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Buzz is a pilot, not a rocket scientist, despite that he's signed on with an AltSpace company that has no hope of sucess... its an elegant concept, its just not practical, getting to and from the cycler is about as hard as getting to and from Mars directly, only its much much safer to go direct.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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At least he is one of the Alt.Space folks not undermining Griffins HLLV infrastructure...but trying to work with it.
The privatize space crowd would do better with marketing big payloads for space manufacture if they were to abandon spaceflight. NASA isn't good at selling99and salesmen don't know how to build rockets.
The old concepts of private companies coming up with craft and NASA buying rides is bass ackwards.
It should be more of the opposite.
A large 100 ton or so SpaceHab left separate from ISS like the original Columbus Free Flyer is somehing the Alt.spacers need to focus on.
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Anything private industry can do to lower the cost for NASA is great. Some projects are either too big for small companies or to advanced. .Hhowever, small companies can contribute key components such as an engine or a tank. They just may not have all the resources to put all the pieces together at a level that exceeds the capabilities of NASA.
Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]
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A large 100 ton or so SpaceHab left separate from ISS like the original Columbus Free Flyer is somehing the Alt.spacers need to focus on.
Why? How are the AltSpace folk going to get to it and back?
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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If Anderson and other think to launch Soyuz or other craft to it--that is there concern. Some piggyback with other vehicles is possible. I just want the NewSpace crowd to work with Griffin for a change--and to try to help work with VSE instead of fighting it while supporting sub-orbital nonsense and LVs they will never launch on their own.
It seems to work for the Russians after all.
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Travelling in comfort necessitates the cycler.
Just like a cruise ship, once on board, you can relax.
Possible to cross an ocean in a lifeboat, but only a few have tried in a small boat.
Ultimate argument for the cycler is protection from radiation.
Heavy shielding, once installed, does not need to be accelerated for each traveller.
The space hotel, tourism model would provide financing.
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You do not understand
The mass of all the extra fuel needed to execute a direct abort in the event of a missed rendezvous with the cycler would easily be hundreds of tonnes, so mass wise you could afford to build a much much bigger ship that goes directly instead of to the cycler with this safety feature.
Comparisons with cruise ships are good: does anyone use cruise ships for transportation anymore? Of course not, they all take faster, smaller airliners. The speed of a ship that goes direct, plus the ability to depart more often since there are more of them, will simply make the many month transit and the months between cycler seem quite silly.
Then there is the cost... to build that huge, heavy cycler you are going to have to accelerate its gargantuan mass to escape velocity, and it will have to be reliable enough to operate without hope of rescue for months lest huge numbers of people die. This thing is going to cost a fortune, or more likly, several fortunes.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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You really can't compare a cycler shuttle to even the most meager transit craft. A shuttle doesn't need to be anymore than a bigelow and tug for CEVs, which once lifted to the right orbit the CEVs can do the "last mile" easier. Over time its the best way to get large crews to Mars in fighting form. Sure, in time we'll have the engines to send people in 4 months in zero g in a 50ton craft, but they'll need help once they get there. Once that help is there then by all means. But in the mean time were better of taking our time.
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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You really can't compare a cycler shuttle to even the most meager transit craft. A shuttle doesn't need to be anymore than a bigelow and tug for CEVs, which once lifted to the right orbit the CEVs can do the "last mile" easier. Over time its the best way to get large crews to Mars in fighting form. Sure, in time we'll have the engines to send people in 4 months in zero g in a 50ton craft, but they'll need help once they get there. Once that help is there then by all means. But in the mean time were better of taking our time.
Except that transfer shuttle has to have and push several hundred tonnes of rocket fuel as a safety feature, which it will need to abort back to port if it fails to dock with the cycler.
The time it takes for a cycler to transit, and the time between cyclers is much too long to support practical interplanetary travel economically. They are too expensive for too little bennefit, and high-Isp direct flight could make the transit several times it takes the cycler to come around just once.
The economic disadvantage of a cycler is obvious and unavoidable, we must not "take our time" or anything of the sort, speed is essential to the economics, not a luxury for some distant future.
A GCNR or NSWR engine has the power to make the transit in as little as sixty days, perhaps even less with the proper planetary allignment. A transit shuttle for a cycler will have to support a crew for several days waiting for the rendezvous, so whats another month and a half? Two months in zero-G should not be a problem for most people either.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Untill you have some place to go the number of boots you can put on the ground in one shot is more important than how fast you can get them there.
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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A direct-flight ship will be able to get them there faster AND in large numbers, because it can make the trip several times in the time it takes to get there with a cycler.
It really is a slam-dunk case, safer, more efficient, and doesn't require building and accelerating a huge hulking space station at fantastic cost.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Eventually such cyclers might be of use as way stations of other craft if troble occurs and a cycler is nearby on a similar course. But that is a way out.
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Once nuclear rockets, space elevators and beamed power for shuttle to the cycler become available, the cycler will become the center of various projects.
Large habitat to explore from. Maybe make a grand tour of the planets.
Slingslotting, Acting as transportation for the Solar system.
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NO, and no again
If you already have high-efficiency nuclear rockets, then you want the painfully slow and agonizingly rigid scheduling of a cycler even less! Why, why would you possibly want to tie yourself to inflexible, rigid departure times that takes 9+ months to transit just to or from Mars, all that time, utterly wasted, when you could make a quick sixty-odd-day hop with a GCNR/NSWR ship almost any time you wanted?
One more time, why a cycler in the first place? So you save on rocket fuel by not having to re-accelerate or re-decelerate your habitat every time you want to travel between planets. The thing of it is, the mass of a habitat is not all that great, so these savings will not be as large as proponets make them out to be. The problem is that a cycler has to be on a fairly specific orbit in order to loop between two bodies without expending much fuel.
Hence, a cycler doesn't save you a single drop of fuel for shipping cargos, since it takes just as much fuel to push it to and from the cycler as it does to send it directly. Not a single gram of fuel saved, and probobly quite a bit wasted with all the rendezvous maneuvering and such.
For passengers or anything that has to go fast though, its a different story: only a free return orbit permits a cycler to loop around without a big boost, but this limits its speed to a pretty slow nine-month (or more) transit to/from Mars. You can't go any faster than this, because if you did, you would overshoot and you wouldn't loop back to the next port at all. The departure times are also set in stone, you either rendezvous with the cycler when it passes, or else you don't hitch a ride at all, so all traffic to/from the cycler has to occur in a short window, maybe just a few hours.
Best of all, is the horrible risk involved... because the cycler is going fast enough that it is above Earth/Mars escape velocity, then so too must your passenger shuttles. If they are going fast enough to escape Earth/Mars, and the rendezvous with the cycler fails, then the shuttle will have to make the whole nine-month (plus) trip by itself... or else carry enough fuel to turn around (and quickly). The amount of fuel needed for this is in the hundreds of tonnes I am sure, and will take as much (or more) fuel then it would to send a direct flight ship all the way to Earth/Mars.
And beamed power? What are you talking about? Beamed power is nothing special, and doesn't eliminate the need to carry large amounts of propellant mass any more then nuclear systems. Such a system would be horrible for large-scale travel, because only a tiny fraction of the energy needed for the beam is ever converted into motion.
Large habitat to explore from? Again, what? A cycler by definition is never going to be useful for this either, because it can't stop. So, the best it can do is drop passengers off or pick them up, which is useless for long-term autonimous exploration at any particular destination. If you have a base at this destination, then there is no good reason not to use a "fast" direct nuclear ship instead of a cycler.
Again, the cycler sounds nice on paper and conjures up notions of the grand ocean liners of Earth, but its really a terrible concept from a practical standpoint. Not that you care about practicality, but I digress, I am not worried about wasting time and money on cyclers because nobody would be stupid enough to invest in them.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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One more time, why a cycler in the first place?
Cycler is not just transportation, occupy the Solar System, to enable numerous projects.
A space city, traveling in safety and comfort, like a nuclear aircraft carrier.
Planets are deep gravity wells.
Better to be flexible and use cyclers, not planets as bases, to operate from.
Over the long term, the need for cyclers will develop, justifying the expense.
Hidden agenda may be the military one; control of the high ground.
Direct to Mars settlement in a few years.
Moving civilization to space, over the long term, will be with cyclers.
Not that you care about practicality
We can do little without better robots.
And with better robots Cyclers will be another affordable option.
A cycler by definition is never going to be useful for this either, because it can't stop.
Neither can the Earth stop, get off one cycler to explore and catch another one when done then, in comfort take a shower in artificial gravity.
And beamed power? What are you talking about?
high power lasers and large adaptive optical Systems
http://www.transorbital.net/Library/D001_S02.html
How long before chemical rockets are replaced into low earth orbit ?
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Military?
Would be utterly useless: a big hulking mass, w/ negligible delta-v, very predictable orbit, it would be vulnerable for starters.
And then:
ensign: "Commander! The Martian colony has revolted! What shall we do?"
Commander: " Change course to... errr... Schuks! Wait one... errr... PREPARE FOR BATTLESTATIONS! estimated arrival time... 23 months, doh!...Too bad we just left Mars's vincinity... Hope them pinko revolutionaries haven't relocated underground and spawned a gazillion kids by then"
(And haven't launched piles of debris, intersecting our course...)
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Military?
Would be utterly useless: a big hulking mass, w/ negligible delta-v, very predictable orbit, it would be vulnerable for starters.
Earth is big hulking mass, with very predictable orbit,
but is a base with high escape velocity to launch from.
Cycler is in between, think of a stealth cycler,
slow and nearly predictable, if you could get a fix on it.
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No such thiing as a stealth cycler, there's enough 'circumstantial' stuff to give it away (when it enters Earth vincinity, resupply-missions to it are a dead giveaway, for starters)
And what about the other drawback I mentioned?
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MarsDog, you keep on uttering words, but they are making progressively less sense...
First a word about your link concerning beamed power propulsion: there are two basic methods, either using the beam to push a propellant out the back, or using the beam to push a solar sail. The former, the only option with much thrust, still has to have some propellant like water or a block of burning rubber or something, so you might as well stick with regular rocket fuel. There is a notion of using the atmosphere as the propellant source, but frankly, this will never work because its not dense enough. Its not practical to build a laser or microwave generator bigger then a few hundred megawatts, and this would not be anywhere close to the power needed for orbital flight. The other option, a solar sail, has accelerations much too slow to rendezvous with the cycler as it passes; note that the author on the link his ship weighs 0.3 grams.
...A space city? Please, which is it, a transport or a space station? A nuclear aircraft carrier, unlike a cycler, has the ability to stop at its destination too. You can't use a cycler as a "base!" Otherwise, its not a cycler anymore.
Over the long term, people will continue to improve the efficiency of nuclear rockets, which will make cyclers worse and worse and worse of a bargain as it requires less and less fuel to get to your destination. "Dirst to Mars settlement" will be literally what happens, people won't bother with the two-year round trip with a cycler when they can have a ~150 day round trip with a nuclear engine directly.
The affordability of cyclers has little to do with robots, the problem is that you have to operate a large autonomious cycler for long periods of time to move the same amount of people in a more dangerous way then you could with a nuclear ship directly faster and safer. If robots will reduce the cost of operating a cycler, why not too a nuclear rocket directly?
"Neither can the Earth stop, get off one cycler to explore and catch another one when done then, in comfort take a shower in artificial gravity."
What are you talking about? The Earth is a destination you are trying to get to or from, with an unlimited amount of rocket fuel too. And who are trying to decieve with this business of transferring between one cycler and another? Listen, and listen well, a cycler is an expensive vehicle that is very slow. They are SLOW. And because they are so slow, it will be months and even YEARS to travel to/from a destination! So do you have any idea how dumb it is to have multiple cyclers so your hypothetical exploration runabout can be picked up by a second cycler before its supplies run out?
And their slowness is what makes them useless. A high-energy nuclear ship would be able to make the trip to Mars and back four times in the time it would take a cycler to do it once. There is a good reason why nobody rides passenger ships across oceans for transport anymore, and nobody will take a 9-18mo (depending on orbits) cycler trip over a 2mo (or less) nuclear ship trip, which will be safer to boot with its extra maneuvering ability and no short-range shuttle needed. And you can depart almost any time!
If you can't come up with a reason why this does not make them impractical but you continue to support them anyway, then you are as stupid as they are.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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No such thiing as a stealth cycler, there's enough 'circumstantial' stuff to give it away (when it enters Earth vincinity, resupply-missions to it are a dead giveaway, for starters)
And what about the other drawback I mentioned?
Stealth would probobly make it easy enough to hide in the interplanetary void, but you could have no artifical gravity: the spinning sections, if faceted like a Stealth Fighter, would eventually reflect a radar beam back to an enemy reciever.
Stealth close to a "hostile" body or probe would be much harder; paint your ship black and it will show up better on infrared, paint your ship silver and it will show up better on visible. A skin-cooling apparatus would be difficult, particularly with spinning sections, and the radiators or hot expelled coolant from your reactor or skin cooling loops would be like a bright running light on an airplane - easy to spot.
And if they spot you? Then you are -dead-, because you couldn't possibly maneuver away from a nuclear missile fired your way. Especially since the missile would be easy to stealth all the way to target.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I dont believe that Mars direct would be big enough to do a decent job of Mars exploration and like many I sort of looked at cyclers as providing the alternative mission architecture. This I have been now abused of. I suspect that a lot of us resist Nuclear powered or engined architectures due to the single term "Nuclear".
My lack of knowledge of nuclear options only shows me that maybe I really have to get off my prejudice but this leaves the question what can be developed and can it be direct launch or will in orbit construction be reguired if only of a few modules.
What sort of ship can be developed to deliver crews to Mars and return to Earth to be reusable. Is it feasible? and just how expensive would this be?. What fuel would it use and what sort of crew capacity would it likely have?
Chan eil mi aig a bheil ùidh ann an gleidheadh an status quo; Tha mi airson cur às e.
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Its not practical to build a laser or microwave generator bigger then a few hundred megawatts,
Combine the beam of a large number.
Phase locked, it would act as one giant large diameter source.
A space city? Please, which is it, a transport or a space station?
Multi purpose, just like the Earth.
You can't use a cycler as a "base!" Otherwise, its not a cycler anymore.
Earth moves, but is the base for humans.
Aircraft carrier is a base for the aircraft.
It is a matter of reference.
Over the long term, people will continue to improve the efficiency of nuclear rockets
Power limited in nuclear reactors.
Potential power considerably greater if you beam the power.
It is something like concentrating sunlight.
The affordability of cyclers has little to do with robots
Moving to space is dependent on robots.
Imagine it and have the robots build it.
Cost is the robot. One good robot to build more.
The Earth is a destination you are trying to get to or from, with an unlimited amount of rocket fuel too
Cycler is a destination. Like a city supported by the countryside.
Cycler is in between a planet and a transportation vehicle.
Some of the advantages of both.
MarsDog, you keep on uttering words, but they are making progressively less sense...
If you can't come up with a reason why this does not make them impractical but you continue to support them anyway, then you are as stupid as they are.
This is a logical fallacy.
http://www.google.com/search?client=ope … 8&oe=utf-8
Attacking the person to try to get an advantage in a debate.
Recently, extremely angry people have become classified as multiple personalities.
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MarsDirect is too small, but there is a happy medium between it and the gigantic "Battlestar Galactica" mission plans proposed back in the SEI days.
My favorite, and the one I hope that Griffin eventually settles on or something similar, is NASA's Design Reference Mission, version three:
http://www.astronautix.com/craft/dession3.htm
The NASA "DRM-III" mission plan is about 50% larger by mass then MarsDirect, but carries about double the payload thanks to using NERVA-style nuclear rocket engines. With a crew of six and all the extra mass, there is roughly 2.0-2.5 times as much habitable volume then MarsDirect or about 50% more per-person.
It splits the mission up into six launches, one ERV that is parked fully fueled in Mars orbit, one acent vehicle with fuel plant/science gear, and finally a third with the crewed habitat. Each of these would weigh about 80MT, and would be mated seperatly to a nuclear-powerd booster stage in Earth orbit. DRM-III could use the currently envisioned Lunar heavy lifter without the EDS booster stage to get off the ground, and the CEV crew capsule to land on Earth. If nuclear engines are not fiscally or politically viable, the big maximal Lunar heavy lifter could bring up a conventional chemical rocket powerful enough to substitute. The crew might also be launched on CEV before transferring to the manned HAB module.
I think that DRM-III could be modified to be partially reuseable: with a supply of water on Mars and a reuseable crew acent/decent vehicle, the ERV could become a reuseable transit shuttle between Earth and Mars orbit, only requiring two HLLV or one HLLV and one heavy EELV launch to refuel it.
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As far as nuclear engines in general suitable for manned flight, there are basically five kinds broken down into two catagories:
-Solid Core (best chemical engines = 460sec)
~NERVA type, experimented with by USA & USSR in the 1960-70s, relativly easy to develop. Maximum Isp is around 900-950sec. Might be used on "low" to provide electrical power, uses Hydrogen for propellant.
~Timberwind type, concieved but not tested signifigantly by the USAF, slightly higher temperature, relativly light weight, perhaps a little simpler compared to NERVA. Isp = 1000-1100sec, uses Hydrogen for propellant.
-Vapor/Gas Core
~GCNR type (gas core nuclear rocket), my favorite, creates a vortex of liquid hydrogen and intentionally makes an ultrahot cloud of uranium at its center, able to reach much higher temperatures. Difficult but realtistic to build, may be somewhat heavy and require materials advances. Isp = 3000-5000sec, uses Hydrogen for propellant.
~NSWR type (nuclear salt water rocket), a concoction from Doc Zubrin, a chemical solution of Uranium salts is made sufficently concentrated that if a large quantity were to be assembled it would easily become a critical mass. The solution is expelled by a pump through a hole in a heat shield and "ignites" behind the vehicle. Probobly the easiest to build, but accidents with the "fuel" would be a continual and severe hazard, and would require a great deal of Uranium. Isp = 5000-10,000sec, using water and Uranium as propellant.
~VCR/VASIMR (vapor core reactor & variable specific impulse magnetoplasma rocket), the VASIMR engine has been experimented on the laboratory scale and holds the best promise for an electric engine for manned flight, having modest thrust and high specific impulse. However, the engine is a voracious energy hog, and conventional nuclear reactors won't cut it. A vapor core reactor, where Uranium gas is circulated between the reactor core, the MHD generator, and the radiators directly could provide such power. The VASIMR engine may also project a magnetic field powerful enough to protect the crew from cosmic/solar radiation, but the contraption is easily the most complex and expensive of the five options. Isp = 10,000sec, maybe a little more, using hydrogen as propellant.
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As far as the safety of nuclear, there is one simple fact that most environmentalists would rather you not know: the length of time a substance is radioactive is inversely proportional to how intense its radioactivity is. Because pure Uranium-235 (not 238) has such a long half life, it is essentially not radioactive at all. A nuclear reactor is perfectly safe, you can even walk up and hug a fresh fuel assembly, provided the reactor has not been previously activated.
The chemical toxticity of Uranium is more dangerous then its radioactivity, so Uranium by itself is not really a radiation hazard, or at least not until it has been brought critical in a reactor. Of all but one of the above, and including solid-core power reactors, are pretty safe until they are activated, which can only be done intentionally. So I have no qualms launching any of them, provided they are not activated until safely in orbit. If they blow up, the Uranium would not make a fallout cloud or anything like that.
The one exception is the NSWR engine, where a serious fuel leak could cause the Uranium to "activate" and become intensely radioactive. I think an NSWR engine should be fueled in orbit only, where the Uranium fuel solution could be mixed up there instead of launched in tanks.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I'll leave aside the NTR or GCNR vrs. Cycler discussion as I think it is an apple to oranges comparision. One is a propulsive technology, and one is propulsion technology and the other a mission profile/approach. High-energy transit systems such as a GCNR are superior to practicaly everything else, which should come as no supprise. However, we are still a long ways off from creating one. A cycler could (in theory) be built with today's technology.
That said, I still think Cycler's lose vrs. a direct approach, regardless of the propulsive technology used. As I (and others) have said before they key to this is delta-V, necessary for the trip, or rather the lack of savings in delta-V. To rendevous with a cycler requires essentialy the same amount of delta-V to get you to Mars. Actualy in most cases it is a little more. And in most cases the trip is signifigantly longer, despite spending more delta-V.
Because to dock with the Cycler you must match it's velocity. There is no other way. The cycler is moving far to fast for any kind of "fly-by snagging" scheme to work. This high speed redevous is slightly dangerous, and is a do or die situation. You must dock with the cycler or die, those realy are your only alternatives.
But this isn't the biggest problem. The biggest problem is that the Cycler realy doesn't save you that much effort in comparison to a direct approach. The only to areas you save in are consumables and hab-mass. Most direct approaches already use a ~95% enclosed LSS so switching to a 99% enclosed one on a cycler will save little mass. A day shuttle can get by with a less massive hull than the crewed vehicle, but not dramaticly so. The day shuttle needs the engines and fuel-tanks of essential the same size as our direct vehicle, and it may require some sort of aero-capture system as well.
So in short, a cycler is more expensive, more dangerous, and slower than a direct mission option, and offers little benifit in return. A marginal saving in hull-mass and consumables. Recycling the ITV on a direct mission makes much more sense.
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As for the Cycler as Space-colony idea, this may have some merit. But it totaly changes the equation, the cycler becomes the destination, not a way-point or means of transportation. If space-colonies make sense anywhere, then having one that cycles back and forth bettwen Earth and Mars might be attractive as well.
But a cycler as a military vehcile is stupid. What good is a military vessle that only approachs it's target once (for a very short time period) every 2 years or so?
He who refuses to do arithmetic is doomed to talk nonsense.
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But a cycler as a military vehcile is stupid. What good is a military vessle that only approachs it's target once (for a very short time period) every 2 years or so?
Cyclers as military bases, to stage missions from.
Biggest military and security issue is information gathering.
Launching spy probes, projecting a presence to control.
As the saying goes; the threat is greater than the execution.
Exploration is exciting, but when there is an asset to protect, dollar to be made.
Who is there to protect US interests ?
From Banana Republics to Middle East oil, extrapolate to space.
Historically, the age of exploration, then colonial wars.
Battlestar Cyclers ?
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