You said: "One word: fusion. As soon as fusion comes along, coupled with ion drives, chemical rocketry is history. Period.'
Unlikely.
There are two main designs for a fission rocket. (1) To couple a semi-conventional PWR or BWR with an ion engine. The big downside to this is that you have to have a large secondary system to use the steam to make electricity. What this means is that you have to have a large heat sink (large radiators) and lots of moving parts. A design like the GT-MHR could simplify this, but not hugely so. (2) Using a bladder of fuel (hydrogen, or water or whatever), you use this as coolant to a critical reactor that jets the superheated portion directly to space. The downside is that this doesn't make electricity, so you would have to divert some of the coolant (which requires construction of the additional secondary systems) or use solar panels or RTGs to electrically power the spacecraft (there will be additional power requirements due to reactor safety equipment).
There are two main designs for fusion power: (1) Tokamak: basically shaped like a donut, a low atomic number elemental plasma is magnetically confined and heated (with I^2*R losses or X-rays) to the point where fusion occurs. The means of useful energy transfer is via neutrons emitted which hit a water tank surrounding the fusion reactor. From here its just like the secondary side of a normal fission nuclear reactor (ex 1 above). (2) A pellet of low atomic number elements is simultaneously hit by energetic radition from all directions compressing it until fusion occurs. Heat transfer like above.
You could argue that either of these fusion reactions could operate like the fission reaction #2 above (with part of coolant directed to make electricity), but an important point is that a significant fraction of the energy released by fusion (if it ever produces more energy than is required to induce it) is required to sustain it. This requires the construction of a very large secondary system compared to that of the fission reactor (a lot more heat being transferred). Since a fission reactor will probably provide way more power than is needed anyways, there is no reason to build a much heavier fusion reactor.
The ATV design strikes me as particularly interesting because it brings up a point that I've been wondering for awhile: Why don't we have more automated exploration and maintenance vehicles in Earth orbit. It seems to me that a spacecraft that could launch, orbit earth, and return to earth (not that the ATV can do that) without humans onboard and built in a mass manufactured way would be extraordinarily effective for Earth orbit science experiments. It might also be useful for maintenance of high value satellites (like HST). Since Earth orbit is almost real-time transmission there is no reason to think that putting a mechanical arm on a spacecraft to do maintenance would be any different that a surgeon doing a remote operation via a mechanical hand. The most complicated part would be the approach of the satellite to be maintained, but since the Space Shuttle obviously had no problem doing this there is no reason to believe that an automated spacecraft (with real-time human backup in a controlling station) couldn't do the same (a little more complicated than the ATV's purpose of docking with the ISS, but I don't think its inanely so).
You said: "The First Ammendment does not give you freedom of speech, but recognizes it in a limited fashion. Likewise, a corporation poses many of the same threats now that a government did when the 1A was drafted, leading me to believe that perhaps the government ought to recognize the freedom of speech in a broader fashion- that is, one which recognizes private relationships as well."
Are you suggesting altering:
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances.
so that the First Amendment doesn't just apply to the government but to corporations? Something like:
Within the bounds of the US and its territories any act preventing the excercise of free speech, etc. will be punishable as a court may direct...
It's pretty easy with government: you say 'NO' when a violation occurs and they have to stop (and if they don't its contempt of court--you throw the respective government agent in jail). In the second case, you have to create an agency to hunt down and track violators (which could be politically biased). People should have to freedom to express themselves in an online forum, but not due to law. It should be by common courtesy (like slashdot) or by an, as of yet determined, Internet Freedom of Speech Standard.
You said "Well, they *are* radio-active, and there is a small chance that one could burst from launch errors and end up polluting a populated area. I agree that the risk is tiny, but it does exist. Noboby sane claims they explode into mushroom clouds."
Prefer using the words 'there is a small probability' or 'there exists a potential'. When you use the word 'chance' you play a trick on people's minds because 'chances' are always associated with a positive outcome, as in saying that the statment is hoped to be true. People tend to say, "I have a chance to win the lottery" vice "I have a chance to lose the lottery" because they want to win the lottery. If you use the word 'chance' in your above context it fuels paranoia vice the logical reasoning of calculated risks.
You said "It's an interesting contrast:- for science we are apparently not willing to take any risk, but for the sake of a feel good exercise we are willing to take an enourmous risk."
Going to Mars is no more of a feel good excercise than the European explorers sailing to the New World or Lewis and Clark's journey. We intend to go to Mars because humanity will eventually spread out and live there. There are incredible opportunities for the future of our species if we colonize the Moon and Mars just as there was incredible opportunities for European countries to colonize the New World.
Its not about science. Science will be done because scientists are smart enough to sneak in science anywhere they can, but in the end it comes down to colonization. While this may be hard to grasp in today's short-term views, in the long-term it will have a significant impact on all of humanity. This is why it is worth the risk and Hubble is not. But selling it in the short-term thinking political world will be immensely difficult.
The article says that if all the lift and tuck maneuvers fail, the rover could just turn and roll of in another direction. I know we have some JPL dudes hanging out here, so the question is, why waste 3 days? Why not just roll off the alternate ramp and start exploring? I guess I just don't understand why the front ramp is so special.
You said: "Balance will be achieved. It is the way of things."
Balance may be achieved with 95% of all species extinct.
As far as it concerns global warming, there are many positive and negative feedback loops, but there are only two that really concern me.
The first is solubility of CO2 in seawater. As ocean temperatures rises, the equilibrium in the oceans will change such that the oceans become a source of atmospheric CO2 rather than a sink. This rate will increase as seawater temperature rises.
The second is the rising of the zone of methane hydrate stability. As seawater floor temperatures rise, this zone of stability rises and allows increased methane releases to the ocean. If sea floor temperature increases to some critical point (where the zone of methane hydrate stability has a depth of zero from the ocean floor), massive releases could occur. Considering that methane is a much more effective greenhouse gas than CO2 and that there are considerable deposits of methane hydrates under the ocean floors, this is probably the larger concern.
Since methane and CO2 take time to heat the atmosphere there will be a considerable delay time. By the time that significant results are seen, the global warming effect will have achieved enough power that cutting all human added greenhouse gases to zero will not be able to reverse the spiral of destruction that global warming will bring.
You said "The first (that others have covered) is spinoff technology. Digital cameras contain technology (CCDs) that astronomers have been using for 20 years or so now. X-ray machines at airports, MRIs, etc"
While the space program has had many many spinoffs, MRI is not one of them. MRI was due to the work of I. I. Rabi and colleagues in the 30's and 40's, not the space race. MRI would have been developed whether we left the Earth or not.
You said: "How does Mars exploration do anything for society beyond improve our knowledge of esoteric things and perhaps get a few very smart scientists their Masters?"
I think this quote pretty much sums it up:
"The dinosaurs became extinct because they didn't have a space program." -Larry Niven
There is a significant amount of difference between a nuclear bomb and a nuclear reactor. A nuclear bomb is designed to release all of its energy (i.e. fission all or almost all of its fuel) in one instant. A nuclear reactor isn't designed to do this and can't do it if it wanted. Since nuclear reactors require the moderation of product fission neutrons in order to make subsequent fission probable (the lower the velocity of a neutron, the more likely it will be near the nuclear radius of a U-235 atom for a longer time and be able to be absorbed), a certain time is expended between each fission during the moderation (there is some average distance between collisions during the moderation and a neutron has to travel it); hence, time for heat transfer to occur. If a nuclear reactor ran out of control, the heat transfer would expand its fuel and other reactor materials to such a degree that it would be improbable for fission neutrons to cause subsequent fissions (i.e. if you are inside a large enough balloon with an 'X' painted on the side and you blew up the balloon, it would be harder and harder to hit the 'X'), and the reactor would shut down without releasing all of its power. Nowhere near the amount of energy released in a nuclear bomb would be released.
You said: " I'm so drunk I can't s up strait and we're asking if some mathematical conjecture has been proved? Is this really the right storey for New Years Eve? Lets go with stories about things that are bright and shiny."
Mathematics and alcohol dont mix. Please don't drink and derive!
You said: " I disagree, the orbital period will be affected, there are more than two bodies involved."
Let me be clear on some assumptions: 1) For Kepler's Third Law: The mass of the sun is much more than the earth. 2) For a L1 object: The mass of the earth or the sun is much more than the mass of the object. The reason is simple: If it were massive, it would pull the earth towards it making the Earth's orbit elliptical (since it is pulling the earth towards the sun but not affecting the velocity of the earth perpedicular to the pull), and therefore not become a L1 point. It would instead fall into an elliptical orbit around the Earth, and the resultant center of mass of the two objects would have a similar orbit (like the earths--almost circular) with a shorter period (since the center of mass of the system moved towards the sun). But this is probably not the system you are thinking of. If it is, then all you need a simple calculation of where the resultant center of mass of the Earth-satellite system is and you plug this value into the previous equation to find the orbital period.
On a side note the first assumption is why spacecraft in orbit around the earth suddenly don't change orbit when they deploy payloads. An altered form is why two objects dropped on earth in a vacuum will fall at the same rate.
Vast quantities of energy are stored that way. In addition to the known resources is probably a hundred or a thousand times more fossil biomass all around the planet.
If the above AC is right with his assumption of "1kg mass per second", it would equate about ~31'500 tons of mass per year. Modestly assuming 5% of this is trapped in fossil material NOT radiated back, we would have ~1'500 tons each year. Multiply this with 90 million years since the extinction of the dinosaurs and you have a weight increase of about 150'000'000'000 tons. 150 billion tons. Not THAT much compared to the entire earth, but surely more than the weight of an average mountain.
Take into account the earth and the plants are much older than 90 mio. years and you'll get insane amounts of energy trapped somewhere."
No.
The average temperature of the earth is 800 degrees C but the average temperature of the surface is about 20 degrees C. Since heat doesn't transfer spontaneously from a colder object to a hotter one, the direction of heat transfer is towards the surface of the earth. Now if there was the same or more incident than emitted radiation, the temperature of the surface would increase, but this is not observed. The temperature is constant on the surface so the emitted radiation from the earth must be greater than the incident radiation by exactly the amount of heat transferred from deep in the earth to the surface. The reason that the subsurface remains constantly 800 degrees C is because of spontaneous fission of natural uranium spread out in the earth and decay of the radioactive products.
Since net energy of the earth is decreasing, the mass of the earth would be decreasing, but this is probably easily made up by all the meteors and debris that is absorbed by the atmosphere.
According to Kepler's Third Law: the orbital period, T, and the semimajor axis, a are related by
T^2/a^3 = 4 * pi^2 / ( G * M),
where M is the mass of the Sun. Neglecting the gravitational attraction between the L1 mass and the earth (the L1 mass will be pulling the earth while its position remains constant since its pull towards earth is balance out by the pull toward the Sun), no change in Earth's mass will change its orbital period.
You said "It does seem that they would have been better off waiting for the MGS imagery before actually landing...;-)
Sometimes even the most obvious things are only clear with hindsight."
This may not have been possible. Three points: 1) Mars Express was designed before the Beagle 2 was agreed to be attached. Since it had to do a correction after entering orbit to make its orbit a polar orbit, it probably wouldn't have had enough fuel to do so with the Beagle 2 still attached. 2) Since the landing area is an ellipse with the major axis parallel to the direction the craft is moving, a polar insertion would probably be unacceptable for the landing area. 3) Additional fuel would be required to decelerate the Beagle 2 out of polar orbit
Obviously since the Beagle was a late 100 kg addition, the idea of adding additional fuel is impossible due to the weight constraints. You can always wait for additional information before you attempt to land your spacecraft, but by then it might be year 3000 and the argument would be over whether the new 1 mm resolution camera is accurate enough to land a spacecraft.
You said: "3) Fusion by-products. Enriched uranium and it's ilk are not found in nature"
Hate to nitpick, but you are probably confused when you talk about fusion. Let me clear this up:
Current technologies for fusion have not gotten to the 'break even' point so they are not in use for power generation and not in use except very localized research centers. Of the products produced, the most common are He-3, H-3 (tritium), He-4, H, and neutrons. This is because normally the reactants are either H-1, H-2 (deuterium), or H-3 (tritum). Of the products and reactants, He-3 and H-3 are not naturally occurring. H-3 is also radioactive but it has a reasonably short half-life, so it really isn't a worry about long term contamination of the earth. Additionally any neutron flux in the reactor can activate metals in the reactor complex.
So as far as fusion technology is concerned, only the activated metals in the reactor complex are of a concern. In reality this material will not be the 'high-level' waste that people always worry about. While it is radioactive, it is really nothing compared to fission products.
If you were confused and talking about fission technologies, it becomes much more interesting. The fission products in a nuclear fission are statistically determined and since the proportion of neutrons to protons for stable nuclei is nonlinear, the fission products are likely to be radioactive (and typically takes many individual decays to reach a stable point). Whenever someone is talking about high-level waste, this is what they are talking about. In addition to the fission products, portions of the reactor complex can become activated by neutrons just like a fusion reactor.
When you talk about radioactive material being able to contaminate the earth you are talking about the fission products. But the secret of nuclear power is that you can do so much with so little. The expended fuel from a fission reactor is really a very small amount and when people talk about nuclear waste, they don't always clarify the difference between high and low level waste. For this reason, it many times appears that there is this huge volume of high-level waste (as this is typically implied when no description of the types of waste is given) when the vast vast majority is low level waste that will have little environmental affect. Taking into account that a fission reaction is at least 40 million times more powerful than the chemical reactions that produce eletricity at coal and gas plants, the waste will be that fraction smaller.
But here's the biggest secret of nuclear power: the earth naturally produces more fission products than all the nuclear reactors in the world. The fact of the matter is that the average temperature of the earth is and has been about 800 degrees C for 4 billion years and this can't be accounted for by solar radiation. What can account for it is the spontaneous fission of minute amounts of uranium spread throughout the earth. Additionally a natural nuclear reactor was found in Africa. The earth isn't as clean from fission products as you may suspect.
You said " APC 1000VA UPS, I just bought, for $150. A friend of mine bought the same one after a rebate was announced, dropping it to $99. With the 4 of those you could buy from my area, at the price you'd pay in your area, you could have power for the entire day (provided you can keep the batteries charged).
The batteries are hot-swappable, too, so you could keep a UPS near your generator for charging purposes."
1000 VA only refers to the power output of the inverter attached to the battery for the UPS, i.e. 120Vac, 8.3 A. I should have been more clear when I was describing it, but there can be several 1000 VA UPS' that only differ in their discharge time. So the 1000VA UPS you bought probably won't give 1KW of power for 20 minutes if it only cost $150.
You said "Err, carr batteries are designed for short heavy loads"
Being a person who has worked with many lead acid batteries, I have to disagree with you. A lead acid battery is at its most efficient when the load is the least. Under very heavy loads a lead acid battery will generate high heat and release alot of hydrogen. The only components that are really suited for short heavy loads are capacitors and inductors. The reason that you can use your car battery to start your car without damaging it is because the duration of the high load is very short.
I agree that lead acid batteries can become damaged if they are discharged to depletion, but if you only discharge about half the capacity of the battery (and then fully recharge it), it should run for a very long time before replacement is necessary.
You said "Another option is get a UPS for your desktop. You can run the machine off of that when the power goes out, night, etc. and they are relatively cheap...if you get a 4 hour one... and can power other devices. The laptop and the UPC will trickle charge while juice is flowing, so you can be pretty sure that when the sun does set, you won't miss a beat with your tech."
Considering a 1000 VA UPS costs about $600 in my area and is only rated to operate for about 20 minutes, a 50W laptop would probably only operate for about 6 or so hours on it. For $200 you could buy a car battery (50 A-hrs at 12V), a battery charger, and a 100W inverter and operate for over 10 hours. Or a cheaper solution that I use is to get an emergency jump start kit (mine is 18 A-hr at 12V), and a cheap inverter. For less than $100 I have an extra 5 hrs of laptop time.
You also said: "Now... how exactly are you going to get on the net? Satellite? Pigeon?"
Fortunately, RFC 2549 exists for just this problem.
You said: " it's seems pretty probable to me that this might be of artificial origin, accidentally or intentionally
with the massive amounts of research we have going on right now with the virii (using them to fight cancer; finding cure for AIDS; studying influenza; sequencing virii's DNA) it's possible that we might have artificially produced SARS or have abused a population of some virus to the point that the population experienced a high mutation rate (e.g. if we tagged them with radiation-produced molecules, which is common practice for studying their spread in an animal)"
This is unlikely, since the SARS-CoV is not more closely related to any known type of coronavirus than any other. If it were a modified virus it should be very similar to a known class of coronavirus.
You said: "France, Russia, China, the USA, and Germany have all provided military equipment to Iraq. The USA has additionally outfitted Iran and several neighbours. The Russians, Germans, and French are owed money largely for infrastructure, electrical generators, sanitation equipment, and the like. But get this straight - no one is innocent in this, and the USA is certainly, far and away, the worst offender."
FUD! Lets get some numbers down. According to SIPRI USSR, France, China, and Czechoslovakia were the largest traders of conventional arms during the period you describe. In fact a nice table summarizes this and shows that the US contributed to about 1% of the arms trade to Iraq from 1973-1990. Looks like the certainly, far and away, worst offender is the USSR.
You said " That is totally crazy - metric is way easier. We have ten fingers. We count in tens. We don't count in 12s or 14s or 16s. Imperial units are not even standardized properly. An inch is different depending on where you are in the world..."
We probably count to ten and use the decimal system more because the Pythagoreans thought of the number 10 as a holy number than because of the number of fingers. The Pythagoreans other future Greek mathematicians had a profound affect on number theory. Multiple base systems were being tossed around at the time of the Pythagoreans including base 4, base 8 (i.e. nine which is novem in latin may be related to novus meaning new), base 10, and base 60, but only base 10 really survived in the Western world (though parts of the others were incorporated like 6 * 60 degrees in a circle and 60 seconds in a minute).
In my opinion any future scientific number system should be in hexadecimal. The reason is that future scientific applications will rely more heavily on computers, and while no base is inherently better than another, hexadecimal does make computers happy (like is 2.0E43 == 2E43? Do I need to make some sort of ranged comparison? Not if the base is in hexadecimal!).
You said: "a vacuum is still a great insulator. (that's why my coffee mug here has a vacuum between the inner and outer shells:)"
There are 3 types of heat transfer: conduction, convection, and radiation. Your thermos-like cup (technically a Dewar flask) effectively prevents conduction and convection, but that does not mean there is no heat transfer. Any object will radiate (with EM waves) away heat according to Stefan's Law. It will also absorb radiation according to Stefan's Law. As I described in another post, the lower the emissivity, the lower the rate at which radiation is absorbed or recieved. What this means is that your thermos-like cup will have silvered walls on the inside of the vacuum chamber to reduce the amount of heat radiated or absorbed.
Re:Decreasing air pressure...
on
Eating in Space
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· Score: 3, Informative
You said: "Do you have any idea how fast heat radiation will cool an object in space?"
Stefan's Law states: P = (sigma) * AeT^4, where P is the power radiated, (sigma) = 5.6696 * 10^-8 W/(m^2 * K^4), A is the surface area, e is the emissivity, and T is the temperature (in Kelvin). The emissivity can vary from 0 to 1 depending on the properties of the surface. An ideal absorber, which is also an ideal radiator, has an emissivity of 1 and is known as a black body. So, since an object can both radiate and absorb, its net power is P-net = (sigma) *Ae (T^4 - T-0 ^4) where T-0 is the temperature of the surroundings.
What this means is that your turkey is always going to be radiating a certain value depending on its temperature, but depending on where that turkey is (in the shade behind the spacecraft or in front of the spacecraft receiving radiation from the sun) it may cool down or heat up (if the suns radiation is enough to overcome the heat radiated away). If the turkey stays in one place it will come to equilibrium because eventually the radiation absorbed and radiation emitted will equal out whether or not it heated up or cooled down.
On one side note though, in the case where a turkey is in the radiation stream from the sun, because the radiation from the sun comes from only one direction, one side of the turkey would be much hotter than the other.
Not hard to find, your car (if you have one) is probably about 100 KWt. Not that that is very useful in space, but 25 KW is still a pretty tiny amount of power generated (down here on Earth). Unfortunately in modern spacecraft, 5 KWe is a large amount of power.
Slashdot Mirror
You said: "One word: fusion. As soon as fusion comes along, coupled with ion drives, chemical rocketry is history. Period.'
Unlikely.
There are two main designs for a fission rocket.
(1) To couple a semi-conventional PWR or BWR with an ion engine. The big downside to this is that you have to have a large secondary system to use the steam to make electricity. What this means is that you have to have a large heat sink (large radiators) and lots of moving parts. A design like the GT-MHR could simplify this, but not hugely so.
(2) Using a bladder of fuel (hydrogen, or water or whatever), you use this as coolant to a critical reactor that jets the superheated portion directly to space. The downside is that this doesn't make electricity, so you would have to divert some of the coolant (which requires construction of the additional secondary systems) or use solar panels or RTGs to electrically power the spacecraft (there will be additional power requirements due to reactor safety equipment).
There are two main designs for fusion power:
(1) Tokamak: basically shaped like a donut, a low atomic number elemental plasma is magnetically confined and heated (with I^2*R losses or X-rays) to the point where fusion occurs. The means of useful energy transfer is via neutrons emitted which hit a water tank surrounding the fusion reactor. From here its just like the secondary side of a normal fission nuclear reactor (ex 1 above).
(2) A pellet of low atomic number elements is simultaneously hit by energetic radition from all directions compressing it until fusion occurs. Heat transfer like above.
You could argue that either of these fusion reactions could operate like the fission reaction #2 above (with part of coolant directed to make electricity), but an important point is that a significant fraction of the energy released by fusion (if it ever produces more energy than is required to induce it) is required to sustain it. This requires the construction of a very large secondary system compared to that of the fission reactor (a lot more heat being transferred). Since a fission reactor will probably provide way more power than is needed anyways, there is no reason to build a much heavier fusion reactor.
The ATV design strikes me as particularly interesting because it brings up a point that I've been wondering for awhile: Why don't we have more automated exploration and maintenance vehicles in Earth orbit. It seems to me that a spacecraft that could launch, orbit earth, and return to earth (not that the ATV can do that) without humans onboard and built in a mass manufactured way would be extraordinarily effective for Earth orbit science experiments. It might also be useful for maintenance of high value satellites (like HST). Since Earth orbit is almost real-time transmission there is no reason to think that putting a mechanical arm on a spacecraft to do maintenance would be any different that a surgeon doing a remote operation via a mechanical hand. The most complicated part would be the approach of the satellite to be maintained, but since the Space Shuttle obviously had no problem doing this there is no reason to believe that an automated spacecraft (with real-time human backup in a controlling station) couldn't do the same (a little more complicated than the ATV's purpose of docking with the ISS, but I don't think its inanely so).
Are you suggesting altering:
so that the First Amendment doesn't just apply to the government but to corporations? Something like:
It's pretty easy with government: you say 'NO' when a violation occurs and they have to stop (and if they don't its contempt of court--you throw the respective government agent in jail). In the second case, you have to create an agency to hunt down and track violators (which could be politically biased). People should have to freedom to express themselves in an online forum, but not due to law. It should be by common courtesy (like slashdot) or by an, as of yet determined, Internet Freedom of Speech Standard.
You said "Well, they *are* radio-active, and there is a small chance that one could burst from launch errors and end up polluting a populated area. I agree that the risk is tiny, but it does exist. Noboby sane claims they explode into mushroom clouds."
Prefer using the words 'there is a small probability' or 'there exists a potential'. When you use the word 'chance' you play a trick on people's minds because 'chances' are always associated with a positive outcome, as in saying that the statment is hoped to be true. People tend to say, "I have a chance to win the lottery" vice "I have a chance to lose the lottery" because they want to win the lottery. If you use the word 'chance' in your above context it fuels paranoia vice the logical reasoning of calculated risks.
You said "It's an interesting contrast:- for science we are apparently not willing to take any risk, but for the sake of a feel good exercise we are willing to take an enourmous risk."
Going to Mars is no more of a feel good excercise than the European explorers sailing to the New World or Lewis and Clark's journey. We intend to go to Mars because humanity will eventually spread out and live there. There are incredible opportunities for the future of our species if we colonize the Moon and Mars just as there was incredible opportunities for European countries to colonize the New World.
Its not about science. Science will be done because scientists are smart enough to sneak in science anywhere they can, but in the end it comes down to colonization. While this may be hard to grasp in today's short-term views, in the long-term it will have a significant impact on all of humanity. This is why it is worth the risk and Hubble is not. But selling it in the short-term thinking political world will be immensely difficult.
The article says that if all the lift and tuck maneuvers fail, the rover could just turn and roll of in another direction. I know we have some JPL dudes hanging out here, so the question is, why waste 3 days? Why not just roll off the alternate ramp and start exploring? I guess I just don't understand why the front ramp is so special.
You said: "Balance will be achieved. It is the way of things."
Balance may be achieved with 95% of all species extinct.
As far as it concerns global warming, there are many positive and negative feedback loops, but there are only two that really concern me.
The first is solubility of CO2 in seawater. As ocean temperatures rises, the equilibrium in the oceans will change such that the oceans become a source of atmospheric CO2 rather than a sink. This rate will increase as seawater temperature rises.
The second is the rising of the zone of methane hydrate stability. As seawater floor temperatures rise, this zone of stability rises and allows increased methane releases to the ocean. If sea floor temperature increases to some critical point (where the zone of methane hydrate stability has a depth of zero from the ocean floor), massive releases could occur. Considering that methane is a much more effective greenhouse gas than CO2 and that there are considerable deposits of methane hydrates under the ocean floors, this is probably the larger concern.
Since methane and CO2 take time to heat the atmosphere there will be a considerable delay time. By the time that significant results are seen, the global warming effect will have achieved enough power that cutting all human added greenhouse gases to zero will not be able to reverse the spiral of destruction that global warming will bring.
You said "The first (that others have covered) is spinoff technology. Digital cameras contain technology (CCDs) that astronomers have been using for 20 years or so now. X-ray machines at airports, MRIs, etc"
While the space program has had many many spinoffs, MRI is not one of them. MRI was due to the work of I. I. Rabi and colleagues in the 30's and 40's, not the space race. MRI would have been developed whether we left the Earth or not.
I think this quote pretty much sums it up:
There is a significant amount of difference between a nuclear bomb and a nuclear reactor. A nuclear bomb is designed to release all of its energy (i.e. fission all or almost all of its fuel) in one instant. A nuclear reactor isn't designed to do this and can't do it if it wanted. Since nuclear reactors require the moderation of product fission neutrons in order to make subsequent fission probable (the lower the velocity of a neutron, the more likely it will be near the nuclear radius of a U-235 atom for a longer time and be able to be absorbed), a certain time is expended between each fission during the moderation (there is some average distance between collisions during the moderation and a neutron has to travel it); hence, time for heat transfer to occur. If a nuclear reactor ran out of control, the heat transfer would expand its fuel and other reactor materials to such a degree that it would be improbable for fission neutrons to cause subsequent fissions (i.e. if you are inside a large enough balloon with an 'X' painted on the side and you blew up the balloon, it would be harder and harder to hit the 'X'), and the reactor would shut down without releasing all of its power. Nowhere near the amount of energy released in a nuclear bomb would be released.
You said: " I'm so drunk I can't s up strait and we're asking if some mathematical conjecture has been proved? Is this really the right storey for New Years Eve? Lets go with stories about things that are bright and shiny."
Mathematics and alcohol dont mix. Please don't drink and derive!
You said: " I disagree, the orbital period will be affected, there are more than two bodies involved."
Let me be clear on some assumptions:
1) For Kepler's Third Law: The mass of the sun is much more than the earth.
2) For a L1 object: The mass of the earth or the sun is much more than the mass of the object. The reason is simple: If it were massive, it would pull the earth towards it making the Earth's orbit elliptical (since it is pulling the earth towards the sun but not affecting the velocity of the earth perpedicular to the pull), and therefore not become a L1 point. It would instead fall into an elliptical orbit around the Earth, and the resultant center of mass of the two objects would have a similar orbit (like the earths--almost circular) with a shorter period (since the center of mass of the system moved towards the sun). But this is probably not the system you are thinking of. If it is, then all you need a simple calculation of where the resultant center of mass of the Earth-satellite system is and you plug this value into the previous equation to find the orbital period.
On a side note the first assumption is why spacecraft in orbit around the earth suddenly don't change orbit when they deploy payloads. An altered form is why two objects dropped on earth in a vacuum will fall at the same rate.
You said: "It doesn't radiate everything back
Prime example: fossil fuels.
Vast quantities of energy are stored that way. In addition to the known resources is probably a hundred or a thousand times more fossil biomass all around the planet.
If the above AC is right with his assumption of "1kg mass per second", it would equate about ~31'500 tons of mass per year. Modestly assuming 5% of this is trapped in fossil material NOT radiated back, we would have ~1'500 tons each year. Multiply this with 90 million years since the extinction of the dinosaurs and you have a weight increase of about 150'000'000'000 tons. 150 billion tons. Not THAT much compared to the entire earth, but surely more than the weight of an average mountain.
Take into account the earth and the plants are much older than 90 mio. years and you'll get insane amounts of energy trapped somewhere."
No.
The average temperature of the earth is 800 degrees C but the average temperature of the surface is about 20 degrees C. Since heat doesn't transfer spontaneously from a colder object to a hotter one, the direction of heat transfer is towards the surface of the earth. Now if there was the same or more incident than emitted radiation, the temperature of the surface would increase, but this is not observed. The temperature is constant on the surface so the emitted radiation from the earth must be greater than the incident radiation by exactly the amount of heat transferred from deep in the earth to the surface. The reason that the subsurface remains constantly 800 degrees C is because of spontaneous fission of natural uranium spread out in the earth and decay of the radioactive products.
Since net energy of the earth is decreasing, the mass of the earth would be decreasing, but this is probably easily made up by all the meteors and debris that is absorbed by the atmosphere.
According to Kepler's Third Law: the orbital period, T, and the semimajor axis, a are related by
T^2/a^3 = 4 * pi^2 / ( G * M),
where M is the mass of the Sun. Neglecting the gravitational attraction between the L1 mass and the earth (the L1 mass will be pulling the earth while its position remains constant since its pull towards earth is balance out by the pull toward the Sun), no change in Earth's mass will change its orbital period.
You said "It does seem that they would have been better off waiting for the MGS imagery before actually landing... ;-)
Sometimes even the most obvious things are only clear with hindsight."
This may not have been possible. Three points:
1) Mars Express was designed before the Beagle 2 was agreed to be attached. Since it had to do a correction after entering orbit to make its orbit a polar orbit, it probably wouldn't have had enough fuel to do so with the Beagle 2 still attached.
2) Since the landing area is an ellipse with the major axis parallel to the direction the craft is moving, a polar insertion would probably be unacceptable for the landing area.
3) Additional fuel would be required to decelerate the Beagle 2 out of polar orbit
Obviously since the Beagle was a late 100 kg addition, the idea of adding additional fuel is impossible due to the weight constraints. You can always wait for additional information before you attempt to land your spacecraft, but by then it might be year 3000 and the argument would be over whether the new 1 mm resolution camera is accurate enough to land a spacecraft.
You said: "3) Fusion by-products. Enriched uranium and it's ilk are not found in nature"
Hate to nitpick, but you are probably confused when you talk about fusion. Let me clear this up:
Current technologies for fusion have not gotten to the 'break even' point so they are not in use for power generation and not in use except very localized research centers. Of the products produced, the most common are He-3, H-3 (tritium), He-4, H, and neutrons. This is because normally the reactants are either H-1, H-2 (deuterium), or H-3 (tritum). Of the products and reactants, He-3 and H-3 are not naturally occurring. H-3 is also radioactive but it has a reasonably short half-life, so it really isn't a worry about long term contamination of the earth. Additionally any neutron flux in the reactor can activate metals in the reactor complex.
So as far as fusion technology is concerned, only the activated metals in the reactor complex are of a concern. In reality this material will not be the 'high-level' waste that people always worry about. While it is radioactive, it is really nothing compared to fission products.
If you were confused and talking about fission technologies, it becomes much more interesting. The fission products in a nuclear fission are statistically determined and since the proportion of neutrons to protons for stable nuclei is nonlinear, the fission products are likely to be radioactive (and typically takes many individual decays to reach a stable point). Whenever someone is talking about high-level waste, this is what they are talking about. In addition to the fission products, portions of the reactor complex can become activated by neutrons just like a fusion reactor.
When you talk about radioactive material being able to contaminate the earth you are talking about the fission products. But the secret of nuclear power is that you can do so much with so little. The expended fuel from a fission reactor is really a very small amount and when people talk about nuclear waste, they don't always clarify the difference between high and low level waste. For this reason, it many times appears that there is this huge volume of high-level waste (as this is typically implied when no description of the types of waste is given) when the vast vast majority is low level waste that will have little environmental affect. Taking into account that a fission reaction is at least 40 million times more powerful than the chemical reactions that produce eletricity at coal and gas plants, the waste will be that fraction smaller.
But here's the biggest secret of nuclear power: the earth naturally produces more fission products than all the nuclear reactors in the world. The fact of the matter is that the average temperature of the earth is and has been about 800 degrees C for 4 billion years and this can't be accounted for by solar radiation. What can account for it is the spontaneous fission of minute amounts of uranium spread throughout the earth. Additionally a natural nuclear reactor was found in Africa. The earth isn't as clean from fission products as you may suspect.
You said " APC 1000VA UPS, I just bought, for $150. A friend of mine bought the same one after a rebate was announced, dropping it to $99. With the 4 of those you could buy from my area, at the price you'd pay in your area, you could have power for the entire day (provided you can keep the batteries charged).
The batteries are hot-swappable, too, so you could keep a UPS near your generator for charging purposes."
1000 VA only refers to the power output of the inverter attached to the battery for the UPS, i.e. 120Vac, 8.3 A. I should have been more clear when I was describing it, but there can be several 1000 VA UPS' that only differ in their discharge time. So the 1000VA UPS you bought probably won't give 1KW of power for 20 minutes if it only cost $150.
You said "Err, carr batteries are designed for short heavy loads"
Being a person who has worked with many lead acid batteries, I have to disagree with you. A lead acid battery is at its most efficient when the load is the least. Under very heavy loads a lead acid battery will generate high heat and release alot of hydrogen. The only components that are really suited for short heavy loads are capacitors and inductors. The reason that you can use your car battery to start your car without damaging it is because the duration of the high load is very short.
I agree that lead acid batteries can become damaged if they are discharged to depletion, but if you only discharge about half the capacity of the battery (and then fully recharge it), it should run for a very long time before replacement is necessary.
You said "Another option is get a UPS for your desktop. You can run the machine off of that when the power goes out, night, etc. and they are relatively cheap...if you get a 4 hour one... and can power other devices. The laptop and the UPC will trickle charge while juice is flowing, so you can be pretty sure that when the sun does set, you won't miss a beat with your tech."
Considering a 1000 VA UPS costs about $600 in my area and is only rated to operate for about 20 minutes, a 50W laptop would probably only operate for about 6 or so hours on it. For $200 you could buy a car battery (50 A-hrs at 12V), a battery charger, and a 100W inverter and operate for over 10 hours. Or a cheaper solution that I use is to get an emergency jump start kit (mine is 18 A-hr at 12V), and a cheap inverter. For less than $100 I have an extra 5 hrs of laptop time.
You also said: "Now... how exactly are you going to get on the net? Satellite? Pigeon?"
Fortunately, RFC 2549 exists for just this problem.
You said: " it's seems pretty probable to me that this might be of artificial origin, accidentally or intentionally
with the massive amounts of research we have going on right now with the virii (using them to fight cancer; finding cure for AIDS; studying influenza; sequencing virii's DNA) it's possible that we might have artificially produced SARS or have abused a population of some virus to the point that the population experienced a high mutation rate (e.g. if we tagged them with radiation-produced molecules, which is common practice for studying their spread in an animal)"
This is unlikely, since the SARS-CoV is not more closely related to any known type of coronavirus than any other. If it were a modified virus it should be very similar to a known class of coronavirus.
You said: "France, Russia, China, the USA, and Germany have all provided military equipment to Iraq. The USA has additionally outfitted Iran and several neighbours. The Russians, Germans, and French are owed money largely for infrastructure, electrical generators, sanitation equipment, and the like. But get this straight - no one is innocent in this, and the USA is certainly, far and away, the worst offender."
FUD! Lets get some numbers down. According to SIPRI USSR, France, China, and Czechoslovakia were the largest traders of conventional arms during the period you describe. In fact a nice table summarizes this and shows that the US contributed to about 1% of the arms trade to Iraq from 1973-1990. Looks like the certainly, far and away, worst offender is the USSR.
You said " That is totally crazy - metric is way easier.
We have ten fingers. We count in tens. We don't count in 12s or 14s or 16s.
Imperial units are not even standardized properly. An inch is different depending on where you are in the world..."
We probably count to ten and use the decimal system more because the Pythagoreans thought of the number 10 as a holy number than because of the number of fingers. The Pythagoreans other future Greek mathematicians had a profound affect on number theory. Multiple base systems were being tossed around at the time of the Pythagoreans including base 4, base 8 (i.e. nine which is novem in latin may be related to novus meaning new), base 10, and base 60, but only base 10 really survived in the Western world (though parts of the others were incorporated like 6 * 60 degrees in a circle and 60 seconds in a minute).
In my opinion any future scientific number system should be in hexadecimal. The reason is that future scientific applications will rely more heavily on computers, and while no base is inherently better than another, hexadecimal does make computers happy (like is 2.0E43 == 2E43? Do I need to make some sort of ranged comparison? Not if the base is in hexadecimal!).
You said: "a vacuum is still a great insulator. (that's why my coffee mug here has a vacuum between the inner and outer shells :)"
There are 3 types of heat transfer: conduction, convection, and radiation. Your thermos-like cup (technically a Dewar flask) effectively prevents conduction and convection, but that does not mean there is no heat transfer. Any object will radiate (with EM waves) away heat according to Stefan's Law. It will also absorb radiation according to Stefan's Law. As I described in another post, the lower the emissivity, the lower the rate at which radiation is absorbed or recieved. What this means is that your thermos-like cup will have silvered walls on the inside of the vacuum chamber to reduce the amount of heat radiated or absorbed.
You said: "Do you have any idea how fast heat radiation will cool an object in space?"
Stefan's Law states: P = (sigma) * AeT^4, where P is the power radiated, (sigma) = 5.6696 * 10^-8 W/(m^2 * K^4), A is the surface area, e is the emissivity, and T is the temperature (in Kelvin). The emissivity can vary from 0 to 1 depending on the properties of the surface. An ideal absorber, which is also an ideal radiator, has an emissivity of 1 and is known as a black body. So, since an object can both radiate and absorb, its net power is P-net = (sigma) *Ae (T^4 - T-0 ^4) where T-0 is the temperature of the surroundings.
What this means is that your turkey is always going to be radiating a certain value depending on its temperature, but depending on where that turkey is (in the shade behind the spacecraft or in front of the spacecraft receiving radiation from the sun) it may cool down or heat up (if the suns radiation is enough to overcome the heat radiated away). If the turkey stays in one place it will come to equilibrium because eventually the radiation absorbed and radiation emitted will equal out whether or not it heated up or cooled down.
On one side note though, in the case where a turkey is in the radiation stream from the sun, because the radiation from the sun comes from only one direction, one side of the turkey would be much hotter than the other.
Not hard to find, your car (if you have one) is probably about 100 KWt. Not that that is very useful in space, but 25 KW is still a pretty tiny amount of power generated (down here on Earth). Unfortunately in modern spacecraft, 5 KWe is a large amount of power.