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sevenperforce

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  1. Well, if the capture arms can catch a falling Superheavy booster, then they should also be able to pick up both the booster and the Starship and move them around. The best part is no part. They may elect to try and lift Starship by the forward flaps to avoid having lift points poking through the heat shield. LOL, came here to post that but I guess I'm late to the party. It definitely looks like those downward-facing triangles mark the bottom of the seam, as previously speculated. If you look higher on that particular image, you can see what appear to be diamond-shaped fillers, but these could simply be fractured tiles that need to be replaced: The seams seem (overall) to be much tighter than I would have expected, though. Once we get a cleaner image we might be able to tell whether they are all hexes or if they have some sort of tapered shape. I'm guessing that they will end up gluing custom tiles to the nosecone, perhaps with one large monolithic hemispheric tile at the very tip. They used glue for custom tiles on the flaps, so....
  2. Orion is very inefficient. It wastes most of the energy it carries. If we had photon portals, no one would bother with lasers or induced fusion or anything like that. These portals are tungsten, after all, so they should be able to handle very high temperatures with ease. The equilibrium temperature for metal reaches about 1700 degrees C around a million miles from the sun, so a tungsten photon portal should be able to get significantly closer: up to around 730,000 miles from the sun, where the equilibrium temperature is just below tungsten's melting point. Insolation there will be 16,000 greater than it is at 1 AU, thanks to the inverse-squared law. Insolation at 1 AU is about 1.4 kilowatts per square meter, so the photon flux through the photon portals will be 19.6 square meters times 1.4 kilowatts per square meters times 16,000 for a total of 440 MW.
  3. Oh this would have been one of my first ideas, except that my understanding of the OP was that the portals only allow photons to pass through, not baryonic matter. No, not at all. You can get the equivalent of an F-1 engine power output in an engine the size of the F-1 simply by hooking up the power of a giant hydroelectric dam to one of the portals. It's really quite straightforward. You don't need it to be big at all. No, it becomes more efficient the more energetic it becomes. If we had magic photon portals, building Orion drives would be the absolute last thing anyone would suggest.
  4. Sorry, haha. Let me cut it down to size. The green line up top, e, represents the eccentricity of Earth's orbit. KSP players will be very familiar with eccentricity, but for those who haven't actually played, it represents the circularity (or lack thereof) of a particular orbit. When the eccentricity is close to zero the orbit is very circular, and so the heat from the sun is fairly constant over the course of the year. When the eccentricity is higher (up to 0.05 on this graph), the orbit is less circular, and so there is much higher solar insolation during part of the year. This is the biggest climate forcing function for our planet. Thanks to resonances between Saturn and Jupiter, the eccentricity of Earth's orbit is on a cycle of approximately 100,000 years. The red and green lines at the bottom represent global temperature (red comes from sedimentary isotope analysis and green comes from ice core analysis). Using these different datasets, scientists are able to reconstruct how insolation impacts global temperature. Here's basically what happens. During periods of low eccentricity, the oceans are cooler, and so they are able to directly absorb a higher amount of carbon dioxide (yes, gases can be dissolved into liquids; that's how fish get their oxygen, after all). Once the eccentricity of Earth's orbit starts to increase and solar insolation starts to spike at certain times of the year, the oceans warm rapidly, releasing their absorbed carbon dioxide and causing a surge in global temperature. However, once the oceans run out of carbon dioxide and the eccentricity of Earth's orbit starts to decline again, the ocean temperatures begin to cool, slowly absorbing more and more carbon dioxide. The last of these surges was in the Medieval Warm Period, so we should be in the cooling-down part of the cycle. Unfortunately, we've been releasing millions of tonnes of carbon that was buried deep underground in oil reserves, and so even though the eccentricity of Earth's orbit is decreasing and we SHOULD be cooling down, there is simply too much carbon being released for the oceans to absorb.
  5. Not stupid, but also not a new idea. This is something that climate scientists have been studying very closely for a very long time. The good news is that we have a LOT of data to work with. We can go back in ice cores and fossil layers and coral reef samples and determine the CO2 levels and global temperatures at any time. We can also look at Earth's position relative to the sun over millions of years to see when the Earth was getting more or less solar irradiance. As you might expect, these numbers line up: This is just the data for approximately the last million years. You can see that there are global cycles in temperature; those cycles line up with the solar cycles resulting from changes in Earth's orbit. The more energy the Earth gets from the sun, the hotter the Earth gets. It's a fairly complex set of variables, of course, but we have enough data to resolve it very, very well.
  6. If you go to the source image you can see that the view we're getting is the lee side, not the windward side. This gives us a general idea of how far around the nosecone the heat shield is going to wrap. I'm really curious to see what they do for the very tip, though, because I don't see any tile studs above the insulation at all. I was reflecting on the possibilities concerning the lifting arm assembly for the tower. We know that the tower is going to catch the booster as well as provide all lifting and stacking capabilities, which means the rail-mounted arms are going to need to turn to one side to pick up a booster or Starship (possibly by the forward elonerons?), grab it, then rotate to the other side. That presents a challenging question with respect to degrees of freedom. Ordinarily, you would want to do something like this: However, the catch frame is mounted on three rails directly underneath the lifting pulleys, so it cannot rotate. Another option would be something like this, with extension elements. But that seems challenging as well. My guess is that there will be a larger frame that is fixed to the rails enclosing a smaller frame that rotates within it, and the catch arms will each have a single degree of freedom on that smaller frame.
  7. Good question. What we know from our study of the carbon cycle over the last billion years or so is that plant growth has difficulty catching up with increased CO2 levels. Plant growth levels are more limited by access to light and fresh water than they are to CO2, and with global temperatures rising and droughts becoming more common, access to fresh water is going to be the biggest problem with that approach. Moreover, most CO2-scrubbing activity is done not by plants, but by marine life -- algae, seaweed, and the like. The oceans are already full of carbon-scrubbing organisms, and here the limiting factor is access to sunlight (since the algae, phytoplankton, etc. needs to be close to the surface in order to get light). This is actually one of the biggest concerns for a runaway feedback loop. Marine life that provides CO2 scrubbing is sensitive to temperature. If the ocean temperature rose too high, it might be curtail the life cycle of that marine life, leading to dramatically decreased ocean CO2 scrubbing capacity, leading to higher temperatures and a runaway loop that could cause a major extinction event within mere decades. Granted, that particular outcome doesn't seem terribly likely right now, but it's still worrisome. There is some good news, though. The most promising carbon capture technology uses marine algae kept in tanks, and it works very well. It's just not being done on a broad enough scale to make much of a difference. The answer is that the current warming is entirely anthropogenic. Solar activity went up in the 1780s, down in the early 1800s, back up slightly, down a little around 1900, up between 1940 and 1990, and is now on its way back down to its lowest levels since the 1840s. Our planet's temperature is increasing due to the increase in carbon dioxide, not due to solar activity. I would argue that we do know. Solar activity has been steadily dropping since the 1990s and the temperature has been steadily rising. It ain't the sun; it's us.
  8. Or you can go the opposite route and offer tax credits direct to suppliers in proportion to the percentage of their energy that comes from renewable resources. One problem comes from failure to distinguish between the "worst-case scenario" in terms of total warming impact and the "worst-case scenario" in terms of how rapidly that total warming impact point is reached. For the former, we are already in the worst-case scenario, and that will not change unless we take drastic action. On our current path, we are going to melt all the land ice. Melting all the land ice is the worst case scenario. We need major change in order to avoid this worst-case scenario. How quickly will we reach that worst-case scenario? We don't know. Hopefully there will not be a sudden and drastic runaway feedback collapse a la Venus. Hopefully the worst-case scenario is at least 80 years away. It doesn't look good, though. In terms of the timing itself, the worst-case scenario is of course a Venusian feedback loop. That particular scenario seems unlikely at this point. I think that climate change skeptics/deniers (along with much of the general public) hear scientists say "we are already in the worst-case scenario" and assume the scientists are talking about the timing of it rather than the overall endpoint. Thus it suggests a higher level of alarmism on the part of the scientists than is actually there, which leads to people ignoring the realities of it all.
  9. Cool image, but fuzzy. I think I can make out the skirt mating points where the rim becomes thicker. Are there three mounting points in the center for pusher separation rods to the Raptors?
  10. There is no limit to waste heat ejection capacity in a thermal rocket. You just design an engine that is large enough to provide the desired flow path and rate for the heat capacity of the propellant you are using. That being said, @Shpaget is absolutely correct; 500 terawatts is nearly thirty times the continuous human and industrial power consumption across our entire planet, from all energy sources. Suggesting the use of a continuous 500-terawatt laser (which would NOT be the NIF laser, because the NIF laser cannot do that) is kind of like suggesting the use of Saturn's moon Rhea as a bowling ball. It's just not a scale that makes any sense. For reference, the F-1 engine had a peak power output of 23 gigawatts. A thermal rocket engine large enough to provide a propellant flow path and flow rate necessary to handle 500 terawatts could be theoretically built, but it would weigh around 183,000 tonnes, 75% heavier than the world's largest aircraft carrier, and it would have a nozzle approximately 21% larger than the entire Pentagon complex. NOTE: this does NOT mean that we would want to build one of these....because, again, we don't have that kind of power source. If the rings each have a mass of two tonnes and you want to use them as the powerplant for a thermal rocket engine, then the associated mass of the heating chamber and nozzle would be in the range of the F-1 engine. So you would need a power source producing around 23 gigawatts to match the power output of the F-1. That's just a little bit higher than the power output of the largest hydroelectric dam in the world, the Three Gorges. You would then need a way to convert all the power output of that dam into light and somehow focus that light into a 5-meter-wide circle, and boom, there you go.
  11. My only mention of you in my last post was to say that you seem like a nice fellow and I would happily buy you a beverage of your choosing.
  12. We know precious little and it is intensely annoying. Tory Bruno told me a few weeks ago that reuse is all still in dev and totally planned but we don't have any idea when it will be implemented, if ever.
  13. Wellllll looks like I'm going to be liquidating those assets.
  14. To be clear, it is MORE than good enough. You can colonize Mars and the Moon using current tech easily enough, if you can get Congress to fund it. You don't need a nuclear saltwater rocket. That being said, Zubrin's 13 meganewton design would boast about 0.8 terawatts of power at full thrust. So yeah, if you could make the NIF laser fire continuously through the portal, then you could produce a power output 625 greater than Zubrin's design. But of course you can't make the NIF laser fire continously, so......?????
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