Photonic Laser Thruster Promises Earth to Mars in a Week

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."

Comments

acceleration?

[OrangeTide]

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

Re:acceleration?

[scoot80]

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

Re:acceleration?

[i_b_don]

actually there is another problem with this concept besides the extremely wasteful "building a second engine" part. Think about crew quarters... if you've got 1G acceleration you've got a floor and a ceiling. If you just reverse directions of the engines without spinning the craft you now swap what is your floor and what is your ceiling. Makes for some interesting redecorating, but not really vary practical. It makes MUCH more sense from an engineering point of view to spin the ship. It's easier and more efficient.

d

Re:acceleration?

[Sunburnt]

Both of these could reasonably considered informative, however the second is likely untrue, since in my experience idiots are quite likely to be the last to realise

Remember, there's a big gap between "likely untrue" and "always untrue." When someone can look at their own statement, realize what it implies about their capacities, and then confidently declare "I am an idiot," they are displaying insight that is well above average, and certainly deserving of mod points.

I, for one, welcome our new self-insight-possessing commenters.

have I accidentally logged into some kind of bizarro-Slashdot, where everyone is polite and respectful? And is there a way of making sure I don't accidentally end up on the other one again?

Staying out of the Politics and YRO threads may reduce your vitriol exposure by as much as 300%. Ask your doctor!

*Disclaimer: poster is a frequent and vitriolic contributor to Politics and YRO threads.

Re:acceleration?

[ultranova]

Or are moderators now giving karma to people who admit their errors?

Well, since this is a science article, let us use the awesome power of experimental empirical experiments to research the issue:

I'm an idiot, so mod me up !

BTW. Isn't "photonic laser" a bit redundant - the "l" in laser stands for "light", after all ?

Re:acceleration?

[TuringTest]

Remember, there's a big gap between "likely untrue" and "always untrue." When someone can look at their own statement, realize what it implies about their capacities, and then confidently declare "I am an idiot," they are displaying insight that is well above average, and certainly deserving of mod points.

I, for one, welcome our new self-insight-possessing commenters.

I'm an idiot, too. ...can I have my +5 Insightfool karma boost?

All a matter of scale...

[Microlith]

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:How "scaled up" is this?

[dethl]

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.

Energy source?

[StefanJ]

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.

Power = Thrust * Exhaust Velocity

[roystgnr]

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

[Harmonious Botch]

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.

"Scaled up"

[Tim C]

Because as we all know, it's just that easy! Nothing that worked at one scale ever proved impractical or impossible to do at another!

Re:How "scaled up" is this?

[FauxPasIII]

> Republicans, you mean.

Anybody who's read my posting history knows I'm a dyed-in-the-wool liberal, but I don't think we can singularly blame the GOP for this one. There's resistance to nuclear power coming from both extreme ends of the spectrum. Environmental activists who don't understand the science on the left, and oil industry lobbyists on the right.

I'm constantly frustrated with people who I know are well-intentioned and genuinely concerned, who are so afraid of nuclear power. I mean I agree, solar and wind power are great ideas, but right now we're generating power using f'ing COAL.

What's in a name?

[R3d Jack]

Isn't "photonic laser" redundant?

Buckaroo?

[Mark_in_Brazil]

Am I the only one getting Buckaroo Banzai vibes from this?

Dr. Bae of the Bae Institute? Seriously?

I went to the Bae Institute's site and found that it is "an independent space and medical research center."

Physics and space science: check.
Institute named after its physicist founder: check.
Medical stuff: check. Dr. Banzai, of course, in addition to being a great physicist, is also a top neurosurgeon. At the Bae Institute site, it says the Institute's medical technologies can be used, among other things, for treating "brain and spinal cord surgeries."

If Dr. Bae is also the leader of a rock band and says things like "wherever you go, there you are," I'll be surprised if we don't see a wave of stories submitted very soon, all by people named named John, saying that Dr. Bae's research cannot be trusted. I expect these submissions to cite the work of another physicist, Dr. Emilio Lizardo.

Laffa while you can, Monkey Boy!

I just showed my age in a way a low Slashdot UID never could.