Laser Propulsion - Light Craft - Black Ops?

This thread is here in GD as, hopefully, a sister thread to the informative Space Elevator discussion. I wish to discuss/debate the viability of the laser propulsion technology, the size of the lasers required to move the tech towards payloads capable of supporting manned flight, and the cost of pulling it all off. Years ago Leik Myrabo began a series of experiments using lasers to propel his “light craft” upwards. He met with early success, peaked my curiosity, and the whole thing seems to have petered out. I don’t understand why, but I have some suspicions. . .

This tech seems very promising. From 1999:

Later, seeming success with moving the project forward.

Then for 3 years I can find no new developments. The last time the LCI website was updated was nearly 3 years ago! I know that the government had him use a plywood board stopper in early experiments to avoid damaging satelites with the laser. I am suspecting that maybe his work (and the work of others in this department) has gone Top Secret. We are talking about powerful lasers that could probably have other military applications as well (star wars anyone?). I fear that we may be sacrificing what could be a terrific launch tech so that we can keep our biggest baddest lasers a secret. Pure conjecture on my part, of course. The military involvement and the prolonged silence just make me suspicious.

So, what would it take to make this tech work? How much would it cost? Would the government let us use this tech yet? Would they keep it from us? Shouldn’t laser propulsion be a top contender for next gen launch tech? I barely see anything in the news about it anymore and am hoping we can find out what progress has occurred in the last 3 years.

DaLovin’ Dj

The tech would be especially cool if we charged the lasers with solar energy . . .

Just off the top of my head I’d say there is a significant difference between propelling a 51 gram rocket (the Lightcraft) and pushing an approximately 170,000+ pound space shuttle (that’s empty with no payload or the external rockets and fuel tank).

10Kw to move 51 grams I can’t even begin to imagine what it’d take to move a (say) 150 pound person much less a vehicle for him/her to ride in and such. The expense would be staggering not to mention a laser of sufficient power would probably vaporize anything it met.

Its not impossible, though. We may need a nuclear power plant in capoe Canveral, but it might well be worth it. pLus its eminently possible to make the laser reciever a shape that automatically corrects itself. :slight_smile:

Another interesting article (and one that hints at the secret funding that likely is involved). How big of a laser would one need for a light craft with a payload size of the suttle? What about if you use microwaves instead? Here is an ABCNews article that gives some data on the strength of the lasers required:

Based on those numbers, how big of a laser do we need to match the shuttle in cargo space and weight?

DaLovin’ Dj

I’ve worked on Laser Propulsion, and have met Leik Myrabo on several occasions. The work is not a black op. It’s featured on TV, fer cryin out loud! Arthur Kantrowitz, who, FAIK first proposed he idea of laser propulsion, fught long and hard to keep it an “open” technology. All the meetings and publications about it have been unclassified.

I’ve just written about it at legth on another thread here today.

This thread:

http://boards.straightdope.com/sdmb/showthread.php?threadid=161710

That seems to be an excessively inefficient way of propulsion.

Consider that you only need a bit less than 10N to move a 1kg object up 1m.

Agreed, it doesn’t seem too useful in getting heavy things up into space - its best use seems to be sending up lots of smaller parts to be put together on the ISS or something.

However, once the heavy object is in space, the (almost) zero friction means that a tiny laser could accelerate an immense ship, given time. (You can push a large metal-hulled ship with your own strength given the right conditions).

I’ve exchanged email with Mr. Myrabo myself. He was polite and directed me towards the film and web locations that discuss his work, and it was all stuff I had seen before years earlier. I’m not suggesting that the ship/launch tech is a black op, but the creation of ground based lasers powerful enough to make the technology a reality just may be. Part of proposed star wars programs include weapons style ground based lasers (some of which are tested at white sands - same place as Leik’s last reported work!) that could destroy satelites and eventually aircraft and missiles. Developing such tech invoke security issues and a GBL race could be highly negative strategy.

Obviously, it will take very powerful lasers to propel a light craft with a shuttle-like payload capacity. Powerful lasers are a big part of the planned star wars program. Revealing publicly that we are building big, bad-ass, ultra-powerful lasers makes for bad press and could be a strategic error. Therefore, until it is PC to delcare that we have these huge lasers in development, they can never be used in a public space program.

I’ll botch this terribly if I try, so hopefully one of the math gods around here will help. If not, I’ll try myself or maybe start a GQ thread for the math questions. Here are the questions:

A. How big of a laser would it take to propel a 170,000 pound payload into orbit using a lightcraft? We know that a 10kw laser can propel a 51 Gram payload to 71 meters. This involves metric conversions and my brain starts to short circuit.

B. What is the “official” most powerful ground based laser in existence today?

C. Politically, how powerful of a laser can we have on the ground without forcing our enemies to make giant laser weapons as part of a race to have their own GBLs capable of destroying satelites?

D. Could the electricity to run one of these lasers be stored in batteries and charged by the sun (partly anyway)? Would this cheapen the cost of launching the ships?

It seems to me that if we could use the sun to charge a laser that propels a ship into orbit we are going to greatly lower the costs. I’m not alone. Mr. Myrabo and others have suggested that a 1000-fold decrease in launch costs may be achievable. All we need is big enough lasers.

DaLovin’ Dj

I guess I’ll try myself. How many grams in a pound? I can find it probably, but I’m busy for a few hours. I’ll do the math after 24 on Fox.

170,000 pounds is about 77 million grams, unless ve done my math wrong.

By my math, that will take a 15 billion watt laser to lift, assuming laser power scales with weight. That’s one big laser.