Elladan

Elladan

  • Commented on Crib Notes: Empire Games
    You might be a bit behind the times, there - ARM produces the ultimate "commodity hardware", and AIUI it's wired in at the hardware level (it certainly exercised some of the people I used to work with)... I think the...
  • Commented on Crib Notes: Empire Games
    About the o/s: you can look up rings of protection in wikipedia, but basically, the way most operating systems work is ring 0 is the kernel, and ring 1 are device drivers. [....] This isn't so. The whole idea of...
  • Commented on Crib Notes: Empire Games
    This whole discussion of computer languages and instruction set architectures is fun (though I think, often misguided). However, thinking about this from the point of view of the story, it seems to miss the real areas where borrowed tech matters....
  • Commented on Excuses
    I have a huge question about reusability. I think a lot of people have questions about Arianespace (and ULA's somewhat similar) reusability plan. Before really getting into the technical specifics, they both seem to be designed mostly to be afterthoughts...
  • Commented on Bread and Circuses (circumlunar version)
    So one is the rotating tether. Rotovators are pretty fun to think about. One of the bits that may not be obvious is that you really don't need them to be zero energy / momentum: because they're in orbit before...
  • Commented on A bright and shiny hell
    The videos that came out at the time had clear machine gun fire sounds on them. He used semi-auto rifles with aftermarket "bump stock" accessories. There are a variety of these sorts of things (new ones come out regularly) which...
  • Commented on Bread and Circuses (circumlunar version)
    Going back to the BFR, what can the US military do with it? If you look at the ground kit requirements both for taking off and for landing, I think a good mental model for this system is more like...
  • Commented on Bread and Circuses (circumlunar version)
    Unlike pulsed laser systems, magbeams won't make for good weapons, which is a significant point in their favor. [....] Current rocket technology is great for getting into space, but pretty awful at getting reasonably sized payloads to another planet in...
  • Commented on Bread and Circuses (circumlunar version)
    I'd like to imagine that those billions of dollars might be more usefully invested in one of the alternative propulsion schemes that have been dreamed up in the last 60+ years. Allow me to play... well... I guess Devil's Advocate...
  • Commented on Bread and Circuses (circumlunar version)
    I know there are various colors and flavors of design of inflatable heatshields for aerobraking (I haven't checked to see if any have actually been tested, mind you) It turns out, NASA actually has tested one of these! Check out...
  • Commented on Bread and Circuses (circumlunar version)
    You still need to get all that fuel into space in the first place though, right? Yes. I imagine their mission profile looks something like this: Launch 1: Tanker #1 flies to LEO and parks. Launch 2-5: Tanker #2 shuttles...
  • Commented on Bread and Circuses (circumlunar version)
    but it does represent two years of the world supply of Xenon ... for a SpaceX BFR size space ship, that is....
  • Commented on Bread and Circuses (circumlunar version)
    I assumed no mass for the engines, just the mass of the arrays Besides massless engines being somewhat optimistic, ion drives still use propellant. By the rocket equation Δv = ve ln (m0/m1), with an exhaust velocity of 31 km/s,...
  • Commented on Bread and Circuses (circumlunar version)
    My calculations suggest that by increasing the power density by about 10x, and using the Dawn mission craft as a baseline, you could accelerate/decelerate to the cumulative 10 km/s delta V in just 3 days Could you explain your calculations?...
  • Commented on Bread and Circuses (circumlunar version)
    Believe that residency is implicit in the 'natural-born'. It's not. They're clearly separate requirements, e.g. if you were born in New York but lived your whole life in France. Also, you can be a citizen because your parent(s) were citizens,...
  • Commented on Bread and Circuses (circumlunar version)
    Please read a little closer. Both Alex Tolley and I were mentioning the vague residency requirement, not the citizenship requirement. She's clearly a citizen. I would guess that she's 100% eligible, and if she were to run this would in...
  • Commented on Bread and Circuses (circumlunar version)
    To expand on Alex Tolley's answer above, as she was born in Puerto Rico she's a natural born citizen and thus eligible. The only sticking point is that there's also a requirement that the president have "been fourteen Years a...
  • Commented on Bread and Circuses (circumlunar version)
    LOX (and methane) can be kept cold in deep space simply by using a sunshield and perhaps a bit of insulation. In case this seems weird, look at the James Webb Space Telescope: the plan there is to use a...
  • Commented on Bread and Circuses (circumlunar version)
    SpaceX isn't the only company betting on methane. Blue Origin & ULA are both planning on using the BE-4 methane (well, natural gas) engine for their new rockets, also in development. My understanding is that besides the Isp boost, methane...
  • Commented on A bright and shiny hell
    OTOH, I would REALLY APPRECIATE, someone's take on the "AI god" meme ..... Natural progression of the singularians? Our AI heaven is a long time coming, let's start worshipping It now? People reading LessWrong too much and start hallucinating that...
  • Commented on Bread and Circuses (circumlunar version)
    You should really track down a copy of 'Ignition! An Informal History of Liquid Rocket Propellants' by John D. Clark Seconded! This book is great....
  • Commented on Bread and Circuses (circumlunar version)
    Just to add a few numbers, if you use Charlie's estimate of 3 kg of water per day, for a 4 month trip that's 360 kg of water per crewmember. For a crew of 7, that's 2.5 metric tons (sans...
  • Commented on Bread and Circuses (circumlunar version)
    Is it the weight or the space/volume taken up by the water that's a problem? In space, it's essentially always the mass (weight). To a first approximation, that's the only thing the matters at all. The only case where volume...
  • Commented on Bread and Circuses (circumlunar version)
    One of your earlier comments specified X amount of water per astronaut per day. However, within a closed system with decent water recycling, total water loss would be minimized. Keep in mind when thinking about real-world systems that there are...
  • Commented on Bread and Circuses (circumlunar version)
    However, I get the impression [...] that folks seem to think that whatever fuel is used, it can only be that one fuel type. I'm not sure I really understand what you're asking. Real-world rocket/satellite systems typically use multiple fuel...
  • Commented on Bread and Circuses (circumlunar version)
    The incident you're thinking of was wonderfully well documented on video! Little Joe II abort test...
  • Commented on Bread and Circuses (circumlunar version)
    They're actually proposing that the BFR can refuel once before landing on the Moon (in a highly elliptical orbit, I believe) and then has plenty of Δv to land, take off again, and fly right back to Earth. I assume...
  • Commented on Bread and Circuses (circumlunar version)
    I've seen this Deep Space Gateway sort of idea proposed a lot, but I just don't really get the necessity. Perhaps you can explain? I understand that refueling high up in Earth's Hill Sphere, e.g. L2 or a distant retrograde...
  • Commented on Bread and Circuses (circumlunar version)
    Existing Ion drives e.g. those on Dawn have an Isp over 3,000 s, and some quick googling indicates that exotic designs reasonably go up to 10,000 s or more. The problem with looking at the Isp of ion and similar...
  • Commented on A bright and shiny hell
    surely you must be able to get in to be able to change the SIM card, if nothing else? The sim card slides in via a little tray that pops out of the side of the phone using a special...
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