Question for the group

[Shankapotomus]

I like trying to think of ways of communicating with real extraterrestrials. It's sort of a weird thought hobby of mine.

I was thinking about using lasers and my first question is about using space based lasers in conjunction with orbital telescopes to burn an image or message on a relatively flat portion of Mars as a first test.

If successful, more powerful lasers and telescopes of the future could be turned on planets much further away. If possible, I figure this would be a much more effective method for transmitting evidence of our presence to ET's than radio signals because there is no prerequisite radio technology required on the other end to detect us, although an advanced civilization on the other end would certainly facilitate a return signal confirming receiption of our message.

Obviously, because of atmospheric interference, we would have to limit our targets to atmosphereless planets that may be near planets with life that may be exploring their nearby atmosphereless neighbors and see our message.

Should this be possible, we could be burning messages on planets throughout our galaxy, increasing our chances of being detected by alien life.

Of course I know all this depends on the possibility of overcoming a number of constraints imposed by the physics of space and planets on lasers and energy.

So my question is, is this remotely possible given any scenario using lasers you can devise?

[BlueJazz]

1. Well, the amount of power needed would be prohibitive, plus there already are signs of life on Mars

...IE: Rover etc.
As far as transmitting lasers to other systems outside of our solar system, it would take more power than the earth could provide plus a laser would spread out so far as to be totally useless.

The normal broadcasting (radio, TV) has already been going out for decades.

...and the above is only a tiny fraction of the problems associated with your scenario .. Sorry...

[Shankapotomus]

2. I expected there to be problems

I figured I would throw it out there anyway just in case there had been advances of which I wasn't aware. You never know.

I'll check back in another hundred years.

[BlueJazz]

3. One of the strange problems associated with contacting other star systems is the fact that...

...it takes so long for a medium to get there that progress would overtake the original... especially human or
even robotic travel.
IE: We send out a spaceship to a Star..at 1/8 the speed of light (which would take decades to get there)
Ten years later we invent a ship to go 1/4 the speed of light...it catches up and passes the original ship.
Ten years after that, we invent a 1/2 light-speed spaceship...it catches up with BOTH of the originals..
The we invent a 3/4 light-speed ship...Etc, Etc....

[Shankapotomus]

4. Exactly

I also forgot that even if we could create a laser powerful enough with a decreasing or static focus through space instead of an expanding one, the target planet would still be in motion, orbiting a star and revolving on its own axis, you'd have to calculate the exact position of the planet maybe 12 light years (or whatever the travel time of the laser) into the future in order to hit anything. The planet 12 light years away which we are looking at now isn't even really "there" anymore. And will the target even exist 12 light years from now? You can only hope it will or it's a complete waste.

[caseymoz]

9. I wouldn't worry about that.

First, the planet's position is already eight light years from where we're seeing it. You can still extrapolate it to some degree of accuracy.

However, the real problem will be that interstellar dust will refract and scatter beam so much along the way that the target would never see it. It would be like spotting a burning match in the fog from a mile away. Sort of.

[Johonny]

5. It is far cheaper to do what Carl Sagan did

And assume there is already a more advanced civilization out there trying to communicate with you. Since there are not bright coherent light coded messages in the night sky (and we've been looking for a while now) we might assume that a) there are no aliens b) be lasers aren't a good way to communicate in space.

To burn a message in a nearby neighbor to your alien is even harder. Your laser has to stay relatively coherent and have a focal point at a target an incredible distance away and stay this way while traveling through space. The target you want to hit is impossibly small at that distance and the movement of the laser beam to create words and messages impossibly smaller still. Your going to need a really, really good micro-positioning system to even move your beam around. The satellite it is stationed on would have to be incredibly well stabilized as well.

Also by international treaty space based weapons are banned and placing a laser that can etch out planets is going to be an international nightmare to say the least. You may have nothing but the best of intentions but out doubt everyone would see it that way.

[Shankapotomus]

6. Good points

Have to say I never thought of any of that, although it makes complete sense...lol. I mean, it's not like I don't know about the incredible distances involved and yet I wasn't thinking about that when I posted. I guess that's what peer review is for. And yes, I never even contemplated the beam being turned around and aimed at earth or used for evil....lol.

However, the near impossibility (and danger for misuse) of such an endeavor noted, once aimed at the target planet, the beam wouldn't have to move to write anything. The beam would just be fired through a pre-fitted template with the design or message already on it like one of those novelty laser pointers.

But you're right. Not a good idea at all. It's actually almost comical (in a macabre sort of way) , if you imagine a giant death ray leaving an enormous smile face on the surface of a distant planet.

[jeff47]

7. Um...we can't currently resolve small planets with a telescope

We can see some gas giants as they reflect light from their star, but we can't see features on their surface. We can't see small planets at all. We can't possibly read text burned onto a planet outside our solar system.

So...why would we expect other civilizations to use this communications method.

[Shankapotomus]

8. Correct

I was thinking long term with this thread. Scientists have proposed super orbital telescope arrays much more powerful than what we have now. Possibly someday capable of zooming in on land formations on distant planets. My original thought was using this super telescope array in conjunction with an equally powerful laser, scientists could direct laser light at these planets. However, for various reasons already mentioned up thread, this scenario is not very likely to work.

[Fumesucker]

10. There are optical SETI projects underway, at least for the receiving end anyway

http://seti.berkeley.edu/opticalseti

One of the two seaches at Berkeley is a search for laser signals that are on continuously, or at least a large fraction of the time. This search, directed by Geoff Marcy, is a 1000 star program to search for ultra narrow band signals in the visible. They plan to search though thousands of extremely high resolution spectra for very sharp lines (lines which are not thermally broadened). Much of the data has already been taken by Marcy and Butler in their ongoing planet search, and more data is coming in all the time, mostly from Lick and Keck observatories, and some from the Southern Hemisphere search for planets in Australia.

The Berkeley pulse search plans to observe 2500 nearby stars, looking for very short bright pulses that might last a billionth of a second or so, perhaps transmitted by a powerful pulsed laser operated by a distant civilization. The target list includes mostly nearby F,G,K and M stars, plus a few globular cluster and Galaxies.

We won't have the kind of lasers that can be detected multiple light years away until we move into space on an industrial scale and that's still some significant amount of time in the future, assuming of course that we don't manage to drive ourselves to extinction or back to the stone age somehow.

[Shankapotomus]

11. Cool!

Um, except for the "drive ourselves to extinction" part.

But the Optical SETI program sounds interesting. I believe, ultimately, our first evidence of intelligent extraterrestrial life will come from space based telescope arrays. Watching alien civilizations play out from afar like an ancient movie with little ability of interacting with or contacting them.

[mzteris]

12. Okay - layman - way off specifics of topic, but

We can't communicate with other intelligent species here on Earth with whom we've dwelled since we began.

Hell - we can't even communicate with each other very damn well.

What hope have we for intelligent communication with an "alien" species. I guess we've always hoped they're a lot damn smarter than we are in order to make it so.

[Shankapotomus]

13. Just don't bring up Religion and Politics

There's always the weather.