back to article Lasers to carry 622 Mbps Earth-Moon link

If all goes to plan, the next few weeks will bring a revolution in communication with spacecraft, with two space-based laser communications demonstrations due to take to the skies. The European Space Agency's Alphasat – also the largest telecommunications satellite built in Europe – is due to launch on July 25. While the …


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  1. Martin Budden Bronze badge


    We do already use lasers for terrestrial communication but of course we get around pesky obstacles by sending the laser beams through special guides commonly known as fibre optic cables. No obstacles in space, natch.

    1. Lee D Silver badge

      Re: terrestrial

      Hell, lasers (but more commonly microwaves) are already used in some site-to-site communications for bog-standard network already.

      The problem is more about the vast distance and the delay than actually how to get the data to the ground. It's a good start on a solar-system-wide communications network, though.

      1. The Mole

        Re: terrestrial

        And there was I thinking the big difference was doing it between two objects in totally different orbits which I imagine is a tadge more complicated compared to doing it between two objects bolted in a fixed position to the same land mass (or failing that two continental plates moving at a relative mm/year to each other).

        1. Lee D Silver badge

          Re: terrestrial

          Not really - NASA pretty much has that sorted.

          Even a cheap amateur "go-to" telescope can keep the ISS in view from Earth at all times enough for that kind of thing. Stick a satellite dish on such a device instead of a telescope and it's done. Hell, it even accounts for Earth's rotation, obstacles in the way, etc. Hell, my cell-phone can do it with it's magnetic and accelerometer sensors good enough to make a "push-to" app as an android app.

          The problem is not keeping it in sight (so much as keeping it in orbit at all), or talking to it when you know where it is. The problem really is that the data network is MUCH MUCH more latent than we are used to, and very noisy, and that involves vast amounts of buffering and protocol redesign to make it work.

          Actually putting something in orbit around the Moon / Mars is infinitely more difficult in comparison to all that. However, once it's there we can track so much space junk and can still communicate with Voyager etc. (70's technology, notice) that actually finding and sending data isn't a problem. It's how to make it work nicely as more than just a single-mission fixed data stream and more like NASA's dream of a deep-space network. And that involves throwing TCP out of the window.

  2. kain preacher

    You know I look at that first pic and I think steam punk.

    1. Steve K Silver badge

      It's the Sorting Hat

      I thought "Sorting Hat" from Harry Potter.....

    2. TeeCee Gold badge

      Er, surely steampunk optical comms systems are based on semaphore, so there should be gears, levers and little flags visible?

  3. A Non e-mouse Silver badge

    What happens when it's cloudy ?

    1. PyLETS

      @A Non e-mouse

      "What happens when it's cloudy ?"

      2 possible approaches or some combination of these 2:

      a. Use somewhere at high altitude in the Atacama desert for the downlink, or somewhere else where it's cloudy very infrequently, degrade to conventional slower downlink when conditions require it . High altitude desert locations are likely best suited.

      b. Have more than 1 downlink station on the ground, and routing between satellites to whichever ones have non-cloudy downlinks accessible.

  4. BigScaryTiger


    Where is the shark logo when you need it?

  5. Anonymous Coward
    Anonymous Coward

    when's BT going to fix my phone then?


    broadband from space - broadband links to the moon! whatever next?

    my family get their BT phone link via microwave dish link (20miles) then a further 2 miles of 'saggy' copper cable to their property.

    disruptions are frequent - storms. low flying aircraft and best of all, can't report a fault as the nearest phone box (yes still exists) is linked to same microwave link!

    cellphones work on top of the hills (1000ft asl) - sometimes.

    they even get freeview telly in the winter but broken signals in the summer - you guessed it leaves and sheep/cattle in the signal path........

    they've asked for broadband - no chance say BT engineers

    farmers nearby ask for broadband - no chance say BT engineers

    it was suggested an optical laser link might work - BT said no - guess they worried it could have been pointed it at BT HQ!

    amazing what technology can do with money behind it - back to baked bean cans & string then!

    1. Elmer Phud

      Re: when's BT going to fix my phone then?

      WTF's this got to do with BT and UK?

      My connection is a bit slow - Should I ring NASA?

      1. Graham Dawson Silver badge

        Re: when's BT going to fix my phone then?

        It would probably get more results than ringing BT...

    2. Bob H

      Re: when's BT going to fix my phone then?

      If you really are at the end of a bit of wet string which BT don't find economical to service then the fact that you have a phone box might be an advantage to you, you need to complain to Ofcom that the phone box has poor availability because BT has an obligation to provide a good service to them. I was also told that phone boxes also have a dual function in that they have switching priority in case of a national emergency (just in-case Tom Cruise needs to call the English President at the last minute to save the world).

      But also two words: community broadband, if you have a community which is poorly served you could club together and get satellite broadband from the likes of Avanti. A lot more expensive than BT, but if you club together you would at least get a wider range of services. Perhaps you could even use VoIP between the locals and save some money. You would need some emergency provision though and I don't know what the licensing is like for operating a small scale telco. But there are plenty of rural broadband initiatives who would be willing to offer help, 'social enterprise' I think the BBC called it on a recent report.

      Sometimes it is better to stop bitching about what other people aren't doing for you and do it yourself.

  6. James 51

    So we can see the pictures from the farside observatory when it finally gets up and running.

    1. Arthur the cat Silver badge

      pictures from the farside observatory

      Oh, Gary Larson is working for NASA these days?

      1. MrT

        Overheard from an observer at the farside observatory...

        ..."Bummer of a birthmark, Mimas"

  7. Kevin Fairhurst

    Astrium? Built in Stevenage, then?

    Well, designed there. Maybe...

    Meanwhile at the other end of town, swathes of properties don't get decent broadband to their homes because it isn't "cost effective" to upgrade the cabinets... :-/

    <--- unlike the lager, I *am* bitter!

  8. Craigie

    Nice, but

    will it slow to a crawl at 10pm?

  9. Yag

    Can only figure one use for broadband in space

    Sending pictures of a cute kitten with the following caption : "Can I haz moonburger?"

    1. AbelSoul

      Re: Can I haz moonburger?

      Or perhaps even : "All ur cheeze r belong 2 us!"

    2. Down not across Silver badge

      Re: Can only figure one use for broadband in space

      You mean it gets lonely up there?

      In space no one can hear you fap

  10. Muckminded


    The NSA will manage to weasel into this.

    1. hplasm

      Re: Somehow

      We're servers on the Moon

      We're full of pirate tunes

      But we cause lost sales

      In Lunar retails

      So they want us all shut doon...

    2. Bob H

      Re: Somehow

      Well, they need to keep their eye on the Moon Nazis:

  11. Anonymous Coward
    Anonymous Coward

    Rural broadband

    When we said we wanted government funding for broadband to remote areas, that was *not* what we had in mind :-)

  12. WibbleMe

    Clearly Dr Evil from Austin powers has been hard at work building a "Lazer Beam" to destroy earths "O Zone Layer"

  13. Anonymous Coward
    Anonymous Coward


    Lasers to carry UP TO 622 Mbps depending on time of day, your phone line and how far you are from your local NASA telephone exchange.

  14. Matthew 17

    It's nice that the Nazi moonbase is finally getting connected

    Will be interesting to see what they've been up to.

  15. Simon Harris

    more prosaic applications...

    like streaming Clanger Porn!

  16. Bob Dunlop

    Since the report said broadband will that be "Up to" 622Mbps ?

    1. TeeCee Gold badge

      I think you'll find that there will be very little contention on that link.......

  17. Matt_payne666

    just don't look up (or down!) when flying past the transmitter....

  18. ElNumbre
    Thumb Up

    RTT Time

    Didn't spot it in the article, but according to WolframAlpha, the one way tranmission path is 1.225 seconds. So 2.5 seconds to resend lost packets.

    That'll be fun trying to use Skype (or should that be Spacepe)?

    1. tony2heads

      Re: RTT Time

      Yes the Ping time will be huge, but you always have that in space communications. I wonder about tracking the earth base from the moon. Earth-Moon should be simple enough but who sets up and checks alignment from the Moon side.

      Do we have contact with extraterrestrial network engineers?

      1. Tom 7 Silver badge

        Re: RTT Time extraterrestrial network engineers?

        be there faster than openreach!

      2. Bob H

        Re: RTT Time

        I suspect that they would use a low bandwidth RF link for monitoring & control, something with less directionality but lower gain. That way the two units could share location information for initial synchronisation then just let it run. I don't know how much risk there is of dust from the limited atmosphere on the moon, but that would be one of my biggest concerns given the mechanical components inherent in laser communications.

  19. Toltec

    An earlier generation?

    I wonder if the test platform for this was the SILEX package on the Artemis satellite?

  20. Anonymous Coward
    Anonymous Coward


    To: Adam Selene <>

    From: Google Fiber team <>

    Subject: Connection appointment

    We will be sending a tech by between 8AM and 5PM local time to connect your Google Fiber connection.

  21. Anonymous Coward
    Anonymous Coward

    Will we get streaming footage of Moon Animals?


  22. Mikel


    For interplanetary communications radio will not do because: cube-square law. Lasers are where it's at.

    1. Anonymous Coward
      Anonymous Coward

      Re: Durr

      Durr, indeed. Lasers also follow inverse square law - they spread out over distance just like radio waves do. They just start out more tightly focused.

  23. Marty-SNGC


    For when you're stuck on the ISS for months on end and run low on bromide.

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