They talk about using them for delivery of harmless supplies, but I agree, as weapons delivery systems they seem to make more sense. They describe a balloon carrying up large numbers of small, largely transparent aerial vehicles that then drift to target locations up to 150km away automatically with a 1,4kg payload, then vaporize via sublimation and/or fracturing electronics to tiny bits from internal stresses. Why exactly couldn't these be carrying small shaped charges? And if they have a processor controlling the descent, then they could probably run at least simple image recognition algorithms, or even just IR seeking, once they get to their destination.
A 1,4kg shaped charge is no laughing matter - a mere 440g charge is said to be able to penetrate 35cm of armour. Even if the charge can't penetrate, say, tank primary armour, a precise delivery system could target things like optics systems, weapons systems, tracks, etc. Such a charge could completely take out unarmoured vehicles and would be particularly destructive to aircraft on the ground. Ammunition, fuel supplies, power substations, etc, etc... there's a lot of things a small explosive payload could take out. A balloon hauling dozens or even hundreds of them at once? You're basically talking "cluster cruise missiles". Carried on small transparent wings with almost no radar signature except for that of your munition.
I'm sure that these possibilities haven't passed over DARPA officials.
And "coders" are so normal today because so many people in STEM fields have to program. It's not rare at all anymore for a scientist, mathematician, or engineer to have to write scripts or whole programs to support their work - either it's not in the budget to hire a programmer for the specific task, or it's just too much effort to bring a programmer up to date with the scientific background needed to really understand the task at hand.
And as mentioned, what exactly is the T in STEM for anyway, given that it's clearly not "engineering" (the E)? It's where computer science should be.
Computers are a critical enabling technology for many if not most types of science these days, they are technology (what else best fits in "technology" if not computer science, given that engineering is a different category?), they're critical for nearly all engineering these days, and most mathematics work. It's an entirely appropriate category.
Where does it say that "computer science must be treated as science, by law"? It declares computer science to be part of STEM. STEM does not simply mean "science" - science is only the "S" in STEM. STEM means "Science, Technology, Engineering, and Math" There's nothing inappropriate about computer science being taught in that grouping.
The main problem I see is that it seems like you're making a lot of assumptions based on geology here on Earth, such as which minerals are likely to be present at sites with particular geologies. Doesn't that depend a lot on the early planetary formation?
Chemistry works the same everywhere. What elements readily form compounds with other elements is the same everywhere. At what temperatures minerals begin to crystalize out of magma is the same everywhere. Etc. Economically valuable deposits of resources are locations in which chemistry tended to concentrate that mineral and leave it at an accessible location. The same parameters must apply to the moon just like on earth.
Also, correct me if I'm wrong, but I thought I had read that, just like you say with the Moon and heavy elements sinking to the core, the exact same thing happened to the Earth, and as a result, we have no heavy metals, including iron(!), accessible here on the crust left over from the formation of this planet.
90% of the mass of the Earth is oxygen, iron, silicon, and magnesium. And these chemicals tend to form compounds with each other. Consequently it's impossible for "all of the Earth's iron", for example, to have sunk to the core. More to the point, these oxides aren't as dense as the pure metals. For example, in the crust a lot of iron is found as limonite (that yellowish-orange color you often see in clays), which can be nearly as light as quartz. The largest single mineral component of the mantle (and thus the Earth) is olivine (commonly known as peridot when sold as gemstones), a magnesium iron silicon oxide.
Unlike the outer layers, earth's core is predominantly metallic iron, not oxides, and thus far denser. It's also highly enriched in many heavier elements which either don't readily oxidize or form heavy oxides. For example, platinium is found at about 5ppb concentrations in the crust, but is believed to be about 6ppm in the inner core, over a thousand times greater concentration. Uranium, thorium, gold, and countless other elements are vastly more common in the core than the crust. That doesn't mean that they're absent elsewhere. Even ignoring deposits from bombardment, you will often find small amounts of rarer elements in minerals with elements that they're chemically similar to.
You can see the nature of mixtures in what erupts to the surface as lava - an igneous flow will ultimately crystalize out into a wide range of tiny mineral grains - various feldspars, quartz, various iron oxides, etc. These crystals have different densities, and they're made from elements with different densities - but the forces keeping them in solution are greater than the forces working to fractionalize them. Differentiation inside magma takes a long time - for example, to get basalt rich in large olivine crystals, like picrite, the magma has to sit and slowly cool over many thousands of years, allowing the olivine time to crystalize out and the crystals time to settle to the bottom without the bulk of the magma hardening and trapping it - then the upper olivine-poor magma erupting, then the olivine-rich magma erupting (again, all without hardening to the point of becoming trapped in the magma chamber).
Or, to put it another way: salt is heavier than water, but the bottom of the oceans is only slowly increases with depth (and is highest near the surface where water evaporates, but that's a side point). It's a lower energy state for the salt to dilute than to all collect at the bottom.
nd that all our valuable ores (iron, gold, silver, even tin and lead) came from asteroid impacts over the eons, which is why they're concentrated in particular places.
First off, our knowledge of the moon is not "some rocks the Apollo astronauts brought back". The Moon is one of the most studied bodies in the solar system, perhaps the second most studied. We have a pretty good idea of what makes it tick. There have been 70 successful or partially successful (overwhelmingly completely successful) missions to the moon, plus some considered "spacecraft failure" that still returned data. 6 of the successful missions are operational right now. There have been 16 missions to land softly on the moon, one of which then re-launched and landed again. There were also two impactor missions to kick up plumes for study. There have been 8 sample return missions, another of which is scheduled for 2017. Modern advanced orbiters have conducted detailed spectral scans of the whole moon and mapped details down to 50 centimeters. We know the thing pretty damned well. It wasn't until the second half of the 20th century that we even knew the Earth that well.
The moon is fundamentally disadvantaged when it comes to valuable mineral resources. Most valuable, rare mineral resources are heavy, as these tend to sink deep into planets during formation, leaving them depleted from the surface. The moon was formed in a collision whose dynamics left most of its heavier materials on earth and left it with lighter materials from itself and Earth. That's not to say that all light minerals are worthless - far from it. Beryllium is worth over $1k per kilogram, and it's quite a light element. But things like that are the exception, not the rule. The moon was then doubly disadvantaged in that the collision left it with a global magma ocean (with no tectonics to recirculate deep crust back to the surface). This led to crystals of lower-melting point and denser minerals to almost universally sink to the bottom, leaving the top layers rather monotonous in composition (a universal plagioclase crust). While various geological activities subsequently modified it (primarily impacts and, long ago, the mare basaltic flows), it was disadvantaged from the beginning.
Then there's the fact that minerals don't just pop up randomly - they need geological phenomena to concentrate them to economic levels, and they're found associated with various geological features and/or tracer minerals. For example, the aforementioned beryllium is found in granitic pegmatites associated with tin and tungsten. The moon has no granite - thus no granitic pegmatites. There are a few other types of minerals beryllium concentrates in, but they don't exist on the moon either. This doesn't mean that there's no beryllium on the moon - there is, it's been studied. But there's nothing to concentrate it to interesting quantities.
The biggest modification to the original lunar rocks has been the formation of the mare. These are ancient mass flows of tholeiitic basalt - not much diversity, except in the concentration of titanium. Lunar titanium concentrations are much higher than on Earth. However, titanium oxides are very cheap, common minerals. Melt pools from impacts also have the potential to be mineral concentrators (on Earth, the Sudbury impactor created some highly valuable mineral deposits in Canada). But there are two problems. One, these tend to solidify deep underground, meaning your mining becomes far more difficult and hardware/labour intensive (on a body that costs many tens of thousands of dollars per kilogram to land hardware on - even with a 10fold price reduction, you're looking at big problems). And two, all its modifying is plagioclase and ti-rich theolitic basalt. And of course, tectonic modification can concentrate minerals. While there have been tectonics on the moon, they're very limited compared to those on Earth.
Now, this isn't to say that there's *nothing* interesting on the moon. The moon is rich in what's called "KREEP" - Potassium Rare-Earth Phosphorus. It can be found from space because it's also associated with higher concentrations of alpha emitters like uranium and thorium (although not anything one wou
Windspeed is irrelevant turbulence is what matters; it does not seem to be significant at 52-56km altitude. While we know that lightning exists on Venus, it's only at about the rate that it exists on Earth, and seems to be biased toward particular locations and altitudes. Of course, we've studied the planet so little, who knows - it obviously takes prep work. A prep mission would basically be a long-term version of Vega, with solar panels for recharging rather than just running on battery power.
If we wanted to send humans anywhere that would pay the most benefit, I really think Venus (cloudtops) would be best. Venus is so under-studied that any mission (manned or otherwise) has the potential to yield huge scientific benefits, and the ability to real-time control probes exploring the surface (aka, where their time that they can spend near the surface is limited before they have to head up to re-chill their cooling reservoir and recharge their batteries, and you don't want the lag time of commands sent all the way from Earth) would be of significant benefit. And in terms of future mining potential, Venus probably has the most useful geology - the types of lava flows found by the Soviets, and the additional potential of carbonatites, combined with the "high radar reflective" precipitated minerals, all are very promising signs for enrichment of rare and economically valuable minerals. Phase-change balloons can descend to the surface and bring minerals up to the cloudtops, and are eminently achievable with current technology - hardly more complicated than the old Soviet Vega probes. Since you're floating, you can move anywhere on the planet in a relatively short period of time (due to superrotation, you really have no choice in the matter;) ), so you're not limited to whatever resources happen to be close to your base. And the cloudtops are a very hospitable environment to humans - at 52-56km a person may even be able to step outside with nothing more than a mask on (oxygen provision and eye protection are a must, but the CO and SOx levels may be low enough to not be problematic to bare skin - the pressure and temperature are fine). The significant atmosphere overhead provides a good deal of radiation protection, even though there is no dynamo-driven magnetic field.
The moon is nearby and a conveniently low gravity well, but as far as minerals go, it's pretty boring - to the point that the best people have come up with is "helium 3 fuel" to power reactors which don't exist and which probably will never be an idea fusion fuel (if you can fuse it and can make an economic case for it, you can probably also fuse P-B which is much better and cheaper). And it will always suffer from "been there, done that" syndrome.
Indeed:) Don't get me wrong, one can achieve great things through small steps but only if those steps are part of a long-term process planned out in advance with the ultimate goal in mind, and full committal from all interested parties (particularly those funding your endeavor) to follow it through to the end. Otherwise, you're just building castles in the sand to be washed away when the tide comes in.
Is the goal to go to Mars just to check off an entry on our species' bucket list, or is to move toward the the eventual colonization of the planet? Then we better have the whole colonization process down, down to what will lubricate the drive axles on the truck that hauls the fluorite ore from the mine on Arsinoes Chaos to the ball mill at Terra Meridiani, or how to make the replacement bolts for the elevation mounts for a sulfuric acid pipeline at the Becquerel chemical plant. That means in no way, shape, or form that nobody should do anything with Mars until you can launch a whole self-sustaining colony. But it's important to have planned out the whole programme in advance - knowing precisely what materials we're going to need, what parts, how quickly they'll be consumed, how much labor every component's operation and maintenance will take, what raw inputs you're going to need, where you can get them, etc, and ensuring that at no point are you consuming more of something than you can produce.
If you send things to Mars without doing this, you're just going to spend your billions of dollars launching dead-ends - made out of materials that it turns out that there's no practical way to make on the planet, or with processes under which particular steps work out to be impractical or impossible on Mars. Due to the tremendous expense to engineer and launch each piece of hardware to Mars, you want each piece to serve a critical role in your long-term goals. Sent a device to freeze carbon dioxide out of Mars's atmosphere to feed a greenhouse or bioreactor? That may sound great... up until the point that you discover that you also need nitrogen or argon collected from the atmosphere for other processes, and that your whole chiller system needs to be replaced with one that can handle lower temperatures. Sent a pipeline made out of polypropylene to carry some sort of fluid? Great, until you discover that you need to multi-use that pipeline and some of the chemicals you need to send aren't compatible with polypropylene, so you're just going to have to build a new one parallel to it. Etc.
NASA of course has no interest in actually planning things out all the way in advance. And never has.
Such a lifeform could easily engage in interstellar travel, even with the hundreds and thousands of years it takes.
Most sci-fi fans vastly underestimate the difficulty of even getting remotely close to the speed of light. The last, optimized, peer-reviewed design for a pure antimatter-driven ship that I saw - the highest performance you're going to get without beamed power, and beamed power suffers from range problems among others - was to reach about 0,4c. That's pure anitmatter, which vastly outperforms fusion and fission. Making antimatter inherently means turning mass to energy, wherein a very tiny fraction will condense out as antiprotons, which you can then trap. So you're taking E=mc^2, reversing it, and then taking only a tiny fraction of even that. Actually mass producing the vast amounts of antimatter needed for such starships would take a civilization advanced to Type 2 scale. It's nice to fantasize that the universe is full of Type 2 and Type 3 civilizations, but that's a huge thing to posit.
It's also easy to posit generation ships. But as the saying goes, shit happens. The longer you're in transit, the more likely that is to happen. Which means you have to make your ship vastly larger, to be increasingly redundant, parts in one part increasingly isolated from others, much larger crews than just the minimum skeleton crew needed to populate a planet, etc. Unless all you're sending are artificial wombs and eggs. But then you're back to my initial posit, that such information could be transmitted to an alien species directly at the speed of light.
Indeed. VW did very egregious cheating, deliberately detecting tests and then optimizing for them. It sounds like these others are not engaging a "test mode"; but have optimized themselves for conditions that are tested for (at the expense of power and fuel efficiency) while optimized themselves for power and fuel efficiency in conditions that aren't tested for. Not as egregious, but still clearly problematic. There's clearly gaping holes in the system.
It also puts to lie this massive increase in diesel cleanliness over the years. It's improved, no question, but not nearly as much as has been marketed, particularly in smaller, cheaper vehicles. The same old choice remains: you can get a ~15% increase in fuel efficiency by mass (~30% by volume), and thus ~15% reduction in CO2 emissions, by going with a diesel, but it'll come at the cost of a more expensive engine (has to be built stronger to handle the higher compression, all issues of additional pollution control systems aside) and will kick out more health-impacting pollutants. And it just comes down to chemistry: if you burn fuel in air at hotter temperatures and/or higher pressures, you favor the production of chemicals like NOx - high temperatures and pressures make nitrogen more reactive. And you're going to kick out more PM for similar reasons. The higher temperatures and pressures help with CO and unburned hydrocarbons (they favor more complete combustion), but the scale of the added NOx and PM problems are much greater.
Contrary to what they've been pretending, a major way that car manufacturers appear to have been reducing NOx emissions in diesels is simply by burning their fuel cooler / less efficiently in conditions that are being tested for, and hotter the rest of the time to keep their performance and efficiency numbers up.
It's not that simple. Mercury also has a magnetic field. Which is a real head-scratcher, as it's even smaller than Mars.
Internal planetary dynamics are complicated. To get a dynamo you need fluid flow. But whether something is liquid or solid depends on both temperature and pressure - temperature increasing melt, pressure decreasing it. So there's a very complicated interplay.
Uber has long proven themselves to be eminently trustworthy and never scheming up shady ways to try to drive their competition out of business, so we can just take them at their word on this.
Very little energy reaches the Venusian surface - Venus's albedo is twice that of Earth's, so most light gets reflected from the cloud deck, and what does enter gets quickly absorbed in the clouds and thick atmosphere. Also, the crust is not what drives a dynamo, the core does. Nuclear decay is what drives terrestrial planet cores, not solar input.
Also I don't know what you mean by "rapid crust recycling", unless you mean Venus's global resurfacing events. But those only happen once every several hundred million years. And they take about 100 million years to complete, they're not rapid.
... that because of Mars' small size, it cooled faster, thus freezing its outer core and shutting down its dynamo? Isn't Venus the far greater mystery? Nearly the same size as Earth, yet no magnetic field and what appears to be occasional whole-crust overturn rather than plate tectonics? Isn't that the one we need to solve?
I agree. The field of extraterrestrial linguistics has seriously advanced beyond then, thankfully, with communications systems based on logic system, and even a transmittable operating system that explains how it should be run (inputs, outputs, etc), enabling one to send interactive programs along with it.
It's funny, but there's a concept I've never seen before in science fiction: that of multiple alien species living amongst each other, but whose homeworlds are vast cosmic distances apart and who have never gotten anywhere close to each other due to the difficulties of approaching relativistic velocities in spacetravel. How? Bit by bit we understand more of "what makes us tick". Not just how DNA codes for proteins, but the whole complex interplay of these proteins in keeping a cell operating. We now understand how to turn skin cells to pluripotent stem cells, stem cells to primordial germ cells, and are approaching being able to turn them into eggs and sperm without having to implant them in testes or ovaries. Some day, probably somewhere between several decades to a century or so from now, we may well have developed the ability to create a fertilized egg completely from scratch - including all of the organelles necessary to keep it alive - and an artificial womb to carry it in. Once one has transmitted the means to convey information and technology, plans can be transmitted (ala Contact, but with technology for biological creation, not communication). One could send to another world every last step needed to create and nurture a human being in-situ, along with a interactive computerized childrearing "system" for the child's early years, along with a discussion of exactly what is being done at each stage. And other species could do this as well in their transmissions to us.
Of course, if the "singularity" people are right, one could just transmit a sentient program to other worlds and be done with it far simpler. Either way, whether anything gets done with a signal depends on whether they're 1) actually out there, 2) close enough, 3) receive the message, 4) detect it, 5) recognize it as carrying information from sentient beings, 6) decipher it, 7) and perhaps most importantly, decide whether they want to actually risk trusting this transmission from an alien world. Lots of "ifs", to say the least.
To be able to hold a pointing orientation in space, one has to be able to understand 2D. To be able to understand changing positions in space, one has to be able to understand 3D. To interact with physical objects, they must have some method to perceive their shape. If they're interacting with spacecraft, they have to be able to do some pretty damned precise things in regards to all three of these things The methods used to be able to do these things may be alien to us, but they have to be able to understand them in some sort of form. They essentially have to be able to perceive the voyager plates, perceive that there's information of some form on there, and have the mental wherewithal to convert it into whatever coordinate space / representation system their minds use, and to begin to make deductions about its meaning.
They could reach the wrong conclusions. But if they're spacefaring, they have to at least be capable of advanced reasoning, so they're going to have a shot at it.
It's the same sort of thing that feeds religion and "The Secret"-type worldviews: if you want something to exist enough, if you really want something to occur with all your heart, then surely it will exist, surely it will occur.
Every signal that we have sent out requires them to be visually oriented. Do you think the TV signals we beam into space will make any sense to beings that communicate ultrasonically? An encoded 2D image interlaced with alternate lines 30 times a second won't be of much use to intelligent vampire bats.
Okay, first off...
1) Vampire bats do not work that way.
2) Humans take information that our senses can't perceive all the time and turn in into forms that we can. That's what false-color images and the like are.
3) A species that can pick up the signal (as the GP posited) is most definitely able to transform signals between mediums. It's pretty much a fundamental part of any receiver technology - you take a propagating signal, turn it into data, then turn the data into a form that you can perceive.
Obviously no species is going to inherently have the recipe for demodulating the signal just handed to them - they'll have to figure it out, even if their senses are precisely the same as ours. They'll have to recognize, "hey there's a signal here, and by its pattern it doesn't appear to be naturally generated and seems to be storing data in some manner". They'll then have to reverse engineer how to pull the data out of the signal. Then they'll have to figure out how the data is structured (probably the hardest part, esp. with modern compressed digital formats). All of these apply to all beings. But once you've figured all of that out, turning it into a form that you can perceive is the easy part.
Say there's a species with no vision that can only experiences the world through ultrasound echolocation, as in what you probably intended to be your example? Once you understand that the signal is, say, periodic frames representing an array of triplet values (what we know to be RGB) and know how to decode it to that, the species may play it back by, say, an "ultrasound screen" that creates the perception of a 3-dimensional surface, with the height representing pixel intensity. Maybe they might combine all three RGB values into one height, maybe they might present them as side by side heightfields, maybe they might use one value to represent height, another to represent surface roughness, another to represent sound absorptive properties of the surface, or somesuch. They'll pick whatever is most convenient for them.
I'm not going to humour your "liquid methane temperature" communication concept because that's far too low bandwidth for a sentient species to practically use. Pheromones also. And "interference patterns of UV radiation", that depends on what you mean by "interference patterns" - you're either talking about a UV equivalent of echolocation, as above, or just visible data shifted into the UV, which is just a frequency shift on the RGB image into their visual range. We as humans do frequency shifts of astronomical data all the time, that's what every image made from a UV, X-ray, IR, radio, etc telescope is.
For any species to be able to get to the phase of being able to receive and demodulate communications, it must have at least the concept and ability to perceive 2D orientation (if not 3D), because it has to be able to align receivers with the right patch of sky. That perception can be of some unthinkably bizarre form by our standards, but it has to exist. Whatever perception of 2D it has, 2d images can be presented in that form.
Your Pi/Tau example is clearly pointless. We as humans clearly know of both constants. Sure, Pi "stands out" more to us at first glance, but if we received something that appeared to be of non-natural origin, you really think nobody would notice if the data was Tau?
Circles are no more "rare in water" than on land. The cross section of a sphere is a circle. What do you think bubbles are? Rounded rocks? Round sea life? Heck, lava underwater, unlike on land, tends to produce round structures called pillow lava. And again, if this to the point of being able to isolate faint radio
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They talk about using them for delivery of harmless supplies, but I agree, as weapons delivery systems they seem to make more sense. They describe a balloon carrying up large numbers of small, largely transparent aerial vehicles that then drift to target locations up to 150km away automatically with a 1,4kg payload, then vaporize via sublimation and/or fracturing electronics to tiny bits from internal stresses. Why exactly couldn't these be carrying small shaped charges? And if they have a processor controlling the descent, then they could probably run at least simple image recognition algorithms, or even just IR seeking, once they get to their destination.
A 1,4kg shaped charge is no laughing matter - a mere 440g charge is said to be able to penetrate 35cm of armour. Even if the charge can't penetrate, say, tank primary armour, a precise delivery system could target things like optics systems, weapons systems, tracks, etc. Such a charge could completely take out unarmoured vehicles and would be particularly destructive to aircraft on the ground. Ammunition, fuel supplies, power substations, etc, etc... there's a lot of things a small explosive payload could take out. A balloon hauling dozens or even hundreds of them at once? You're basically talking "cluster cruise missiles". Carried on small transparent wings with almost no radar signature except for that of your munition.
I'm sure that these possibilities haven't passed over DARPA officials.
No, that's what STncsEM stands for.
Maybe you should put one of the two in English instead. ;)
See here.
Robotics is a combination of engineering and computer science. Given that engineering is already covered...
And "coders" are so normal today because so many people in STEM fields have to program. It's not rare at all anymore for a scientist, mathematician, or engineer to have to write scripts or whole programs to support their work - either it's not in the budget to hire a programmer for the specific task, or it's just too much effort to bring a programmer up to date with the scientific background needed to really understand the task at hand.
And as mentioned, what exactly is the T in STEM for anyway, given that it's clearly not "engineering" (the E)? It's where computer science should be.
Computers are a critical enabling technology for many if not most types of science these days, they are technology (what else best fits in "technology" if not computer science, given that engineering is a different category?), they're critical for nearly all engineering these days, and most mathematics work. It's an entirely appropriate category.
Where does it say that "computer science must be treated as science, by law"? It declares computer science to be part of STEM. STEM does not simply mean "science" - science is only the "S" in STEM. STEM means "Science, Technology, Engineering, and Math" There's nothing inappropriate about computer science being taught in that grouping.
Chemistry works the same everywhere. What elements readily form compounds with other elements is the same everywhere. At what temperatures minerals begin to crystalize out of magma is the same everywhere. Etc. Economically valuable deposits of resources are locations in which chemistry tended to concentrate that mineral and leave it at an accessible location. The same parameters must apply to the moon just like on earth.
90% of the mass of the Earth is oxygen, iron, silicon, and magnesium. And these chemicals tend to form compounds with each other. Consequently it's impossible for "all of the Earth's iron", for example, to have sunk to the core. More to the point, these oxides aren't as dense as the pure metals. For example, in the crust a lot of iron is found as limonite (that yellowish-orange color you often see in clays), which can be nearly as light as quartz. The largest single mineral component of the mantle (and thus the Earth) is olivine (commonly known as peridot when sold as gemstones), a magnesium iron silicon oxide.
Unlike the outer layers, earth's core is predominantly metallic iron, not oxides, and thus far denser. It's also highly enriched in many heavier elements which either don't readily oxidize or form heavy oxides. For example, platinium is found at about 5ppb concentrations in the crust, but is believed to be about 6ppm in the inner core, over a thousand times greater concentration. Uranium, thorium, gold, and countless other elements are vastly more common in the core than the crust. That doesn't mean that they're absent elsewhere. Even ignoring deposits from bombardment, you will often find small amounts of rarer elements in minerals with elements that they're chemically similar to.
You can see the nature of mixtures in what erupts to the surface as lava - an igneous flow will ultimately crystalize out into a wide range of tiny mineral grains - various feldspars, quartz, various iron oxides, etc. These crystals have different densities, and they're made from elements with different densities - but the forces keeping them in solution are greater than the forces working to fractionalize them. Differentiation inside magma takes a long time - for example, to get basalt rich in large olivine crystals, like picrite, the magma has to sit and slowly cool over many thousands of years, allowing the olivine time to crystalize out and the crystals time to settle to the bottom without the bulk of the magma hardening and trapping it - then the upper olivine-poor magma erupting, then the olivine-rich magma erupting (again, all without hardening to the point of becoming trapped in the magma chamber).
Or, to put it another way: salt is heavier than water, but the bottom of the oceans is only slowly increases with depth (and is highest near the surface where water evaporates, but that's a side point). It's a lower energy state for the salt to dilute than to all collect at the bottom.
That's not why elements are concentrated, as a
First off, our knowledge of the moon is not "some rocks the Apollo astronauts brought back". The Moon is one of the most studied bodies in the solar system, perhaps the second most studied. We have a pretty good idea of what makes it tick. There have been 70 successful or partially successful (overwhelmingly completely successful) missions to the moon, plus some considered "spacecraft failure" that still returned data. 6 of the successful missions are operational right now. There have been 16 missions to land softly on the moon, one of which then re-launched and landed again. There were also two impactor missions to kick up plumes for study. There have been 8 sample return missions, another of which is scheduled for 2017. Modern advanced orbiters have conducted detailed spectral scans of the whole moon and mapped details down to 50 centimeters. We know the thing pretty damned well. It wasn't until the second half of the 20th century that we even knew the Earth that well.
The moon is fundamentally disadvantaged when it comes to valuable mineral resources. Most valuable, rare mineral resources are heavy, as these tend to sink deep into planets during formation, leaving them depleted from the surface. The moon was formed in a collision whose dynamics left most of its heavier materials on earth and left it with lighter materials from itself and Earth. That's not to say that all light minerals are worthless - far from it. Beryllium is worth over $1k per kilogram, and it's quite a light element. But things like that are the exception, not the rule. The moon was then doubly disadvantaged in that the collision left it with a global magma ocean (with no tectonics to recirculate deep crust back to the surface). This led to crystals of lower-melting point and denser minerals to almost universally sink to the bottom, leaving the top layers rather monotonous in composition (a universal plagioclase crust). While various geological activities subsequently modified it (primarily impacts and, long ago, the mare basaltic flows), it was disadvantaged from the beginning.
Then there's the fact that minerals don't just pop up randomly - they need geological phenomena to concentrate them to economic levels, and they're found associated with various geological features and/or tracer minerals. For example, the aforementioned beryllium is found in granitic pegmatites associated with tin and tungsten. The moon has no granite - thus no granitic pegmatites. There are a few other types of minerals beryllium concentrates in, but they don't exist on the moon either. This doesn't mean that there's no beryllium on the moon - there is, it's been studied. But there's nothing to concentrate it to interesting quantities.
The biggest modification to the original lunar rocks has been the formation of the mare. These are ancient mass flows of tholeiitic basalt - not much diversity, except in the concentration of titanium. Lunar titanium concentrations are much higher than on Earth. However, titanium oxides are very cheap, common minerals. Melt pools from impacts also have the potential to be mineral concentrators (on Earth, the Sudbury impactor created some highly valuable mineral deposits in Canada). But there are two problems. One, these tend to solidify deep underground, meaning your mining becomes far more difficult and hardware/labour intensive (on a body that costs many tens of thousands of dollars per kilogram to land hardware on - even with a 10fold price reduction, you're looking at big problems). And two, all its modifying is plagioclase and ti-rich theolitic basalt. And of course, tectonic modification can concentrate minerals. While there have been tectonics on the moon, they're very limited compared to those on Earth.
Now, this isn't to say that there's *nothing* interesting on the moon. The moon is rich in what's called "KREEP" - Potassium Rare-Earth Phosphorus. It can be found from space because it's also associated with higher concentrations of alpha emitters like uranium and thorium (although not anything one wou
Windspeed is irrelevant turbulence is what matters; it does not seem to be significant at 52-56km altitude. While we know that lightning exists on Venus, it's only at about the rate that it exists on Earth, and seems to be biased toward particular locations and altitudes. Of course, we've studied the planet so little, who knows - it obviously takes prep work. A prep mission would basically be a long-term version of Vega, with solar panels for recharging rather than just running on battery power.
If we wanted to send humans anywhere that would pay the most benefit, I really think Venus (cloudtops) would be best. Venus is so under-studied that any mission (manned or otherwise) has the potential to yield huge scientific benefits, and the ability to real-time control probes exploring the surface (aka, where their time that they can spend near the surface is limited before they have to head up to re-chill their cooling reservoir and recharge their batteries, and you don't want the lag time of commands sent all the way from Earth) would be of significant benefit. And in terms of future mining potential, Venus probably has the most useful geology - the types of lava flows found by the Soviets, and the additional potential of carbonatites, combined with the "high radar reflective" precipitated minerals, all are very promising signs for enrichment of rare and economically valuable minerals. Phase-change balloons can descend to the surface and bring minerals up to the cloudtops, and are eminently achievable with current technology - hardly more complicated than the old Soviet Vega probes. Since you're floating, you can move anywhere on the planet in a relatively short period of time (due to superrotation, you really have no choice in the matter ;) ), so you're not limited to whatever resources happen to be close to your base. And the cloudtops are a very hospitable environment to humans - at 52-56km a person may even be able to step outside with nothing more than a mask on (oxygen provision and eye protection are a must, but the CO and SOx levels may be low enough to not be problematic to bare skin - the pressure and temperature are fine). The significant atmosphere overhead provides a good deal of radiation protection, even though there is no dynamo-driven magnetic field.
The moon is nearby and a conveniently low gravity well, but as far as minerals go, it's pretty boring - to the point that the best people have come up with is "helium 3 fuel" to power reactors which don't exist and which probably will never be an idea fusion fuel (if you can fuse it and can make an economic case for it, you can probably also fuse P-B which is much better and cheaper). And it will always suffer from "been there, done that" syndrome.
Indeed :) Don't get me wrong, one can achieve great things through small steps but only if those steps are part of a long-term process planned out in advance with the ultimate goal in mind, and full committal from all interested parties (particularly those funding your endeavor) to follow it through to the end. Otherwise, you're just building castles in the sand to be washed away when the tide comes in.
Is the goal to go to Mars just to check off an entry on our species' bucket list, or is to move toward the the eventual colonization of the planet? Then we better have the whole colonization process down, down to what will lubricate the drive axles on the truck that hauls the fluorite ore from the mine on Arsinoes Chaos to the ball mill at Terra Meridiani, or how to make the replacement bolts for the elevation mounts for a sulfuric acid pipeline at the Becquerel chemical plant. That means in no way, shape, or form that nobody should do anything with Mars until you can launch a whole self-sustaining colony. But it's important to have planned out the whole programme in advance - knowing precisely what materials we're going to need, what parts, how quickly they'll be consumed, how much labor every component's operation and maintenance will take, what raw inputs you're going to need, where you can get them, etc, and ensuring that at no point are you consuming more of something than you can produce.
If you send things to Mars without doing this, you're just going to spend your billions of dollars launching dead-ends - made out of materials that it turns out that there's no practical way to make on the planet, or with processes under which particular steps work out to be impractical or impossible on Mars. Due to the tremendous expense to engineer and launch each piece of hardware to Mars, you want each piece to serve a critical role in your long-term goals. Sent a device to freeze carbon dioxide out of Mars's atmosphere to feed a greenhouse or bioreactor? That may sound great... up until the point that you discover that you also need nitrogen or argon collected from the atmosphere for other processes, and that your whole chiller system needs to be replaced with one that can handle lower temperatures. Sent a pipeline made out of polypropylene to carry some sort of fluid? Great, until you discover that you need to multi-use that pipeline and some of the chemicals you need to send aren't compatible with polypropylene, so you're just going to have to build a new one parallel to it. Etc.
NASA of course has no interest in actually planning things out all the way in advance. And never has.
They'll rape you to death, eat your flesh, and sew your skin into their clothing, and if you're very very lucky, they'll do it in that order.
Big percentage of small number = slightly bigger small number
Perhaps you should go around hospitals and explain this to the children with the excess cases of thyroid cancer while they're receiving their chemo.
Most sci-fi fans vastly underestimate the difficulty of even getting remotely close to the speed of light. The last, optimized, peer-reviewed design for a pure antimatter-driven ship that I saw - the highest performance you're going to get without beamed power, and beamed power suffers from range problems among others - was to reach about 0,4c. That's pure anitmatter, which vastly outperforms fusion and fission. Making antimatter inherently means turning mass to energy, wherein a very tiny fraction will condense out as antiprotons, which you can then trap. So you're taking E=mc^2, reversing it, and then taking only a tiny fraction of even that. Actually mass producing the vast amounts of antimatter needed for such starships would take a civilization advanced to Type 2 scale. It's nice to fantasize that the universe is full of Type 2 and Type 3 civilizations, but that's a huge thing to posit.
It's also easy to posit generation ships. But as the saying goes, shit happens. The longer you're in transit, the more likely that is to happen. Which means you have to make your ship vastly larger, to be increasingly redundant, parts in one part increasingly isolated from others, much larger crews than just the minimum skeleton crew needed to populate a planet, etc. Unless all you're sending are artificial wombs and eggs. But then you're back to my initial posit, that such information could be transmitted to an alien species directly at the speed of light.
Indeed. VW did very egregious cheating, deliberately detecting tests and then optimizing for them. It sounds like these others are not engaging a "test mode"; but have optimized themselves for conditions that are tested for (at the expense of power and fuel efficiency) while optimized themselves for power and fuel efficiency in conditions that aren't tested for. Not as egregious, but still clearly problematic. There's clearly gaping holes in the system.
It also puts to lie this massive increase in diesel cleanliness over the years. It's improved, no question, but not nearly as much as has been marketed, particularly in smaller, cheaper vehicles. The same old choice remains: you can get a ~15% increase in fuel efficiency by mass (~30% by volume), and thus ~15% reduction in CO2 emissions, by going with a diesel, but it'll come at the cost of a more expensive engine (has to be built stronger to handle the higher compression, all issues of additional pollution control systems aside) and will kick out more health-impacting pollutants. And it just comes down to chemistry: if you burn fuel in air at hotter temperatures and/or higher pressures, you favor the production of chemicals like NOx - high temperatures and pressures make nitrogen more reactive. And you're going to kick out more PM for similar reasons. The higher temperatures and pressures help with CO and unburned hydrocarbons (they favor more complete combustion), but the scale of the added NOx and PM problems are much greater.
Contrary to what they've been pretending, a major way that car manufacturers appear to have been reducing NOx emissions in diesels is simply by burning their fuel cooler / less efficiently in conditions that are being tested for, and hotter the rest of the time to keep their performance and efficiency numbers up.
It's not that simple. Mercury also has a magnetic field. Which is a real head-scratcher, as it's even smaller than Mars.
Internal planetary dynamics are complicated. To get a dynamo you need fluid flow. But whether something is liquid or solid depends on both temperature and pressure - temperature increasing melt, pressure decreasing it. So there's a very complicated interplay.
Uber has long proven themselves to be eminently trustworthy and never scheming up shady ways to try to drive their competition out of business, so we can just take them at their word on this.
Very little energy reaches the Venusian surface - Venus's albedo is twice that of Earth's, so most light gets reflected from the cloud deck, and what does enter gets quickly absorbed in the clouds and thick atmosphere. Also, the crust is not what drives a dynamo, the core does. Nuclear decay is what drives terrestrial planet cores, not solar input.
Also I don't know what you mean by "rapid crust recycling", unless you mean Venus's global resurfacing events. But those only happen once every several hundred million years. And they take about 100 million years to complete, they're not rapid.
... that because of Mars' small size, it cooled faster, thus freezing its outer core and shutting down its dynamo? Isn't Venus the far greater mystery? Nearly the same size as Earth, yet no magnetic field and what appears to be occasional whole-crust overturn rather than plate tectonics? Isn't that the one we need to solve?
I agree. The field of extraterrestrial linguistics has seriously advanced beyond then, thankfully, with communications systems based on logic system, and even a transmittable operating system that explains how it should be run (inputs, outputs, etc), enabling one to send interactive programs along with it.
It's funny, but there's a concept I've never seen before in science fiction: that of multiple alien species living amongst each other, but whose homeworlds are vast cosmic distances apart and who have never gotten anywhere close to each other due to the difficulties of approaching relativistic velocities in spacetravel. How? Bit by bit we understand more of "what makes us tick". Not just how DNA codes for proteins, but the whole complex interplay of these proteins in keeping a cell operating. We now understand how to turn skin cells to pluripotent stem cells, stem cells to primordial germ cells, and are approaching being able to turn them into eggs and sperm without having to implant them in testes or ovaries. Some day, probably somewhere between several decades to a century or so from now, we may well have developed the ability to create a fertilized egg completely from scratch - including all of the organelles necessary to keep it alive - and an artificial womb to carry it in. Once one has transmitted the means to convey information and technology, plans can be transmitted (ala Contact, but with technology for biological creation, not communication). One could send to another world every last step needed to create and nurture a human being in-situ, along with a interactive computerized childrearing "system" for the child's early years, along with a discussion of exactly what is being done at each stage. And other species could do this as well in their transmissions to us.
Of course, if the "singularity" people are right, one could just transmit a sentient program to other worlds and be done with it far simpler. Either way, whether anything gets done with a signal depends on whether they're 1) actually out there, 2) close enough, 3) receive the message, 4) detect it, 5) recognize it as carrying information from sentient beings, 6) decipher it, 7) and perhaps most importantly, decide whether they want to actually risk trusting this transmission from an alien world. Lots of "ifs", to say the least.
I have a solid background in phrenology, is that good enough?
To be able to hold a pointing orientation in space, one has to be able to understand 2D. To be able to understand changing positions in space, one has to be able to understand 3D. To interact with physical objects, they must have some method to perceive their shape. If they're interacting with spacecraft, they have to be able to do some pretty damned precise things in regards to all three of these things The methods used to be able to do these things may be alien to us, but they have to be able to understand them in some sort of form. They essentially have to be able to perceive the voyager plates, perceive that there's information of some form on there, and have the mental wherewithal to convert it into whatever coordinate space / representation system their minds use, and to begin to make deductions about its meaning.
They could reach the wrong conclusions. But if they're spacefaring, they have to at least be capable of advanced reasoning, so they're going to have a shot at it.
It's the same sort of thing that feeds religion and "The Secret"-type worldviews: if you want something to exist enough, if you really want something to occur with all your heart, then surely it will exist, surely it will occur.
Basically, "magical thinking".
Okay, first off...
1) Vampire bats do not work that way.
2) Humans take information that our senses can't perceive all the time and turn in into forms that we can. That's what false-color images and the like are.
3) A species that can pick up the signal (as the GP posited) is most definitely able to transform signals between mediums. It's pretty much a fundamental part of any receiver technology - you take a propagating signal, turn it into data, then turn the data into a form that you can perceive.
Obviously no species is going to inherently have the recipe for demodulating the signal just handed to them - they'll have to figure it out, even if their senses are precisely the same as ours. They'll have to recognize, "hey there's a signal here, and by its pattern it doesn't appear to be naturally generated and seems to be storing data in some manner". They'll then have to reverse engineer how to pull the data out of the signal. Then they'll have to figure out how the data is structured (probably the hardest part, esp. with modern compressed digital formats). All of these apply to all beings. But once you've figured all of that out, turning it into a form that you can perceive is the easy part.
Say there's a species with no vision that can only experiences the world through ultrasound echolocation, as in what you probably intended to be your example? Once you understand that the signal is, say, periodic frames representing an array of triplet values (what we know to be RGB) and know how to decode it to that, the species may play it back by, say, an "ultrasound screen" that creates the perception of a 3-dimensional surface, with the height representing pixel intensity. Maybe they might combine all three RGB values into one height, maybe they might present them as side by side heightfields, maybe they might use one value to represent height, another to represent surface roughness, another to represent sound absorptive properties of the surface, or somesuch. They'll pick whatever is most convenient for them.
I'm not going to humour your "liquid methane temperature" communication concept because that's far too low bandwidth for a sentient species to practically use. Pheromones also. And "interference patterns of UV radiation", that depends on what you mean by "interference patterns" - you're either talking about a UV equivalent of echolocation, as above, or just visible data shifted into the UV, which is just a frequency shift on the RGB image into their visual range. We as humans do frequency shifts of astronomical data all the time, that's what every image made from a UV, X-ray, IR, radio, etc telescope is.
For any species to be able to get to the phase of being able to receive and demodulate communications, it must have at least the concept and ability to perceive 2D orientation (if not 3D), because it has to be able to align receivers with the right patch of sky. That perception can be of some unthinkably bizarre form by our standards, but it has to exist. Whatever perception of 2D it has, 2d images can be presented in that form.
Your Pi/Tau example is clearly pointless. We as humans clearly know of both constants. Sure, Pi "stands out" more to us at first glance, but if we received something that appeared to be of non-natural origin, you really think nobody would notice if the data was Tau?
Circles are no more "rare in water" than on land. The cross section of a sphere is a circle. What do you think bubbles are? Rounded rocks? Round sea life? Heck, lava underwater, unlike on land, tends to produce round structures called pillow lava. And again, if this to the point of being able to isolate faint radio