One of the biggest myths is that shows like Star Trek are pure "science fiction" in the idea that the show encompasses actual theory or testable idea.
Unfortunately it's far from true. Much of Trek is not science, but actually fantasy magic redressed and given a chrome/plastic packaging. Many people mistake some of the more exotic ideas of quantum physics as bridges to actual engineering. Moreover much of Trek isn't even based on any real theory at all. There is no real theory for a practical warp drive and no engineer worth his salt is going to give you a timeline on a personal ground to orbit to FTL spacecraft that you can park in a somewhat larger version of the family garage. As for the transporter and antimatter carried around about as casually as gasoline plug in 100 kilograms or so into Einstein's E=mc(squared) equation and see how much energy you'd have to fool around with.
Or on a more subtle level, decades of research have yet to get us any closer to a true cybernetic self aware sentience and there is growing field of thought that perhaps it's not the right tree to bark up on when it comes to AI.
While much of SF deserves it's credits for prophecy, it should also be noted on the promises it hasn't delivered on and seems not likely to. Who remembers these Space Age and Atomic Age promises?
1. The 4 day (or less) work week. And remember this was coded during an age which still envisioned only one breadwinner per family.
2. Radio tube trains
3. The elimination of paper work
4. Mass enlightenment of mankind due to increased access to data.
5. Power so cheap you wouldn't have to meter it.
This list is far from exhaustive, but I've made my point. Trek is what much of present science fiction has become, wish fulfillment fantasy.
Obviously you do, since you took the trouble to not only read down to the end of this thread and type your mini-biography on to it.
Maybe you're like most zealots, you feel a need to justify the choices you made by bashing down everyone elses. If your last experience with a Mac was with a black/white Classic, it doesn't say much for the present relevancy of your observations.
We use Macs and PCs at home. The PC's mainly for gaming and the Macs for everything else including my banking. (although I do plan on buying an Intel Mac which I'll use for both and clear up some desk space).
I don't need to justify my Mac use by bashing Windows. Would I recomend a Mac over a Winbox to a diehard PC gamer? No. But I probably would to anyone else, especially if the bulk of their gaming like mine, is World of Warcraft. (although if they're playing WOW,I'd at least recommend a kitted out iMac over a mini). The fact is that for people doing real work. Macs run Office, and at this point in time the OS is a safer vehicle, plain fact.
I remember my Amiga days fondly. In these days the closest thing I find to the Amiga is in OS X. down to it's UNIX core and the explosion of shareware and free applications.
But beyond the Mac and even the iPod, there is the simple fact of Apple's success. It's not just Jobs, it's people like Ives and the uncanny sense of what people want. Sure I'd rather buy CD's and rip them rather than get them off of ITMS, but they have a great knackof getting exclusives, they signed up record companies who were still being gunshy over Napster and they have the episode of Lost! which I missed last night!
Apple succeeds because they've come back to that one core issue that makes or breaks any company. During the early days of the Macintosh, Jobs hung up a sign at Apple that he expected everyone to take to heart.
REAL ARTISTS SHIP.
And that's why Apple is doing as well as they are. Apple's promises may not always overwhelm, but they have value that people can recognise. And they're shipping now.
No. The XServe RAID isn't a variety of XServe it's an external hardware RAID unit, very conventional in function. You could actually use this RAID on any fileserver that you could put a fiber-optic adaptor on it, be it Mac, Intel, SGI, for example. Conversely you could use for example, a ROARKE RAID on an XServe. Like most RAIDS it does not run a computer-type operating system but an embedded OS. The extras on the XRaid are the managment features, and that it does not use SCSI to run it's drives. (I think it's SATA based), and the management software, which you could use whether your XRaid is servicing a Mac server or an SGI box.
As discussed before, Voyager is powered by radioisotope generators which derive power from the heat produced by radioactive decay. It's not a very efficient power source but it is reliable and long term the two neccessities for a mission of this type.
The answer to the second question is that it's an ordinary radio transimitter using the X-band frequency as I recall. The key to our reception is not Voyager's radio but the fact that we have very powerful tranceivers that can both receive it's very weak signal and transmit with enough boost so that Voyager's receiver can pick up commands.
The other real question is whether a fusion reactor could even be made small enough to be used as a drive. It may very well be that the minimum size for a fusion power source could be many times that of it's fission equivalent.
The real thing is that if you want the kind of easy travel you see in Star Trek, you'd need a reactionless drive. Unfortunately we don't even have a theory path that might lead to practical engineering.
It can give us some actual environmental data on the conditions of interstellar space. What will happen once Voyager gets to the point where solar wind and magnetism finally gives way to the interstellar medium.
Lesson 102: Space is not simply an empty vacum. It's an environment of it's own with lots of forces that can come into play. Gravity, magnetic fields, solar and cosmic radiation. For all we know we might find the spacecraft picking up a slight electrical charge which could alter it's course the same way that CRTs work.
That'd be valid if I thought the SPS itself were a good idea. Environmentally it's questionable. Efficiency wise it's the pits. It would be a miracle to get 5 percent transmission efficency from orbit to ground. And beaming all that waste microwave through the atmosphere is bound to have some environmental effect.
If you were to take a dump in my backyard, I'd have you do it in my garden and you'd yield fertilizer. Battries on the other hand yield heavy metal wastes which along with the refuse from electronics are the fastest growing landfill issue of current times.
Even rechargeable batteries have limited lifespans. Hence I wind up generating more battery waste with each battery powered item I buy. So I try to keep them to a minimum.
I think the major problem would be the bloody inefficiency. In a world with shrinking oil supplies and surging energy prices do we need something that would be at beast about 10 percent efficient in transmitting electricity?
I've passed on wireless keyboards and mice mainly because I don't want to generate more battery waste which ranks up there as among the most offensive types of garbage we accumulate.
Again, again, again. Lack of profit has nothing to do with copyright or fair use. or performance. You want to show Lord of the Rings to 300 people and not charge them for it? You still have to pay the same kind of license a movie theater has to shell out. becasue anything beyond the scale of living room viewing goes into distribution, no exceptions, period.
One of the key differences is temperature. If Titan were placed in Earth orbit the situation would be dramatically different, the atmosphere and probably a good deal of Titan itself would evaporate and be blown away. However out by Saturn way, the mean temperature is what we call in the technical sense cold.
Also, Titan's orbit is filled by a toroidal cloud of hydrogen much of what does escape is reabsorbed by the moon itself. Sky and Telescope had a good article about it a decade or two ago.
A bit of Earth's atmosphere blows out into space as well. Apollo 16 brought back some nice UV photos of the Earth's hydrogen corona, caused by splitting of H20 molecules in the upper atmosphere by UV light. The hydrogen is eventually lost to space but not at a rate that we have to worry about losing our oceans soon... at least not to evaporation.
That was about the same orbit as Skylab which came down in about a decade. Of course the period of high solar flare activity during that day did play a role in hastening it's desecent. But neither Hubble , nor the ISS are in long duration orbits. Such long duration orbits are not within the ceiling of the shuttle, nor are they safe for manned stations.
"Like it or not your brain is a meat based computer. If it's not running code, then how are you thinking?"
Maimonedes, a Jewish philospher who did his best work about 12 centuries or so, posed an interesting example about a donkey placed in the exact middle of a line connecting two distant oasises. He propouded that if the donky acted only on pure logic, it would die of thirst having no logical reason to choose one over the other.
The code analogy of the human brain is useful but it hs some inherent differences in addressing the (perhaps literally) quantum gap between technology and actual living systems. A human or any other living animal placed in the Logical Donkey's position would make a choice. Humans in particular are not limited to binary yes/no logic. Yes there have been talk of quantum computers with things like yes/no/maybe states, but it is unclear whether that alone would bridge the distance anytime soon.
Technology can copy many biological prrocesses, The airplane for example can fly like birds. But for a plane like a DC3 to fly a hundred miles as energy efficiently as does a certain hummingbird species which migrates across the Caribbean, it would have to do it on a gallon of fuel.
Quite frankly, I don't believe that choices of for office should be about individuals. They should be about parties, specifically positions that parties represent, issues such as education, defense, environment, foreign affairs etc. When elections become contests about individuals these affairs get pushed aside by meaningless distractions such as the recent CBS "Helveticagate", a tempest about when it comes down to it a really trivial teapot. Bernie Sanders may be one of the greatest guys around, but the present system leaves him nowhere to go and little to acheive.
It is because of the focus on individuals, especially Presidential candidates as some kind of media stars slugging it out in a forum more like a gladitorial arena than serious candidates for public office that the Democrats and Republicans, once parties that couuld be clearly identified by issues have drifted so close together that they've become what Ralph Nader and others have referred to as the "Two Headed Beast".
It leaves them as having a shot at government presently denied by the two party duopoly. Any party that can muster a sufficient number of signatures would be elligible to run. The price is that all parties would need to think on a national level instead of state.
The major flaw in the present system is that it was designed to accomodate as much as possible the original thirteen colonies' desire to be treated as separate republics, (i.e. the original Articles of Confederation) The present Presidential campaign in fact is not as it should be, aimed at the American public at large, it's aimed at a relatively small percentage of states whose electoral votes will theorectically swing the total after counting the states where each party has uncontested domminance.
The present state system is designed to insure the continuance of the present monopolies and destroy the possiblitiy of any real progresss of independent.
No, I'd say the way to fix it is to go the other way. Eliminate state by state voting for Federal Elections and go the parlimentary route, the citizens vote for parties as represented by their local figures. Then tally up the votes, and award seats in Congress to each party proportionate to the total fraction of votes each party earns instead of this "winner take all" nonsense we have today, and let Congress choose the Head of State, i.e. the President. While this plays hob with the original Federalist concept of the three balancing branches of government, the last few years proved that the trinary model if it ever worked in the past, is simply no longer applicable now.
Actually the value of a bowl is in how well it serves as a bowl. It could be ugly and deter from the dish set in which it is a part. It could be microwave safe and therefore allow an increased convience to heat the left over dinner that you put in the fridge last nite. It might withstand accidental droppage. The value is in it's function as well as form.
Watch your definitions, the term FCC approved link has nothing to do with the rights and limitations of a public institution's network access. As a student there are implied and implicit agreements and use of univerisity facilities falls within such.
The First Amendement only reads "Congress shall make no law" it does not prohibit limitations within private or semi-private spheres. You can be tossed out and arrested for making abusive use of your free speech rights in a movie theatre for example.
I would strongly suggest that anyone who intends to make a serious case on First Amendment rights do some real boning up on the legal issues. Check out the writings of some real experts like the late Ed Bloustein, onetime President of Rutgers University, like this http://www.bnet.fordham.edu/public/comm/pnapoli/fi rst.htmpaper he wrote for Fordham Univiersity
Only if this can be construed as a speech rights issue. The university can argue it as an issue of access to a network they own and operate as a public institution. They are within their legal rights to regulate and limit the access to it.
Look up the Thomas Jefferson concept of "inalienable rights". It's used many times to justify a lot of Christian coalistion crap, but the basic premise is that men, being men are endowed with rights that can not be ethically taken or given away. i.e. you can't legally sell yourself or your children into slavery (as was fairly common in Roman days) and that you can not give someone the legal right to maim you. etc.
Libertarian? Like "Liberal" or "Conservative" it's fast becoming little more than a flag to wave, I'd be surprised if more than 10 percent of the folks who go calling themselves "Libertarian" have any real concept of political-social dynamics.
Van Allen rightly points out that analogies put for by space enthuisasts to Columbus, Magellan, Clark et. al. are false. It has not been proven that manned spaceflight of neccessarily limited endurance and high risk can return science on the level of today's sophisticated probes. While the Apollo astronauts returned far more material than the Russian automated landers, the justification of mere bulk is not sufficient to make the argument for science.
The top candidates for an interplanetary expedition would not generally have the scientific credentials of the teams that currently manage the remote missions now. (all but perhaps one of the Apollo lunarnauts was an Air Force test pilot as I recall)
Van Allen from what I've read has not said that manned space travel should be shelved for all time. What he has said and I agree is that many of the present ideas such as Bush's so-called Moon and Mars mission are simply impractical in terms of investment/risk vs. return. These are not the days of Columbus when a Queen could hock her jewels to finance an expedition (which by the way she was rather disappointed in the results "Yes, that's nice but where is the gold?" Nor are those the days of Lewis and Clark where it was just a matter of walking.
The resource mobilisation demanded by space travel means that it simply can not be conducted on the basis of whim. It requires that justification be made for the expense either on the terms of economic return or the advancement of science. What Van Allen has said is that manned space flight at this time has not demonstrated to meet either criteria.
To answer this criticism takes a more indept approach than merely repeating the canard of the so-called limitations of robotic explorers. What you seem to forget is that when we send missions like Cassini we're not just sending sophisticated hunks of transistors and metal. They're the extended arm of teams of scientists, engineers, and planners who continuously show amazing aptitudes with dealing with the unexpected and inventing new unforseen tricks when circumstances demand.
Slashdot Mirror
One of the biggest myths is that shows like Star Trek are pure "science fiction" in the idea that the show encompasses actual theory or testable idea.
Unfortunately it's far from true. Much of Trek is not science, but actually fantasy magic redressed and given a chrome/plastic packaging. Many people mistake some of the more exotic ideas of quantum physics as bridges to actual engineering. Moreover much of Trek isn't even based on any real theory at all. There is no real theory for a practical warp drive and no engineer worth his salt is going to give you a timeline on a personal ground to orbit to FTL spacecraft that you can park in a somewhat larger version of the family garage. As for the transporter and antimatter carried around about as casually as gasoline plug in 100 kilograms or so into Einstein's E=mc(squared) equation and see how much energy you'd have to fool around with.
Or on a more subtle level, decades of research have yet to get us any closer to a true cybernetic self aware sentience and there is growing field of thought that perhaps it's not the right tree to bark up on when it comes to AI.
While much of SF deserves it's credits for prophecy, it should also be noted on the promises it hasn't delivered on and seems not likely to. Who remembers these Space Age and Atomic Age promises?
1. The 4 day (or less) work week. And remember this was coded during an age which still envisioned only one breadwinner per family.
2. Radio tube trains
3. The elimination of paper work
4. Mass enlightenment of mankind due to increased access to data.
5. Power so cheap you wouldn't have to meter it.
This list is far from exhaustive, but I've made my point.
Trek is what much of present science fiction has become, wish fulfillment fantasy.
Or someone who managed to escape the deluge, perhaps?
"Nobody cares" ?
Obviously you do, since you took the trouble to not only read down to the end of this thread and type your mini-biography on to it.
Maybe you're like most zealots, you feel a need to justify the choices you made by bashing down everyone elses. If your last experience with a Mac was with a black/white Classic, it doesn't say much for the present relevancy of your observations.
We use Macs and PCs at home. The PC's mainly for gaming and the Macs for everything else including my banking. (although I do plan on buying an Intel Mac which I'll use for both and clear up some desk space).
I don't need to justify my Mac use by bashing Windows. Would I recomend a Mac over a Winbox to a diehard PC gamer? No. But I probably would to anyone else, especially if the bulk of their gaming like mine, is World of Warcraft. (although if they're playing WOW,I'd at least recommend a kitted out iMac over a mini). The fact is that for people doing real work. Macs run Office, and at this point in time the OS is a safer vehicle, plain fact.
I remember my Amiga days fondly. In these days the closest thing I find to the Amiga is in OS X. down to it's UNIX core and the explosion of shareware and free applications.
But beyond the Mac and even the iPod, there is the simple fact of Apple's success. It's not just Jobs, it's people like Ives and the uncanny sense of what people want. Sure I'd rather buy CD's and rip them rather than get them off of ITMS, but they have a great knackof getting exclusives, they signed up record companies who were still being gunshy over Napster and they have the episode of Lost! which I missed last night!
Apple succeeds because they've come back to that one core issue that makes or breaks any company. During the early days of the Macintosh, Jobs hung up a sign at Apple that he expected everyone to take to heart.
REAL ARTISTS SHIP.
And that's why Apple is doing as well as they are. Apple's promises may not always overwhelm, but they have value that people can recognise. And they're shipping now.
No. The XServe RAID isn't a variety of XServe it's an external hardware RAID unit, very conventional in function. You could actually use this RAID on any fileserver that you could put a fiber-optic adaptor on it, be it Mac, Intel, SGI, for example. Conversely you could use for example, a ROARKE RAID on an XServe. Like most RAIDS it does not run a computer-type operating system but an embedded OS. The extras on the XRaid are the managment features, and that it does not use SCSI to run it's drives. (I think it's SATA based), and the management software, which you could use whether your XRaid is servicing a Mac server or an SGI box.
As discussed before, Voyager is powered by radioisotope generators which derive power from the heat produced by radioactive decay. It's not a very efficient power source but it is reliable and long term the two neccessities for a mission of this type.
The answer to the second question is that it's an ordinary radio transimitter using the X-band frequency as I recall. The key to our reception is not Voyager's radio but the fact that we have very powerful tranceivers that can both receive it's very weak signal and transmit with enough boost so that Voyager's receiver can pick up commands.
The other real question is whether a fusion reactor could even be made small enough to be used as a drive. It may very well be that the minimum size for a fusion power source could be many times that of it's fission equivalent.
The real thing is that if you want the kind of easy travel you see in Star Trek, you'd need a reactionless drive. Unfortunately we don't even have a theory path that might lead to practical engineering.
It can give us some actual environmental data on the conditions of interstellar space. What will happen once Voyager gets to the point where solar wind and magnetism finally gives way to the interstellar medium.
Lesson 102: Space is not simply an empty vacum. It's an environment of it's own with lots of forces that can come into play. Gravity, magnetic fields, solar and cosmic radiation. For all we know we might find the spacecraft picking up a slight electrical charge which could alter it's course the same way that CRTs work.
That'd be valid if I thought the SPS itself were a good idea. Environmentally it's questionable. Efficiency wise it's the pits. It would be a miracle to get 5 percent transmission efficency from orbit to ground. And beaming all that waste microwave through the atmosphere is bound to have some environmental effect.
If you were to take a dump in my backyard, I'd have you do it in my garden and you'd yield fertilizer. Battries on the other hand yield heavy metal wastes which along with the refuse from electronics are the fastest growing landfill issue of current times.
Even rechargeable batteries have limited lifespans. Hence I wind up generating more battery waste with each battery powered item I buy. So I try to keep them to a minimum.
I think the major problem would be the bloody inefficiency. In a world with shrinking oil supplies and surging energy prices do we need something that would be at beast about 10 percent efficient in transmitting electricity?
I've passed on wireless keyboards and mice mainly because I don't want to generate more battery waste which ranks up there as among the most offensive types of garbage we accumulate.
Again, again, again. Lack of profit has nothing to do with copyright or fair use. or performance. You want to show Lord of the Rings to 300 people and not charge them for it? You still have to pay the same kind of license a movie theater has to shell out. becasue anything beyond the scale of living room viewing goes into distribution, no exceptions, period.
One of the key differences is temperature. If Titan were placed in Earth orbit the situation would be dramatically different, the atmosphere and probably a good deal of Titan itself would evaporate and be blown away. However out by Saturn way, the mean temperature is what we call in the technical sense cold.
Also, Titan's orbit is filled by a toroidal cloud of hydrogen much of what does escape is reabsorbed by the moon itself. Sky and Telescope had a good article about it a decade or two ago.
A bit of Earth's atmosphere blows out into space as well. Apollo 16 brought back some nice UV photos of the Earth's hydrogen corona, caused by splitting of H20 molecules in the upper atmosphere by UV light. The hydrogen is eventually lost to space but not at a rate that we have to worry about losing our oceans soon... at least not to evaporation.
That was about the same orbit as Skylab which came down in about a decade. Of course the period of high solar flare activity during that day did play a role in hastening it's desecent. But neither Hubble , nor the ISS are in long duration orbits. Such long duration orbits are not within the ceiling of the shuttle, nor are they safe for manned stations.
Remember to the PC users of the Horde they're Skull flagged Level 40 Elite Deveopers led by the Level 60 Boss Black Turtleneck. :)
Maimonedes, a Jewish philospher who did his best work about 12 centuries or so, posed an interesting example about a donkey placed in the exact middle of a line connecting two distant oasises. He propouded that if the donky acted only on pure logic, it would die of thirst having no logical reason to choose one over the other.
The code analogy of the human brain is useful but it hs some inherent differences in addressing the (perhaps literally) quantum gap between technology and actual living systems. A human or any other living animal placed in the Logical Donkey's position would make a choice. Humans in particular are not limited to binary yes/no logic. Yes there have been talk of quantum computers with things like yes/no/maybe states, but it is unclear whether that alone would bridge the distance anytime soon.
Technology can copy many biological prrocesses, The airplane for example can fly like birds. But for a plane like a DC3 to fly a hundred miles as energy efficiently as does a certain hummingbird species which migrates across the Caribbean, it would have to do it on a gallon of fuel.
Well the latest G5 systems have required water-cooling :)
The only slight problem might be the rumored replacement of the hard drive in the newer X-Box by a large Flash disk.
Quite frankly, I don't believe that choices of for office should be about individuals. They should be about parties, specifically positions that parties represent, issues such as education, defense, environment, foreign affairs etc. When elections become contests about individuals these affairs get pushed aside by meaningless distractions such as the recent CBS "Helveticagate", a tempest about when it comes down to it a really trivial teapot. Bernie Sanders may be one of the greatest guys around, but the present system leaves him nowhere to go and little to acheive.
It is because of the focus on individuals, especially Presidential candidates as some kind of media stars slugging it out in a forum more like a gladitorial arena than serious candidates for public office that the Democrats and Republicans, once parties that couuld be clearly identified by issues have drifted so close together that they've become what Ralph Nader and others have referred to as the "Two Headed Beast".
It leaves them as having a shot at government presently denied by the two party duopoly. Any party that can muster a sufficient number of signatures would be elligible to run. The price is that all parties would need to think on a national level instead of state.
The major flaw in the present system is that it was designed to accomodate as much as possible the original thirteen colonies' desire to be treated as separate republics, (i.e. the original Articles of Confederation) The present Presidential campaign in fact is not as it should be, aimed at the American public at large, it's aimed at a relatively small percentage of states whose electoral votes will theorectically swing the total after counting the states where each party has uncontested domminance.
The present state system is designed to insure the continuance of the present monopolies and destroy the possiblitiy of any real progresss of independent.
No, I'd say the way to fix it is to go the other way. Eliminate state by state voting for Federal Elections and go the parlimentary route, the citizens vote for parties as represented by their local figures. Then tally up the votes, and award seats in Congress to each party proportionate to the total fraction of votes each party earns instead of this "winner take all" nonsense we have today, and let Congress choose the Head of State, i.e. the President. While this plays hob with the original Federalist concept of the three balancing branches of government, the last few years proved that the trinary model if it ever worked in the past, is simply no longer applicable now.
Actually the value of a bowl is in how well it serves as a bowl. It could be ugly and deter from the dish set in which it is a part. It could be microwave safe and therefore allow an increased convience to heat the left over dinner that you put in the fridge last nite. It might withstand accidental droppage. The value is in it's function as well as form.
Watch your definitions, the term FCC approved link has nothing to do with the rights and limitations of a public institution's network access. As a student there are implied and implicit agreements and use of univerisity facilities falls within such.
i rst.htmpaper he wrote for Fordham Univiersity
The First Amendement only reads "Congress shall make no law" it does not prohibit limitations within private or semi-private spheres. You can be tossed out and arrested for making abusive use of your free speech rights in a movie theatre for example.
I would strongly suggest that anyone who intends to make a serious case on First Amendment rights do some real boning up on the legal issues. Check out the writings of some real experts like the late Ed Bloustein, onetime President of Rutgers University, like this http://www.bnet.fordham.edu/public/comm/pnapoli/f
Only if this can be construed as a speech rights issue. The university can argue it as an issue of access to a network they own and operate as a public institution. They are within their legal rights to regulate and limit the access to it.
Look up the Thomas Jefferson concept of "inalienable rights". It's used many times to justify a lot of Christian coalistion crap, but the basic premise is that men, being men are endowed with rights that can not be ethically taken or given away. i.e. you can't legally sell yourself or your children into slavery (as was fairly common in Roman days) and that you can not give someone the legal right to maim you. etc.
Libertarian? Like "Liberal" or "Conservative" it's fast becoming little more than a flag to wave, I'd be surprised if more than 10 percent of the folks who go calling themselves "Libertarian" have any real concept of political-social dynamics.
Van Allen rightly points out that analogies put for by space enthuisasts to Columbus, Magellan, Clark et. al. are false. It has not been proven that manned spaceflight of neccessarily limited endurance and high risk can return science on the level of today's sophisticated probes. While the Apollo astronauts returned far more material than the Russian automated landers, the justification of mere bulk is not sufficient to make the argument for science.
The top candidates for an interplanetary expedition would not generally have the scientific credentials of the teams that currently manage the remote missions now. (all but perhaps one of the Apollo lunarnauts was an Air Force test pilot as I recall)
Van Allen from what I've read has not said that manned space travel should be shelved for all time. What he has said and I agree is that many of the present ideas such as Bush's so-called Moon and Mars mission are simply impractical in terms of investment/risk vs. return. These are not the days of Columbus when a Queen could hock her jewels to finance an expedition (which by the way she was rather disappointed in the results "Yes, that's nice but where is the gold?" Nor are those the days of Lewis and Clark where it was just a matter of walking.
The resource mobilisation demanded by space travel means that it simply can not be conducted on the basis of whim. It requires that justification be made for the expense either on the terms of economic return or the advancement of science. What Van Allen has said is that manned space flight at this time has not demonstrated to meet either criteria.
To answer this criticism takes a more indept approach than merely repeating the canard of the so-called limitations of robotic explorers. What you seem to forget is that when we send missions like Cassini we're not just sending sophisticated hunks of transistors and metal. They're the extended arm of teams of scientists, engineers, and planners who continuously show amazing aptitudes with dealing with the unexpected and inventing new unforseen tricks when circumstances demand.