said by Locutus65 :

Just think, communicating with rovers or men (eventually) on mars would take seconds instead of 20 minutes.

said by NickD :

It's still limited by the speed of light

said by PolarBear :

Yeah, because 670,616,629 mph is so damn slow.

said by Tzale :

Locutus65 who said "Just think, communicating with rovers or men (eventually) on mars would take seconds instead of 20 minutes." which is false since radio waves and light waves still travel at the same speed in a vacuum, so it will still take a long time for the signal to be transmitted between the Earth and Mars, but more info will be able to be transmitted FASTER than before. After the last packet is sent via laser, it will still take a couple minutes (whatever the speed of light to Mars is) before it is received.

said by Tzale :

..light waves still travel at the same speed in a vacuum, so it will still take a long time for the signal to be transmitted between the Earth and Mars, but more info will be able to be transmitted FASTER than before.

said by DRM Killler :

No, not FASTER. The same exact speed, just a lot more of it. WIDER maybe ? Does anybody want some wide band ?
Why the sudden fascination with the visible part of the RF spectrum Last time I checked, commercial microwave radios can be modulated in excess of 1 Gbps.

said by rradina :

Visible light is much more susceptible to being blocked by the atmosphere than RF frequencies. If the frequency is beyond 30mhz, it should penetrate the ionosphere and leave the planet without any problem. Frequencies below 30mhz tend to be reflected by the ionosphere. This is why short-wave and AM stations can be received even though the transmitter, due to the curvature of the planet, is below the horizon. Contrast this with frequencies above 30mhz which generally require line-of-sight between receiver and transmitter.

Consider radio astronomy versus visible astronomy. Until Hubble, radio astronomy was the only way to "see" the most distant objects in the universe. That may still be the case but the Hubble Ultra Deep Field surveys have greatly expanded the distance at which visible light can be seen.

What would be interesting is using an infrared data link. It's my understanding that infrared light waves penetrate clouds and dust. Infrared astronomy is allowing us to penetrate dust clouds in space and see what's going on inside nebula and other "dirty" celestial objects.

I'm guessing the real advantage of using light is that space has a lot of radio background noise. A focused beam of light wouldn't be have to compete with the this noise and would enable a higher signal to noise ratio and therefore greater resolution to support faster data rates.

said by rradina :

Why would it spread out in space? Are you saying we don't have the technology to focus it that tight at the source and any refraction from perfectly straight would cause it to spread? Unless there is dark matter or micro-meteors, there shouldn't be anything in space to disperse the beam. Still, I get your point.

Ever read Asimov's I-Robot series of short stories? There was a story about beaming energy from Mars to earth in tightly focused beams. Obviously SciFi then but perhaps not so much now...

said by rradina :

Where does the beam originate? Does it go through the Earth's atmosphere? What do they hit on the moon to reflect the beam? Are they aiming at equipment left behind by Apollo missions?

This is pure speculation but I would theorize that a beam originating in space and sent to receiving optics in space would remain focused. If such a beam did remain focused, the biggest problem would be keeping the sending and receiving devices aligned. In fact, it may be advantageous to create spread. A completely focused beam over millions of miles would be incredibly susceptible to any kind of variance at the source. I think something like a .01 degree deflection at the source would cause a beam 1 million miles long to vary by 100 miles.

said by misiek :

How?

said by Locutus65 :

Just think, communicating with rovers or men (eventually) on mars would take seconds instead of 20 minutes.

said by inteller :

That would be the Sharks With Friggin Laser Beams Networks.

said by axus :

The whole communications system on the satellite would need to be upgraded to handle that much speed, though. Faster CPU, memory, etc.

said by Anti_Cyrix :

All of that hardware we already have, so its just a matter of time.
Considering hardware we already have, NASA should invest in a new satellite that can use broadband laser technology to transmit HD feeds from say... rovers with cameras sent to Mars.
If clouds are a problem for the transmission (and we don't get around that problem in the next 5 years) then put another satellite into orbit to receive the transmission, record it, and send to earth any way it can.

I love the idea of an HD feed from another planet

said by Tzale :

Same idea I had, but then upon further thought I realized that even transmitting at 10Mbps from Mars to a satellite orbiting Earth (to avoid weather) would still have the problem of getting the signal from the satellite to a ground station on Earth which would be limited to what? 128kbps? So you might as well just transmit at 128kbps directly from Mars. There is nothing stopping them from making HD movies on Mars and just taking a long long time to upload it back to Earth.
-Tzale

said by axus :

Maybe it could replace microwave transmission links for ground communications? Good to have the technology either way.

The whole communications system on the satellite would need to be upgraded to handle that much speed, though. Faster CPU, memory, etc.

I wonder how many of these laser links could be put on one satellite. You of course lose the broadcast ability you get from radio waves.