Sounds like a kluge when they have to do things like:

'Even at distances nearer than Mars, the laser signal is relatively fragile.. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'

https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms

On Sunday, November 19, 2023 at 10:53:15 AM UTC-6, Fred Bloggs wrote:
> Sounds like a kluge when they have to do things like:
>
> 'Even at distances nearer than Mars, the laser signal is relatively fragile. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'
>
> https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms

Your Sloman rating: "recycled news", 0

I'm thinking of a system where you'd have classify the post you were reacting as "on-topic" - electronics, or "science", "culture", "politics", "recycled propganda" or "personal abuse/flattery" and rate it on a five point scale, from useful (+2) down through helpful (+1) through neutral (0") to unhelpful (-1) to misleading (-2).

On Sun, 19 Nov 2023 08:53:08 -0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>Sounds like a kluge when they have to do things like:
>
>'Even at distances nearer than Mars, the laser signal is relatively fragile. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'
>
>https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms

No RF antenna can deliver sub-arc-second divergence like a laser can.

On Sunday, November 19, 2023 at 12:52:10 PM UTC-5, John Larkin wrote:
> On Sun, 19 Nov 2023 08:53:08 -0800 (PST), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
>
> >Sounds like a kluge when they have to do things like:
> >
> >'Even at distances nearer than Mars, the laser signal is relatively fragile. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'
> >
> >https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms
> No RF antenna can deliver sub-arc-second divergence like a laser can.

Not from deep space certainly- but for the orbital stuff they could have repeaters in orbit with large aperture antennas. They could be geostationary and steered electronically (phased) for a geospatial separation sharing of the same band. A 1o beam at 24,000 miles would be about 400 mile spread, so that would work out quite well.

On Sun, 19 Nov 2023 10:53:25 -0800 (PST), Fred Bloggs
<bloggs.fredbloggs.fred@gmail.com> wrote:

>On Sunday, November 19, 2023 at 12:52:10?PM UTC-5, John Larkin wrote:
>> On Sun, 19 Nov 2023 08:53:08 -0800 (PST), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>>
>> >Sounds like a kluge when they have to do things like:
>> >
>> >'Even at distances nearer than Mars, the laser signal is relatively fragile. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'
>> >
>> >https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms
>> No RF antenna can deliver sub-arc-second divergence like a laser can.
>
>Not from deep space certainly- but for the orbital stuff they could have repeaters in orbit with large aperture antennas. They could be geostationary and steered electronically (phased) for a geospatial separation sharing of the same band. A 1o beam at 24,000 miles would be about 400 mile spread, so that would work out quite well.

A laser relay station in space would be a good idea too.

It wouldn't have to be very "large aperature" either. Received optical
density, watts per square meter, would be ballpark a billion times
higher if the deep-space transmitter is a laser.

The earth downlink could certainly be RF. That's the easy part.

I know people who are working on laser communications between cubesats
in low orbits.

On Sunday, November 19, 2023 at 9:52:10 AM UTC-8, John Larkin wrote:

> No RF antenna can deliver sub-arc-second divergence like a laser can.

Yeah, but... sub-arc-second aiming wouldn't be an easy spec to meet, so
you probably want some divergence. Otherwise, there's never a receiver
in the right place, so communication doesn't happen. Heck, at arm's length,
you need a millimeter or so clearance to plug in an RJ45... so
Ethernet needs thousands of arc seconds divergence, in some sense.

On Sunday, November 19, 2023 at 2:31:18 PM UTC-6, John Larkin wrote:
> On Sun, 19 Nov 2023 10:53:25 -0800 (PST), Fred Bloggs
> <bloggs.fred...@gmail.com> wrote:
> >On Sunday, November 19, 2023 at 12:52:10?PM UTC-5, John Larkin wrote:
> >> On Sun, 19 Nov 2023 08:53:08 -0800 (PST), Fred Bloggs
> >> <bloggs.fred...@gmail.com> wrote:
> >>
> >> >Sounds like a kluge when they have to do things like:
> >> >
> >> >'Even at distances nearer than Mars, the laser signal is relatively fragile. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'
> >> >
> >> >https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms
> >> No RF antenna can deliver sub-arc-second divergence like a laser can.
> >
> >Not from deep space certainly- but for the orbital stuff they could have repeaters in orbit with large aperture antennas. They could be geostationary and steered electronically (phased) for a geospatial separation sharing of the same band. A 1o beam at 24,000 miles would be about 400 mile spread, so that would work out quite well.
> A laser relay station in space would be a good idea too.
>
> It wouldn't have to be very "large aperature" either. Received optical
> density, watts per square meter, would be ballpark a billion times
> higher if the deep-space transmitter is a laser.
>
> The earth downlink could certainly be RF. That's the easy part.
>
> I know people who are working on laser communications between cubesats
> in low orbits.

Paul Horowitz covers much of this in his talk at Google:
https://www.youtube.com/watch?v=sImBlq542TQ

Very enjoyable.

On Sun, 19 Nov 2023 18:49:17 -0800 (PST), John Smiht
<utube.jocjo@xoxy.net> wrote:

>On Sunday, November 19, 2023 at 2:31:18?PM UTC-6, John Larkin wrote:
>> On Sun, 19 Nov 2023 10:53:25 -0800 (PST), Fred Bloggs
>> <bloggs.fred...@gmail.com> wrote:
>> >On Sunday, November 19, 2023 at 12:52:10?PM UTC-5, John Larkin wrote:
>> >> On Sun, 19 Nov 2023 08:53:08 -0800 (PST), Fred Bloggs
>> >> <bloggs.fred...@gmail.com> wrote:
>> >>
>> >> >Sounds like a kluge when they have to do things like:
>> >> >
>> >> >'Even at distances nearer than Mars, the laser signal is relatively fragile. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'
>> >> >
>> >> >https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms
>> >> No RF antenna can deliver sub-arc-second divergence like a laser can.
>> >
>> >Not from deep space certainly- but for the orbital stuff they could have repeaters in orbit with large aperture antennas. They could be geostationary and steered electronically (phased) for a geospatial separation sharing of the same band. A 1o beam at 24,000 miles would be about 400 mile spread, so that would work out quite well.
>> A laser relay station in space would be a good idea too.
>>
>> It wouldn't have to be very "large aperature" either. Received optical
>> density, watts per square meter, would be ballpark a billion times
>> higher if the deep-space transmitter is a laser.
>>
>> The earth downlink could certainly be RF. That's the easy part.
>>
>> I know people who are working on laser communications between cubesats
>> in low orbits.
>
>Paul Horowitz covers much of this in his talk at Google:
>https://www.youtube.com/watch?v=sImBlq542TQ
>
>Very enjoyable.

Cool. I worked with Paul and Win a while back, loaned them my parts
exploder for a section of the X-chapters. They exploded the exploder!

A few of the guys in this ng are named in AoE3 and the X-chapters,
including Phil Hobbs and the late Jim Thompson.

On 19/11/2023 17:51, John Larkin wrote:
> On Sun, 19 Nov 2023 08:53:08 -0800 (PST), Fred Bloggs
> <bloggs.fredbloggs.fred@gmail.com> wrote:
>
>> Sounds like a kluge when they have to do things like:
>>
>> 'Even at distances nearer than Mars, the laser signal is relatively fragile. The package arriving at the Hale telescope from Psyche will consist of only a few photons, which is why decoding it relies on an extremely sensitive, cryogenically cooled photon-counting detector (made with superconducting nanowire) attached to the telescope.'
>>
>> https://knowablemagazine.org/article/physical-world/2023/why-nasa-is-turning-to-lasers-next-gen-space-comms
>
> No RF antenna can deliver sub-arc-second divergence like a laser can.

The VLA could do it if operated as a phased array to transmit. However,
it is normally operated as an ultra sensitive receiver when it has sub
arcsecond resolution for any frequency above 5GHz.

The global VLBA network is a few orders of magnitude better still when
it is all configured and phase corrected - about 25 microarcseconds. It
would be impossible to use it to transmit in realtime though since the
phase corrections from the atmosphere over each site have to be
determined painstakingly slowly and it relies on a bright nearly point
source object to be able to do that reliably.

--
Martin Brown