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I have posted in a couple of places (including here) about the recent (in the past year) news about future probes, landers, etc. using strong visible light lasers to send data back to us at much higher rates, .... but,.....

Why don't current missions already use small masers or IR lasers? Masers were the first type of 'laser' invented, and their signals should experience less interference anyway....

Is even the smallest, 'oldest-tech' maser still too power-hungry to put on a rover or probe?

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    $\begingroup$ Don't make every reader go look for your posts! Cite your evidence that it's done with visible and not infrared lasers right here where people can verify that this is the case. $\endgroup$
    – uhoh
    Jan 1 at 9:23
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    $\begingroup$ The ground station for deep space communication using strong visible light lasers is placed within the Atacama desert to avoid problems with a cloud covered sky? $\endgroup$
    – Uwe
    Jan 1 at 23:20
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    $\begingroup$ @Uwe only slightly related because it's a proposed commercial network: Have these optical satellite ground station locations been chosen for clear skies? The maps in the answers are interesting. If you can find a link supporting visible light rather than infrared, that will be great! $\endgroup$
    – uhoh
    Jan 2 at 23:18
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    $\begingroup$ @Uwe Also note that in the future, deep space communications optical stations at Earth will most likely be in Earth orbit, not on the ground: Will future deep space optical communications "ground stations" actually be in space, or on the ground? so the wavelengths will be driven by hardware and space propagation issues, not atmospheric issues. $\endgroup$
    – uhoh
    Jan 2 at 23:21

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"Why don't current missions already use small masers..."

So we have already been using conventional traveling wave tube amplifiers for microwave communications in space. Ka band is around 30 GHz. That's microwave amplification (the "MA" in MASER) and so don't need stimulated emission.

The electronics and amplifiers (TWTAs or semiconductor) are small enough and powerful enough already. A 5 meter diameter MASER would have the same narrow beam and gain of a 5 meter diameter parabolic reflector, and you still need to have the parabolic reflector to receive signals.

"...or IR lasers?"

I think the premise that infrared lasers haven't and/or won't be used for optical communications with deep space will not be easily supported.

According to Design of the ESA Optical Ground Station for Participation in LLCD (Proc. International Conference on Space Optical Systems and Applications (ICSOS) 2012, 3-1, Ajaccio, Corsica, France, October 9-12 (2012) Copyright (c) ICSOS 2012.)

There is so much existing, mature, reliable, well-characterized technology for the optical communications bands around 900, 1300 and 1550 nm (lasers, modulators, amplifiers, fibers, receivers, etc.) that these are the wavelength bands we're likely to "see" in deep space and cis-lunar free-space optical communications.

The use of the DPSS 1064 nm rather than a semiconductor laser and standard optical communications band was a surprise, I don't think we'll see that again for high speed communications, though it's a great pulsed laser for LIDAR and a great beacon wavelength for optical target acquisition before the high speed communications begins.

We'd be fighting an uphill battle pushing into visible light and getting the same quality and reliability that already exists ubiquitously in near IR.

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