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I meant to include the more recent amateur satellites such as cubesats, and also amateur radio satellites - where the heritage of amateur satellite building (mostly) has its roots.

Have amateur satellites ever experimented with optical communications - basic studies or more?

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  • $\begingroup$ Using optical communication in a cubesat with no attitude control would be difficult. There are omnidirectional antennas, but no true omnidirectional optical transmitters and receivers. Each side of the qube should be equipped with a transmitter and receiver with an angle of beam greater than 90 °. $\endgroup$
    – Uwe
    Commented Oct 13, 2016 at 16:13
  • $\begingroup$ @Uwe you are right. While there are plenty of 3U cubesats with reasonable attitude control - more than a hundred perhaps, I'm asking here about experiments, not internet service providers. And there's this one blinking morse code: directory.eoportal.org/web/eoportal/satellite-missions/f/… $\endgroup$
    – uhoh
    Commented Oct 13, 2016 at 16:30

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There was one that I can find, a beacon that used infrared light to communicate at a rate or 400 bits/second, on AO-40, which was a technology demonstration mission by AMSAT.

Wikipedia doesn't include any amateur missions.

It is proposed to use laser based communication for satellites beyond Earth's orbit, such as the Moon or Mars. I can't find any reference of them being used currently, however.

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    $\begingroup$ Interesting video, or audio at least. There's more info in this comment $\endgroup$
    – uhoh
    Commented Oct 13, 2016 at 13:33
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Not really amateur, but CubeSats for sure.

AeroCube 7 / OCSD would have already tested it, but had attitude control problems. Should relaunch in a few months. One can find plenty of detailed publications too.

ArgoMoon will be one of the next. Testing it from beyond Moon orbit, but not much is known yet.

Edit 2018-12-08: AeroCube-7B successfully demonstrated laser communications from a CubeSat in 2018. More details from Small Sat 2018 presentation and official press release.

Radix from Analytical Space was launched in the summer of 2018 and also includes optical communications module. Radix-2 is planned for January 2019 based on this Constellations podcast.

There are over 10 CubeSats with laser transmitter payloads in development now. Several of them will launch in 2019 (Golbriak Space module on FSSCat A/B, Tesat-Spacecom module on OSIRIS etc).

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Don't think so. Optical comms (I'm thinking of the well known -in theory- free space laser communications) require very precise optical instruments (not easy to prevent misalignments after launch or with orbit temperatures) plus very precise pointing methods down to microradians and being able to sustain that during a pass over a ground station.

That means in practice using expensive star trackers for AD instead of sun sensors or magnetometers and reaction wheels for attitude control, not magnetorquers, so they go one if not two orders of magnitude in cost and complexity.

I was involved in such a project and they planned to use MEMS mirrors on top of the above for a fast and fine control of the optics, plus being able to compensate for (correctable) deviations.

Aiming a laser beam with a minimum divergence (otherwise power and signal are lost) to a small point (metres if not less) on Earth from >500 km above while moving at 8 km/s and keeping it locked there for some minutes is not an "amateur" challenge.

While the perturbations on the satellite are small and, most important, very slow -except for temperature effects as, for example, the sat comes out of the shade and warms up-, the continuous actuation of optical systems as the SC moves tends to be relatively jerky (for the limited resolution of sensors, noise, etc that even kalman filters can't completely fix) so it all goes over the fine tuning system, that may or may not cope with what has been given...

Typically, satellite optical comms work both ways with the satellite tracking an uplink beam. If the uplink is lost, a "search procedure" starts (basically moving in circles to find it back) and if that takes too long, most of the pass time will also be lost, so is not very promising in terms of reliability.

We will see it in the near future as there are many working on that, but not anything amateur. Sat laser comms are interesting for the privacy they offer, they won't aim to your back garden, and even if they do, your receiving station may need an active uplink laser beam potentially with fast steering capabilities to track and lock the DL beam.

I doubt it's easy for the plain person to get hold of a 20-40 W laser, and even though, all the testing, aligning, calibration, etc. to be carried out with it to operate it is not something you just take the common laser googles and work in your garage with equipment from your hobby budget. A 40 W laser will simply go through laser googles, and what is behind... meaning, not only instantly blind but also a potential brain injury. Not a toy.

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    $\begingroup$ on your last paragraph: 40W lasers are actually dirt cheap on eBay and extremely poorly regulated (at least in the US). Laser safety isn't taken nearly seriously enough considering the distances at which permanent damage can be done to people with them. $\endgroup$
    – Erin Anne
    Commented Apr 20, 2023 at 14:30

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