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Dr. Young Bae stands next to his invention, which he built from off the shelf components.  (Source: The Bae Institute)

The PLT in action, producing a weapons grade beam in a small package.  (Source: The Bae Institute)
Dr. Young Bae has created a working prototype that promises to provide effective laser propulsion in space at unprecedented speeds.

Dr. Young Bae of the Bae Institute definitely thinks outside the box when it comes to aerospace propulsion techniques.  Where others are thinking fuel, he's thinking photons.

Last December, Dr. Young Bae unveiled a unique invention: the Photonic Laser Thruster (PLT) with an amplification factor of 3,000 in December, 2006.  The engine promised to provide a novel new means of transportation in space.

Word spread fast and before long Dr. Bae had visitors from some of aerospace's strongest organizations--NASA JPL, DARPA (Defense Advanced Research Projects Agency), and AFRL (Air Force Research Laboratory) --among others.

Dr. Franklin Mead, Senior Aerospace Engineer, and leading rocket scientist in laser and advanced propulsion at the Air Force Research Laboratory (AFRL) was quoted in Bae Institute press release as stating, "I attended Dr. Bae's presentation about his PLT demonstration and measurement of photon thrust here at AFRL. It was pretty incredible stuff and to my knowledge, I don’t think anyone has done this before. It has generated a lot of interest around here."

In the past, photons thrusters have been relegated to science fiction as they were considered too unpractical for modern space flight.  While such a device would have the advantage of nearly constant thrust, unlike a fuel rocket, photons have no mass so it could take years to equal the speed of traditional propulsion techniques.

Part of the Photonic Laser Thrust's secret lies in amplifying and bouncing the photon beam.  The photon beam is bounced back and forth between a set of mirrors, creating a powerful net propulsion force.

Dr. Bae Young built the PLT using off the shelf components at the Southern California laboratory of the Bae Institute.  The patent pending device uses an egg-size laser head to produce a laser so powerful, only massive weapons and commercial grade lasers are able to match it.

The laser generates 35 uN of thrust and is scalable to much larger amounts of propulsion.  Dr. Young Bae has stated that the device could propel a spacecraft to speeds well beyond 100 km/sec.  He recently announced that a spacecraft utilizing the PLT could transit the 100 million km to Mars in less than a week.

Aside from being used as propulsion, the device could be used to control a group of objects in space to carefully fly together in formation--think something like an Air Force jet squadron.  Dr. Bae is patenting a process to use the PLT in a Photon Tether Formation Flight (PTFF), which could offer control of spacecraft flying in formation with nanometer precision. The laser’s current power requirements are within current acceptable space limits and its abilities could accommodate a wide range of NASA spacecraft formation flight configurations, such as SPECS and MAXIM.

The project was built on a very small budget and its accomplishments have helped it secure funding from a prestigious Phase II NIAC grant (NASA Institute for Advanced Concepts), which funds only the most revolutionary ideas for the next generation NASA space missions.

Dr. Bae's PLT demonstration paper, "Photonic Laser Propulsion: Proof-of-Concept Demonstration" has been accepted for publication later this year in the peer-reviewed AIAA (American Institute of Aeronautics and Astronautics) Journal.  In the paper Dr. Bae contrasts his technique with past attempts at laser propulsion.  In the paper Dr. Bae reveals the secret to the PLT's coherency and stability--placing the laser medium in a resonant optical cavity.

Dr. Bae presented his PLT concepts this week with demonstrations at the AIAA Space 2007 Conference in four sessions: Space Transportation Systems, Promising Space Concepts from the NASA Institute of Advanced Concepts (NIAC), Space Systems for the Next 50 Years, and Advanced Vehicle Systems.

The device is pretty incredible and the idea that it could cut the journey to Mars to only a week shows its potential.  Much more work is to be done, but Dr. Young Bae's PLT may revolutionize the aerospace propulsion industry.

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small correction
By masher2 (blog) on 9/21/2007 11:28:49 AM , Rating: 1
quote:
The patent pending device uses an egg-size laser head to produce a laser so powerful, only massive weapons and commercial grade lasers are able to match it.
The beam isn't as powerful as those weapon-grade lasers, the propulsive force from the beam is, due to the repeatedly bouncing the beam between two points.

Details on the site are a bit sketchy, but its important to realize this isn't a standalone propulsion system. As I read it, its feasible only for surface launching of micro-payloads. The beam is generated here on Earth, then bounces back and forth between the launch site and the payload, generating additional thrust each time.

Quite obviously, once the payload is more than a few thousand miles from Earth, problems with beam collimation and alignment are going to make it unfeasible...and of course, the payload will need to aerobrake (or find some other way to decelerate) once it reaches its destination.

Sounds like an excellent system for launching tiny deep-space probes...but if people are seeing this as a rocket engine we can use to flit between planets, they're wrong.




RE: small correction
By masher2 (blog) on 9/21/2007 11:33:33 AM , Rating: 2
Another benefit, of course, is the potential to drastically cut lifting costs to NEO. A laser-based launch system could drastically cost the costs of getting small packages into orbit, which would go a long way towards making the commercialization of space feasible.


RE: small correction
By 16nm on 9/21/2007 12:23:21 PM , Rating: 3
But could continual use eventually push the planet closer toward the sun thereby exacerbating global warming? An important question that we must spend a few billion dollars of education funding to answer. (tongue-in-cheek)


RE: small correction
By jak3676 on 9/21/2007 12:28:52 PM , Rating: 4
I'll take that cheque and begin researching immediatly. If you give me enough money I'll even produce a sensationalized movie about it.


RE: small correction
By Polynikes on 9/21/2007 12:32:13 PM , Rating: 5
Hmm, good point. I think we should ban basketball; all that jumping up and down is surely causing us to get closer to the sun, thereby increasing global warming. The NBA was founded in 1946, and a lot of climate data shows our average temperatures going up a lot in the last 40 or 50 years! I SEE A CORRELATION!


RE: small correction
By jak3676 on 9/21/2007 12:40:09 PM , Rating: 5
But wait - if we only play basketball on the lighted side of the earth - wouldn't that push us further away from the sun. We need to get the NBA to balance their schedule between day and night games or we could either fall into the sun or bounce ourselves out of orbit. Quick someone go secure government funding to fight this pending catastrophy.

We also need an agency set up to study the possible negative impact of all this wasting of gravity. If we are not careful we may exhaust our supply of gravity.


RE: small correction
By Polynikes on 9/21/2007 2:03:55 PM , Rating: 3
Well the NBA season is during the winter months, so most of the games are played at night. Hence, we are being pushed towards the sun! Maybe not quite straight at it, but we're certainly getting closer.


RE: small correction
By Polynikes on 9/21/2007 2:05:52 PM , Rating: 4
I forgot to reply to your comment about gravity. Egads, I had no idea we were running out of it! I'm building a shelter underground so I don't fall off the earth!


RE: small correction
By jak3676 on 9/21/2007 7:54:55 PM , Rating: 5
Here's a quick list we can all follow to start conserving gravity.

1. Just make sure you move all the heavy objects in your house to the floor or to the lowest possible shelf.

2. Don't do any needless jumping (or any exercise for that matter - just do your part by packing on that extra mass so gravity doesn't have to work so hard to keep you to the ground - or at least when we start running out of gravity you'll be one of the last few people flung into outer space.

3. Call/write your congressman and your presidential candidate of choice.

4. The gravity conservation movement really needs a good celebrity spokesperson. Write to all your favorite celebrities to get them involved.

5. We should all start wearing some color of ribbon on our lapels to proclaim to the world that we are serious about our cause. (Anyone know a cheap slave-labor type sweat shop in a 3rd world country that can make us the ribbons for cheap? I'd like to start selling them for personal profit).

p.s. Can someone explain how I get rated up for my first jokes on this topic, then rated down for the 2nd? I know we don't generally have a sense of humor here - but I at least thought we'd be consistent.


RE: small correction
By Spoelie on 9/22/2007 9:26:27 AM , Rating: 3
Because trying too hard to sound funny isn't funny.

And making jokes just to get rated up isn't either :p Not saying you did all that, it's just a general trend: funny post -> lame follow-ups


RE: small correction
By jak3676 on 9/22/2007 12:31:53 PM , Rating: 1
Well I fully except all the blame for my warped sense of humor. It's just weird that one post will go to -1, then the next day it's back up to 5. Good for me we seem to have a pretty fickle readership here - who knows if I could live with myself if I got a negative rating. Unless I'm going to get banned here, you all are stuck with me.


RE: small correction
By Visual on 9/24/2007 3:36:32 AM , Rating: 1
well in fact due to preservation of momentum, it is obvious that no amount of jumping or dribbling or anything in basketball at all can cause a change in earth's motion. if players or balls were floating off into space, yes that would mean a net momentum change for the earth. but if they are returning to a previous position, then they are canceling out their own effect.

but lets not let reality interfere with our jokes, huh? your post still was fun to read :)


RE: small correction
By McTwist on 9/21/2007 1:09:58 PM , Rating: 2
Do you really think this system can be used to launch anything into space? This thing only has a thrust of 35 µN. It says it is scalable but even if you made it one million times bigger to get just 35 N, the laser would be huge and the reflector would have to be much heavier to reflect such a powerful beam. It seems like this thing will be confined to the formation flying missions that the linked articles mention. But even then spacecraft could only push off from each other. Once they push off, how do they stop from drifting further apart? It'll be interesting to read the paper in AIAA Journal.


RE: small correction
By masher2 (blog) on 9/21/2007 1:51:11 PM , Rating: 1
> "Do you really think this system can be used to launch anything into space?"

Not until we can build bigger lasers. That's most likely why Bae is looking at this for attitude control of satellites now.

> "Once they push off, how do they stop from drifting further apart?"

In a satellite formation, they wouldn't impart enough momentum to escape orbit entirely. Just entire to correct your orbital parameters slightly.

Imagine three geosynch satellites spaced around the globe. Each of the 3 could bounce a beam off the other two, lifting all three into a slightly higher orbit, for instance.


RE: small correction
By McTwist on 9/21/2007 2:14:14 PM , Rating: 2
quote:
Not until we can build bigger lasers.

Bigger lasers mean stronger reflectors which means more weight. I'm curious what the trade-off between laser power vs. reflector weight is.
quote:
In a satellite formation, they wouldn't impart enough momentum to escape orbit entirely. Just entire to correct your orbital parameters slightly.

I wasn't talking about trying to escape Earth. This and above is why I don't think you feasibly use this thing to launch spacecraft. That's why I think this is confined to on-orbit operations during formation flying missions.

I like the idea of using this to push a constellation of GEO satellites to a higher orbit though.


RE: small correction
By wordsworm on 9/21/2007 9:38:53 PM , Rating: 2
quote:
Bigger lasers mean stronger reflectors which means more weight. I'm curious what the trade-off between laser power vs. reflector weight is.
hmmm... no engine means lighter weight. I don't know where you got the idea that having a reflector in place of an engine would signify a heavier vehicle.


RE: small correction
By AnnihilatorX on 9/21/2007 2:03:44 PM , Rating: 5
35µN may seem small. But note that this is a constant force

If you can scale it to say 35N, in a week 7 days, assuming mass of a small spacecraft is 1000kg;

Applying a = F / m = 0.035m/s^2
7 days = 7 * 24 * 60 * 60 = 604800 seconds
Initial velocity u = Escape velocity = 11.2km/s
distance travelled = ut + 0.5*at^2 = 11200 * 604800 + 0.5*0.035*604800^2
= 13174963200 metres
= 13174963.2 km

Minimum distance between Earth and Mars is about 100 million km. So not quite there yet. Also, at half way you want to reverse the propulsion to slow down the spacecraft, otherwise you will be a blazing shooting star flying pass Mars at insane speed.


RE: small correction
By McTwist on 9/21/2007 2:32:58 PM , Rating: 2
Thanks for the elementary physics lesson. I do understand that it is a constant force but it would only be constant as long as the laser was able to bounce back and forth between the spacecraft and another body. As the distance grows, this becomes exceedingly hard to do.

Speaking of distances, while the minimum distance between Earth and Mars is more like 80 million km, spacecraft don't move in straight lines to their destinations. Kepler showed they move along paths defined by conic sections. A common interplanetary trajectory would escape from Earth on a hyperbolic trajectory and then appear to be elliptical with respect to the Sun and then approach Mars on another hyperbolic path. This adds a significant amount of time and distance to the flight. Therefore you need to fly farther than the minimum distance.

All this still doesn't change the fact that you aren't going to be able to launch a 1000 kg satellite with a 35 N thruster, which was the point of my original post.