Insulting people is ALWAYS a good way to show how smart you are.
Stop insulting my intelligence with fallacious or ignorant objections and you won't have your nose rubbed in them. If you don't have complete confidence in your knowledge, qualify your statements appropriately.
I said it would take a lot of engines...
Or unless you plan on using those Shuttle engines in some other launcher.
Let's see, I recall saying this (and you quoted me):
1 launch window every 2 years, 2 vehicles per launch window, 4 engines per vehicle = 4 engines per year.
A Shuttle orbiter has three SSME's, not four. It should have been obvious to you that I was not talking about launching Shuttle Orbiters to Mars, I was talking about putting SSME's under a variant Shuttle stack with no Orbiter at all.
the R&D on a new launcher large enough to hoist those Mars payloads into orbit / off to Mars could eat up $10 billion or more.
How about you provide some figures to support that $1e10 claim? Besides, that's only 2/3 of 1 year's NASA budget, hardly a big deal over an 8-10 year program.
Otherwise, you have to eat the cost of 4 Shuttle engines with every launch. How many flights will this adventure take?
1 launch window every 2 years, 2 vehicles per launch window.... That's 4 engines per year for as long as you run the exploration program with that vehicle. If you assume $500 million per launch, you are talking about half of what a Shuttle costs to launch and your net cost is a small fraction of Shuttle's because you are only launching at a rate of 2 vehicles every 2 years. The Mars program a la Mars Direct would be much cheaper than the Shuttle program.
Wait a minute. You're telling us that this Martian contraption to manufacture hydrogen and oxygen and liquid water and everything else the astronauts are gonna need once they get to Mars is only gonna weigh 50 tons? An Apollo spacecraft at departure from earth orbit only weighed about 45 tons, and most of that weight was fuel.
You just answered your own question, you just don't realize it yet. How much would Apollo have had to weigh if it could get rid of 94.5% of its fuel, and only carry some hydrogen? Oxygen and carbon are available in vast quantities from the Martian atmosphere. It may be possible to harvest some water or ice, but that is a chancy thing to base the first missions on; carrying the hydrogen assures the supply. Ergo, you ship the hydrogen from Earth and gather the carbon and oxygen when you get there.
If you burn a stoichometric mixture of methane and oxygen, your mass-balance looks like this:
CH4 + 2 O2 -> CO2 + 2 H2O
This is 4 AMU of hydrogen, 12 AMU of carbon and 64 AMU of oxygen for a total of 80 AMU; the hydrogen is only 1/20 of the total. If you assume a slightly methane-rich mix instead, you might wind up with 18:1 [1]. If Apollo lofted 40 tons of fuel and 5 tons of actual hardware, and you could convert that to 5 tons of fuel and 40 tons of hardware, just what do you think you could have done instead? Now figure 21st century electronics and other engineering.
Now you want to transport tons of liquid hydrogen to Mars and land it all safely. So scrap the bulldozer, but add on probably ten times as much weight in LH2.
If I put 50 tons on a TMI trajectory, I'd probably put 45-48 tons on Mars. If I only need 5 tons of vehicle to get me home, my Mars-escape vehicle's mass-ratio is 6 (wild-assed guess) and I have an 18:1 multiplier, I only need 1.39 tons of hydrogen (25 tons fuel&oxygen/18). This is a rather small fraction of my total mission mass. I do not have numbers for the delta-V to go from Mars surface to Earth transfer orbit ready to hand, or I'd use them.
On top of that, you have not done your homework. On anything. Your post is so ignorant, you ought to do something really drastic to expiate your shame. I would suggest learning to study, and not posting on any subject that you have not studied.
None of the components you listed in your message do us much good for a manned Mars exploration program. Take the Shuttle engines you list as one component. Only they aren't. They're needed in the (remaining) Shuttles. We'd have to build more of them to make a Mars mission possible before the end of the next decade - many, many more of them.
Let's see, 1 launch window every 2 years, 2 vehicles per launch window, 4 engines per vehicle = 4 engines per year. Manufacture of High Pressure Fuel Turbopumps: "Production rate > 1 unit / month since first flight in July 2001 (STS-104)[1]. At the rate of 1 unit per month, you could have enough engines to fly a Shuttle every month and replace engines every 5 flights, send 4 vehicles to Mars every launch window instead of 2, and have about 3 brand-spanking new engines left over.
It would take several launches just to get the gadgets to Mars to make liquid water and oxygen and hydrogen and everything else for the astronauts to use once they finally arrived.
It would take one launch, carrying about 50 tons on a trans-Mars orbit.[2] The Shuttle orbiter weighs about 100 tons fully loaded; its engines are around 10 tons, leaving 90 tons for vehicle, payload and trans-Mars injection fuel. The required delta-V to get from LEO to TMI is roughly 4.3 km/sec. [3] Vacuum-specific impulse of an SSME is 452 seconds [4], or exhaust velocity of 4430 m/sec; the required TMI mass-ratio is 2.64 by the rocket equation. If you retained one SSME (modified to be restartable in flight) for the trans-Mars injection, you would need to start with ~53 tons * 2.64, or roughly 140 tons. This appears to be well within the capacity of a vehicle using 4 SSMEs and 3 SRBs to put into LEO.
Then there are the cargo / habitat landers, which also cannot fail.
Yes they can. You send them first, perhaps several of them, one launch window before you send people. If they don't land and work correctly, you hold the manned mission off for another launch window. If you send 3 and only 1 of them lands and works, you have one usable landing site; if 2 or 3 of them land and work, you have your choice of options. You can use the unused landers later, or for supply depots for long surveys.
In-situ propellant production may have been demonstrated in the lab here on earth, but we don't know yet if it would even work on Mars. Right now we're having trouble getting simple robot rovers to function correctly, at $400 million a pop.
You have some serious misconceptions about price tags here. The cost is almost entirely for research, development and engineering; manufacturing is a drop in the bucket. You could probably crank out rovers for a few million apiece now that we have the design.
A small chemical plant is much, much simpler than a rover. The biggest issue might be filtering dust to keep it out of the machinery, and you would have a lot of trouble claiming that we don't have any applicable experience with filters.
What you're proposing is that we drop a small chemical factory on Mars, along with an automated tractor and bulldozer to haul it icy rock for processing.
No, that's your proposal. I'm proposing Zubrin's scheme of carrying LH2 to the site and processing it into methane and LOX via the reactions
You show signs of a proper indoctrination into the Politically Correct mode of thinking (Politically Correct being a euphemism for bullshit). I'm going to try to shake you up a bit (this may hurt if the positions are dear to you).
Labour, clever people and energy are some of the limited resources that are consumed by such an endeavour. Consider if these could be used in a better way, such as to invent a way to de-pollute the atmosphere, replenish the ozone layer, or figure out how to stop people from starving to death.
It is easy to refute every assertion you made (and yes I love lists):
Smart people tend to enter career paths which capture their imaginations. Do you want them to go into science and technology which expands human capability, or into zero-sum career paths like law and politics which mainly restrict and redistribute the products of others? There was a huge surge in interest in the hard sciences in the USA during the heyday of the space program, whereas interest now goes toward law and business schools (not the kind of creativity that solves the issues you hold forth as problems).
Look around you. Are you blind? Have you failed to notice that one of the complaints on Slashdot is that creative jobs are hard to find, and creative technical people are unemployed? There are millions of sharp people entering the technical labor force in places like China and India. When companies are chasing lower wages by opening new supplies, it makes excellent sense to add a bit to the demand and stop wasting that talent in unemployment lines.
Finally, it's ridiculous to think that smart people are "consumed" in such pursuits. Everything they produce has multiple uses, and one of the most easily multiplied is hope. If people believe that any technical problem can be solved, and many more of them have the education and expertise to do it, you're not going to convince many serious thinkers that the problem becomes harder rather than easier to attack. (People who are mindlessly repeating the position adopted by their political in-group, or who find it harder to break ranks with their friends than to follow reason, will not be convinced regardless. I suspect you are in this group.)
The energy use is trivial. Take one supertanker's worth of oil, multiply by the number which fill and sail per day just from the Middle East, and compare against the fuel requirements to launch 2 year's worth of a Mars exploration program. If you think there is any significance to the latter compared to the former, you are smoking crack. Or perhaps you are just innumerate.
Do you seriously think that we'd learn nothing about de-polluting an atmosphere by having to maintain one that's mission-critical?
The ozone layer is a solved problem. Note that the key to the solution was in the hands of the scientists who asked the questions about where all the chlorine in those refrigerants and aerosol propellants was going, and the engineers who designed systems to use different refrigerants. You write like a Brit; you owe the fact that you can buy a refrigerator chilled by isobutane (no halogens at all) to those scientists and engineers.
Last, people don't starve to death because of a lack of food production, people starve because of belligerent or political interference with their production and supplies. If you wanted to end starvation in Zimbabwe, you would do it much more quickly and permanently by sending a military force to capture or kill Robert Mugabe and his cronies than by sending shiploads of corn.
I suspect that you find much of this out-of-the-box thinking to be heretical, especially that last. That would say a lot about you.
I think there are cheaper ways to reduce crime than send people to Mars. One such way is to teach them properly in school so that they are motivated to better themselves.
How do you motivate them? People are motivated by images and ideas; m
Just to play a devil's advocate: what business do we have throwing our limited resources to other planets when we have so many problems already down here?
I am not a philosopher, but I've got these proposed responses:
Throwing resources? What's a few tons of aluminum to the Earth? All the money stays right here.
We are not throwing resources, we are exercising imagination and initiative. These are not limited resources, they are amplified by being used... and they are the same things needed to solve problems on earth.
"When there is no vision, the people perish." Giving people a reason to look up from their petty squabbles to see a possible future on another world might solve some of those problems. Crime fell drastically during the first Moon landings, because most everyone was glued to the story unfolding on live television. We should try to do this again.
Shouldn't we consider it a general religious imperative to learn what we can about where we came from and what else there is, starting with the history of other planets (including the life on them, if any)?
That's hardly an exhaustive list, and it won't convince anybody who doesn't want to be convinced. But something along those lines might persuade even the moralists that they don't have the high ground all to themselves.
If we had to develop something really new and different to do this, it might take the 8 years that Apollo required to put people on the Moon. But look at what we've got on the shelf already:
Very high-performance hydrogen-oxygen rocket motors, courtesy of the Space Shuttle program.
Two different final descent and landing systems:
Rocket-assisted, descended via the Surveyor (Luna) and Viking (Mars) landers.
Airbag, descended from the Mars Pathfinder system.
(I note that Cameron's proposal is to use both, with the crew landing via rocket and cargo bouncing down inside inflated habs.)
In-situ propellant production has already been demonstrated using simulated Mars inputs.
We've had most of the other necessary re-entry heat shield, space suit, rover and other technology since Apollo, and the rest (mostly space suits and bigger rovers) are either relatively straightforward or outgrowths of things like the Shuttle EVA suit.
The technology is ready for us. The problem is that we are fearful and refuse to take the idea seriously enough to put real effort into it. This is largely due to people (like the idiot BBC commentator this morning) who see Mars as a sideshow or even an immoral waste of resources. Their goals are served by pushing any real mission ever-further into the future, so that it never gets done. If you really DO want it done, you have to get to Mars before the political will to do it has been sapped by the obstructionists. This means that you cannot get to Mars in 20 years, you only have a hope of doing it if you do it in 10 or even 8.
... because the engineer knows that we're already doing these things on the sort of scale we'd need, and how to do more or less of it. The scientist is the guy who has to find out how much needs to be done, and put the error bars on it.
Suppose you spread ajust a wee bit too much soot. how would you know and how would you undo it?
You'd know because too much ice melted too fast, and you'd spread less next year. The soot washes off with the meltwater and is removed from the equation every spring, so you have to make new soot every year.
You're comparing a chaotic system (the weather) with what appears to be a reasonably stable system, albeit with oscillations like El Nino (the climate). Climate is the "average" of weather, so the fact that you cannot predict exactly when the next warm front is going to dump a bunch of freezing rain on you does not mean that you can't project when the ground is going to be up to planting temperature or when your first killing frost will be. The former is an issue for daily conversation, the latter is of vital importance to agriculture in the temperate zone.
The thesis is that to have an ice age you need increaced moisture transport to the polls. with out this it could get cold but it would be dry and no ice age. Once enough ice accumulates the reflectivity of the earth shifts and global warming becomes global cooling. this last for ~90,000 years.
If that thesis is correct, it appears to be a simple matter to over-ride the trend and force the ice back: put soot on the ice. Maybe campfires have been keeping the ice at bay for the past few thousand years; wouldn't that be something?
during this time glaciers grind rocks up and create mineral rich soils. When trees return they thrive on this till the nutirents run low which takes about 10,000 years. then plant death starts the cycle.
For the past several centuries, humans have been taking direct control of the cycling of nutrients. (Yes, large parts of Nauru
look like a moonscape because of this control... or hadn't you heard?) If a dearth of nutrients is the trigger, then engineering can put on the safety.
Funny, I thought the classic example of a person of negotiable virtue was an un-named Brit in this apocryphal exchange:
Winston Churchill: Madam, would you sleep with me for a million pounds?
Unnamed Woman: Certainly!
WC: Madam, would you sleep with me for a hundred pounds?
UW: Of course not! What kind of woman do you take me for?
WC: We've already settled that, we're just negotiating the price.
Apocrypha and stereotypes aside, there are people of principle and whores in probably every society on Earth bigger than a small town. Also, people tend to see others as they see themselves.
If the area is dry, there is nothing to keep the CO2 from just seeping up through the soil.
If the area is wet, there is nothing to keep the CO2 from dissolving in the groundwater and percolating to a place where it can seep up through the soil, seep into springs or streams where it can bubble off, etc.
That said, I've read that there have been enough experiments with the pumping of "sour gas" (containing H2S) into deep disposal without any obvious leaks (and they WOULD be obvious) that we can be certain that many of these things would work as proposed.
Unfortunately, your link does not take one to the entire article.
I recall that one such iron-seeding experiment was done in the tropics. One would almost expect the results to be different in the arctic, because cold arctic waters are where the coldest deep-ocean water is formed. If that water is sinking, it seems likely that it would tend to take dead algae with it. (On the other hand, the fact that many Antarctic waters are relatively fertile suggests that there are upwelling currents there which account for the productivity. Perhaps the area being seeded is a downwelling zone... this is not detailed in the article either.)
The word does not derive from "photo", for light, but phyein, to bring forth via its derivative "phyton". Phytoplankton are the self-feeders, the "autotrophs"; everything else is an other-feeder, or heterotroph.
... exhausted oil and gas wells and other deep aquifers. These have the known geological stability to be able to hold gases for aeons, and a great many of them have pipes running into them already.
The previous responder's link identifies "abandoned mine shafts" as one of the several possibilities, but I suppose those mines would have to be very deep and have few fractures, else the CO2 would leak right out again.
FWIW, one of the advantages of using "spent" oil wells is that you can't recover all of the oil just by pumping. CO2 is a nice non-polar solvent and it dissolves the remaining oil stuck in the pores of the rock, so you can circulate it and boil off the CO2 from the stuff you bring back up, leaving oil as the bottoms. This might not be economical to do for its own sake, but if you are already paying for the CO2 disposal the oil recovery would be icing on the cake.
Maybe not even skilled trades will help you, depending. For instance, Austin TX was chock-full of "undocumented" day-laborers a few years back, and anyone who expected to be paid over the table, be eligible for workman's comp, Social Security credits etc. was SOL. Just because something can't be exported to cheap labor doesn't mean that the cheap labor can't be imported.
You are modded +1 interesting for proposing to torture convicts ?
You'll have to ask the moderator about the choice. It was (mostly) a joke.
My father spent 5 years in a Goulag for writing poetry
If your father wrote poetry about penis enlargers and horny teenage sluts and spammed millions of mailboxes with them, he would have deserved it. I will say that I have not encountered any spam that I would call poetic, so apparently your father has not fallen in with such bad company.
For instance: it wouldn't be an appropriate punishment to take a pusher of Viagra and stick him in prison if e.g. he were gay, though males who peddle breast-enlargement devices belong there.
The sellers of compounds containing Ephedra or related herbs would probably be killed if they took enough. Sounds like a fitting punishment to me!
Last, the people who hijack other people's computers for use as either spam relays or HTTP proxies for spam sites ought to have to perform technical support to clean up those problems, 12 hours a day 6 days a week, for no pay.
Do you understand what "going critical" is? Very specifically, it's a build up of heat from a "melt-down".
"Positive, adj.: Wrong at the top of one's voice."
That's you all right. "Critical" in the nuclear sense is the state of being able to sustain a chain reaction. Every nuclear powerplant on earth is "critical" while it's running, and none of them have melted down in the last 20 years or so.
Just so you don't say anything else stupid, "critical point" means something completely different when you're talking about phase diagrams.
And I hope the nitwits who modded you up to 5 get meta-modded into oblivion. Moderators, a hint: If you don't know how to evaluate the truth of a claim, you cannot properly moderate it as "informative".
Yes, the rover is operating outside the jurisdiction of the FCC (though not outside of international treaties regulating interference between space probes). Yes, the rover can use as much bandwidth "as it wants". But how much is that?
The answer is, not much. The problem is that you're trying to get a tiny signal across a very large distance back to Earth, and even though Earth is listening with dishes up to 70 meters across you still have serious limits. That squeak of signal coming in has to compete against the rush of thermal noise coming from everything, including the receiver itself. (The first stages of the receivers are cryogenically cooled to reduce thermal noise.) The amount of noise you have to listen to is more or less proportional to the width of the channel you're demodulating (the noise power spectrum varies with frequency, but it's a thermal curve that varies slowly across small frequency ranges). The more bandwidth you use, the wider your receiver filters have to be set, and the more noise comes in with your signal. Once you get to -1.7 dB signal/noise ratio, in principle your ability to tell signal from noise disappears (in practice we don't use encodings which give such a sharp cutoff, so your error rate starts heading up well above that).
Using more bandwidth is pointless unless you have more power to push a signal. On a platform as power-limited as Spirit, ten KHz or so is about all that they appear to be able to use productively over the interplanetary link.
The best "patch" antenna on that page has 14 dB of gain over isotropic (which almost nobody bothers to make because isotropic antennas are not generally useful on Earth; a much more realistic assessment is gain over a dipole). That same page lists 24 dB "grid" (non-solid parabolic reflector) and 20 dB "panel" (apparently flat-panel phased array) antennas.
Energy is conserved; you are not going to get a stronger signal across one part of the sphere without taking signal away from some other part. Beam width is always traded off against gain. Indeed, beamwidth is a pretty good function of gain.
Claimer: I am an electrical engineer, I have studied wave mechanics, and I have seen devices like this antenna built into devices such as aircraft weather radars.
The rover antenna appears to be an example of a flat-plate phased array antenna, which is a generalization of the "slot antenna". The basics are that you have a feedpoint where energy is coupled to/from a cable which goes to your transceiver. This feedpoint is coupled, either through transmission line divider/combiner networks of the appropriate impedance or the equivalent in waveguides, to each individual radiating element. In this case the radiating elements are segments of the surface of the disc, which happen to be connected electrically (which is not of great consequence). So long as each slot is at least a half-wavelength long, applying an RF voltage across its center lets it radiate just like a dipole perpendicular to the slot. Connecting a large number of slots via feedlines or waveguides so that they are all driven in phase gives you a nice, flat wavefront, which is also what you get from the reflection of a spherical wave off a parabola. The details differ, the result is more or less the same.
None of this would have been strange to a techno-geek of fifty years ago, because geeks of that time were into ham radio instead of computers.
As soon as you start blocking AOL and Earthlink's IP blocks because of the high volume of spam you get from them...
If AOL and Earthlink implement SPF correctly, and also throttle outgoing mail to prevent use by spammers (say, 1 message per minute), wouldn't that effectively make them useless to spammers without affecting grandma in the least?
First, there's no real magic here; the news release says that the transistor is "made from indium gallium phosphide and gallium arsenide."
What this means is that someone has taken the same materials which emit light as part of a single-junction device (a diode) and have also made them do so as part of a bi-junction device. While this looks like it might be a good way to integrate light emission with the control circuitry, it's not going to do anything to make them easier to integrate into large devices (silicon works for this because its oxide, SiO2, is a pretty good insulator while gallium doesn't do anything so convenient).
I will admit that it's clever, and someone may find some unobvious way of turning it into a useful device (massively parallel optical interconnects?), but there's just no way that this is going to be slapped onto the next Intel or AMD die. It especially will not replace aluminum or copper interconnects between parts of one processor.
Uh-huh. What evidence do you have that this occurs at a significant rate, let alone one fast enough to offset greenhouse warming? How much energy would it take, and where would you get it?
We can trap some of the heat beneath the surface. The earth naturally draws heat out of the atmosphere and absorbs it below the surface.
The Earth emits heat on average. Pumping atmospheric heat into the crust (a reversal of geothermal energy) would require a large source of energy to power the heat pumps. Where would you get it?
There are certain gasses that naturally reflect sunlight away from out planet.
You mean, like sulfuric acid aerosols? How much would you need, where would you get them, how much energy would it require and where would you get that, and what other unwelcome effects (such as acid rain and reduction in biological productivity due to reduced sunlight) would you produce?
We can convert some of the heat into energy stored in molecular bonds. There are chemical reactions that result in a lowering of the temperature of the medium the reaction occured in. Bonus points if the chemical reaction involves remove greenhouse gasses from the atmosphere and deposits it safely on the earth's surface.
You really need to study chemical equilibria, because it's painfully obvious that you have no understanding of Gibbs Free Energy. A hint: if it were feasible to convert heat energy at ambient temperature to chemical energy, just about every living thing on Earth would be doing it. The forces of entropy inexorably push things the other way.
Seems logical, but the problem is that the atmosphere has so much CO2 in it that it is already mostly opaque to outgoing longwave radiation. Adding more CO2 doesn't make it much more opaque.
From sea level, maybe. But the atmosphere thins on a more or less exponential curve as altitude increases, and the transparency of the air above it along with it. If you consider the "surface" of the Sun, what you're seeing is the layer where the transfer of energy by radiation suddenly becomes quicker than transfer by convection; the overlying corona is so thin as to be essentially transparent. It's the same with Earth's atmosphere.
Below the "radiating layer" heat transfers largely by convection, and temperature usually follows an approximately linear lapse rate with altitude. If you increase the infrared opacity of the atmosphere you don't change the temperature of the radiating layer much, but you increase the depth over which the lapse rate applies and thus the temperature at the surface.
The theory also assumes the amount of CO2 in the atmosphere will increase exponentially. Can we really predict how much CO2 will be put into the atmosphere 40 years from now? What happens as oil becomes more and more expensive? Will things like nuclear power be much more in use?
There have been some reductions in CO2 emission in places like Russia, but they've been associated with unwelome trends like economic collapse. I think we can agree that this is a Bad Thing. I believe that oil and nuclear are largely irrelevant to the question of CO2 emission potential; coal is abundant in the US, Australia, China and India, and we're unlikely to promote nuclear power for "developing nations" ever again. The only thing that is likely to help with the issue is a shift in technologies to ones which do not put CO2 into the atmosphere (either by not producing it or by sequestering it), and the trend right now is strongly in the other direction.
And what about Kyoto? Well, even it's supporters agree that it will delay warming by a modest 6 years or so.
Yet another reason why the inability to negotiate and agree to such a modest measure bodes ill for the future. If we need a 70% reduction and can't even agree to a 10% reduction, we're in pretty sad shape.
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Stop insulting my intelligence with fallacious or ignorant objections and you won't have your nose rubbed in them. If you don't have complete confidence in your knowledge, qualify your statements appropriately.
Let's see, I recall saying this (and you quoted me):
1 launch window every 2 years, 2 vehicles per launch window, 4 engines per vehicle = 4 engines per year.
A Shuttle orbiter has three SSME's, not four. It should have been obvious to you that I was not talking about launching Shuttle Orbiters to Mars, I was talking about putting SSME's under a variant Shuttle stack with no Orbiter at all.
How about you provide some figures to support that $1e10 claim? Besides, that's only 2/3 of 1 year's NASA budget, hardly a big deal over an 8-10 year program.
1 launch window every 2 years, 2 vehicles per launch window.... That's 4 engines per year for as long as you run the exploration program with that vehicle. If you assume $500 million per launch, you are talking about half of what a Shuttle costs to launch and your net cost is a small fraction of Shuttle's because you are only launching at a rate of 2 vehicles every 2 years. The Mars program a la Mars Direct would be much cheaper than the Shuttle program.
You just answered your own question, you just don't realize it yet. How much would Apollo have had to weigh if it could get rid of 94.5% of its fuel, and only carry some hydrogen? Oxygen and carbon are available in vast quantities from the Martian atmosphere. It may be possible to harvest some water or ice, but that is a chancy thing to base the first missions on; carrying the hydrogen assures the supply. Ergo, you ship the hydrogen from Earth and gather the carbon and oxygen when you get there.
If you burn a stoichometric mixture of methane and oxygen, your mass-balance looks like this:
This is 4 AMU of hydrogen, 12 AMU of carbon and 64 AMU of oxygen for a total of 80 AMU; the hydrogen is only 1/20 of the total. If you assume a slightly methane-rich mix instead, you might wind up with 18:1 [1]. If Apollo lofted 40 tons of fuel and 5 tons of actual hardware, and you could convert that to 5 tons of fuel and 40 tons of hardware, just what do you think you could have done instead? Now figure 21st century electronics and other engineering.
If I put 50 tons on a TMI trajectory, I'd probably put 45-48 tons on Mars. If I only need 5 tons of vehicle to get me home, my Mars-escape vehicle's mass-ratio is 6 (wild-assed guess) and I have an 18:1 multiplier, I only need 1.39 tons of hydrogen (25 tons fuel&oxygen/18). This is a rather small fraction of my total mission mass. I do not have numbers for the delta-V to go from Mars surface to Earth transfer orbit ready to hand, or I'd use them.
Let's see, 1 launch window every 2 years, 2 vehicles per launch window, 4 engines per vehicle = 4 engines per year. Manufacture of High Pressure Fuel Turbopumps: "Production rate > 1 unit / month since first flight in July 2001 (STS-104)[1]. At the rate of 1 unit per month, you could have enough engines to fly a Shuttle every month and replace engines every 5 flights, send 4 vehicles to Mars every launch window instead of 2, and have about 3 brand-spanking new engines left over.
It would take one launch, carrying about 50 tons on a trans-Mars orbit.[2] The Shuttle orbiter weighs about 100 tons fully loaded; its engines are around 10 tons, leaving 90 tons for vehicle, payload and trans-Mars injection fuel. The required delta-V to get from LEO to TMI is roughly 4.3 km/sec. [3] Vacuum-specific impulse of an SSME is 452 seconds [4], or exhaust velocity of 4430 m/sec; the required TMI mass-ratio is 2.64 by the rocket equation. If you retained one SSME (modified to be restartable in flight) for the trans-Mars injection, you would need to start with ~53 tons * 2.64, or roughly 140 tons. This appears to be well within the capacity of a vehicle using 4 SSMEs and 3 SRBs to put into LEO.
Yes they can. You send them first, perhaps several of them, one launch window before you send people. If they don't land and work correctly, you hold the manned mission off for another launch window. If you send 3 and only 1 of them lands and works, you have one usable landing site; if 2 or 3 of them land and work, you have your choice of options. You can use the unused landers later, or for supply depots for long surveys.
You have some serious misconceptions about price tags here. The cost is almost entirely for research, development and engineering; manufacturing is a drop in the bucket. You could probably crank out rovers for a few million apiece now that we have the design.
A small chemical plant is much, much simpler than a rover. The biggest issue might be filtering dust to keep it out of the machinery, and you would have a lot of trouble claiming that we don't have any applicable experience with filters.
No, that's your proposal. I'm proposing Zubrin's scheme of carrying LH2 to the site and processing it into methane and LOX via the reactions
Note that the methane-production reaction is e
It is easy to refute every assertion you made (and yes I love lists):
Look around you. Are you blind? Have you failed to notice that one of the complaints on Slashdot is that creative jobs are hard to find, and creative technical people are unemployed? There are millions of sharp people entering the technical labor force in places like China and India. When companies are chasing lower wages by opening new supplies, it makes excellent sense to add a bit to the demand and stop wasting that talent in unemployment lines.
Finally, it's ridiculous to think that smart people are "consumed" in such pursuits. Everything they produce has multiple uses, and one of the most easily multiplied is hope. If people believe that any technical problem can be solved, and many more of them have the education and expertise to do it, you're not going to convince many serious thinkers that the problem becomes harder rather than easier to attack. (People who are mindlessly repeating the position adopted by their political in-group, or who find it harder to break ranks with their friends than to follow reason, will not be convinced regardless. I suspect you are in this group.)
I suspect that you find much of this out-of-the-box thinking to be heretical, especially that last. That would say a lot about you.
How do you motivate them? People are motivated by images and ideas; m
- Throwing resources? What's a few tons of aluminum to the Earth? All the money stays right here.
- We are not throwing resources, we are exercising imagination and initiative. These are not limited resources, they are amplified by being used... and they are the same things needed to solve problems on earth.
- "When there is no vision, the people perish." Giving people a reason to look up from their petty squabbles to see a possible future on another world might solve some of those problems. Crime fell drastically during the first Moon landings, because most everyone was glued to the story unfolding on live television. We should try to do this again.
- Shouldn't we consider it a general religious imperative to learn what we can about where we came from and what else there is, starting with the history of other planets (including the life on them, if any)?
That's hardly an exhaustive list, and it won't convince anybody who doesn't want to be convinced. But something along those lines might persuade even the moralists that they don't have the high ground all to themselves.- Very high-performance hydrogen-oxygen rocket motors, courtesy of the Space Shuttle program.
- Two different final descent and landing systems:
- In-situ propellant production has already been demonstrated using simulated Mars inputs.
- We've had most of the other necessary re-entry heat shield, space suit, rover and other technology since Apollo, and the rest (mostly space suits and bigger rovers) are either relatively straightforward or outgrowths of things like the Shuttle EVA suit.
The technology is ready for us. The problem is that we are fearful and refuse to take the idea seriously enough to put real effort into it. This is largely due to people (like the idiot BBC commentator this morning) who see Mars as a sideshow or even an immoral waste of resources. Their goals are served by pushing any real mission ever-further into the future, so that it never gets done. If you really DO want it done, you have to get to Mars before the political will to do it has been sapped by the obstructionists. This means that you cannot get to Mars in 20 years, you only have a hope of doing it if you do it in 10 or even 8.- Rocket-assisted, descended via the Surveyor (Luna) and Viking (Mars) landers.
- Airbag, descended from the Mars Pathfinder system.
(I note that Cameron's proposal is to use both, with the crew landing via rocket and cargo bouncing down inside inflated habs.)You're comparing a chaotic system (the weather) with what appears to be a reasonably stable system, albeit with oscillations like El Nino (the climate). Climate is the "average" of weather, so the fact that you cannot predict exactly when the next warm front is going to dump a bunch of freezing rain on you does not mean that you can't project when the ground is going to be up to planting temperature or when your first killing frost will be. The former is an issue for daily conversation, the latter is of vital importance to agriculture in the temperate zone.
Winston Churchill: Madam, would you sleep with me for a million pounds?
Unnamed Woman: Certainly!
WC: Madam, would you sleep with me for a hundred pounds?
UW: Of course not! What kind of woman do you take me for?
WC: We've already settled that, we're just negotiating the price.
Apocrypha and stereotypes aside, there are people of principle and whores in probably every society on Earth bigger than a small town. Also, people tend to see others as they see themselves.
- If the area is dry, there is nothing to keep the CO2 from just seeping up through the soil.
- If the area is wet, there is nothing to keep the CO2 from dissolving in the groundwater and percolating to a place where it can seep up through the soil, seep into springs or streams where it can bubble off, etc.
That said, I've read that there have been enough experiments with the pumping of "sour gas" (containing H2S) into deep disposal without any obvious leaks (and they WOULD be obvious) that we can be certain that many of these things would work as proposed.I recall that one such iron-seeding experiment was done in the tropics. One would almost expect the results to be different in the arctic, because cold arctic waters are where the coldest deep-ocean water is formed. If that water is sinking, it seems likely that it would tend to take dead algae with it. (On the other hand, the fact that many Antarctic waters are relatively fertile suggests that there are upwelling currents there which account for the productivity. Perhaps the area being seeded is a downwelling zone... this is not detailed in the article either.)
Thus endeth the grammar lesson for the day.
The previous responder's link identifies "abandoned mine shafts" as one of the several possibilities, but I suppose those mines would have to be very deep and have few fractures, else the CO2 would leak right out again.
FWIW, one of the advantages of using "spent" oil wells is that you can't recover all of the oil just by pumping. CO2 is a nice non-polar solvent and it dissolves the remaining oil stuck in the pores of the rock, so you can circulate it and boil off the CO2 from the stuff you bring back up, leaving oil as the bottoms. This might not be economical to do for its own sake, but if you are already paying for the CO2 disposal the oil recovery would be icing on the cake.
Maybe not even skilled trades will help you, depending. For instance, Austin TX was chock-full of "undocumented" day-laborers a few years back, and anyone who expected to be paid over the table, be eligible for workman's comp, Social Security credits etc. was SOL. Just because something can't be exported to cheap labor doesn't mean that the cheap labor can't be imported.
They can still spam from wheelchairs; I think you ought to go for the knuckles.
The sellers of compounds containing Ephedra or related herbs would probably be killed if they took enough. Sounds like a fitting punishment to me!
Last, the people who hijack other people's computers for use as either spam relays or HTTP proxies for spam sites ought to have to perform technical support to clean up those problems, 12 hours a day 6 days a week, for no pay.
That's you all right. "Critical" in the nuclear sense is the state of being able to sustain a chain reaction. Every nuclear powerplant on earth is "critical" while it's running, and none of them have melted down in the last 20 years or so.
Just so you don't say anything else stupid, "critical point" means something completely different when you're talking about phase diagrams.
And I hope the nitwits who modded you up to 5 get meta-modded into oblivion. Moderators, a hint: If you don't know how to evaluate the truth of a claim, you cannot properly moderate it as "informative".
Yes, the rover is operating outside the jurisdiction of the FCC (though not outside of international treaties regulating interference between space probes). Yes, the rover can use as much bandwidth "as it wants". But how much is that?
The answer is, not much. The problem is that you're trying to get a tiny signal across a very large distance back to Earth, and even though Earth is listening with dishes up to 70 meters across you still have serious limits. That squeak of signal coming in has to compete against the rush of thermal noise coming from everything, including the receiver itself. (The first stages of the receivers are cryogenically cooled to reduce thermal noise.) The amount of noise you have to listen to is more or less proportional to the width of the channel you're demodulating (the noise power spectrum varies with frequency, but it's a thermal curve that varies slowly across small frequency ranges). The more bandwidth you use, the wider your receiver filters have to be set, and the more noise comes in with your signal. Once you get to -1.7 dB signal/noise ratio, in principle your ability to tell signal from noise disappears (in practice we don't use encodings which give such a sharp cutoff, so your error rate starts heading up well above that).
Using more bandwidth is pointless unless you have more power to push a signal. On a platform as power-limited as Spirit, ten KHz or so is about all that they appear to be able to use productively over the interplanetary link.
Energy is conserved; you are not going to get a stronger signal across one part of the sphere without taking signal away from some other part. Beam width is always traded off against gain. Indeed, beamwidth is a pretty good function of gain.
The rover antenna appears to be an example of a flat-plate phased array antenna, which is a generalization of the "slot antenna". The basics are that you have a feedpoint where energy is coupled to/from a cable which goes to your transceiver. This feedpoint is coupled, either through transmission line divider/combiner networks of the appropriate impedance or the equivalent in waveguides, to each individual radiating element. In this case the radiating elements are segments of the surface of the disc, which happen to be connected electrically (which is not of great consequence). So long as each slot is at least a half-wavelength long, applying an RF voltage across its center lets it radiate just like a dipole perpendicular to the slot. Connecting a large number of slots via feedlines or waveguides so that they are all driven in phase gives you a nice, flat wavefront, which is also what you get from the reflection of a spherical wave off a parabola. The details differ, the result is more or less the same.
None of this would have been strange to a techno-geek of fifty years ago, because geeks of that time were into ham radio instead of computers.
What this means is that someone has taken the same materials which emit light as part of a single-junction device (a diode) and have also made them do so as part of a bi-junction device. While this looks like it might be a good way to integrate light emission with the control circuitry, it's not going to do anything to make them easier to integrate into large devices (silicon works for this because its oxide, SiO2, is a pretty good insulator while gallium doesn't do anything so convenient).
I will admit that it's clever, and someone may find some unobvious way of turning it into a useful device (massively parallel optical interconnects?), but there's just no way that this is going to be slapped onto the next Intel or AMD die. It especially will not replace aluminum or copper interconnects between parts of one processor.
Below the "radiating layer" heat transfers largely by convection, and temperature usually follows an approximately linear lapse rate with altitude. If you increase the infrared opacity of the atmosphere you don't change the temperature of the radiating layer much, but you increase the depth over which the lapse rate applies and thus the temperature at the surface.
There have been some reductions in CO2 emission in places like Russia, but they've been associated with unwelome trends like economic collapse. I think we can agree that this is a Bad Thing. I believe that oil and nuclear are largely irrelevant to the question of CO2 emission potential; coal is abundant in the US, Australia, China and India, and we're unlikely to promote nuclear power for "developing nations" ever again. The only thing that is likely to help with the issue is a shift in technologies to ones which do not put CO2 into the atmosphere (either by not producing it or by sequestering it), and the trend right now is strongly in the other direction. Yet another reason why the inability to negotiate and agree to such a modest measure bodes ill for the future. If we need a 70% reduction and can't even agree to a 10% reduction, we're in pretty sad shape.