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Modular Laser Launch Systems
BerntB writes "I don't think Jordin Kare's NIAC article has been covered? It's about using new laser tech to build modular
laser launch systems. The modular nature makes it easier to test and build. The only other launch ideas as cool are the Orion Project and the space elevator."
...that offers a built-in light show and 1600x DVD burning.
Just so cool to watch the meter go from "000350 Number of Hits Since Mar 10, 2000" to "000501" in a mater of seconds (by hitting reload). Mesmerizing!
I miss seeing more hit meters around the web.
Oh. Nevermind...
Show me on the doll where his noodly appendage touched you.
has gotten more visits in 5 minutes then it has in 4 years...
I need a sig.
Oh, well, at least it's less likely to get slashdotted this way.
Anyway, more ontopic; this doesn't seem like that new an approach. Modularisation of space items has always been around. It allows you to concentrate on getting each item working at 100% instead of having to rely on one monolithic structure. Modularising laser launch control systems has just not been done in the past because it was hitherto too inconvenient.
How high do the fricken' sharks go?
cheap labor conservatives - they want to keep you hungry enough to be thankful for minimum wage.
The only other launch ideas as cool are the Orion Project and the space elevator.
You forgot Project Promethius.
Fly me to the moon Let me sing among those stars Let me see what spring is like On jupiter and mars
I really don't understand this fascination with a space elevator. I mean, I take an elevator every day into work and I don't wet my pants doing it. They're just really not that exciting after the age of 3.
a) the vehicle may blind by reflected light at a considerable distance (100m - 1km or more- think of the wildlife [handwring]).
b) it ideally uses pure liquid hydrogen fuel; this means that the fuel tank ends up pretty heavy relative to the fuel (heavier than the space shuttle, because the Space Shuttle tank also holds LOX, so the average propellent density is rather better.) The ratio of the vehicle weight full/empty is critical in a high performing rocket- so this rocket doesn't perform as well as you would hope- it's not a SSTO solution, not quite, so he has a drop tank or two.
c) got a few billion? The lasers are very expensive... note that conventional rockets can be designed for *well* under a billion if you don't do anything fancy (see SpaceX)
d) it works best when you are launching a lot, but then again, just about any launch system gets cheap real fast if you launch a lot; and this one is expensive up front, so you have to launch even more to offset this.
Still, it's a very cool idea, and he's still working on it. But I can't shake the feeling Jordin has missed something that will move the idea up one more notch.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"That article is terrible. It glosses over and dismisses some very complex and seriously non-trivial engineering issues. Laser aiming; Heat exchanger design; Transitional aerodynamics; An entirely new propulsion system. These are not "easy to develop and inexpensive to test".
Since the prior story is about Carnegie Mellon its rather ironic that the most intriguing launch technology was left off entirely -- and it is out of the robotics department of CM: the Rotovar(tm) by Hans Moravec.
Seastead this.
and now 1867 hehe
I'm worried there's been a DNS attack or something, and it's being faked just a little too well.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"In this Phase I effort, we will analyze the performance requirements and scaling of modular laser launchers using various current and proposed laser technologies, develop baseline designs for possible beam modules, and define a roadmap for technology development and deployment of a modular laser launch system.
they are just doing a requirements analysis, they are deciding if its feasable, so he's not missing anything.
I don't think Jordin Kare's NIAC article has been covered?
it probably has. but what the heck, this is slashdot, where the third time's a charm!
Kare, who's been plugging this idea for decades, writes "A rule of thumb for laser launchers is that the unit payload is 1 kg per MW of laser power." The Apollo lunar module (all the stuff that went to the moon) massed about 6500 Kg, of which 2500Kg made the round trip. So we're going to need several gigawatts of laser power for a moon shot.
Kare is talking about using continuous diode lasers in the 1KW range. These don't exist, but 60W units are available, so this isn't totally unreasonable. Kare proposes to use maybe 150 of these future 1KW units in a prototype. That only launches a 150g craft.
Launching something the size of the Apollo lunar module would take six million such units, and about 12 gigawatts of electrical power for several minutes. This is twice the power output of Grand Coulee Dam, the biggest single power source in the US.
The power storage problem might be overcome using ultracapacitors. You can get 2600 farad capacitors (not ufd, farads) at 2.5V today, and you can take current out fast. Auto engines can be started with six of these things, weighing a total of about 3Kg. With a big budget, a laser launch system could have enough energy storage to do the job.
Six million lasers, though, is a bit much. The prototype doesn't put enough mass in orbit to be useful, and the real version is too big.
If you want to launch a microsat, you call Orbital Sciences Corporation, and they launch a Pegasus rocket from a L-1011 for you. The X-prize guys get all the press, but Orbital actually puts stuff in orbit. They've launched 45 payloads so far. Click here for their user manual.
Here's a similar, but more interesting article: http://science.nasa.gov/newhome/headlines/prop16ap r99%5F1.htm
;-) A flying saucer that flies straight up by creating a vacuum above it that literally sucks it upward. Plus, it uses no propellant at all, which means significantly less weight to lift.
j an%5Fen virorocket.htm
Now that's cool.
Quote:
"You could go halfway around the world in 45 minutes, or from the Earth to the Moon in about 5-1/2 hours."
If NASA wants to build a base on the moon, they need something similar to this. Even if technical problems make it difficult to lift people this way (i.e. excessive heat, microwave radiation, or G-forces), it sounds perfect for lifting heavy cargo and supplies into orbit or to the moon.
Of course, I like the candle-based rocket fuel as well:
http://science.nasa.gov/headlines/y2003/29
Looks like I screwed up your insult pretty bad? It's four sentences not three. There are no non-sequiturs. My verbs don't match. My karma whoring self is teh suck.
Do i understand this correctly? Nasa wants to use a high-power ground-based laser as the heating supply for the power needed to ignite the H2 fuel in the Primary Propellant Tank? And as such they gonna aim their laser over very large distances to a so-called Leighweight Heat Exchanger as a shooting target ? (see figure 1 on page 6).
:
There's some rather severe pitfalls to be considered with this method
1. if the spacecraft abusively rotates around its length axis, the power from the ground laser might not be able to reach/hit that Heat Exchanger target any anymore, hence the rockets drops its speed instantly, leading to even more fatal flight manouvring.
2. As the rocket is approaching large heights, the laser guiding system will be put to the real test. When the "lock-in" signal is lost, you loose everything.
3. The conventional iginition system should allways be present as a backup system. In that case the net effect is just that extra costs are introduced.
I personally see this project more as a nice step-up for developing and deploying guided high-power ground-based lasersystems, which can follow ("lock-in") their target to very large heights. a laser "lock-in" in the end might even be possible on rockets (targets) which are near the moon. Doesn't that closely resemble the "StarWars" program of former president Ronnie Reagan ?
Robert
When are lasers going to finally hit 'real' efficiancies?
Ive heard about using a cannon to launch satalites and other rockets-- eg, get them high up as possible, then have the engines take over
This rocket skips the oxygen, which is heavy.
There is only hydrogen being boiled off by the laser.
Hydrogen is only 2 protons per molecule,
the same as helium, without the neutrons.
(plus some insignificant electrons, minus some
bits from e=mc^2, and so on)
At low altitude of course, all that hydrogen
will burn when it hits the air outside the rocket.
Oh well. So the exhaust catches on fire.
Dean Ing's "The Big Lifters" talked about this 15 years ago, with a prototype unit that used a maglev train to push the orbiter to just about transsonic, a short-lived ramjet booster to get upright, then hit it in the @$$ with a laser to get to orbit.
Ing talked about other interesting transportation options in that book, such as delta dirigibles to handle cargo off-load from moving trains, and engineering trucks for intermodal hauling over short distances that are better at city driving than highway. Good socioeconomics for hard sci-fi.
Design for Use, not Construction!
You are wrong.
LH tank weight is exactly the same problem with both shuttle and this approach (using LH as monopropellant + laser heating).
The main limitation of rocket propulsion is the weight of the oxidizer. Even with LOX (most weight-efficient oxidizer) the weight of the oxygen is 8x higher than the weight of hydrogen. And you need lotsa fuel/oxidizer to lift the weight of the fuel/oxidizer, etc. Any weight savings will greatly reduce the overal rocket mass and size.
Compared to shuttle (without SRBs) you would be flying the laser/hydrogen rocket with about the same tank of LH but without oxydizer.
Umm...I may be wrong here but light has almost no pusing power. Even those solar sails rely on the solar wind
If opportunity came disguised as temptation, one knock would be enough.
3^2 * 67^1 * 977^1
It's not an article either -- it's a research report. The whole site is quite interesting, really. I should have given a link to it, too.
Karma: Excellent (My Karma? I wish...:-( )
I love re-reading older science fiction just to see how badly they foretold their futures. Most stories understandably miss the mark on the spread of cellular telephone and personal computing in our culture. The only other serious anachronism in Footfall is that they employ the shuttle Challenger in the story climax. Besides that, the story could still be made into a plausible miniseries or movie.
[
Make sure you bring enough extra batteries for the landing, rewelding the tower, and the second required flight.
As someone else reminded you, hydrogen molecules
contain two atoms.
The weight per molecule matters. For rockets
and explosives, you get a better device if the
exhaust gases are composed of lightweight
particles. Hydrogen satisfies this better
than any other stable molecule.
Superconductive coils are better: Cost scales a little less than radius, but energy scales as radius squared. On the other hand there may be problems getting the energy out fast enough. (Problems like radially pumping ground water that rips open the coil container.)
Another possibility is gas dynamic lasers. They scale all the way up, and fuel/oxygen tanks are cheap.
Orbital's approach is insanely expensive and logistically apalling. It's fine for launching must-not-fail satellites serving lucrative markets, but worthless for the human conquest of space. What I want is the flying equivalent of Conestoga wagons.We'll be able to escape the Coal Sack.
Funny, I've been seeing these asymmetric brown creatures running around - and things seem to be working better - the coffee is simply wonderful.
A Shadeless room is a brighter room.
Similar if not the same concept was used in the book _The_Mote_In_God's_Eye.
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SKYKING SKYKING DO NOT ANSWER
You can only be as effecient as the pumping levels. It turns out that wallplug efficiency limits systems to about 50%.
Magnetic monopoles were hardly considered crackpot in 1977, and Hans Moravec is hardly considered a crackpot in engineering. It is always dangerous to try to predict future advances in engineering based on present speculative theory -- as was necessary when trying to derive the "unobtanium" required for various proposed structures such as the Rotovar(tm). He did at least spend the lions share of his speculation on graphite "whiskers" which is related to carbon nanotubes.
Seastead this.
Yeah, right.
"I'm so moist I'm sticking to the leather." -Kermit the Frog on The Late Late Show
How much of a loan do you have to take out to pay for an elevator? How much of a loan do you have to take out to pay for a Rotovar(tm)?
Now, what's the mass flow rate to orbit of the elevator? What's the mass flow rate of the Rotovar?
I think if you do the calculations you'll find there's really no comparison -- the Rotovar wins hands-down.
Seastead this.
a) The vehicle could be dropped from several km up in the air where no wildlife would be endangered (like the recent launch of SpaceShip One)
b) Being able to launch with reduced/no oxidizer would be a HUGE weight savings, significantly decreasing launch cost (as a sibling post noted). There are actually two tanks within the external fuel tank of the shuttle, a huge one storing LOX and a much smaller one storing the H2.
c) The lasers would be completely reusable (I presume their maintenance cost would be very modest compared with Shuttle maintenance, a pretty safe assumption IMO).
d) This depends on how fast you want this to pay for itself and exactly how much the initial cost is. It could catch up with traditional rocket systems pretty quickly if they can significantly reduce the amount of oxidizer they carry up.
Another concern would be blinding or damaging the optics of orbiting satellites. This could be a serious issue if each laser must be substantially powerful.
Oh, never mind.
Ok, this is a crazy idea, so you might want to make fun of me.
1. Push a really long cylindar (full of air, or much lighter than water) strait down into the ocean.
2. Put something on top, to go to space.
3. Let the cylindar go.
correction: liquid oxygen weight is responsible for most of the shuttle weight (8 tons of oxygen are needed to burn 1 ton of hydrogen) but the volume of liquid oxygen is actualy rather small, much smaller than the volume of liquid hydrogen.
There are 2 tanks within the external tank - a small one for LOX sits on top, the rest underneath of it is filled with LH.
The reason for this "paradox" is extremely low density of liquid hydrogen.
I have an Idea, it's probably been proposed before but, i'm wondering if anyone with a better physics backround could verify or deny this idea. Basically For Satalites/already in space systems. Is it feasible to use some sort of lazer propulsion system? I.e Light energy is the most readily available source of power (through solar panel) Could A series of high powered lazers be used to hit an adjustable pannel (also attached to the satalite) with enough force to move the satalite. Thereby getting rid of any sort of fuel need? Considering that the satalite's mass is nearly 0 in space. Firing a lazer with enough force to propell the satalite would be simple. Or am I missing somthing here.??
AEnertia
Witty, tag line goes here
Didn't Russia launch a solar sail probe a few years ago, while sticking us with their Soviet boondoggle tech in the Space Station? Now we're cleaning up their expensive, tardy messes at the ISS, while they're planting *their* Red, White and Blue flag in the rest of the Solar System. They're always first out there - we should be capitalizing (pun intended) on the chance to be first to be second, learning from their mistakes. Not repeating them at the ISS.
--
make install -not war
Well done with the spoilers.
One nice thing about this approach, compared to many other systems, is that it could lend itself to distributed production which would spread wealth around to many companies and local economies rather than concentrating wealth in the hands of a few. The design requires over 2000 laser/telescope modules each in an intermodal container. Instead of having one contractor build them all, imagine having a hundred contractors (average two per state), perhaps many in university towns, each building 20 units to a common design. Move the factory to the workers instead of vice versa. Each production facility would have a large flatbed CNC mill, mirror grinder, welding equipment, and a small electronics shop or would be a consortium of local manufacturing shops with excess capacity (i.e. a machine shop and a welding shop). Many more smaller companies would produce subassemblies. Assuming that production was not continuous but came to an end, making them all in one factory would require large numbers of people to move to one city which would then have a large layoff and unemployment that the local economy could not absorb at the end of production. By spreading it out, local economies would be better able to absorb the layoffs. And the number of layoffs would actually be reduced because the 100 different companies could each have different transition plans to developing other products so you wouldn't need another project of the same magnitude to absorb the labor and manufacturing surplus at the conclusion of the project. The distributed surplus of manufacturing capability would then spur innovation in other areas. I am thinking that each factory would have, rather than single purpose fixtures, a more general purpose programmable production ability (such as CNC tools) that would need little retooling to work on other projects. Also, many of the manufacturers would be applying existing facility and labor surpluses to this project. Manufacturing the individual lasers would still be handled by a small number of plants with a few more turning them into laser arrays. Specialized tasks like silvering the mirrors might be cheaper to do by shipping an intermodal container based factory with metalization equipment to the various factories or by shipping the mirrors in to a central site. Mass producable electronics like tracking systems could be manufactured at a smaller number of plants and shipped to the individual plants. The honeycomb mirror blanks could be manufactured by the University of Arizona Mirror lab, Corning, or similar glass manufacturer and possibly spin cast to approximate curvature. When the booster modules are completed a tilt bed truck picks them up and transports them to the nearest railroad container facility to be put on a rail car for shipment to the final laser site.
The only huge scale production operation would be if you decided to build a nuclear power plant to power the system.
The individual launch craft would be small enough that their manufacture could be distributed as well.
The distributed nature would reduce cost overruns which are routine for large contractors since how many systems were ordered from each manufacturer would depend on the quality and cost of the systems they produced. The first (prototypes) would necessarily be built in small shops; this could be extended to final production and still keep a reasonable economy of scale by using flexible tooling and centralized engineering costs and by eliminating beaurocracy and monopolistic thinking and by reusing idle factory spaces around the country. The quantity of units isn't really high enough, anyway, to fall into the economy of scale of a fixed purpose production line (like for an automobile).
I imagine the laser site looking like a freight yard with perhaps 20 widely spaced parallel sidings with 100 containers each. The added expense of leaving rail cars under each container is offset by the ease of replacing modules although you could use a crane to move the container onto smaller wheel
Basically, there are two types of laser rocketry, as defined by fuel: air-burning, as used by Dr. Leik Myrabo and has been seen on tv; and soild fuel (usally a dense metal) burning, as being developed by Dr. Andrew Pakhomov at the University of Alabama in Huntsville. The problem with the Myrabo method is that the laser is tuned be absorbed by the air, and thus is inefficent over long distances. Ablative laser propulsion doesn't have this problem. It is however still very much theoretical: I've seen their first fight model; it's 3/4 of a cm tall...
;)
More info on Dr. Pakhomov: pakhomov.uah.edu
Simon
Do'h. I knew that... Thanks for the correction.
This is the typical fallacy. Fuel weight by itself is irrelevant since you will need a tank to hold it. You need to take into acount the whole cost, tank+fuel weight. Also take into account that a larger tank means a larger vessel which requires a larger (heavier) exterior shell.
Excuse me, but is there another potential technical challenge to be overcome?
Won't a large array of coherent power sources, presumably very close in frequency, and at varying distances by definition interfere with eachother and thereby reduce the efficiency of energy transfer quite a bit?
A single 100 Gazillion Watt laser has an advantage in coherency over a Gazillion 100 watt lasers - no matter how you measure Gazillion.
Did I miss something in physics class?
I'm pretty sure I'm right about this, and probably not the first to think about it - so what is the loss due to the generation of interference patterns at the collection point?
Is there a point of diminishing returns where increasing the number of lasers becomes less efficient than increasing the size of the lasers?
If so, does that point define an optimum output per source for a given launch vehicle?
What about increasing the size of the collector and diverging the targeting pionts of the sources to minimize overlap - is that even worth doing?
What about multiple diverse collectors for redundancy and an improvement in power transfer efficiency and if so, at what point does that strategy reach diminishing returns due to increased complexity, weight, and drag?
You can vary the wavelength across the array, and that avoids most of the problems with speckle patterns.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"True, but the sheer number of emmitters and the limited bandwidth available for efficient transfer through the atmosphere will impose some important limits I suspect.
correction: liquid oxygen weight is responsible for most of the shuttle weight (8 tons of oxygen are needed to burn 1 ton of hydrogen) but the volume of liquid oxygen is actualy rather small, much smaller than the volume of liquid hydrogen There are 2 tanks within the external tank - a small one for LOX sits on top, the rest underneath of it is filled with LH.
The reason for this "paradox" is extremely low density of liquid hydrogen.
And this is why liquid hydrogen is bad as a fuel for a craft that has significant flight stresses - you need a huge tank, which weighs a lot and is large enough that the square/cube law starts to bite you for structural strength (increasing the weight even more). It turns out that the drawbacks of increased craft size per unit cargo weight outweigh the benefits of using alternate fuels. This is why most new craft proposals use hydrocarbon-based fuels. There have been several papers on this topic (some linked from Slashdot).
The reason why the proposed laser craft can get away with using hydrogen is that they claim an Isp of 600-900, vs. an Isp of around 400 for H2+O2, and around 300 for CH4+O2. This drastically reduces the propellant:cargo mass ratio, to the point where the hydrogen tanks aren't cripplingly large. Whether this Isp can be achieved in practice remains to be seen (though a fair bit of work has been done on the type of engine they cite, and their numbers for lasers are fairly accurate, suggesting similarly thorough engine research).
The only place it makes sense to use hydrogen in a chemical rocket is for a low-thrust drive in space, and chemical rockets are out-competed there by electric drives.
You can vary the wavelength across the array, and that avoids most of the problems with speckle patterns.
They already do this within each launcher node. This is described in detail in the description of how bar lasers would be combined into arrays with sufficiently high luminance to drive the craft.
I personally doubt the combined light from all of the lasers would be coherent enough to get much speckle, and even if it was, the craft is moving fast enough that it would see a constantly-changing pattern that would average out to something reasonable, but I certainly haven't run the numbers to prove this.
Please mod informative!
I guess it comes as no surprise, seeing as how he did a cut 'n paste on this front page troll of a review that was posted elsewhere. What can you expect from an idiot like bonchly Critical Guy?