Laser Launch Vs. Space Elevator?

[j05h]

What are the pros and cons of Myrabo-type Laser Launch compared with Space Elevators? Which is closer to reality now? Which can place more mass in orbit per unit of time? Which pollutes the least in short and long term?<br /><br />http://www.space.com/businesstechnology/technology/laser_craft_001103-1.html<br />http://www.spaceelevator.com/<br />http://www.space.com/businesstechnology/technology/space_elevator_020327-1.html<br /><br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[eniac]

The latest news on the Lightcraft site is from December 2000, so they may no longer represent the field at this time. Are there any others?<br /> <div class="Discussion_UserSignature"> </div>

 

[richalex]

Dr. Leik N. Myrabo is still publishing papers on the subject, at least up until 2006. <br /><br />Leik N. Myrabo<br /><br />I'm still googling around to see what I can find. <br /><br />

 

[richalex]

Well, one thing I found is that one of Lightcraft's financial backers--the guy who made the flight mentioned earlier financially possible--was arrested in 2005 for income tax evasion. That might have put a damper on the business. <br /><br />Look on Page 3 of this article: <br /><br />Washington Post: Telecom Mogul's Lofty Dreams Plummet

 

[richalex]

"Dr. Myrabo’s research relies on a combined experimental/ theoretical/ numerical investigative approach. His current MURI project investigates the propulsion physics of high power laser-beam launched nanosatellites (i.e., 1 to 10 kg) for affordable, rapid access to space. Myrabo has authored and co-authored more than 210 journal, symposium, and conference articles, and one book—The Future of Flight. <b>His second book—The Lightcraft Technical Manual—is nearing completion.</b>"<br /><br />Rensselaer's School of Engineering Faculty Directory: Leik N. Myrabo<br /><br />"Synopsis<br />"Myrabo and Lewis reveal an intriguing preview of Next Generation, manned lightcraft technology. ... The very same microwave lightcraft concept is seriously under investigation in NASAs Advanced Space Transportation Program (ASTP) - as one of only two viable options 'now on the books' for cutting launch costs by 1000X - within the foreseeable future."<br /><br />Amazon: Lightcraft Technical Manual: 2025 Space Command's Lt1-20 Lightcraft (Apogee Books Space Series) (Paperback) by Myrabo L.N. (Author). Publisher: Collector's Guide Publishing (4 Jan 2008). <br /><br />I guess that NASA has cast its vote as to which technology is more realistic in the near-term.

 

[richalex]

Two other names that I ran across that seem closely related to research on laser-launched rockets are Dr. Lee S. Valentine and Rick Tumlinson. Both were involved in critical roles in Professor Myrabo's launches and both are associated through Orbital Outfitters.

 

[kelvinzero]

Here is a link on the comparison of microwave vs laser.<br /><br />http://www.hobbyspace.com/nucleus/index.php?itemid=680<br /><br />I would say a beamed power launcher is much closer to reality. I think it was the pdf referred to in my link that speculated less than a billion to get a version launching small payloads into orbit. With SSP things just get better.<br /><br />As I understand it, the space elevator is iffy even assuming the theoretical limits of these as yet undeveloped miracle materials are reached.

 

[eniac]

<blockquote><font class="small">In reply to:</font><hr /><p><br />As I understand it, the space elevator is iffy even assuming the theoretical limits of these as yet undeveloped miracle materials are reached.<br /><p><hr /></p></p></blockquote>True, but after the material, the next iffy problem is that of beaming power to the elevator car. It requires focussing a 1-2 MW laser beam onto the car to lift 20 tons.<br /><br />As I understand, current laser launch proposals are about sending 100 MW beams to launch 100 kg. Given that the former is considered a tough problem, I would not call the latter "close to reality" by any measure.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[j05h]

There might be some key differences between laser-powered climbers and the Myrabo-type laser launch. One is that the elevator laser has to be able to power the elevator car without damaging the cable or affecting anything above the car. Building megawatt and gigawatt class lasers are a question of scale while the space elevator still uses theoretical materials. On top of that, the cable will sway under load/orbital pumping/wind which complicates powering the cars. For laser/maser launch, we know it is possible just difficult. Myrabo's experiments had some very interesting results. <br /><br />If it was my project, the space elevator cable would carry power for the cars. It would be nice to see a demo laser launcher that could put CubeSats in orbit.<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[richalex]

<blockquote><font class="small">In reply to:</font><hr /><p>the next iffy problem is that of beaming power to the elevator car. It requires focussing a 1-2 MW laser beam onto the car to lift 20 tons.<br /><br />As I understand, current laser launch proposals are about sending 100 MW beams to launch 100 kg. Given that the former is considered a tough problem, I would not call the latter "close to reality" by any measure. <p><hr /></p></p></blockquote>For reference, the U.S. is developing airborne missile defense systems that would project megawatt-power laser beams from a moving generator (the aircraft) to a rapidly moving and accelerating, small target (the rocket body) as much as 100 miles distant. It seems straightforward that 10 such aircraft all pointed at the same target would supply the necessary power that you describe. I don't believe that the actual application requires such advanced technology.

 

[eniac]

I am not saying it is impossible, just that you need 100 times more power than for the space elevator. So, if the U.S. somehow succeeds in building those megawatt lasers, they will have solved that particular problem for the space elevator, but not yet for laser launch. You'll need 100 times more. Thus, in terms of lasers the space elevator is eminently more doable than laser launch.<br /><br />I think it might happen that neither of these or other mass-launch system will be worth developing, because ultimately the things we need in space will be produced in space. Earth launch will be limited to low mass, high value goods such as humans. Most of whom will probably not want to go, just as most of us don't ever go to Antarctica or the bottom of the ocean. Or Mt. Everest, no matter how good the view is from there.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[j05h]

<i>> I am not saying it is impossible, just that you need 100 times more power than for the space elevator.</i><br /><br />If the lasers can be ganged together instead of being monolithic, this is a solved problem. The ABL fits in the nose of a 747, just build 100 more units and install them in a circles on the ground with adjacent telescopes. The challenge technically is to do it with a few gigawatt class lasers. <br /><br />Your second paragraph is spot-on. Humans, chips and exotic compounds will eventually be the payloads going up the Well with everything else made in space. That is a long, long time away and requires these sorts of "mass" launch technologies. <br /><br />What are the largest commercially available lasers? <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[richalex]

Lasers and power supplies were never the show-stoppers of the space elevator. The elevator part of the space elevator is. Solving the laser problem for the laser-launcher solves most of the problem with the laser launcher. Solving it for the space elevator still leaves you with the problem of creating and stringing a 15k mile-long cable from space to Earth, a much, much bigger problem than the lasers ever would be.

 

[eniac]

<blockquote><font class="small">In reply to:</font><hr /><p>If the lasers can be ganged together instead of being monolithic, this is a solved problem.<br /><p><hr /></p></p></blockquote>It will still cost 100 times as much.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>That is a long, long time away and requires these sorts of "mass" launch technologies.<p><hr /></p></p></blockquote><br />It may be a long time, depending on our motivation, but it will not require a mass launch system. The easiest is oxygen (Lunox), followed by ceramics and metals, which all could be produced on the moon with a few missions worth of machinery. Then a small workshop, to make parts. With automation, teleoperation and miniaturization it will not take all that many launches before we can make things on the moon (including mining, smelting and workshop machines, even spacecraft) containing 90% or more local materials. <br /><br />Once that happens, the need for launches will decrease while the industrial base will increase exponentially. I believe that the first phases of such an industrial build-up will happen without people. People will come later when the hotels are built and the beds made...<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[richalex]

<blockquote><font class="small">In reply to:</font><hr /><p>It will still cost 100 times as much.<p><hr /></p></p></blockquote>The power supplies for the laser rider might be more expensive than for the space elevator, but the power supply cost is a small fraction of the cost of the space elevator. Again, the lasers are not the show-stoppers for the space elevator. It is the cable that is the show-stopper! The lasers are the least of our worries for making the space elevator work.

 

[j05h]

<i>> It will still cost 100 times as much. </i><br /><br />100x as much as the mass-produced single ABL, not 100X as much as the unobtainium needed to build a space elevator. We can build the lasers for laser-launch now (relatively) whereas the elevator's ribbon is highly theoretical. <br /><br />Being able to put lots of little payloads into space would be a very interesting way of building infrastructure. I'm unconvinced of the need to eliminate regular rockets, but think these next-gen technologies have promise. The problem is how do you build stations and crewed structures with 100kg or 10t payloads? <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[eniac]

<blockquote><font class="small">In reply to:</font><hr /><p>Lasers and power supplies were never the show-stoppers of the space elevator. The elevator part of the space elevator is. Solving the laser problem for the laser-launcher solves most of the problem with the laser launcher. Solving it for the space elevator still leaves you with the problem of creating and stringing a 15k mile-long cable from space to Earth, a much, much bigger problem than the lasers ever would be.<br /><p><hr /></p></p></blockquote><br />I disagree. The material can either be made or not. If it can be made, it will not be particularly expensive. Artificial materials are never very expensive, because once there is a process to make it, manufacture of any needed amount is straigthforward. If it is carbon, which it looks like it will be, the raw material will be exceedingly cheap and plentiful.<br /><br />Stringing it from space to Earth is also not particularly challenging, you launch a spool to GEO and unroll it towards Earth. In principle, it is easier than building a suspension bridge. In fact, the Brooklyn Bridge masses more than the space elevator. Of course, the devil is in the details, but that goes for laser launch just as much.<br /><br />The laser beaming, on the other hand, is expensive. It requires huge 24 hour, year-round ground operations, energy supply infrastructure, etc, etc. Lasers are not cheap, to build or operate, and I can easily see how laser beaming cost could destroy the economics of the space elevator. <br /><br />Of course, that also goes for laser launch, by a few orders of magnitude worse.<br /> <div class="Discussion_UserSignature"> </div>

 

[eniac]

<blockquote><font class="small">In reply to:</font><hr /><p><br />100x as much as the mass-produced single ABL, not 100X as much as the unobtainium needed to build a space elevator.<br /><p><hr /></p></p></blockquote><br />Of course, it is obvious that the space elevator cannot compete if the material cannot be made. <br /><br />In order to have this discussion, we need to assume that it is possible, and then the laser power beaming will almost certainly be the dominant cost factor for the space elevator.<br /> <br />At todays power laser efficiencies (<5%), laser launch would require many Gigawatts of power. For a 100 kg payload. Sure, Gigawatt power plants are old technology, but cheap they are not.<br /><br />In fact, if you think about it, how much fuel do we really waste by taking it with us in a conventional rocket? It cannot be all that more than would be wasted by laser efficiency plus loss of light that misses the collector.<br /> <div class="Discussion_UserSignature"> </div>

 

[richalex]

<blockquote><font class="small">In reply to:</font><hr /><p>The material can either be made or not.<p><hr /></p></p></blockquote>The big question for this thread is, "When can it be made?" Do you believe we are closer to being able to construct a 100 MW laser that can keep a focused spot on a vehicle 100 miles distant, or are we closer to being able to construct a 15k mile ribbon that is 1k times stronger than steel? I think the answer to that question is obvious; the laser, by far. We have built many lasers that are within an order of magnitude of this one, but we have yet to produce so much as a single foot (or meter) of this super-ribbon. <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>If it can be made, it will not be particularly expensive. <p><hr /></p></p></blockquote>We can make antimatter. It costs $1 trillion an ounce. <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Artificial materials are never very expensive, because once there is a process to make it, manufacture of any needed amount is straigthforward. <p><hr /></p></p></blockquote>So, why are Kevlar battle jackets so expensive? <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>If it is carbon, which it looks like it will be, the raw material will be exceedingly cheap and plentiful.<p><hr /></p></p></blockquote>Microprocessors are made out of sand, but the silicon boule costs much more than a bucket of sand does. <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Stringing it from space to Earth is also not particularly challenging, you launch a spool to GEO<p><hr /></p></p></blockquote>How much does this spool weigh? Quite a bit, I would imagine. It's probably going to take a hefty rocket to get the ribbon and machinery into orbit. <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>The laser beaming, on the other hand, is expensive. It requires huge 24 hour, year-round ground operations<p><hr /></p></p></blockquote>Why? With the laser launcher, you can turn off the laser

 

[richalex]

<blockquote><font class="small">In reply to:</font><hr /><p>At todays power laser efficiencies (<5%), laser launch would require many Gigawatts of power.<p><hr /></p></p></blockquote>It depends on the laser. CO2 lasers are capable of burning a hole through steel and operate at 30% efficiency. COIL (chemical lasers) are 40% efficient and can generate multi-megawatt laser beams. In contrast, the weak HeNe laser in your grocery store is only about 1% efficient. <br /><br />

 

[eniac]

<br />You have some good points.<br /><br />However, I think you overestimate current laser technology. Your mention of petawatt and exawatt makes me suspect that you do not appreciate the difference between continuous and pulsed lasers. The ABL is continuous, but fires only for 10 seconds or so.<br /><br />I also resist the cavalier attitude of "just build 100 times as many". With this motto, all our energy problems are solved, since all we have to do is build 10 times as many nuclear reactors.<br /> <div class="Discussion_UserSignature"> </div>

 

[serak_the_preparer]

Sort of related to this discussion:<br /><br />It may be a weapon, but it certainly is cool !!<br /><br />Whatever the upsides and downsides of either option, the military remains a huge driver in the push for new technologies. And the military seems to be pushing hard for beam devices.

 

[j05h]

beam weapons and beamed power are the future of war-fighting. The army is testing out a "pot-bellied pig" laser rifle, saw a picture a while ago. Looked just like a sci-fi laser rifle I drew as a kid. Currently beam weapons include the Marine's microwave crowd-control device, sound "cannons" that are mounted on some dangerous-waters vessels, the ABL/ATL and talk of laser/particle weapons in fighter aircraft. Any others?<br /><br />"Airliners'n'deathware behemoth Boeing announced yesterday that it had fitted a high-energy laser cannon aboard a C-130"<br /><br />That's hilarious - "deathware"? <img src="/images/icons/crazy.gif" /> Hadn't heard of the ATL before, but it makes sense. There isnt' that big of a need for for theater missile like the ABL.<br /><br />Serak, what do you think of the main subject? Laser launch or space elevator?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[serak_the_preparer]

I think the main subject is a fair question. More than that, it is an intelligent one.<br /><br />The pool of available funds is only so large. How will it be allocated? We need to get payloads into orbit using technologies we are willing (and able) to include in our budgets. Which technologies might those be?<br /><br />As for what I personally think about how the question might be answered, I hope my previous post gives a good indication. Whatever the merits and potential of the idea may be, it does not appear to be the space elevator.

 

[richalex]

<blockquote><font class="small">In reply to:</font><hr /><p>I think you overestimate current laser technology. Your mention of petawatt and exawatt makes me suspect that you do not appreciate the difference between continuous and pulsed lasers. The ABL is continuous, but fires only for 10 seconds or so.<p><hr /></p></p></blockquote><br /><br />FWIW, long, long ago, back in 1992, I earned an AAS in Laser Electro-Optic Technology. I haven't really done anything with that degree since 1994. I only mention it so you know that I am aware of the basics (though I have forgotten some of the details). <br /><br />I mentioned the petawatt and exowatt lasers just to point out that we can make high-powered lasers to spec without too much trouble. We (or, rather, engineers and scientists) have been doing this for 40+ years, and it really isn't too difficult. <br /><br />The laser rider uses a pulsed laser. The Lightcraft that flew in Lightcraft's video used a 10 kW pulsed carbon dioxide laser named PLVTS, and it wasn't even working trouble-free the day of the test. <br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>I also resist the cavalier attitude of "just build 100 times as many". With this motto, all our energy problems are solved, since all we have to do is build 10 times as many nuclear reactors. <p><hr /></p></p></blockquote>But, that would be essentially correct. It is worth pointing out though, that nuclear power is a bit more problematic than laser technology. <br />