Laser Communications in Outer Space

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Discussion Overview

The discussion revolves around the feasibility and limitations of laser communications in outer space, particularly in the context of NASA's Lunar Probe and the transmission of high-resolution images and data. Participants explore theoretical distances for accurate data transmission, the role of error-correcting codes, and the nature of the information being transmitted.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the distance at which laser communications can remain "fully accurate," noting that there is no such state as "fully accurate" in data transmission.
  • Another participant suggests that error-correcting codes are crucial for reducing data loss, with distance depending on various factors including laser quality and receiver capabilities.
  • A participant mentions the successful use of lasers for precise measurements in the Lunar Laser Ranging Experiment over the past 40 years.
  • There is a proposal that quantum information could be transmitted over distances of 10 AU, though this is challenged by another participant who argues that classical data transmission is more efficient.
  • Clarification is provided that the term "quantum information" is misused, with a focus on classical data transmission akin to fiber optics.
  • Participants discuss the potential limits of laser communication, with one suggesting that while 10 AU is feasible, questions remain about the viability of distances like 100 AU or 1,000 AU.
  • It is noted that while communication over light years is theoretically possible, the data rate would significantly decrease compared to closer distances.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the information being transmitted and the limits of laser communication distances. There is no consensus on the maximum effective distance for accurate data transmission, as multiple competing perspectives are presented.

Contextual Notes

The discussion highlights the dependence on various technical factors for effective laser communication, including the quality of equipment and the nature of the data being transmitted. Limitations regarding data rates and efficiency at greater distances remain unresolved.

bodykey
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I just saw an article regarding NASA's Lunar Probe that will use lasers to communicate high resolution images and data from the Earth to the probe for faster comms.

My question is...in Outer Space with no atmospheric influence, at what distance would laser communications like this remain fully accurate (no loss of data)?
 
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There is no "fully accurate", but you can reduce the risk to something like "on average 1 bit per 1 million years of data transmission", where you don't care about the hypothetical probability of this any more.
Error-correcting codes play an important role there.
The distance depends on the laser quality, power, wavelength, receiver telescope quality, data rate and many other factors.
 
We have been bouncing lasers off the moon for over 40 years now [re: Lunar Laser Ranging Experiment]. The data quality is sufficient for incredibly precise measurements.
 
So it would be safe to say that several bursts of lasers containing quantum information could be successfully transmitted without much of a flaw over say a 10 AU distance and received on the other end by another satellite?

:)
 
What exactly do you mean with "quantum information"? Do you want to share entangled photon pairs? That will lead to a very low efficiency for reasonable designs.
Just sending classical data is way easier, as you can send many photons, it does not matter if 99.999% (or more) are lost if you have enough of them.
 
I just mean information, similar to the way that fiber optics send information along fiber cables. In pulses that are represented as zero's and one's.
 
That is not quantum information.
Transmitting data over a distance of 10 AU is possible, the data rate depends on sender and receiver.
 
I suppose my more core question is, what is the limit of such communication? If 10 AU is possible, what about 100 AU, or 1,000 AU?
 
The limit is the data rate.
You can transmit data to other planetary systems, light years away (where 1 light year is ~63 000 AU). You just won't achieve the same data rate as in the communication with a satellite orbiting earth.
 
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Ok, gotcha. Thanks :)
 

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