Laser Communication

[redliox]

Curious on the specifics of laser communication.  Created an earlier thread pondering about how it could be utilized at Mars here: https://forum.nasaspaceflight.com/index.php?topic=55758.0  Wanting to delve into how advanced it is and what routes it could take in the near future.  I'm aware how radio is close to it's peak and missions, both crewed and robotic, are hitting a wall because of it.

One thought-and-question regarding lasers: I understand with modern tech, DVDs a prime example, how laser light is slowly expanding from infrared to optical and ultraviolet; I presume this is partly for data compression.  While I wouldn't expect the x-ray and gamma-ray spectra to ever be utilized since the materials are complicated, but how far can lasers go with spectra?  Would UV lasers have issues with the Earthly or Martian atmospheres due to interferance? (curse you ozone layer!  )

[Robotbeat]

There’s no hard wall with radio. You can always increase aperture size and/or power or reduce wavelength. Laser’s advantage is you can use a really small aperture on each side and also aren’t limit in near Earth space by radio frequency limitations.

On DVDs and BluRays, you have the wavelength limit for data density on the disk, but that’s not a real problem for data transmission for the most part, so fiber telecom usually uses near infrared like 1000nm.

[sanman]

Isn't NASA working on some technology called XCOM?

https://www.nasa.gov/feature/goddard/2019/nasa-set-to-demonstrate-x-ray-communications-in-space

[DanClemmensen]

There’s no hard wall with radio. You can always increase aperture size and/or power or reduce wavelength. Laser’s advantage is you can use a really small aperture on each side and also aren’t limit in near Earth space by radio frequency limitations.

On DVDs and BluRays, you have the wavelength limit for data density on the disk, but that’s not a real problem for data transmission for the most part, so fiber telecom usually uses near infrared like 1000nm.

For free-space optics (FSO) in a vacuum, life is simple like that and you can use pretty much any wavelength. For fiber things are different. There are two principle forms of attenuation in the commonly-used single-mode fiber: absorption and Raliegh scattering. One form increases with wavelength and the other decreases with wavelength, so there is a specific range of wavelengths that has a minimum attenuation. This is the optical C band at about 1500 nm. As a result, there are a lot of off-the-shelf components that function at these wavelengths. A single C-band link (one fiber pair or one pair of FSO telescopes) can handle 160 lambdas of 10 GHz each or 80 lambdas of 40 GHz each: call it 3.2 Tbit/sec assuming a fairly conservative FEC and using decade-old components.

[Robotbeat]

Sure, but it's also a fairly efficient range for diode lasers to begin with. And you can piggy back on the fiberoptic industry.

[Comga]

I am an optical engineer, and have worked with lasers and optical fibers and such for decades.
Some of the questions and answers here are so far off the mark, however well intentioned, that helping with them is beyond a reasonable post. Some of them, like wavelength choice, are real engineering issues that need real (ie complex and conditional) analysis to answer.
JPL has run and will laser communications tests from space, and the newer Starlink satellites will use them operationally. There is a discussion of Polaris Dawn patching into the Starlink lasercom systems for frequent to continuous high speed downlinking.
A great deal of this and more can be found with simple Google searches.

[redliox]

I am an optical engineer, and have worked with lasers and optical fibers and such for decades.
Some of the questions and answers here are so far off the mark, however well intentioned, that helping with them is beyond a reasonable post. Some of them, like wavelength choice, are real engineering issues that need real (ie complex and conditional) analysis to answer.

That's a respectable answer from a professional, and greatly appreciated.

To narrow the query, when it comes to wavelengths, what challenges are there working with optical or ultraviolet?

[sanman]

Here's a recent video on the topic:

[polar_bear]

Government players involved in laser communication development today include:
-    Department of Defense agencies: DARPA, Space Force, US Army, US Navy, US Air Force...
-    Space Agencies: NASA, ESA, JAXA (Japan), CNSA (China), Roscosmos (Russia), UK Space Agency.

A lot of private companies have contributed to the industry:

-    The mass production laser communication terminal supplier Mynaric.
-    Commercial service providers: OneWeb, Google, Facebook Aquilla, SpaceX, Amazon Kuiper
-    Defense contractors: Northrop Grumman, Aerospace Corp, General Atomics, BAE Systems, Raytheon...
-    Space prime contractors: Just picking the letter T, there's Telesat, Tesat Spacecom, Thales Alena Space..
-    Telecoms network providers: Nokia, Orange, Xenesis.. some of these companies will be involved in getting the internet on the Moon, very soon, starting with the Artemis missions in 2024.

This year alone, the US Government through the Space Development Agency has just committed $1.8 billion into proliferated LEO satellite constellations. The UK government committed £1.4 billion with similar intentions.

The number of satellites in general is exploding in recent years (with a trajectory going from dozens, to hundreds, to many thousands in just a few years) spurred on by proliferated commercial satellite communications and the need for more resilient lower latency defense networks, e.g. for missile early warning systems, using a mesh of satellites with optical intersatellite links. Starlink is just one player out of hundreds involved in laser communication, which has also included big names like Amazon, Facebook, Google, Airbus, Lockheed, Raytheon, Boeing, and others.

Every national space agency is now investing heavily in lasercom. They already demonstrated the ability in 2013/2014 with the LADEE spacecraft. NASA are in fact building the groundwork for deep space networks (an "interplanetary internet") using Disruption Tolerant Networking, a protocol which they helped develop. In a couple of months or so, NASA will be streaming data back from the Psyche asteroid via deep space laser communication. NASA spokespeople have announced that they expects as part of Artemis to stream back live footage of astronauts using laser communication from the moon.

The agencies actually want to build a laser communication enabled network around the moon. NASA is working on LunaNet, and ESA is working on Moonlight. One foreseen benefit of lasers here also includes no interference with radio astronomy should someone build a radio telescope on or around the moon.

Telecom companies are demanding faster and more secure networks on Earth. The Irish/American telecom company Rivada Networks just days ago announced plans to build an LEO constellation of 600 satellites with laser communication intersatellite links. Meanwhile Starlink have launched 2,086 functioning satellites, of which 1,575 are currently operational. A good chunk of those have lasercom ability (most since Jan 2021). Thousands more are to follow, all of which from now on will have the ability to deploy intersatellite laser communication.

Militaries are demanding faster, more secure and resilient networks and more effective interconnected defense systems and early warning systems in space. It also includes connecting drones and spy planes via secure laser communication. The US, via the Space Development Agency, is building mega-constellations of in Low Earth Orbit, pivoting from the traditional approach of relying on relatively few large GEO satellites. The German company Mynaric just days ago announced a $36 million order from Northrop Grumman for laser terminals ultimately for the Space Development Agency's network. Just a month ago, the Space Development Agency has awarded $700 million to Lockheed Martin, $692 million to Northrop Grumman, and $382 million to York Space for this laser communication enabled LEO communications network, the "Transport Layer Tranche 1".

Science is demanding faster networks to eliminate the huge bottleneck posed by space data downlinks, and they know laser communication is an enabling solution. At the same time, the space industry is demanding more compact satellite communications modules, so satellites can be smaller, cheaper, and still carry more useful payloads to get more out of its mission, still something that laser communication offers.

Internet service providers and banking/finance are demanding much lower latency and faster networks. Space lasers are even lower latency than terrestrial fiber. This is partly due to the faster speed of light through free space compared with glass, and partly due to the ability to travel a more direct path over long distances (even after accounting for the hop up to LEO and back down again). Finance and particularly high frequency traders are taking note and looking for opportunity.

Finally, Western governments demand much more secure comms and particularly the adoption of quantum communications. China already has a 4,600 km quantum communication network using lasers, satellites and fibre, and Europe is working on EuroQCI and LuxQCI quantum communication networks, with satellites delivering the quantum keys to the ground via laser.

[MickQ]

Hey, welcome to the forum.  Very informative first post.

Are you involved in the industry??

Cheers.

[Robotbeat]

Wait, I don’t think OneWeb is using lasers?

[jimvela]

I am an optical engineer, and have worked with lasers and optical fibers and such for decades.
Some of the questions and answers here are so far off the mark, however well intentioned, that helping with them is beyond a reasonable post. Some of them, like wavelength choice, are real engineering issues that need real (ie complex and conditional) analysis to answer.

That's a respectable answer from a professional, and greatly appreciated.

To narrow the query, when it comes to wavelengths, what challenges are there working with optical or ultraviolet?

I'm not an optical engineer, but I am a test engineer- and I can give one example real quick- UV optics introduce significant contamination control constraints as there are an amazing number of everyday chemicals that can degrade the optics in the UV realm.  Significant pain in my career has occurred as a result.

[polar_bear]

Wait, I don’t think OneWeb is using lasers?

They probably aren't using laser intersatellite links right now, they are probably using Ka band feeder links, and Ku band user links. But they have for sure investigated laser communication, hired experts, and put work into the design. Given the advantages I would say the scale tips towards 'likely' that the company will transition to all laser intersatellite links in the future of the company.

[polar_bear]

Hey, welcome to the forum.  Very informative first post.

Are you involved in the industry??

Cheers.

Hey yes I'm involved. Actually I moderate this forum: https://reddit.com/r/lasercom. I saw this thread and thought I could chip in and provide some insight. But first an account would be needed.

[Robotbeat]

Wait, I don’t think OneWeb is using lasers?

They probably aren't using laser intersatellite links right now, they are probably using Ka band feeder links, and Ku band user links. But they have for sure investigated laser communication, hired experts, and put work into the design. Given the advantages I would say the scale tips towards 'likely' that the company will transition to all laser intersatellite links in the future of the company.

How much of that is speculation? Have you seen actual job postings for laser experts at OneWeb, or is this just speculation?

[polar_bear]

Wait, I don’t think OneWeb is using lasers?

They probably aren't using laser intersatellite links right now, they are probably using Ka band feeder links, and Ku band user links. But they have for sure investigated laser communication, hired experts, and put work into the design. Given the advantages I would say the scale tips towards 'likely' that the company will transition to all laser intersatellite links in the future of the company.

How much of that is speculation? Have you seen actual job postings for laser experts at OneWeb, or is this just speculation?

It's informed. OneWeb said they would have laser intersatellite links, had engineers look into it, then they pivoted to Ka band, shying away from intersatellite links, and then they went bankrupt and were bailed out. OneWeb then stated that their generation 2 satellites would have optical inter-satellite links so there is still that expectation for the future.

Here are a couple of news pieces on the topic:

https://www.capacitymedia.com/article/29otd15ias3ir9ctsjegw/news/oneweb-plans-optical-links-for-next-generation-of-satellites

https://www.ispreview.co.uk/index.php/2021/03/future-oneweb-leo-broadband-satellites-may-adopt-laser-links.html

[Robotbeat]

Thanks!

[catdlr]

https://twitter.com/NASAJPL/status/1846687979668217932

Space lasers aren’t just science fiction!

Data transmission via laser could revolutionize deep space exploration by enabling ultra-HD video and complex science data transfer.

Join us live on Thursday, Oct. 17, to learn about this emerging tech:

[Asteroza]

https://twitter.com/NASAJPL/status/1846687979668217932

Space lasers aren’t just science fiction!

Data transmission via laser could revolutionize deep space exploration by enabling ultra-HD video and complex science data transfer.

Join us live on Thursday, Oct. 17, to learn about this emerging tech:

The commercial replacement for TDRS is going to need lasercomm, but which standards will they settle on? The SDA one apparently is apparently thought poorly of by industry, but industry wants something CCCSS-ish toallow interoperability in the face of the Starlink Plug&Plazer elephant in the room becoming a defacto standard.

[InterestedEngineer]

https://twitter.com/NASAJPL/status/1846687979668217932

Space lasers aren’t just science fiction!

Data transmission via laser could revolutionize deep space exploration by enabling ultra-HD video and complex science data transfer.

Join us live on Thursday, Oct. 17, to learn about this emerging tech:

The commercial replacement for TDRS is going to need lasercomm, but which standards will they settle on? The SDA one apparently is apparently thought poorly of by industry, but industry wants something CCCSS-ish toallow interoperability in the face of the Starlink Plug&Plazer elephant in the room becoming a defacto standard.

what is "CCCSS" and "SDA" and "TDRS"?