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Photonic Laser Thruster Promises Earth to Mars in a Week

CowboyNeal posted about 7 years ago | from the buckle-up dept.

Space 413

serutan writes "Using lasers to drive spaceships has been a subject of interest for many years, but making a photonic engine powerful enough for practical use has been elusive. Dr. Young Bae, a California physicist, has built a demonstration photonic laser thruster that produces enough thrust to micro-maneuver a satellite. This would be useful in high-precision formation flying, such as using a fleet of satellites to form a space telescope with a large virtual aperture. Scaled up, a similar engine could speed a spacecraft to Mars in less than a week."

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You can't go home again (4, Funny)

Harmonious Botch (921977) | about 7 years ago | (#20599273)

...we fried it duing liftoff.

acceleration? (4, Insightful)

OrangeTide (124937) | about 7 years ago | (#20599283)

What sort of acceleration would that be? Would it be multi G-force worth, that might be impractical for humans.

Re:acceleration? (5, Funny)

scoot80 (1017822) | about 7 years ago | (#20599353)

They didn't say you would get there alive. They just said you would get there in a week.

Re:acceleration? (4, Informative)

Harmonious Botch (921977) | about 7 years ago | (#20599609)

About 1/2 G.

Re:acceleration? (2, Insightful)

chis101 (754167) | about 7 years ago | (#20599655)

Assuming this is a real calculation, does this include slowing down at Mars without killing the people on the spaceship, or is it just 1/2G to *get* to Mars in 1 week?

Re:acceleration? (5, Informative)

Harmonious Botch (921977) | about 7 years ago | (#20599729)

It includes turnaround at the halfway point.

Re:acceleration? (2, Insightful)

iocat (572367) | about 7 years ago | (#20600101)

Getting to Mars is included. Stopping once you get there is an exercise left to the reader. Seriously though, TFA (or TFPressRelease) first had me skeptical, since it's Dr. Bae of the Bar Institute claiming to have done something no one's even done before (I got that cold fusion feeling). But it's getting published in a peer-reviewed journal, so... man, sounds kind of impressive.

Re:acceleration? (5, Informative)

Score Whore (32328) | about 7 years ago | (#20599881)

Half a G will get you way further than Mars in a week. The greatest distance between Earth and Mars is 391 million Km. Assuming you're going to go constant acceleration half way and constant acceleration in the other direction the second half of the trip, 1/2 G acceleration will get you 897 million Km end to end in seven days.

If you don't mind going through the Sun, that 1/2 G will get you Earth to Jupiter, in the worst geometry possible, in seven days and one hour and thirty minutes.

Re:acceleration? (1)

Harmonious Botch (921977) | about 7 years ago | (#20600067)

Whoops! You're right. I should check my figures before posting...

Re:acceleration? (0)

Anonymous Coward | about 7 years ago | (#20599769)

Do not stare into Photonic Laser Thruster with remaining eye....

That doesn't necessarily matter (1)

Rix (54095) | about 7 years ago | (#20599361)

Even ignoring the use for robot probes, extended manned missions will still need supply drops.

Re:acceleration? (3, Funny)

ozmanjusri (601766) | about 7 years ago | (#20599481)

Would it be multi G-force worth, that might be impractical for humans.

Forget humans.

How much faster will my shark go with this thing bolted to it's head?

Re:acceleration? (4, Interesting)

AKAImBatman (238306) | about 7 years ago | (#20599487)

As I recall, the computations for reaching Mars in a week were predicated on One-G acceleration. i.e. Earth normal gravity for a ship in transit. To slow down, you simply spin the ship at the halfway point and accelerate in the opposite direction.

If (and I stress *if*) this invention is not so much hyperbole, it could change the face of space travel forever. We could build interplanetary starships (in this context, ships that never land on a planet) that would be limited only by their power-generation capabilities and not by their reactive fuel. Which means that we could build a ship with a large nuclear powerplant on board, and it could cruise the solar system for as long as its Uranium/Plutonium fuel held out.

Of course, we still need to solve the problem of high cost of launch, but that little issue would be easier to solve if we actually had somewhere to go once we got in orbit. Scaling up the number of launches would almost certainly bring the price per launch down. In fact, the reason why the Space Shuttle never reached its promised price-per-kilo is because it was predicated on regular launches that never materialized. Starships could change all that. Especially if the cost of moving personnel and equipment was marginalized by carrying more of them per trip.

For example, I always figured that a special module could be fitted to the Shuttle's cargo bay to carry as many as 60 people to the ISS. Given that the Shuttle has to be man-rated for flight, carrying people makes a lot more sense than hauling around equipment that's better served by a Delta or Atlas rocket.

How exciting! And probably too good to be true.

Re:acceleration? (1)

Inmatarian (814090) | about 7 years ago | (#20599819)

Good thing about the 1G acceleration rate is that it provides for a comfortable flight experience for the passengers. Having to turn the ship at the halfway point and decelerate seems like too delicate of an operation. Wouldn't it be better to just build a second engine at the "front" of the ship and tell everyone to get in their seats during the switch over? In fact, the design of such a personnel carring vessel would probably place the nuclear reactor at the center between the two engines with the passenger areas arranged in a cylinder and connected by some spokes. It'd probably look like a crazy space bicycle wheel.

Re:acceleration? (1)

Hucko (998827) | about 7 years ago | (#20600097)

Not really because then you need to build the ship twice, designed for both directions. With small chemical rockets (retro rockets) you can spin the ship around the centre of gravity as a pivot point. Shouldn't be all that more difficult than calculating slingshots and other maneuvers.

A better Idea(tm) would be to have another laser on the Mars end, so it is easier to line up. However I imagine the principle of achieving this with a solitary Earth (orbit?) laser (an array?) would be similar to 'tacking' for sailing ships.

Damn, now I'm going to read the article... :s

Re:acceleration? (1)

scoot80 (1017822) | about 7 years ago | (#20599875)

Does this mean a constant One-G acceleration until you get half way and then decelerate? That might be a tad uncomforable?

Re:acceleration? (5, Funny)

Hucko (998827) | about 7 years ago | (#20600015)

Do you currently find 1G uncomfortable?

Re:acceleration? (5, Insightful)

scoot80 (1017822) | about 7 years ago | (#20600055)

That was funny, I'll give you that one. I am an idiot.

Re:acceleration? (1)

Alaria Phrozen (975601) | about 7 years ago | (#20600043)

Did somebody say hyperbolic space time chamber?

"The gravity here is ten times that of Earth!"

"Maybe if it was 500 times gravity you MIGHT have a chance, but ten times? I don't even feel it."

Re:acceleration? (2, Informative)

Score Whore (32328) | about 7 years ago | (#20599761)

It seems likely that it would be quite a small amount of thrust, it's photons that you are "pushing" against. Even on the big engine.

The important thing is that it'll accelerate all the way there. With continuous acceleration it doesn't take much to get going really fast.

According to the article Mars is 100 Million km away and a big version of this will travel that in a week. We'll assume that you want to stop when you get there so just figure half the trip in half the time (since the second half will be braking):

50,000,000 Km = a * (302400 sec) ^ 2

a = .0005467722 Km/s^2

Acceleration due to gravity is 9.81 m/s^2, or 0.00981 Km/s^2. So he's talking about 1/18th G acceleration. Speed at turnover will be: .0005467722 Km/s^2 * 302400 sec = 165 Km/s.

Whee!

Of course it's more complicated than that since that low of an acceleration won't get you off the ground. So you'll be starting your trip in orbit. Which means you've got to take some time to get to a high enough orbit that you can accelerate away from the earth without having to do lots of high thrust maneuvers. Still, you can probably plan on Mars in a month.

Re:acceleration? (5, Funny)

E++99 (880734) | about 7 years ago | (#20600125)

His demonstration thruster produces 35 micronewtons.

35 micronewtons / .0005467722 Km/s^2 = 64 milligrams, so if we were using this to power a marscraft with the mass of the acetominophen contained in a single extra strength tylenol tablet, it would be more than 10x too heavy. Of course they said it could be scaled up, but that's a heckuvalot of scaling.

I doubt the smallesst possible manned Mars vehicle could be less than 1,000kg. That's a scaling factor of 15.6 million. I can jump over 3 feet on the trampoline in my back yard, which translates to a maximum velocity of 4.23 m/s. If I scale that up by 15.6 million, I would be launching myself at 66,000,000 m/s, far exceeding escape velocity, and reaching Mars under my own power in under 30 minutes.

Earth calling CowboyNeal, come in (-1)

Anonymous Coward | about 7 years ago | (#20599427)

Earth calling CowboyNeal, come in.

IMPULSE DRIVE (2, Funny)

Anonymous Coward | about 7 years ago | (#20599985)

Hooray! They've finally discovered how to make an Impulse Drive engine. Now all they have to do is tie in a fusion reactor and voila! sublight speed! I'm just kidding. I didn't RTFA.

you know it's coming (-1, Offtopic)

syrinx (106469) | about 7 years ago | (#20599285)

Can we put this frickin' laser on a shark?

How "scaled up" is this? (3, Interesting)

jandrese (485) | about 7 years ago | (#20599291)

Are we talking about "accidentally cut Venus in half" scaled up? Typically the downside of photonic thrust has been the low power to weight ratio, so for a laser powerful enough to propel a ship to Mars (don't forget that it has to both accelerate and decelerate) that fast I have to wonder just how powerful the laser has to be.

Re:How "scaled up" is this? (5, Funny)

Mothinator (1103295) | about 7 years ago | (#20599301)

It only says it can get the spacecraft to Mars in a week. It does claim to be able to stop once it gets there.

Re:How "scaled up" is this? (5, Funny)

Dachannien (617929) | about 7 years ago | (#20599337)

Actually, it says that it can get the spacecraft to Mars in a week and can stop once it gets there. But it doesn't claim that anyone will survive the impact.

Re:How "scaled up" is this? (5, Funny)

MrNaz (730548) | about 7 years ago | (#20600103)

Survival isn't necessary. Just get your ass to Mars. G-G-Get your ass to Mars.

Re:How "scaled up" is this? (5, Funny)

azenpunk (1080949) | about 7 years ago | (#20599505)

nasa knows how to stop things at mars, that's easy. (think: "feet, meters, same difference")

Re: Metric Joke (5, Informative)

Telephone Sanitizer (989116) | about 7 years ago | (#20599791)

A harsh lesson that I have learned here...

If you're going to make a lame joke, at least include a cite so there's a chance of getting modded up as "informative."

The Mars Climate Orbiter:
http://en.wikipedia.org/wiki/Mars_Climate_Orbiter [wikipedia.org]

"The Mars Climate Orbiter was intended to enter orbit at an altitude of 140-150 km above Mars. However, a navigation error caused the spacecraft to reach as low as 57 km. The spacecraft was destroyed by atmospheric stresses and friction at this low altitude. The navigation error arose because a NASA subcontractor (Lockheed Martin) used Imperial units (pound-seconds) instead of the metric units (newton-seconds) as specified by NASA."

Re:How "scaled up" is this? (3, Insightful)

dethl (626353) | about 7 years ago | (#20599327)

I would think that scaling wouldn't make the laser bigger but would instead use multiple lasers like they do with ion engines. Of course, IANARS (I am not a rocket scientist) so take what I say with a big grain of NaCl.

Re:How "scaled up" is this? (2, Interesting)

Lloyd_Bryant (73136) | about 7 years ago | (#20599469)

Are we talking about "accidentally cut Venus in half" scaled up? Typically the downside of photonic thrust has been the low power to weight ratio, so for a laser powerful enough to propel a ship to Mars (don't forget that it has to both accelerate and decelerate) that fast I have to wonder just how powerful the laser has to be.
If you RTFA, you'll note that the quote about reaching Mars in a week doesn't mention anything about a manned mission.

The real question: how the hell are they going to power this laser? For micro-thrusts for satellites, solar panels are fine, but for an interplanetary trip you'd need something like a nuclear reactor (unless that "interplanetary vessel" consisted of a mass of solar panels and a payload about the mass of a postage stamp).

I'd classify this one as just more hype about a technology with an, at present, very limited usefulness. Maybe at some point in the future the human race may use something like this on a large scale. But for now, don't hold your breath.

I guess I don't get... (1)

markov_chain (202465) | about 7 years ago | (#20599765)

...how the momentum is somehow created. Doesn't the sunlight absorbed during power generation cancel the laser output?

Re:I guess I don't get... (1)

MadnessASAP (1052274) | about 7 years ago | (#20599809)

As long as the solar panel is black and energy that isn't turned into electricity goes towards heating up the panel, Are you maybe thinking of a solar sail? If the panel was white and pointed towards the sun you could get a tiny amount of thrust that way but I suspect at loss of efficency in generating power.

Re:I guess I don't get... (3, Informative)

arivanov (12034) | about 7 years ago | (#20599867)

No. The momentum gathered from sunlight points in one direction, the laser in another and you are going wherever the vector sum leads you.

Re:How "scaled up" is this? (1)

shaitand (626655) | about 7 years ago | (#20599961)

'The real question: how the hell are they going to power this laser? For micro-thrusts for satellites, solar panels are fine, but for an interplanetary trip you'd need something like a nuclear reactor'

Didn't you just answer your own question. I'm pretty sure we managed nuclear technology at some point.

Power = Thrust * Exhaust Velocity (5, Insightful)

roystgnr (4015) | about 7 years ago | (#20599489)

To send a ship to Mars in a week, Thrust should be roughly 10m/s^2 times the ship's weight, which we'll say is only ten metric tons. (Because we're getting there in a week, we can pack light... pack light, get it? I slay me.) That gives us 10^5 Newtons of thrust.

Exhaust Velocity is the speed of light, or about 3*10^8 m/s.

So our power consumption is 3*10^13 Watts.

By comparison, the USA is currently consuming less than 1*10^13 Watts on average.

In other words, if think you think it costs too much to refuel an RV now...

It's not completely implausible to use light to propel a spacecraft, but either that propulsion will be ridiculously slow (e.g. solar sails, laser sails, or the "precisely tweak your satellite's orbit a tiny bit" applications mentioned in the article), or it's going to require ridiculous "cheap antimatter" amounts of energy.

Minor correction (3, Insightful)

Harmonious Botch (921977) | about 7 years ago | (#20599673)

To get to Mars in a week, only about 5m/s^2 is necessary. ( Mars at 1G is about 3.5 days, so a week is 1/2 G, turnaround halfway )
So call it a mere 1.5*10^13 watts.

Re: Minor correction (0)

Black Parrot (19622) | about 7 years ago | (#20599787)

Mars at 1G is about 3.5 days, so a week is 1/2 G, turnaround halfway
Don't mistake acceleration for velocity.

Re:Power = Thrust * Exhaust Velocity (2, Interesting)

Beryllium Sphere(tm) (193358) | about 7 years ago | (#20599795)

Thrust is the derivative of momentum with respect to time, and momentum is conserved, so in an open-loop drive F=dp/dt=d/dt(E/c)=(1/c)dE/dt, so power (dE/dt) is force times C.

But here's where the novel part comes in. Every photon is bounced back and forth thousands of times between the spacecraft and a mirror. The mirror experiences the same force as the spacecraft but in the opposite direction. The spacecraft's momentum comes from "pushing against" the mirror, rather than "pushing against" the exhaust photons.

For every photon with momentum E/c, the spacecraft gets a momentum kick of E/c when it emits the photon, 2E/c when the photon bounces off it again after a round trip to the mirror, 2E/c again on the next round trip, and so on until the limits of the optics lose the photon out into space. If the drive could really deliver the thousands of photon reuses Dr. Bae talks about, then the power requirements drop to more like 1E10 watts.

OK, fitting that into ten metric tons means we still need antimatter.

Re:How "scaled up" is this? (3, Interesting)

Nefarious Wheel (628136) | about 7 years ago | (#20599861)

You could make a laser out of water ice in orbit to any size using fusion purification and rotation of the billet, doping with chromium or rare earths as you go. Thermal mass should keep it solid enough to pipe light through, and if it's long enough you could add energy slowly enough to pump it to some pretty fantastic numbers of photons before the coherent beam left the less-reflective mirror. Fifty metre aperture? Kilometer in length? Mine the ice from the rings of one of the gas giants and use shaped solar reflectors. You could use silicon too, I imagine, but I like ice because it's cool. Plentiful, too, once we evolve past the point of STS and SFS (Space Food Sticks).

Re:How "scaled up" is this? (2, Funny)

dwywit (1109409) | about 7 years ago | (#20600049)

Moties, here we come!

Re:How "scaled up" is this? (2, Interesting)

kocsonya (141716) | about 7 years ago | (#20600091)

> ... I have to wonder just how powerful the laser has to be.

Well, you can do a back-of-the-envelope calc easily. The mass of the ship is, let's say, about 10 tons or 1E4 kg. You want a 1g acceleration, or about 10 m/s^2 all the way. Assuming a laser with 500nm wavelength a photon leaving will give you an impulse of h/lambda, that is, 6.6E-34 / 5E-7 ~ 1E-27 kg*m/s. Your craft needs to get 1E5 kg*m/s impulse per second to maintain its acceleration, which is then roughly 1E32 photons per second. An 500nm photon has the energy of h * c / lambda, 6.6E-34 * 3E8 / 5E-7 that is ~ 4E-19 J. Thus, all together you need about 4E13 Watts of power, if you have a 100% efficient laser. Now that's about 40TW. Considering that the US produces 4TWh electricity in a year and that a year is about 8760 hours long, you need a power source that is approximately 90 thousand times as powerful as all the power stations of the US put together and it has to fit snugly in your 10 ton rocket, including the fuel. The latter is not as bad as it sounds: if you generate the power by 100% efficient matter-antimatter annihilation the required 40TW power output only needs about a quarter of a gram of each per second, so for a 1-week trip, which is roughly 600,000 seconds, you can get away with about 150kg of each.

So, unless I did a gross miscalculation (entirely plausible) the 1-week Mars flight seems to be a bit out of the realm of reality yet.

All a matter of scale... (5, Insightful)

Microlith (54737) | about 7 years ago | (#20599315)

And if scaled up, cockroaches run at 800mph and fleas could jump over a mile. However, the increase in mass and energy requirements would make it impossible.

Small scale thrusters using only lasers is a good start, but we'll have to see what else gets bigger with scale, other than just the thrust.

Re:All a matter of scale... (4, Funny)

iamhassi (659463) | about 7 years ago | (#20599397)

"we'll have to see what else gets bigger with scale, other than just the thrust."

That's what she said ;)

Re:All a matter of scale... (0)

Anonymous Coward | about 7 years ago | (#20599513)

best thing i've read all day...

tho thats not very hard, im east coast and it's only been today for the past 55 minutes or so.

Re:All a matter of scale... (1)

rucs_hack (784150) | about 7 years ago | (#20599879)

Small scale thrusters using only lasers is a good start, but we'll have to see what else gets bigger with scale, other than just the thrust.

For one thing, if the laser gets big enough to reach Mars, imagine what size the frickin shark will be...

Re:All a matter of scale... (1)

WindowsIsForArseWipe (990338) | about 7 years ago | (#20600035)

Sorry to point out you have a bug in your sig it should be (\_/) (x.x) teh (>I) supar horney ascii bunny

The Warriors (4, Interesting)

PresidentEnder (849024) | about 7 years ago | (#20599325)

At least now we'll have a way to beat the Kzinti [wikipedia.org] when we make first contact.

Re:The Warriors (1)

Visceral Monkey (583103) | about 7 years ago | (#20599617)

Ahh, so glad I'm not the only one who thought about this when I saw it!

Re:The Warriors (1)

texlan (1136601) | about 7 years ago | (#20600047)

ditto. I immediately saw the smoking fur. Kitties always liked it darker, anyways.

"Scaled up".... (1)

mark-t (151149) | about 7 years ago | (#20599329)

And in response to those two words, I have these eight: "a whole friggin' lot easier said than done".

<sarcasm>Yup... it's just a matter of scale. </sarcasm>

I smell bullshit (4, Interesting)

Rix (54095) | about 7 years ago | (#20599335)

The Bae Institute was founded in 2002 by Dr. Young K. Bae
In other words, no existing institution would accept the good doctor, so he made his own, and issued a press release written in false third person.

Do you really want to smell something? (-1, Troll)

Anonymous Coward | about 7 years ago | (#20599409)

Even faster than the "Photonic Laser Thruster", is the magical flying monkies from Dr. Bae's butt - let's say he is about 160lbs, and each monkey is about 40 lbs - that is some force!

Since they are magical, there is an infinite supply, so, yeah, a week to Mars is no problem.

Re:I smell bullshit (1)

lordvalrole (886029) | about 7 years ago | (#20599623)

Or he wanted fame and fortune. Which is why a lot of people start their own businesses, institutes, etc.

There is a damn reason why our government and top aerospace engineers are looking into this. Maybe because it's credible and you have no clue how his device works.

Re:I smell bullshit (4, Informative)

s4m7 (519684) | about 7 years ago | (#20599865)

In other words, no existing institution would accept the good doctor, so he made his own, and issued a press release written in false third person.
http://www.photonics.com/content/news/2007/September/7/88894.aspx [photonics.com]

Bae founded the institute to develop space technologies and has pursued concepts such as photon, antimatter and fusion propulsion for more than 20 years at SRI International, Brookhaven National Lab and the Air Force Research Lab. He has a PhD in atomic and nuclear physics from UC Berkeley. Several aerospace organizations have expressed interest in collaborating with the institute to further develop and integrate PLT into civilian, military and commercial space systems, Bae said, and he has recently been invited to present his work by NASA, JPL, DARPA and the Air Force Research Laboratory (AFRL).

Re:I smell bullshit (2, Informative)

Rie Beam (632299) | about 7 years ago | (#20599925)

His website [baeinstitute.com] doesn't exactly inspire confidence, either

Bae Institute is a unique institute dedicated to creating revolutionary technologies for the next generation space and medical endeavors, yet aiming at facilitating their rapid implementation and commercialization. For that reason, we specialize in applying highly focused proven technologies to innovative solutions, thereby reducing development time while improving the viability of practical applications. An important goal of the Bae Institute is the commercialization of our innovative and revolutionary technologies. By licensing our unique intellectual properties, launching commercially viable companies, or by partnering with existing companies - we hope to quickly bring proven solutions to market.

Re:I smell bullshit (2, Interesting)

Rie Beam (632299) | about 7 years ago | (#20599981)

Bae also does Acupuncture research [medicalacupuncture.org] , if that reflects on him in any way. NASA saw him fit enough to give him a grant [photonics.com] , however.

I don't know what to make of this guy. He doesn't seem like a quack, but I really don't know enough about the subjects to know if what he's spewing is genius or something else entirely.

Re:I smell bullshit (2, Insightful)

dbIII (701233) | about 7 years ago | (#20600113)

MIT also has a website for a materials science group promoting the idea of ridiculous superhero underwear (ridiculous because being able to spread the energy of impacts is how bullet proof stuff is made so nanometre thick stuff is not going to solve the problem on it's own) that none of their students would believe past first year. Loud Lysenkoism is how things are done these days even if the people actually doing the stuff are legit. We really need work on the K-12 education system because that is all our decision makers are really going to get, and currently snakeoil scams are attracting a lot of serious attention from poeple that we would hope would know better.

Re:I smell bullshit (2, Insightful)

suv4x4 (956391) | about 7 years ago | (#20599931)

In other words, no existing institution would accept the good doctor, so he made his own, and issued a press release written in false third person.

On the other hand even the current institutions started as someone creating them at some point.
And quite a lot of scientists were ridiculed by the establishment at a time they made a revolutionary discovery.

What worries me more is his unsubstantiated "if we just scale it up" argument. That doesn't stand basic math/logic/physics.

Star Trek anyone? (1, Funny)

thatskinnyguy (1129515) | about 7 years ago | (#20599345)

Wasn't the Photonic Thruster invented by Gene Roddenberry?

Re:Star Trek anyone? (2, Informative)

Short Circuit (52384) | about 7 years ago | (#20599563)

I don't believe it was mentioned in TOS. However, 1970s scifi books used it. (Notably The Mote in God's Eye).

not this again (1, Troll)

ILuvRamen (1026668) | about 7 years ago | (#20599349)

Anyone know why they keep trying to make extremely super low energy particles and modes of movement into rocket thrusters? If you turn on a flashlight or laser pointer, do you go flying backwards from the kick back? How about if you light off a flashlight sized model rocket motor while holding it? I mean seriously, if they'd been focusing on technologies that are traditionally used to create thrust instead of seeing how they can trick the weakest possible thrust methods into working as an engine, I'd be posting this FROM MARS! This is almost as bad as that giant million mile wide solar sail thing that was supposed to capture the forward energy from particles that barely qualifiy as mass. Oh here's an idea, why don't they take a billion of those little handheld electric fans and try and thrust it out of our atmosphere with that. One of them creates more thrust in an atmoshpere than the equal volume of photon's for God's sake.

Lasers are better with Photons... (4, Funny)

fahrbot-bot (874524) | about 7 years ago | (#20599373)

Photonic Laser Thruster

Muuuuch better than using those LASERS without Photons.

[I hear that adding the photons also makes them lighter...]

Re:Lasers are better with Photons... (0)

Anonymous Coward | about 7 years ago | (#20599449)

Of course don't forget to hang a mirror off the back of the laser rocket for those photons to reflect off of or it's not going anywhere...

right?

anyone?

Re:Lasers are better with Photons... (3, Funny)

markov_chain (202465) | about 7 years ago | (#20599503)

Guys, stop making light of this invention! I'm sure Dr. Bae is a perfectly bright young man.

Re:Lasers are better with Photons... (2, Funny)

Anonymous Coward | about 7 years ago | (#20599561)

Of course don't forget to hang a mirror off the back of the laser rocket for those photons to reflect off of or it's not going anywhere...

Newton's Third Law of Motion would like to have a word with you.

Re:Lasers are better with Photons... (1)

bar-agent (698856) | about 7 years ago | (#20600045)

I hear that adding the photons also makes them lighter...

I still says it's because of the R-type stickers we slapped on that bad boy.

Can we rename Constellation to Galactica? (1)

tjstork (137384) | about 7 years ago | (#20599379)

Hell, with that kind of ISP, why even explore Mars, when we can INVADE IT!

Another sleasy patent though! (1)

tjstork (137384) | about 7 years ago | (#20599395)

Why is he getting a patent ... for something the government funded!

Re:Another sleasy patent though! (0)

Anonymous Coward | about 7 years ago | (#20599453)

Because the law allows it? It's pretty common in the sciences, though most universities end up with the patents. Look at it this way, it still requires a lot of development, which costs money. Without a patent protecting things, Party A could go through the cost and effort of designing and testing a working model only to have Party B come along and make a cheap knock off without the development costs. In that scenario, it's probably that no one will take the time to create the product.

Energy source? (4, Insightful)

StefanJ (88986) | about 7 years ago | (#20599435)

Where is the energy coming from to create those photons?

Since you're dealing with a photon drive, the reaction mass usage (as determined by the classic rocket equation) is going to be negligible for the speeds required for interplanetary travel.

In fact, I'm not sure what the reaction mass would be in this case.

But in any case, you're going to need a lot of energy to create that photon thrust. Great phrigging big reactors, which means great, great, phrigging big radiators since you don't have the luxury of a river to carry away your waste heat.

Antimatter might be a compact way to store the required energy, but converting the gamma rays from matter/antimatter reactions to electricity is going to require heat exchangers and great big radiators as well.

Well, anyway, scaling this up is going to involve several bears of a problem.

Also, please note that this "article" is a press release from the guy who made the invention.

Re:Energy source? (5, Interesting)

Arabani (1127547) | about 7 years ago | (#20599597)

I did quite a bit of reading on spacecraft propulsion recently (specifically Nuclear pulse propulsion [wikipedia.org] and basically what I got out of it is that if you have a massive energy source (say, antimatter) you're better off just blowing it up and riding the blast wave. You can get extremely high thrust AND specific impulse that way, which is not possible with almost any other engine technology (either high thrust and low specific impulse like chemical rockets, or low thrust and high specific impulse like ion engines). NPP (and its derivatives) is basically the best way we know of right now to get high enough performance for interplanetary, or even interstellar, missions.

NPP originally started with using nuclear explosions, but more recent research has focused on inertial confinement fusion and even antimatter-catalyzed fusion. The obvious extreme is using antimatter-matter detonations and riding the blast wave, which I'm fairly certain would be more efficient and yield better performance than taking that energy and pumping it into a laser.

Re:Energy source? (1)

AKAImBatman (238306) | about 7 years ago | (#20599635)

Antimatter might be a compact way to store the required energy, but converting the gamma rays from matter/antimatter reactions to electricity is going to require heat exchangers and great big radiators as well.

Why bother? A graser [wikipedia.org] is practically the same thing as a laser, so just focus the output of the reaction into a semi-cohesive beam. It doesn't have to be fully coherent as long as it exits the vehicle in the direction of thrust.

Of course, antimatter engines have been on the drawing board for decades. The key issue is actually storing enough antimatter to make the trip possible. Until that problem is solved, we're still looking at far longer trips than the article promises. Even a fission reactor is unlikely to produce enough energy to make a one-week trip to Mars feasible. Maybe a month with sufficient thrust and nuclear materials. I'd have to crunch the numbers to give you a better answer. Something which I'm terribly rusty at.

Re:Energy source? (3, Interesting)

zippthorne (748122) | about 7 years ago | (#20599675)

Since you're using photon pressure, the reaction mass is zero. With sufficient energy, you could travel anywhere in the universe. But unfortunately, Thrust = Power / speed of light.

Even a 1 Newton thruster requires 300 MW at 100% efficiency.

You've gotta scale up the power plant to get more thrust, and it's already going to be pretty massive (I believe that puts it on the order of a medium sized commercial nuke plant.) so I just don't see you reaching Mars in a week. Proxima Centauri in a lifetime, perhaps, but no way on the mars thing.

Of course, since he's talking about a laser, it's possible he means to have the equipment on the ground (or moon, or earth orbit) and propel a much smaller craft. With sufficiently focused optics, you could propel a small probe the whole way to mars (in a week? My envelope just ran out of space...), though it would require some pretty heat-resistant mirrors. Fortunately, the energy requirements for that Newton drop by half when you factor reflection into the equation.

OK, I'm game.. (1)

Anonymouse Cow-Orker (1156595) | about 7 years ago | (#20599445)

But they hafta promise me a headrest on the seat-back.


Incredible (1)

gardyloo (512791) | about 7 years ago | (#20599465)

"Dr. Bae's PLT demonstration and measurement of photon thrust (is) pretty incredible. I don't think anyone has done this before. It has generated a lot of interest."
Mead must have meant "incredible" in its proper, older use.

Snakes..... (0, Offtopic)

trouser (149900) | about 7 years ago | (#20599467)

.... on a motherfucking Photonic Laser Thruster. I'm not reading the article and I don't give a shit who wants to thrust what where but that wins my award for the best name ever in the history of technology that might facilitate STL interplanetary travel. Snakes. Fuck yeah.

perpetual motion (0)

Anonymous Coward | about 7 years ago | (#20599483)

This chap has been around for some time; no one takes his drive
seriously for good reason. Guess he's putting out his own press
releases.

Scaled up huh :P (1)

suv4x4 (956391) | about 7 years ago | (#20599495)

I don't want to be skeptical, but...:

Scaled up, a similar engine could speed a spacecraft to Mars in less than a week.

Right, just like a scaled up ant could carry a house. In movies.

But as any junior engineer knows, you can't just scale things up linearly and expect linearly scaled integrity and results.

In other words, there are solar powered toy cars out there [siliconsolar.com] . But math and physics prevent us from simply "scaling" this up to drive actual cars with linearly scaled up speeds.

The "Prius of Space" (1)

sighted (851500) | about 7 years ago | (#20599509)

Meanwhile, it's old-fashioned ion engines for an asteroid mission scheduled for launch later this month, Dawn [nasa.gov] , which NASA has now taken to calling "The Prius of Space [nasa.gov] ."

Scaling up is fun (4, Funny)

suv4x4 (956391) | about 7 years ago | (#20599549)

I wonder why we don't just scale up a bridge right to Mars and drive to there with a drag racer car. If the latter is too slow, I suppose no problem, we can scale it up as necessary.

Solar system escape velocity! (0)

Howzer (580315) | about 7 years ago | (#20599559)

...a similar engine could speed a spacecraft to Mars in less than a week.

Assuming you had another one on Mars to slow the thing down!

Let's assume they mean Earth to Mars in a week at their closest to each other (approx. 50 million kms). That's an average speed of approx. 300,000 km/h, or 80 km/s. Presumably the speed at the mid-point would be even higher. So anyone riding the spacecraft better hope that there isn't a malfunction of the "slowing down" laser at the other end, as depending on the angle, that might be enough to exit the solar system altogether!

Re:Solar system escape velocity! (2, Insightful)

tftp (111690) | about 7 years ago | (#20599631)

Presumably the speed at the mid-point would be even higher.

Twice the average speed if you want constant acceleration.

Re:Solar system escape velocity! (2, Interesting)

Howzer (580315) | about 7 years ago | (#20599663)

Twice the average speed if you want constant acceleration.

Bingo! 160 km/s somewhere between Earth and Mars absolutely qualifies as solar system escape velocity! I'm a little rusty, but isn't it 400 km/s from the surface of the sun, and around 15 km/s out past Pluto? Voyager II was doing 16 km/s when it left the building...

Re:Solar system escape velocity! (4, Informative)

AKAImBatman (238306) | about 7 years ago | (#20599703)

So anyone riding the spacecraft better hope that there isn't a malfunction of the "slowing down" laser at the other end, as depending on the angle, that might be enough to exit the solar system altogether!

The article calls this a "Photon Thruster". What that means is that the device would be mounted on the vehicle as a thruster rather than the vehicle "riding" a laser-beam like in Beam-powered propulsion [wikipedia.org] . So as long as the laser restarts after you flip the ship, you're good to go.

Note that this is a separate issue from powering a laser cluster large enough to reach Mars in a week...

Fresh from the doctor via PR Newswire via NewsEdg (0)

Anonymous Coward | about 7 years ago | (#20599565)

9/6/2007 4:20:33 PM --- PR Newswire

Photon Propulsion Breakthrough Could Cut Mars Transit From Six Months to a Week

PR Newswire via NewsEdge Corporation :


Well, great to see that PR Newswire has branched out. They're not just about scientology scams and scientology front group scams, anymore.

promises Earth to Mars? (1)

Doppler00 (534739) | about 7 years ago | (#20599577)

So the Martian alien invasion IS imminent.

35 micro Newtons? (1)

Mr Z (6791) | about 7 years ago | (#20599605)

The article says he achieved thrust of 35 uN. 35 micro Newtons? That's a lot of "up" to scale into.

Re:35 micro Newtons? (1)

Enderandrew (866215) | about 7 years ago | (#20599737)

I tried figuring micro Newtons to Fig Newtons and couldn't, but I figured it was one of those wacky English/metric calculations NASA is so good at, so I'll leave it to them. Oh, those wacky NASA mathematicians! Friends don't let friends drink and derive!

And if Volkswagen engineering taught us anything, if you can launch a Fig Newton into space it becomes farfegnugen.

Misread the article title (0)

Anonymous Coward | about 7 years ago | (#20599733)

Damn. I read the title as

"Pontiac Laser Thruster Promises Earth to Mars in a Week"

I think I need to get help.

Incredible! (3, Funny)

Riktov (632) | about 7 years ago | (#20599783)

Senior Aerospace Engineer at AFRL, Dr. Franklin Mead, "Dr. Bae's PLT demonstration and measurement of photon thrust (is) pretty incredible. I don't think anyone has done this before. It has generated a lot of interest."

Perhaps the demonstration would generate even more interest if it were credible.

"Invention" (0)

Anonymous Coward | about 7 years ago | (#20599845)

"In contrast, Bae's patent-pending PLT breakthrough places the laser medium within a resonant optical cavity between two platforms to produce a very stable and reliable thrust that is unaffected by mirror movement and vibration -- ideal for spacecraft control or propulsion."

Ummm... yeah the laser gain medium is ALWAYS inside a resonant optical cavity. That's what makes it a fricken LASER.

Whatever "between two platforms" means is completely unexplained.

Scale. (3, Interesting)

Rie Beam (632299) | about 7 years ago | (#20599873)

The problem with all of this is scale, right? The energy required to send larger and larger objects would be impractical.

So, what's the smallest thing we can send, then? How small can we make a satellite that can send some information back?

It may not be useful for transporting people to the other end of the universe in a practical amount of time, but I'm sure sending a probe that can check up on Mars every week or so would be of some sort of slight interest to researchers...

Of course, there's the issue of the touchdown...

Re:Scale. (2, Funny)

Admiral Justin (628358) | about 7 years ago | (#20599969)

Not really, NASA has perfected slamming things into Mars. We're quite good at it.

Remember the lightcraft? (1)

GodfatherofSoul (174979) | about 7 years ago | (#20599995)

I took a space tech studies class eons ago at Rensselaer Polytechnic Institute from a guy named Leik Myrabo. He was working on a terrestrial laser powered spacecraft (I think his book was named The Future of Flight. Basically, you fire a laser at a mirrored ship that reflects the beam and heats air to produce thrust. When I took the class he wanted the lasers to be mounted on satellites, then he started working with ground-based designs. I looked up his research a while back and wasn't able to find anything new (I'm guessing the research hit a wall). There's a video of a small demo model being shot up, but I'm too lazy to track it down again.

The really interesting thing about his class though was that the previous summer he was out in the desert somewhere doing research for the government. Several times he became absolutely convinced that he had seen UFOs. So, about 1/3 to 1/2 of the class was spend on UFOs and he even brought in "expert" guest speakers. A lot of the evidence looked very credible, but "seeing is believing" as they say.

The BAE Institute (2, Interesting)

Rie Beam (632299) | about 7 years ago | (#20600013)

His institute seems to have a lot of promising ideas, but no real substance. It has three major projects, one of which relies on the photon thruster and some kevlar straps to toss around satellites, and some sort of undeveloped nano-microscrope.

http://www.baeinstitute.com/ [baeinstitute.com]

Bullshit, I indeed smell.

My first question (1)

artifex2004 (766107) | about 7 years ago | (#20600079)

How do you get those satellites to slow down, later?

With all due respect to James Doohan... (5, Funny)

Spasmodeus (940657) | about 7 years ago | (#20600117)

Scaled up, a similar engine could speed a spacecraft to Mars in less than a week.
Aye. And if my grandmother had wheels, she'd be a wagon.
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