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Researchers Unveil High-Speed Laser Communications Device For Space
coondoggie writes "Using lasers to communicate quickly through the long distances of space has generally been the purview of science fiction. But researchers at the National Institute of Standards and Technology (NIST) and NASA's Jet Propulsion Laboratory (JPL) are out to change that notion with a prototype array (pdf) that can read more information — and allow much higher data rates than conventional systems — than usual from single particles of light. Lasers can transmit only very low light levels across vast distances, so signals need to contain as much information as possible, NASA said."
Using lasers to communicate quickly through the long distances of space has generally been the purview of science fiction.
The ESA Artemis satellite used the SILEX laser link to communicate with the SPOT-4 satellite. It was not the first project to use laser communications in space either. The datarates mentioned in this article are better than those of SILEX though.
Does it matter whether the emitted photons are from RF or Light? They both travel at the same speed.
I've invested way too much time to movies and books to not see laser communications, to at the very least, to the moon in my lifetime. There are many authors that have enjoyed my 25 cents or less of royalties they received that should finally be vindicated by including laser based communications in their books!
Does it have a Shark2Shark protocol (S2S) implemented?
Funny that this news release is from NIST/JPL, when LLCD came from Lincoln Labs/Goddard http://esc.gsfc.nasa.gov/267/271/Space-Terminal.html
I've found that most WiFi connections bragging about being highspeed, are not that far from being modem speeds. If it's high-speed, the marketers feel the terminology forces the users into giving them more cash. Evey time I here the phrase, I figuartively want to randomly strangle someone, anyone working in sales.
Lasers at modem speeds; there's a thought, or not.
...unless their laser can send signals traveling faster than the speed of light.
Even out of a high-gain antenna radio waves spread enough to lower EIRP a lot compared to a laser.
Yes.. deep space links today are energy limited, not bandwidth limited. However, optical comm helps in another way related to the energy: you can make a narrower transmit beam with a limited size device, so you can squirt the limited energy you have in narrower beam, increasing the effective isotropic radiated power (EIRP).
To a first order, the beamwidth is 70/diameter in wavelengths So going from 3 meters at Ka band (32 Ghz, 1cm wavelength, 0.3 degree beamwidth) to 50cm at 500 nm (1,000,000 wavelengths diameter, some incredibly small beamwidth) helps a lot. (practical optical systems can't do that well).
Of course, now you have to point that very, very narrow beam, which is non-trivial. Spacecraft vibration is an issue, knowing where to point is another. When your beam is 0.3 degrees wide, you can point in the general direction of earth and call it done. But when your beam is 1 microradian wide, and you're a billion km away (Saturn), the "spot" is 1000km wide: not only do you have to point it at Earth, you have to point it at the right place on earth.
I think the equipment is of comparable reliability: doped fiber amplifiers, etc. are standard items. We've been flying pretty exotic lasers for a lot of years.
It's more that the whole system isn't really mature or available. You've got a set of microwave receiving stations (DSN) that have been around for 40 years, gradually upgraded, so a mission that wants to use radio has existing infrastructure to use. There's no similar infrastructure of optical receiving terminals (yet).
I wonder if this will have any application to the delay-tolerant networking concepts for interplanetary networking done by Vint Cerf.
Keep the faith, share the code
According to the article, they use positioning information to generate additional bits of information. My question is how do they determine position at large distances when both bodies are obviously not standing still. The only thing I can think of is having one constant laser being used as a position reference for all communication lasers. Of course, they still have to be able to hold the laser on the detector array.
....by the folks in a nondescript campus near the base of Haleakela, for transmission from their rather large facility on the top of the mountain. The building says it is a defense contractor...but most of the folks inside are AF. The clients are military and various three letter acronyms.
If you are in the area looking like you know what you might be doing with fancy, uncommon sorts of cameras that may or may not image certain wavelengths, you will be asked to leave, public property or private.
Not that I would know anything at all about that, of course.
...also exploits polarization to a high degree. In fact, many developmental optical communication systems exploit polarization purity for higher base digital transmission, and even if polarization modulation slows things down for some schemes, the resulting bandwidth can overcome the obstacles by an order of magnitude or more over the reduced rate of the mux/demux. The issues with these schemes is more about cost. But most of these programs are directed at n-fold increases in existing optical fiber network bandwidth. Their time will come.
Let's see:
High Speed WiFi >> Check
High Speed Lasers >> Check
High Speed Warp Drive >> Still a To Do; must invent regular warp drive first.