing is waving a white flag and declaring victory. If you're offended by the truth and wish to continue believing the illusions rather than doing the research in the sources I provided - that's on you, not me. When the employees do not properly keep management informed, then they must perforce take a share of the blame. In the real world, employees are not universally innocent angels and managers are not universally guilty demons. As far as providing links, the meat of the reference material is in Dennis Jenkin's history of the Shuttle. (Not everything is on the web.)
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Why is SpaceX building the Brownsville Launch Complex?
DerekL1963 replied to fredinno's topic in Science & Spaceflight
It's never wrong to question, although sometimes it's best to question in the privacy of your own head. Being critical without being aware of all the relevant facts (as we're almost certainly doing here) isn't wrong but it is a) largely pointless and b) dumb. The problem generally isn't being critical and questioning - it's refusing to accept answers that don't fit with the pre-ordained assumptions behind the question and criticism. -
o.0 It honestly never occurred to you that there's more to the story than a report that's over thirty years old? Find a copy of Dennis Jenkin's history of the Shuttle and the story of the seals is there. Google up Tufte's criticism of the the presentations of the ongoing damage to the seals. And then look for even one piece of documentary evidence (not flags, not points to, actual documentary evidence) that anyone took any action over the seals to stop the flights prior to the eve of the accident. The more you dig into the documented history of the seals... it becomes abundantly clear that everyone thought blow by was a problem, bad enough that a redesign of the joint was in progress at the time of the accident, but nobody said they should stop flying until the Morton Thiokol engineers piped up out of the blue on the evening of the launch. (Heck, even in testimony before the Commission (as shown in the Rogers Commission Report), on the eve of the accident the Morton Thiokol engineers recommended not that they stop flying but that they wait until it was warmer.) Boisjoly and Ebeling and others have done a very good job of leaving an impression that they fought NASA tooth and nail prior to the accident - but there's not one shred of evidence that they actually did so. And they stop very carefully short in their public utterances of actually claiming to have done so.
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How is this possible? (New Roscosmos space capsule)
DerekL1963 replied to fredinno's topic in Science & Spaceflight
Given that they're put zero effort into preserving the existing vehicles, I suspect they put even less effort into preserving the production tooling and jigs. -
No he didn't. The SRB joints were failing during ground testing in the 1970's - and Boisjoly and Ebeling and the others stood silent. The SRB joints were failing were failing when the Shuttle started flying - and Boisjoly and Ebeling and the others stood silent. Seriously, Challenger wasn't lost because the cold made the o-rings leak, Challenger was lost because the cold made an existing (and dangerous) leak in a design known to be flawed worse. (In fact the worst damage pre-Challenger, near complete failure of the primary ring and damage to the secondary, was with launch temperatures in the eighties.) The joint rotation problem first appeared during ground testing in the 1970's, and the fix was to use a second o-ring as a backup (and in a way o-rings aren't meant to be used in the first place). When they started flying, and blow-by and o-ring damage was much worse than it had been in ground testing... they continued to fly because the joint never actually failed completely. At no point during these years where this flawed design was known to be failing and should have been known to be a risk to the vehicle and crew did Boisjoly and Ebeling stand up and try to stop the flights. It was only when the cold made complete failure of the joint a near certainty that they finally decided, much too late, to make a stand. The worse part is that the leakage was so dangerous (and NASA and Morton Thiokol knew it) that they were in the process of designing a new joint, but continued to fly anyhow.
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While all this is true, it is pretty pedantic to suggest that liquid oxygen is anything but an explosive. It might not be, but it can make virtually anything it touches an explosive (charcoal + LOX is a favorite industrial explosive. If the detonator fails, just wait for the thing to be a dud detonator (still dangerous) and a pile of charcoal (not so much)). Be that as that may be... But you miss a critical difference from the point of view of the smallsat launcher operator. Said operator has to pretty much provide everything when it comes to solid fuels. Liquid fuels and LOX are black boxes though - a phone call and credit card info go in one side, and LOX and fuel come out the other. If there's an accident with either in production or transport, it's the fuel (or LOX) provider or the transport company that have to deal with it.
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Moonshot - short films about Google Lunar XPRIZE
DerekL1963 replied to RainDreamer's topic in Science & Spaceflight
The creation of the spaceport took away from money and manpower they could have used for the vehicle. 0.o The spaceport was provided gratis by the state and county governments. And the minimal personnel they have there are unlikely in the extreme to have effected the development and construction of the engine and airframe, doubly so since the types of personnel are completely different.- 31 replies
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