I don't know the exact electrical schematics of the shuttle, but typically when you have four sensors you are running two independent power supplies. Two instruments (one for each sensor) are powered by one power supply, and the other two on the other power supply. This is so that if one power supply fails you will still have two good instruments powered. If one power supply fails in a way that can damage the instruments (perhaps an overvoltage condition?) you will still have two good instruments, because they are not electrically connected. If the electrical system is as I described, then if a power supply would fail, it could drop another two instruments, bringing the total number of instruments down to one. Since the system operates based on coincidence logic, one sensor would not be enough for control functions (unless they have an additional loss of power function to the coincidence logic).
Systems that have 3 sensors and associated instruments typically have either auctioneering power supplies or automatic bus transfer (ABT) devices to ensure that if a power supply fails, the three instruments would have power. Perhaps the shuttle has auctioneering power supplies or an ABT, but I doubt it. Both three and four instrument designs typically follow the one expected failure model. There is no reason to have a fourth instrument with an auctioneering power supply or ABT if you only expect one failure. If you expect two or more, it becomes much more complex (involving more power supplies and perhaps more ABTs or auctioneering power supply assemblies). The one expected failure model assumes that all instruments are normal prior to operation and that all failures occur during operation. If a failure occurs before operation, the model is invalid. This is probably why they had to scrub the launch.
They were filling the tank. So either one sensor or associated I&CE broke, or three sensors or I&CE broke--because those sensors indicate that the hydrogen level is above the low level setpoint. I would say that it is very unlikely that three failed instead of one.
They had a fuel low level sensor fail. This was some sort of instrumentation and control equipment or sensor fault. The possible causes could be that the actual sensor failed (which might require replacing the liquid fuel tank) or there was an instrumentation fault. Since they were using a test circuit to simulate a low level (since the tank is actually full), an instrumentation failure could be either a failure in the normal instrumentation circuitry or a failure in the test circuitry. Either of these two cases should be easy to fix.
As someone who has worked extensively on I&CE operation, maintenance, and repair on nuclear reactors, I fully understand why they scrubbed the launch. Redundancy is for faults in operation, not to compensate for damaged equipment prior to operation. From my experience, it is probably the test circuit that failed. Then the instrumentation circuitry. Then, in the most unlikely case, the sensor itself.
An astronaut on NASA TV explained that the there is a coincidence circuit if two low level alarms trigger that will cause an automatic engine turnoff. If this did not happen and the tank completely emptied, he said that it could cause major damage to the shuttle's main engines. I'm not sure exactly how, perhaps because either without liquid hydrogen, only the oxygen would flow through the engine and no chemical reaction would occur, cooling parts of the engine below their specifications? Or flow characteristics wouldn't be predictable?
It has been observed that galaxies on the whole do not obey Kepler's Laws of Planetary Motion. In particular, stars along different positions moving outwards from the core have about the same measured period (to do a complete orbit of the core). Kepler's Third Law says that the square of the period of a star is directly proportional to the cube of the stars' semimajor axis. Stars further out should have a much longer period (like Pluto) than those close to the core. Dark matter is an invention that compensates for discrepancy by saying that there is perhaps a large halo of non-detectable mass around the galaxy (about 10 or more times the observed mass). There are reasons to believe (too complex to go into here) that dark matter is not like ordinary matter but still has mass.
The Hubble constant, which was discovered by Edwin Hubble, showed that the universe was expanding. If the universe began at the Big Bang (and there is a significant amount of data to support this assertion) then the speed of expansion should be fairly straightforward to calculate. What is observed at great distances is greater than that value. For this reason scientists have named (very poorly) another potential fundamental force dark energy which accounts for the expansion. Dark energy would be like gravity, but repulsive, and is only significant at extreme distances (so that it wouldn't hurt the formation of galaxies).
"The lesson to learn from your example is to properly classify and prioritize potential problems. It is a major waste of time and effort to address every single tiny problem which creeps up, especially in highly complex systems it is close to impossible. There are only a limited amount of resources available. You must prioritize the truly important vs the trivial or you will never accomplish anything."
The classification of large and small is by the person observing the problem, not the person interpreting it. With 20/20 hindsight we can say that the failure of airport security to find weapons on the 9/11 hijackers was a big problem, but to the supervisors, it was a small problem (they were looking for guns and drugs).
While your logic works well for software development projects where noone can be killed if it fails, high-risk or high-value technologies cannot follow the same procedure, especially when they are of an integrated design (where many items can affect the operations of remote items). NASA operates high-risk and high-value technologies. So do nuclear plants. The QA system for a nuclear reactor is not Bugzilla. The developer's of Brown's Ferry nuclear power plant did not realize that having a non-redundant cable run was a problem. Noone did. They did know; however, that their materials were not correct and that their personel were not following procedures. They took no action and almost had a nuclear accident. At no time did they have a meeting discussing the safety of the foam insulation, what procedures to take until the foam could be replaced, and what would be the worst case scenario if the foam caught fire. By your definition this isn't a problem because a reactor meltdown didn't occur. But if the nuclear community would have learned from it, TMI might not have occured. (By the way, I'm not overemphasizing it because I believe that "any reactor malfunction is 30 minutes to meltdown". I work as a reactor operator. This was a very serious incident.)
"When you build something (or write code) for the first time, is it perfect? I am also suspect of your conclusion that this problem indicates that "there are problems at JPL that are not being looked at." There may very well be problems in the bureaucracy, however this problem is indicative of nothing more than "shit happens."
Wrong attitude. When you build something, you build it to specification, and you write procedures for it. If it ever deviates, you carefully analyze the problem and fix it. If something breaks, you determine why it broke, because you might have a bigger problem. And then you test your product to verify that it meets the standards. You never say that "shit happens". "Shit happens" is just a codeword for "I'm too lazy to determine the real cause".
"It was an easy mistake to make. It happened during some very busy and stressful times."
The article says that he also says it is not fair to compare it to past mishaps because the spacecraft suffered no damage.
"There isn't going to be an investigation. We know when it happened."
He doesn't get it. The big problem here isn't that a technician goofed. The big problem is that noone caught it. The purpose of the investigation is not just to assign blame. It will also find the root causes like I previously described. While JPL will probably never have instruments swapped again, there will probably be another case where procedures aren't followed and noone notices.
Squyres statements from the article state that he isn't embarrased that his QA program and monitoring programs were inadequate, that his team did not take adequate precautions during stressful times to make sure that procedures were followed, that it's not an incident because no damage occured (sort of like it's not speeding unless you get pulled over), and that he doesn't believe there are any larger problems from this incident.
I'm not saying that I expect the work of JPL to be perfect. There will always be problems. Thats the nature of engineering work. But once problems occur they need to be investigated to ensure that they aren't repeated and to find larger underlying problems. One of the worst types of problems that you can find are repeat problems (of the same nature). They indicate that you knew a problem existed but your corrective actions were inadequate. Without performing an investigation Squyres does not even have the chance to assign corrective actions! He is taking no action whatsoever to try to prevent future problems. Once the repeat problem occurs (and it will occur), heads will fly!
Small problems lead to medium sized problems which lead to big problems. Example: In the 1970's the NRC was similar to the Department of Transportation or FAA (pre 9/11) in that their job was to help facilitate the nuclear economy, not to beat down offenders. In the early 70's plant managers at a nuclear power plant in Alabamba, Browns Ferry Nuclear Power Plant, received reports that their insulation connecting to a cable room was not in accordance with fire specifications (small problem). Since this was not a significant problem, managers ignored it. Later workers testing the air-tightness of the room failed to follow the correct procedures by using candles to check the air tightness (if the flame is deflected, air is moving in that direction--small problem). Managers were aware but dismissed the problem. During testing for air leaks the flame of a candle was sucked into insulation and a fire erupted. The cable run that caught on fire was non-redundant and carried all of the control features for two nuclear reactors. Control of the reactors was lost and reactor safety was severly compromised. Problems that occured included that the operators of the reactors did not know how to properly respond to this casuality (including attempts to put out a large class A fire with portable CO2 extinguishers). Over $100 million in damages occured, but the reactors narrowly escaped tragedy (medium sized problem). This occured in 1975 and the NRC mostly covered up the problem. No congressional hearing were held. No significant corrective actions were issued and review of the ability of the operators to fight a casuality at a nuclear power plant was not reviewed. Fast forward four years and we arrive at Three Mile Island (big problem), where many of the shortcomings of the Brown's Ferry Plant and of the NRC being able to regulate and control the nuclear industry were exposed.
The lesson to learn here: if small problems exist, dig at them to see how far you can get and then fix *all* of the problems that you uncover. There are many other examples (including the 9/11 incident) but I think the point is obvious: there are problems at JPL that are not being looked at because *nothing* happened. They should be examined and corrected prior to a medium or large problem occuring.
"Compared to the fact that the rovers are still running long after they were expected to die, this is a tiny, tiny thing."
Except for the fact that the same organization that made this error is designing other spacecraft. If they don't get to the root causes of the problem, like the failure of the technicians to properly follow the correct procedure to install the instrument and the failure of any other engineer or management to catch their failure to follow procedure, much larger problems could occur. Lets examine a couple of JPL's problem's in the last couple of years:
Galileo: High power antenna failed to deploy resulting in a much lower data transfer rate. This was due to technical specifications in the lubrication of the antenna not being reviewed when the project was delayed. Mars Climate Orbiter: Burned up because the technical requirements were not met (converting from BES to metric). Mars Polar Lander: Lost on landing. Cause is not known. Project team was rushed in accordance with faster, better, cheaper plan. Genesis: Failed to deploy parachute and crashed on landing due to technical requirements not being met (backwards specification for G-force meters). Mars Exploration Rovers: Software glitch early in mission due to failure to test software for its entire expected lifespan. Instruments swapped due to failure to follow procedure.
Some things we can get out of this analysis are that the QA was unsatisfactory. Procedures were not followed. Technical specifications were not verified. The culture was rushed (go-fever or product push environment). None of these are small problems, but they also point to much bigger problems: failure of the leadership to properly plan the project so that rushed timelines would not occur. This same culture is building new spacecraft. While JPL is a great agency and they do tremendous and incredible feats, they are not perfect and have lost several spacecraft and have had severe faults in others. These problems did not have to occur and more importantly these problems do not have to occur again in the future.
While the lead scientist says that it wasn't a big deal and no investigation will be held, I think he isn't analyzing the significance of this event. While scientists are more focused on the validity of data, engineers have to analyze not just events that occur (like loss of a rover), but also events that could occur. Putting the wrong instrument into a rover is due to "failure to follow procedure". This is a big deal. Failure to follow procedures could have been caught by a better QA system, better monitoring of the installation, and better training (including walkthroughs on the installation of the instruments).
Even though this minor event that has had no impact on the mission, it has shown that there are holes in JPL's QA system, their monitoring system, and their training program for building these rovers. If you want to dig further you might find that all of these problems were caused by an unnecessary sense of urgency which may have been caused by poor project planning. These exact problems have caused the loss of spacecraft before (and many of them were cited for the loss of Challenger and Columbia).
No investigation? The lead scientist really needs to take a look at his project management priorities. Having experience working in nuclear power I have learned and have been trained that small problems are many times the only symptoms of much larger problems. The lead scientist's attitude on the problem gives me no confidence in his ability to run a more complicated mission. Like in gambling, one or two successes doesn't mean that you are going to win on the next roll.
You said: "IIRC, Mars is geologically (or "areologically," if you prefer) dead -- obviously it had significant volcanic activity a long time ago, as evidenced by Olympus Mons, but none that we've ever detected going on now or in the recent past."
The idea that Mars is geologically dead is based on old data. After the Mars Global Surveyor mission, alot of new information came about. One of the estimates was that Mars had volcanic activity about 20 million years ago. Considering a 4.5 billion year existance, 20 million years is hardly dead. This data was from crater counting. Older structures will have many craters and younger structures will have few craters. Obviously this has a fairly large margin of error (but a 2 billion year old structure still won't be confused with a 20 million year old structure). New studies from the Mars Express mission have said that vulcanism may have occured as early as 4 million years ago. This tends to support the idea that volcanos on Mars are dormant, not dead.
As far as having a magnetic field or having plate tectonics, yes Mars is dead. Mars may have had plate tectonics (which in general is due to convection of the mantle) in one localized region in its early history, but there is no evidence of it now.
Recent studies of gullies, volcanism, and the planet's precession tend to indicate that Mars may be alot more active than we think.
According to the oft quoted ORNL report, there is 0.00427 millicuries/ton of coal, and each ton releases 6150 kilowatt-hours(kWh)/ton. This is therefore 6.9431e-7 mCi/kWh. The DOE's Energy Information Agency gives the world total of energy production for 2002 as 4.0512e17 BTU or 1.18699e14 kWh. Since only 9.756e16 BTU or 24.08% of the world energy production is coal for 2002, we can come to a total of 19.85 MCi/yr. Some estimates for Chernobyl put the radiation released at 1.2e19 Bq or 320 MCi. It would take coal plants at the 2002 rate of production 16 years to equal the release from Chernobyl. On the 26th of April, it will be the 19th anniversary of the Chernobyl accident! Is it really that intelligent to put the noose around the neck of our nuclear industry because a near bankrupt Cold War enemy with a poorly designed reactor had an accident that almost certainly could not happen with US reactors?
You said: "I encourage you to try it without the sodium... chlorine ions are, shall we say, not very good for you. Salt may dissociate in water, but it's safe there in equal quantities. Surprising that something so bad for you doesn't violate sanjimon(?)'s principle."
And chlorine isn't good for the metal either. If you are interested in preserving the mechanical properties (especially the surface properties), using chlorine in an electrolytic metal removal process is a bad idea (in general, any electrolytical metal removal process will contaminate the remaining surface). Many bad types of corrosion are started with just a little bit of chlorine. Do a google search for chloride stress corrosion cracking for one of the very worst types of corrosion known.
Anyone interested in using electrolytic metal removal for any project that is under high temperature and stress (a case mod *probably* won't qualify) should definately not use the NaCl procedure. In fact, if you ever want to do a project under high temperature and stress you need to carefully monitor the exposure of chlorine, oxygen, hydrogen, and sulfur ions (to name a few) as well as things like the pH to ensure that your piping doesn't fail.
You said "If it's as recent as 4 million years that would put to bed the dead Mars theory. The idea that Mars lacks a molten core. If there was magma that recently there would still be a molten core. It would take hundreds of millions if not billions of years to go from volcanic to a cold core. There would almost have to be liquid underground water. Good news for life and also water for explorers."
For the core to be molten there is a non-linear temperature and pressure dependance. On Earth, the inner core is solid and the outer core is liquid even though the temperature of the inner core is higher. This is because the increased pressure at the inner core forces iron to stay solid while the decreased pressure at the outer core boundary allows it to melt. The pressure at the core of Mars should be less because of the smaller size of Mars, but the core temperature will almost certainly be lower because of the higher surface area to volume ratio (more heat can be radiated into space per the given mass of the planet). This makes it difficult to say for sure whether it is solid or liquid (though the lack of a magnetic field makes me inclined to believe that its solid).
It should also be noted that the mantle is solid on Earth (yet still deformable) yet liquid magma is found near the surface (and lava on the surface). This is for the same reason described (since the pressure is much less near the surface). A solid core can still allow vulcanism.
You said: "Nuclear reactors do not produce large amounts of isotopes "hundreds of thousands of times more radioactive" than "natural" uranium. And if they did, the half-life for them would be extremely short."
Nuclear reactors do produce lots of isotopes hundreds of thousands of times more radioactive than natural uranium. And the half-lives are fairly short compared to that of U-238 (~4.5 billion years) or U-235 (~700 million years). For an isotope that has a half-life of 10,000 years, it will have an activity 70,000 times higher than U-235. This is not to say that all the fuel is converted to a 10,000 year half-life, but enough is to make it very significant. Additionally activity only measures the number of decays per second, not the energy. Shorter half-lives have higher energies per decay and are more damaging. An isotope with a 10,000 year half-life will typically be much more damaging than U-235 with a 700,000,000 yr half-life.
You said: "On top of that, if breeder and pellet based plutonium reactors were actual in service we could use the waste from standard light water reactors to feed breeder reactors whose waste would feed the pellet based reactors. Drastically reducing the amount and lethality of the nuclear waste that we'd ultimately have to store
Only odd isotopes of Thorium, Uranium, or Plutonium are suitable for use in a self-sustaining fission reaction. Plutonium is created in a breeder reactor by neutron absorption and subsequent beta decay of U-238. While there are cases where other radioactive materials absorb neutrons and revert to a more stable isotope, this will not be more significant than the radioactive fission products released by uranium or plutonium fission. For this reason breeder reactors will still produce significant amounts of radioactive waste. Due to the fact that breeder reactors need a higher neutron flux to stay critical (self-sustaining chain reaction) more lower atomic mass isotopes will be transmuted to stable isotopes by neutron absorption. But this will not drastically reduce the activity of a depleted core.
You said: "So what happens when the temperature (down to -90C) goes below the sublimation temperature of CO2 (-76C, if I recall correctly)? Does it just freeze out of the air?"
Most likely. The phase diagram for CO2 shows that for our standard atmospheric pressure, CO2 freezes at -78.5 C. If the temperature is only slightly lower than -78.5 C it may take some time for a significant amount of CO2 to precipitate due to the latent heat of solidification for CO2 of -43 cal/g (smaller than the absolute value of water which is about -80 cal/g) . Additionally some CO2 may remain in the air which varies by temperature (which would be relative humidity for water). As the temperature drops the amount of CO2 that can be dissolved in air decreases. Unfortunately I couldn't find a reference for CO2 saturation vs temperature. If it is reasonably low (which it should be) at -90 C, CO2 frost will develop.
On Mars with an atmospheric pressure that varies from about 5 - 10 mbar (1 atm = 1013.25 millibars), CO2 frost can develop as seen by Viking 2 and by satellite pictures of the poles. Snowflakes won't form, since the shape of a snowflake is determined by van der Waals forces (don't occur in CO2). CO2 frost should look similar to this.
This effect isn't completely new (at least I don't think so). The space shuttles would roll and yaw back and forth a few degrees on reentry to slow down faster. If you ignore the horizontal speed of the spacecraft, this is somewhat similar to a piece of paper falling (but obviously more controlled--sometimes). Seems to me that the two items might be conceptually related. That being the case, I wouldn't be suprised if we saw a new style of atmospheric slowdown in future space probes.
I'm glad that your hardware works under MacOS X. After all that is the target audience. If you read the specifications page for your monitor, you would note that Linux was not supported. This is an important point when buying high-end hardware. Some things aren't supported for Linux. But as another poster pointed out, many things aren't supported for MacOS X either. No big deal, life goes on. If you research (note: I put that in bold before) before you spend $5000 on a monitor, you will get a system that will perform correctly. Saying Linux has poor hardware support is unjustified because high-end hardware typically has a narrow audience. Covering common hardware used in systems is probably more appropriate (and Linux performs very well there).
This is a Catch-22. Without Linux being mainstream, hardware manufacturers feel no need to support it immediately (especially the more obscure companies). But without complete hardware support, Linux cannot gain mainstream acceptance. This looks unsurmountable.
Not so. On the server and workstation side, Linux has alot of support (because it is mainstream there). Once Linux crushes the rest of the Unix brands (as it appears is going to occur) and cuts into Windows Server spaces, it can start to leverage into the desktop realm (similar to how Microsoft got into the server realm).
One of the key points in this fight is to cut out the FUD on hardware support. For small servers, it is very good. For desktop systems, it depends (but it is typically much better than is often portrayed). But most desktop systems aren't built out of random parts. They usually are sold prebuilt with operating systems installed (and with no obvious conflicts). With this in mind, Linux vendors may be very sucessful in the future on converting businesses over to Linux (which was how Microsoft won the desktop war). If they follow the Dell or Gateway model, peripheral support will not be an issue either. Other markets will follow, and hardware support will become better.
As far as support for family computers (other than for computer geeks): wrong war, wrong time.
You said: "THEN YOU ARE NOT A DESKTOP USER. THIS WHOLE ARGUMENT IS ABOUT USING LINUX AS A DESKTOP, NOT A SERVER. It's a fine OS for serving."
I don't often see desktop systems run high-end hardware. If you are using high-end hardware, you are probably not running a normal desktop system. For this reason my response assumes that the grandparent was talking about a system that you would actually put high-end hardware into (certain workstations or servers). I've done many crazy things with computers, but I've never, for example, put a $15,000 digital signal reader card into a $2,000 box. I've never even heard of that happening (though someone has done something like that, I'm sure).
Now if you are using a $50,000 custom workstation that has sold only 500 systems in a year, there is a good chance Linux is going to give you some hiccups. But then again its not a desktop system.
Wow! I've been using Linux for 9 years now and I've only had a few driver issues (most of which I was able to work around). Of course, one of the main things that I recognized about Linux is that it is best suited for small servers (using modest, common hardware). Once you get to the uncommon, high end hardware you are going to have problems with most operating systems (as the hardware developers narrow their audience). This hardly makes Linux inferior. The developers of Linux can hardly be expected to write drivers for every piece of hardware ever designed. When you want to go high-end with Linux the key is: RESEARCH! The fact that Mac hardware works with Mac OS X should not be bragging rights. Thats the design audience (and it would be insane if it didn't work).
If you use Linux for small servers with modest, slightly older hardware, you will rarely have a problem.
If you use Linux for high-end servers and research before you install, you will rarely have a problem.
If you have uncommon high-end hardware and install Linux there very well may be a problem. But its not Linux's.
Magnetic field lines are an exceptional abstraction. Since the density of magnetic field lines (say taking a box around some part in your diagram) matches the density of the magnetic field, you can say that a box with some density of field lines at point A in your diagram compared to a point B has the the ratio of the density of field lines at A divided by the density of field lines at B multiplied by the field strength at B (assuming we know the field strength at B). Field lines are also used in the description of the electrical field and gravitational field and obey the inverse square law (meaning the only information lost by field line abstractions is the coefficients).
But if it annoys you that magnetic field lines are an abstraction you should also be annoyed that the magnetic field is also an abstraction of the effect of moving charges taking into account relativity. I, for one, believe that it would be almost impossible to talk without the abstractions in discussing sunspots (particularly the second abstraction) because it would hide the concepts away in the technicalities of the electrical field and relativity.
The current theory (at least how I get it) is that sunspots are related to the magnetic field of the Sun. We start by assuming that the magnetic field of the sun starts a cycle by resembling a bar magnet (where a magnetic field line goes directly from the geographic south pole to the geographic north pole without curving). Due to the faster rotation of the Sun at the equator than at the poles (observed), the magnetic field slowly becomes twisted around the Sun (in a helix). Any field lines that resist the twisting can unwind causing them to erupt from the surface forming a sunspot pair (one where it exited and one where it returned). It is theorized that the greater magnetic flux at these points causes a reduction in convective heat transfer to the surface resulting in a dimming of the light at these spots. Eventually due to the interaction of the erupted magnetic field lines with the non-erupted magnetic field lines, the sunspots are forced towards the poles. Once enough sunspots are at the poles and their fields are stronger than the non-erupted fields, the field of the sun can flip, anhililating all the sunspots and returning the Sun to a normal bar magnet orientation (except with the opposite polarity). This is observed to take about 11 years.
It seems that if all the sunspots have disappeared, this should mean that the magnetic field has reversed early.
You said: "Rising standards of living solve most of the pressing problems facing the world today. Birth rates are lowest in the free/wealthy nations and highest in the poor/oppressed ones. Wealthy/Free nations don't tend to make war on each other. Wealthy nations don't tend to produce terrorists either."
Nothing new sadly enough. George C. Marshall said in his 1953 Nobel Peace Prize lecture:
The third area I would like to discuss has to do with the problem of the millions who live under subnormal conditions and who have now come to a realization that they may aspire to a fair share of the God-given rights of human beings. Their aspirations present a challenge to the more favored nations to lend assistance in bettering the lot of the poorer. This is a special problem in the present crisis, but it is of basic importance to any successful effort toward an enduring peace. The question is not merely one of self-interest arising from the fact that these people present a situation which is a seed bed for either one or the other of two greatly differing ways of life. Ours is democracy, according to our interpretation of the meaning of that word. If we act with wisdom and magnanimity, we can guide these yearnings of the poor to a richer and better life through democracy.
Of course Marshall wasn't the first to say this (general idea), and was not the last either. If you look through the lectures in the Nobel archives, you will see this point stated over again many times. Its probably the most overlooked item by most people for achieving world peace because it is also one of the most difficult to accomplish.
Re:Could you have a SUV and not put excess carbon.
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A Viable Biofuel?
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· Score: 2, Insightful
Don't be so fast, cowboy! The carbon comes out of the air when the plant grows, and is put back into the air when you burn your fuel. Its a novel idea.
The key to the energy production is using the incident solar radiation (of about 1 KW/m^2 on the surface of the Earth) to effectively take carbon out of the air and turn it into fuel. There is alot of energy required to do this which be impossible for us to do today economically (except perhaps with a nuclear plant). This is why it is impractical to have underground corn fields, for example. This is also why food production on distant planets, in the future, may require nuclear power to shine light on plants for extended periods of time.
What I am particularly interested in biodiesel is if it can be successfully adapted to be used in fuel cells for higher effeciency (is there a technology where the impurities won't poison the cell).
Additionally, an adaptation of this idea could help reduce the CO2 in the atmosphere. Consider burying 10% of the oil produced over time. If the oil is mass produced, that is a lot of CO2 that has left the atmosphere.
You are selectively ignoring parts of my posts. I brought up cars to give a good comparison example (that homes are a small fraction of energy use when compared to cars and especially industry). Let me put this in numbers: to supply my home overnight I need ~20 car batteries, or your ~8 of your larger batteries. Asimi, a silicon refiner outside my hometown, would need 40,000 at night. Thats just one company. There are several companies in my hometown, especially the mining companies, that would need over 10,000 at night. The point isn't about fuel technology for cars, its that way too many batteries are needed to support a solar system (pun intended). I have no problem with solar (other than some solar cell production processes), but I don't see any reasonable way for when the sky goes dark to stay off the grid. In order to power an entire area, both industry (which often works 24 hours a day) and residential areas must have power. Residential is often cited because its easy to do. When you can cite an example that a 5 MW or larger plant uses on solar cells and batteries, I will be very impressed.
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I don't know the exact electrical schematics of the shuttle, but typically when you have four sensors you are running two independent power supplies. Two instruments (one for each sensor) are powered by one power supply, and the other two on the other power supply. This is so that if one power supply fails you will still have two good instruments powered. If one power supply fails in a way that can damage the instruments (perhaps an overvoltage condition?) you will still have two good instruments, because they are not electrically connected. If the electrical system is as I described, then if a power supply would fail, it could drop another two instruments, bringing the total number of instruments down to one. Since the system operates based on coincidence logic, one sensor would not be enough for control functions (unless they have an additional loss of power function to the coincidence logic).
Systems that have 3 sensors and associated instruments typically have either auctioneering power supplies or automatic bus transfer (ABT) devices to ensure that if a power supply fails, the three instruments would have power. Perhaps the shuttle has auctioneering power supplies or an ABT, but I doubt it. Both three and four instrument designs typically follow the one expected failure model. There is no reason to have a fourth instrument with an auctioneering power supply or ABT if you only expect one failure. If you expect two or more, it becomes much more complex (involving more power supplies and perhaps more ABTs or auctioneering power supply assemblies). The one expected failure model assumes that all instruments are normal prior to operation and that all failures occur during operation. If a failure occurs before operation, the model is invalid. This is probably why they had to scrub the launch.
They were filling the tank. So either one sensor or associated I&CE broke, or three sensors or I&CE broke--because those sensors indicate that the hydrogen level is above the low level setpoint. I would say that it is very unlikely that three failed instead of one.
They had a fuel low level sensor fail. This was some sort of instrumentation and control equipment or sensor fault. The possible causes could be that the actual sensor failed (which might require replacing the liquid fuel tank) or there was an instrumentation fault. Since they were using a test circuit to simulate a low level (since the tank is actually full), an instrumentation failure could be either a failure in the normal instrumentation circuitry or a failure in the test circuitry. Either of these two cases should be easy to fix.
As someone who has worked extensively on I&CE operation, maintenance, and repair on nuclear reactors, I fully understand why they scrubbed the launch. Redundancy is for faults in operation, not to compensate for damaged equipment prior to operation. From my experience, it is probably the test circuit that failed. Then the instrumentation circuitry. Then, in the most unlikely case, the sensor itself.
An astronaut on NASA TV explained that the there is a coincidence circuit if two low level alarms trigger that will cause an automatic engine turnoff. If this did not happen and the tank completely emptied, he said that it could cause major damage to the shuttle's main engines. I'm not sure exactly how, perhaps because either without liquid hydrogen, only the oxygen would flow through the engine and no chemical reaction would occur, cooling parts of the engine below their specifications? Or flow characteristics wouldn't be predictable?
It has been observed that galaxies on the whole do not obey Kepler's Laws of Planetary Motion. In particular, stars along different positions moving outwards from the core have about the same measured period (to do a complete orbit of the core). Kepler's Third Law says that the square of the period of a star is directly proportional to the cube of the stars' semimajor axis. Stars further out should have a much longer period (like Pluto) than those close to the core. Dark matter is an invention that compensates for discrepancy by saying that there is perhaps a large halo of non-detectable mass around the galaxy (about 10 or more times the observed mass). There are reasons to believe (too complex to go into here) that dark matter is not like ordinary matter but still has mass.
The Hubble constant, which was discovered by Edwin Hubble, showed that the universe was expanding. If the universe began at the Big Bang (and there is a significant amount of data to support this assertion) then the speed of expansion should be fairly straightforward to calculate. What is observed at great distances is greater than that value. For this reason scientists have named (very poorly) another potential fundamental force dark energy which accounts for the expansion. Dark energy would be like gravity, but repulsive, and is only significant at extreme distances (so that it wouldn't hurt the formation of galaxies).
"The lesson to learn from your example is to properly classify and prioritize potential problems. It is a major waste of time and effort to address every single tiny problem which creeps up, especially in highly complex systems it is close to impossible. There are only a limited amount of resources available. You must prioritize the truly important vs the trivial or you will never accomplish anything."
The classification of large and small is by the person observing the problem, not the person interpreting it. With 20/20 hindsight we can say that the failure of airport security to find weapons on the 9/11 hijackers was a big problem, but to the supervisors, it was a small problem (they were looking for guns and drugs).
While your logic works well for software development projects where noone can be killed if it fails, high-risk or high-value technologies cannot follow the same procedure, especially when they are of an integrated design (where many items can affect the operations of remote items). NASA operates high-risk and high-value technologies. So do nuclear plants. The QA system for a nuclear reactor is not Bugzilla. The developer's of Brown's Ferry nuclear power plant did not realize that having a non-redundant cable run was a problem. Noone did. They did know; however, that their materials were not correct and that their personel were not following procedures. They took no action and almost had a nuclear accident. At no time did they have a meeting discussing the safety of the foam insulation, what procedures to take until the foam could be replaced, and what would be the worst case scenario if the foam caught fire. By your definition this isn't a problem because a reactor meltdown didn't occur. But if the nuclear community would have learned from it, TMI might not have occured. (By the way, I'm not overemphasizing it because I believe that "any reactor malfunction is 30 minutes to meltdown". I work as a reactor operator. This was a very serious incident.)
"When you build something (or write code) for the first time, is it perfect? I am also suspect of your conclusion that this problem indicates that "there are problems at JPL that are not being looked at." There may very well be problems in the bureaucracy, however this problem is indicative of nothing more than "shit happens."
Wrong attitude. When you build something, you build it to specification, and you write procedures for it. If it ever deviates, you carefully analyze the problem and fix it. If something breaks, you determine why it broke, because you might have a bigger problem. And then you test your product to verify that it meets the standards. You never say that "shit happens". "Shit happens" is just a codeword for "I'm too lazy to determine the real cause".
"[He is] not embarrassed at all".
"It was an easy mistake to make. It happened during some very busy and stressful times."
The article says that he also says it is not fair to compare it to past mishaps because the spacecraft suffered no damage.
"There isn't going to be an investigation. We know when it happened."
He doesn't get it. The big problem here isn't that a technician goofed. The big problem is that noone caught it. The purpose of the investigation is not just to assign blame. It will also find the root causes like I previously described. While JPL will probably never have instruments swapped again, there will probably be another case where procedures aren't followed and noone notices.
Squyres statements from the article state that he isn't embarrased that his QA program and monitoring programs were inadequate, that his team did not take adequate precautions during stressful times to make sure that procedures were followed, that it's not an incident because no damage occured (sort of like it's not speeding unless you get pulled over), and that he doesn't believe there are any larger problems from this incident.
I'm not saying that I expect the work of JPL to be perfect. There will always be problems. Thats the nature of engineering work. But once problems occur they need to be investigated to ensure that they aren't repeated and to find larger underlying problems. One of the worst types of problems that you can find are repeat problems (of the same nature). They indicate that you knew a problem existed but your corrective actions were inadequate. Without performing an investigation Squyres does not even have the chance to assign corrective actions! He is taking no action whatsoever to try to prevent future problems. Once the repeat problem occurs (and it will occur), heads will fly!
Small problems lead to medium sized problems which lead to big problems. Example: In the 1970's the NRC was similar to the Department of Transportation or FAA (pre 9/11) in that their job was to help facilitate the nuclear economy, not to beat down offenders. In the early 70's plant managers at a nuclear power plant in Alabamba, Browns Ferry Nuclear Power Plant, received reports that their insulation connecting to a cable room was not in accordance with fire specifications (small problem). Since this was not a significant problem, managers ignored it. Later workers testing the air-tightness of the room failed to follow the correct procedures by using candles to check the air tightness (if the flame is deflected, air is moving in that direction--small problem). Managers were aware but dismissed the problem. During testing for air leaks the flame of a candle was sucked into insulation and a fire erupted. The cable run that caught on fire was non-redundant and carried all of the control features for two nuclear reactors. Control of the reactors was lost and reactor safety was severly compromised. Problems that occured included that the operators of the reactors did not know how to properly respond to this casuality (including attempts to put out a large class A fire with portable CO2 extinguishers). Over $100 million in damages occured, but the reactors narrowly escaped tragedy (medium sized problem). This occured in 1975 and the NRC mostly covered up the problem. No congressional hearing were held. No significant corrective actions were issued and review of the ability of the operators to fight a casuality at a nuclear power plant was not reviewed. Fast forward four years and we arrive at Three Mile Island (big problem), where many of the shortcomings of the Brown's Ferry Plant and of the NRC being able to regulate and control the nuclear industry were exposed.
The lesson to learn here: if small problems exist, dig at them to see how far you can get and then fix *all* of the problems that you uncover. There are many other examples (including the 9/11 incident) but I think the point is obvious: there are problems at JPL that are not being looked at because *nothing* happened. They should be examined and corrected prior to a medium or large problem occuring.
"Compared to the fact that the rovers are still running long after they were expected to die, this is a tiny, tiny thing."
Except for the fact that the same organization that made this error is designing other spacecraft. If they don't get to the root causes of the problem, like the failure of the technicians to properly follow the correct procedure to install the instrument and the failure of any other engineer or management to catch their failure to follow procedure, much larger problems could occur. Lets examine a couple of JPL's problem's in the last couple of years:
Galileo: High power antenna failed to deploy resulting in a much lower data transfer rate. This was due to technical specifications in the lubrication of the antenna not being reviewed when the project was delayed.
Mars Climate Orbiter: Burned up because the technical requirements were not met (converting from BES to metric).
Mars Polar Lander: Lost on landing. Cause is not known. Project team was rushed in accordance with faster, better, cheaper plan.
Genesis: Failed to deploy parachute and crashed on landing due to technical requirements not being met (backwards specification for G-force meters).
Mars Exploration Rovers: Software glitch early in mission due to failure to test software for its entire expected lifespan. Instruments swapped due to failure to follow procedure.
Some things we can get out of this analysis are that the QA was unsatisfactory. Procedures were not followed. Technical specifications were not verified. The culture was rushed (go-fever or product push environment). None of these are small problems, but they also point to much bigger problems: failure of the leadership to properly plan the project so that rushed timelines would not occur. This same culture is building new spacecraft. While JPL is a great agency and they do tremendous and incredible feats, they are not perfect and have lost several spacecraft and have had severe faults in others. These problems did not have to occur and more importantly these problems do not have to occur again in the future.
While the lead scientist says that it wasn't a big deal and no investigation will be held, I think he isn't analyzing the significance of this event. While scientists are more focused on the validity of data, engineers have to analyze not just events that occur (like loss of a rover), but also events that could occur. Putting the wrong instrument into a rover is due to "failure to follow procedure". This is a big deal. Failure to follow procedures could have been caught by a better QA system, better monitoring of the installation, and better training (including walkthroughs on the installation of the instruments).
Even though this minor event that has had no impact on the mission, it has shown that there are holes in JPL's QA system, their monitoring system, and their training program for building these rovers. If you want to dig further you might find that all of these problems were caused by an unnecessary sense of urgency which may have been caused by poor project planning. These exact problems have caused the loss of spacecraft before (and many of them were cited for the loss of Challenger and Columbia).
No investigation? The lead scientist really needs to take a look at his project management priorities. Having experience working in nuclear power I have learned and have been trained that small problems are many times the only symptoms of much larger problems. The lead scientist's attitude on the problem gives me no confidence in his ability to run a more complicated mission. Like in gambling, one or two successes doesn't mean that you are going to win on the next roll.
You said: "IIRC, Mars is geologically (or "areologically," if you prefer) dead -- obviously it had significant volcanic activity a long time ago, as evidenced by Olympus Mons, but none that we've ever detected going on now or in the recent past."
The idea that Mars is geologically dead is based on old data. After the Mars Global Surveyor mission, alot of new information came about. One of the estimates was that Mars had volcanic activity about 20 million years ago. Considering a 4.5 billion year existance, 20 million years is hardly dead. This data was from crater counting. Older structures will have many craters and younger structures will have few craters. Obviously this has a fairly large margin of error (but a 2 billion year old structure still won't be confused with a 20 million year old structure). New studies from the Mars Express mission have said that vulcanism may have occured as early as 4 million years ago. This tends to support the idea that volcanos on Mars are dormant, not dead.
As far as having a magnetic field or having plate tectonics, yes Mars is dead. Mars may have had plate tectonics (which in general is due to convection of the mantle) in one localized region in its early history, but there is no evidence of it now.
Recent studies of gullies, volcanism, and the planet's precession tend to indicate that Mars may be alot more active than we think.
According to the oft quoted ORNL report, there is 0.00427 millicuries/ton of coal, and each ton releases 6150 kilowatt-hours(kWh)/ton. This is therefore 6.9431e-7 mCi/kWh. The DOE's Energy Information Agency gives the world total of energy production for 2002 as 4.0512e17 BTU or 1.18699e14 kWh. Since only 9.756e16 BTU or 24.08% of the world energy production is coal for 2002, we can come to a total of 19.85 MCi/yr. Some estimates for Chernobyl put the radiation released at 1.2e19 Bq or 320 MCi. It would take coal plants at the 2002 rate of production 16 years to equal the release from Chernobyl. On the 26th of April, it will be the 19th anniversary of the Chernobyl accident! Is it really that intelligent to put the noose around the neck of our nuclear industry because a near bankrupt Cold War enemy with a poorly designed reactor had an accident that almost certainly could not happen with US reactors?
You said: "I encourage you to try it without the sodium... chlorine ions are, shall we say, not very good for you. Salt may dissociate in water, but it's safe there in equal quantities. Surprising that something so bad for you doesn't violate sanjimon(?)'s principle."
And chlorine isn't good for the metal either. If you are interested in preserving the mechanical properties (especially the surface properties), using chlorine in an electrolytic metal removal process is a bad idea (in general, any electrolytical metal removal process will contaminate the remaining surface). Many bad types of corrosion are started with just a little bit of chlorine. Do a google search for chloride stress corrosion cracking for one of the very worst types of corrosion known.
Anyone interested in using electrolytic metal removal for any project that is under high temperature and stress (a case mod *probably* won't qualify) should definately not use the NaCl procedure. In fact, if you ever want to do a project under high temperature and stress you need to carefully monitor the exposure of chlorine, oxygen, hydrogen, and sulfur ions (to name a few) as well as things like the pH to ensure that your piping doesn't fail.
You said "If it's as recent as 4 million years that would put to bed the dead Mars theory. The idea that Mars lacks a molten core. If there was magma that recently there would still be a molten core. It would take hundreds of millions if not billions of years to go from volcanic to a cold core. There would almost have to be liquid underground water. Good news for life and also water for explorers."
For the core to be molten there is a non-linear temperature and pressure dependance. On Earth, the inner core is solid and the outer core is liquid even though the temperature of the inner core is higher. This is because the increased pressure at the inner core forces iron to stay solid while the decreased pressure at the outer core boundary allows it to melt. The pressure at the core of Mars should be less because of the smaller size of Mars, but the core temperature will almost certainly be lower because of the higher surface area to volume ratio (more heat can be radiated into space per the given mass of the planet). This makes it difficult to say for sure whether it is solid or liquid (though the lack of a magnetic field makes me inclined to believe that its solid).
It should also be noted that the mantle is solid on Earth (yet still deformable) yet liquid magma is found near the surface (and lava on the surface). This is for the same reason described (since the pressure is much less near the surface). A solid core can still allow vulcanism.
You said: "Nuclear reactors do not produce large amounts of isotopes "hundreds of thousands of times more radioactive" than "natural" uranium. And if they did, the half-life for them would be extremely short."
Nuclear reactors do produce lots of isotopes hundreds of thousands of times more radioactive than natural uranium. And the half-lives are fairly short compared to that of U-238 (~4.5 billion years) or U-235 (~700 million years). For an isotope that has a half-life of 10,000 years, it will have an activity 70,000 times higher than U-235. This is not to say that all the fuel is converted to a 10,000 year half-life, but enough is to make it very significant. Additionally activity only measures the number of decays per second, not the energy. Shorter half-lives have higher energies per decay and are more damaging. An isotope with a 10,000 year half-life will typically be much more damaging than U-235 with a 700,000,000 yr half-life.
You said: "On top of that, if breeder and pellet based plutonium reactors were actual in service we could use the waste from standard light water reactors to feed breeder reactors whose waste would feed the pellet based reactors. Drastically reducing the amount and lethality of the nuclear waste that we'd ultimately have to store
Only odd isotopes of Thorium, Uranium, or Plutonium are suitable for use in a self-sustaining fission reaction. Plutonium is created in a breeder reactor by neutron absorption and subsequent beta decay of U-238. While there are cases where other radioactive materials absorb neutrons and revert to a more stable isotope, this will not be more significant than the radioactive fission products released by uranium or plutonium fission. For this reason breeder reactors will still produce significant amounts of radioactive waste. Due to the fact that breeder reactors need a higher neutron flux to stay critical (self-sustaining chain reaction) more lower atomic mass isotopes will be transmuted to stable isotopes by neutron absorption. But this will not drastically reduce the activity of a depleted core.
You said: "So what happens when the temperature (down to -90C) goes below the sublimation temperature of CO2 (-76C, if I recall correctly)? Does it just freeze out of the air?"
Most likely. The phase diagram for CO2 shows that for our standard atmospheric pressure, CO2 freezes at -78.5 C. If the temperature is only slightly lower than -78.5 C it may take some time for a significant amount of CO2 to precipitate due to the latent heat of solidification for CO2 of -43 cal/g (smaller than the absolute value of water which is about -80 cal/g) . Additionally some CO2 may remain in the air which varies by temperature (which would be relative humidity for water). As the temperature drops the amount of CO2 that can be dissolved in air decreases. Unfortunately I couldn't find a reference for CO2 saturation vs temperature. If it is reasonably low (which it should be) at -90 C, CO2 frost will develop.
On Mars with an atmospheric pressure that varies from about 5 - 10 mbar (1 atm = 1013.25 millibars), CO2 frost can develop as seen by Viking 2 and by satellite pictures of the poles. Snowflakes won't form, since the shape of a snowflake is determined by van der Waals forces (don't occur in CO2). CO2 frost should look similar to this.
This effect isn't completely new (at least I don't think so). The space shuttles would roll and yaw back and forth a few degrees on reentry to slow down faster. If you ignore the horizontal speed of the spacecraft, this is somewhat similar to a piece of paper falling (but obviously more controlled--sometimes). Seems to me that the two items might be conceptually related. That being the case, I wouldn't be suprised if we saw a new style of atmospheric slowdown in future space probes.
I'm glad that your hardware works under MacOS X. After all that is the target audience. If you read the specifications page for your monitor, you would note that Linux was not supported. This is an important point when buying high-end hardware. Some things aren't supported for Linux. But as another poster pointed out, many things aren't supported for MacOS X either. No big deal, life goes on. If you research (note: I put that in bold before) before you spend $5000 on a monitor, you will get a system that will perform correctly. Saying Linux has poor hardware support is unjustified because high-end hardware typically has a narrow audience. Covering common hardware used in systems is probably more appropriate (and Linux performs very well there).
This is a Catch-22. Without Linux being mainstream, hardware manufacturers feel no need to support it immediately (especially the more obscure companies). But without complete hardware support, Linux cannot gain mainstream acceptance. This looks unsurmountable.
Not so. On the server and workstation side, Linux has alot of support (because it is mainstream there). Once Linux crushes the rest of the Unix brands (as it appears is going to occur) and cuts into Windows Server spaces, it can start to leverage into the desktop realm (similar to how Microsoft got into the server realm).
One of the key points in this fight is to cut out the FUD on hardware support. For small servers, it is very good. For desktop systems, it depends (but it is typically much better than is often portrayed). But most desktop systems aren't built out of random parts. They usually are sold prebuilt with operating systems installed (and with no obvious conflicts). With this in mind, Linux vendors may be very sucessful in the future on converting businesses over to Linux (which was how Microsoft won the desktop war). If they follow the Dell or Gateway model, peripheral support will not be an issue either. Other markets will follow, and hardware support will become better.
As far as support for family computers (other than for computer geeks): wrong war, wrong time.
You said: "THEN YOU ARE NOT A DESKTOP USER. THIS WHOLE ARGUMENT IS ABOUT USING LINUX AS A DESKTOP, NOT A SERVER. It's a fine OS for serving."
I don't often see desktop systems run high-end hardware. If you are using high-end hardware, you are probably not running a normal desktop system. For this reason my response assumes that the grandparent was talking about a system that you would actually put high-end hardware into (certain workstations or servers). I've done many crazy things with computers, but I've never, for example, put a $15,000 digital signal reader card into a $2,000 box. I've never even heard of that happening (though someone has done something like that, I'm sure).
Now if you are using a $50,000 custom workstation that has sold only 500 systems in a year, there is a good chance Linux is going to give you some hiccups. But then again its not a desktop system.
Wow! I've been using Linux for 9 years now and I've only had a few driver issues (most of which I was able to work around). Of course, one of the main things that I recognized about Linux is that it is best suited for small servers (using modest, common hardware). Once you get to the uncommon, high end hardware you are going to have problems with most operating systems (as the hardware developers narrow their audience). This hardly makes Linux inferior. The developers of Linux can hardly be expected to write drivers for every piece of hardware ever designed. When you want to go high-end with Linux the key is: RESEARCH! The fact that Mac hardware works with Mac OS X should not be bragging rights. Thats the design audience (and it would be insane if it didn't work).
If you use Linux for small servers with modest, slightly older hardware, you will rarely have a problem.
If you use Linux for high-end servers and research before you install, you will rarely have a problem.
If you have uncommon high-end hardware and install Linux there very well may be a problem. But its not Linux's.
Magnetic field lines are an exceptional abstraction. Since the density of magnetic field lines (say taking a box around some part in your diagram) matches the density of the magnetic field, you can say that a box with some density of field lines at point A in your diagram compared to a point B has the the ratio of the density of field lines at A divided by the density of field lines at B multiplied by the field strength at B (assuming we know the field strength at B). Field lines are also used in the description of the electrical field and gravitational field and obey the inverse square law (meaning the only information lost by field line abstractions is the coefficients).
But if it annoys you that magnetic field lines are an abstraction you should also be annoyed that the magnetic field is also an abstraction of the effect of moving charges taking into account relativity. I, for one, believe that it would be almost impossible to talk without the abstractions in discussing sunspots (particularly the second abstraction) because it would hide the concepts away in the technicalities of the electrical field and relativity.
The current theory (at least how I get it) is that sunspots are related to the magnetic field of the Sun. We start by assuming that the magnetic field of the sun starts a cycle by resembling a bar magnet (where a magnetic field line goes directly from the geographic south pole to the geographic north pole without curving). Due to the faster rotation of the Sun at the equator than at the poles (observed), the magnetic field slowly becomes twisted around the Sun (in a helix). Any field lines that resist the twisting can unwind causing them to erupt from the surface forming a sunspot pair (one where it exited and one where it returned). It is theorized that the greater magnetic flux at these points causes a reduction in convective heat transfer to the surface resulting in a dimming of the light at these spots. Eventually due to the interaction of the erupted magnetic field lines with the non-erupted magnetic field lines, the sunspots are forced towards the poles. Once enough sunspots are at the poles and their fields are stronger than the non-erupted fields, the field of the sun can flip, anhililating all the sunspots and returning the Sun to a normal bar magnet orientation (except with the opposite polarity). This is observed to take about 11 years.
It seems that if all the sunspots have disappeared, this should mean that the magnetic field has reversed early.
Nothing new sadly enough. George C. Marshall said in his 1953 Nobel Peace Prize lecture:
Of course Marshall wasn't the first to say this (general idea), and was not the last either. If you look through the lectures in the Nobel archives, you will see this point stated over again many times. Its probably the most overlooked item by most people for achieving world peace because it is also one of the most difficult to accomplish.
Don't be so fast, cowboy! The carbon comes out of the air when the plant grows, and is put back into the air when you burn your fuel. Its a novel idea.
The key to the energy production is using the incident solar radiation (of about 1 KW/m^2 on the surface of the Earth) to effectively take carbon out of the air and turn it into fuel. There is alot of energy required to do this which be impossible for us to do today economically (except perhaps with a nuclear plant). This is why it is impractical to have underground corn fields, for example. This is also why food production on distant planets, in the future, may require nuclear power to shine light on plants for extended periods of time.
What I am particularly interested in biodiesel is if it can be successfully adapted to be used in fuel cells for higher effeciency (is there a technology where the impurities won't poison the cell).
Additionally, an adaptation of this idea could help reduce the CO2 in the atmosphere. Consider burying 10% of the oil produced over time. If the oil is mass produced, that is a lot of CO2 that has left the atmosphere.
You are selectively ignoring parts of my posts. I brought up cars to give a good comparison example (that homes are a small fraction of energy use when compared to cars and especially industry). Let me put this in numbers: to supply my home overnight I need ~20 car batteries, or your ~8 of your larger batteries. Asimi, a silicon refiner outside my hometown, would need 40,000 at night. Thats just one company. There are several companies in my hometown, especially the mining companies, that would need over 10,000 at night. The point isn't about fuel technology for cars, its that way too many batteries are needed to support a solar system (pun intended). I have no problem with solar (other than some solar cell production processes), but I don't see any reasonable way for when the sky goes dark to stay off the grid. In order to power an entire area, both industry (which often works 24 hours a day) and residential areas must have power. Residential is often cited because its easy to do. When you can cite an example that a 5 MW or larger plant uses on solar cells and batteries, I will be very impressed.