SpaceX launch of Psyche mission to bizzare metal asteroid just 1 month away...

[Jan Panteltje]

SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...

 

[jeroen]

On 2023-09-07 11:51, Jan Panteltje wrote:

SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...

High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Jeroen Belleman

 

[Jan Panteltje]

On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen
<jeroen@nospam.please> wrote in <udcrf8$31pr5$1@dont-email.me>:

On 2023-09-07 11:51, Jan Panteltje wrote:
SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?

 

[jeroen]

On 2023-09-07 18:30, Jan Panteltje wrote:

On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <udcrf8$31pr5$1@dont-email.me>:

On 2023-09-07 11:51, Jan Panteltje wrote:
SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?

Thanks for the URLs. I suppose the link budget factors are mostly the same
as for a radio link. We know that radio can be made to work to well beyond
the astroid belt.

Jeroen Belleman

 

[John Larkin]

On Thu, 07 Sep 2023 20:13:20 +0200, jeroen <jeroen@nospam.please>
wrote:

On 2023-09-07 18:30, Jan Panteltje wrote:
On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <udcrf8$31pr5$1@dont-email.me>:

On 2023-09-07 11:51, Jan Panteltje wrote:
SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?


Thanks for the URLs. I suppose the link budget factors are mostly the same
as for a radio link. We know that radio can be made to work to well beyond
the astroid belt.

Jeroen Belleman

A receiver can detect single photons at optical wavelengths and light
focusses better than radio waves.

 

[jeroen]

On 2023-09-07 22:06, John Larkin wrote:

On Thu, 07 Sep 2023 20:13:20 +0200, jeroen <jeroen@nospam.please
wrote:

On 2023-09-07 18:30, Jan Panteltje wrote:
On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <udcrf8$31pr5$1@dont-email.me>:

On 2023-09-07 11:51, Jan Panteltje wrote:
SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?


Thanks for the URLs. I suppose the link budget factors are mostly the same
as for a radio link. We know that radio can be made to work to well beyond
the astroid belt.

Jeroen Belleman

A receiver can detect single photons at optical wavelengths and light
focusses better than radio waves.

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Jeroen Belleman

 

[John Larkin]

On Fri, 08 Sep 2023 00:06:59 +0200, jeroen <jeroen@nospam.please>
wrote:

On 2023-09-07 22:06, John Larkin wrote:
On Thu, 07 Sep 2023 20:13:20 +0200, jeroen <jeroen@nospam.please
wrote:

On 2023-09-07 18:30, Jan Panteltje wrote:
On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <udcrf8$31pr5$1@dont-email.me>:

On 2023-09-07 11:51, Jan Panteltje wrote:
SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?


Thanks for the URLs. I suppose the link budget factors are mostly the same
as for a radio link. We know that radio can be made to work to well beyond
the astroid belt.

Jeroen Belleman

A receiver can detect single photons at optical wavelengths and light
focusses better than radio waves.


I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Jeroen Belleman

The earth end of an RF link can have a giant antenna, but the
satellite end can\'t. An optical receiver, with a lens or curved
mirror, funnels light into a small photodiode.

Downlink transmit power is probably similar for RF and light, but
light focusses much better.

How about an optical fiber up to a geosynchronous satallite?

 

[a a]

On Friday, 8 September 2023 at 00:50:46 UTC+2, John Larkin wrote:

On Fri, 08 Sep 2023 00:06:59 +0200, jeroen <jer...@nospam.please
wrote:

On 2023-09-07 22:06, John Larkin wrote:
On Thu, 07 Sep 2023 20:13:20 +0200, jeroen <jer...@nospam.please
wrote:

On 2023-09-07 18:30, Jan Panteltje wrote:
On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen
jer...@nospam.please> wrote in <udcrf8$31pr5$1...@dont-email.me>:

On 2023-09-07 11:51, Jan Panteltje wrote:
SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?


Thanks for the URLs. I suppose the link budget factors are mostly the same
as for a radio link. We know that radio can be made to work to well beyond
the astroid belt.

Jeroen Belleman

A receiver can detect single photons at optical wavelengths and light
focusses better than radio waves.


I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Jeroen Belleman
The earth end of an RF link can have a giant antenna, but the
satellite end can\'t. An optical receiver, with a lens or curved
mirror, funnels light into a small photodiode.

Downlink transmit power is probably similar for RF and light, but
light focusses much better.

How about an optical fiber up to a geosynchronous satallite?

Elon has plans to test laser links between Starlinks in the space
but the problem is live guidance or tracking in triangulation configuration

 

[a a]

>

Darius the Dumb has posted yet one more #veryStupidByLowIQaa article.

 

[Anthony William Sloman]

On Friday, September 8, 2023 at 6:06:51 AM UTC+10, John Larkin wrote:

On Thu, 07 Sep 2023 20:13:20 +0200, jeroen <jer...@nospam.please
wrote:
On 2023-09-07 18:30, Jan Panteltje wrote:
On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen
jer...@nospam.please> wrote in <udcrf8$31pr5$1...@dont-email.me>:

On 2023-09-07 11:51, Jan Panteltje wrote:
SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?


Thanks for the URLs. I suppose the link budget factors are mostly the same
as for a radio link. We know that radio can be made to work to well beyond
the astroid belt.

A receiver can detect single photons at optical wavelengths and light focusses better than radio waves.

Light focusses in exactly the same way as radio waves, but with radio waves you can make bigger mirrors out of wire gauze.

Single photon detection for a radio wave would call for a super-coooled detector. Even in an He-3 cryostat the Johnson noise would probably swamp the photon energy.

--
Bill Sloman, Sydney

 

[Anthony William Sloman]

On Friday, September 8, 2023 at 8:50:46 AM UTC+10, John Larkin wrote:

On Fri, 08 Sep 2023 00:06:59 +0200, jeroen <jer...@nospam.please
wrote:

On 2023-09-07 22:06, John Larkin wrote:
On Thu, 07 Sep 2023 20:13:20 +0200, jeroen <jer...@nospam.please> wrote:
On 2023-09-07 18:30, Jan Panteltje wrote:
On a sunny day (Thu, 07 Sep 2023 17:49:59 +0200) it happened jeroen <jer...@nospam.please> wrote in <udcrf8$31pr5$1...@dont-email.me>:
On 2023-09-07 11:51, Jan Panteltje wrote:

SpaceX launch of NASA\'s Psyche mission to bizarre metal asteroid just 1 month away
https://www.space.com/nasa-psyche-metal-asteroid-mission-one-month-launch

Interesting is the laser communication system that will be tested:
https://en.m.wikipedia.org/wiki/Psyche_(spacecraft)

I am curious how well that will work.
Uses IR lasers...


High power IR lasers are a common enough. I\'m interested in
their superconducting nanowire receiver though. Apparently,
it\'s not a TES, which I think would be too slow.

Google for \'how does a superconducting nanowire receiver work\' leads to wikipedia:
https://en.m.wikipedia.org/wiki/Superconducting_nanowire_single-photon_detector

The psyche experiment is a link in that page:
https://en.m.wikipedia.org/wiki/Deep_Space_Optical_Communications

TES is different I think:
https://en.m.wikipedia.org/wiki/Transition-edge_sensor

It is fascinating, but at 2 or more astronomical units from the laser not much signal expected,
add the atmospheric influences...
And the other way? Does that thing have a big dish receiver to focus the received beam?


Thanks for the URLs. I suppose the link budget factors are mostly the same as for a radio link. We know that radio can be made to work to well beyond the astroid belt.

A receiver can detect single photons at optical wavelengths and light focusses better than radio waves.

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

The earth end of an RF link can have a giant antenna, but the satellite end can\'t. An optical receiver, with a lens or curved mirror, funnels light into a small photodiode.

Downlink transmit power is probably similar for RF and light, but light focusses much better.

Light is just electromagnetic radiation, and focusses in exactly the same way.

> How about an optical fiber up to a geosynchronous satellite?

An Arthur C. Clarke style

https://en.wikipedia.org/wiki/Space_elevator

Might be expensive. Lots of bucky-tubes to sustain the tension.

--
Bill Sloman, Sydney

 

[Jan Panteltje]

On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
<jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.
So for the spacecraft some sort of dish (like James Webb has) or like used for RF (Voyagers have a dish) should
work better than a \'telescope\' (with lenses).
For transmission a lens system is cool, although lasers already have a narrow beam by default?
Searching finds this:
https://www.jpl.nasa.gov/news/nasas-deep-space-communications-to-get-a-laser-boost#carousel-27fdb231-a68f-434e-ad7e-5e92f104b2f1-1
you can enlarge the photo inset, shows a small mirror.
I sure hope they get enough signal.
Very small compared to the radio dish.
Now one could argue about the IR wavelength being much shorter
so for waves per square surface area more for IR..
But with such a small mirror back in a long tube, pointing becomes critical.
?
Seems sort of \'tucked on\'?

 

[John Larkin]

On Fri, 08 Sep 2023 06:18:35 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.

Aim a laser pointer at the wall. Then try the equivalent with RF.

So for the spacecraft some sort of dish (like James Webb has) or like used for RF (Voyagers have a dish) should
work better than a \'telescope\' (with lenses).
For transmission a lens system is cool, although lasers already have a narrow beam by default?
Searching finds this:
https://www.jpl.nasa.gov/news/nasas-deep-space-communications-to-get-a-laser-boost#carousel-27fdb231-a68f-434e-ad7e-5e92f104b2f1-1
you can enlarge the photo inset, shows a small mirror.
I sure hope they get enough signal.
Very small compared to the radio dish.
Now one could argue about the IR wavelength being much shorter
so for waves per square surface area more for IR..
But with such a small mirror back in a long tube, pointing becomes critical.
?
Seems sort of \'tucked on\'?

 

[Anthony William Sloman]

On Friday, September 8, 2023 at 9:18:30 PM UTC+10, John Larkin wrote:

On Fri, 08 Sep 2023 06:18:35 GMT, Jan Panteltje <al...@comet.invalid> wrote:
On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen <jer....@nospam.please> wrote in <uddhi4$34vlh$1...@dont-email.me>:

<snip>

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong, but for a receive antenna to collect as much signal as possible, a focussing dish surface catches a lot more light than a telescope aperture.

Aim a laser pointer at the wall. Then try the equivalent with RF.

Scale the experiment to equal numbers of wavelenghts. Visible light has a wavelength of about 500nm.
Microwaves have wavelengths of millimeters, some 10,000 times longer. It makes a difference.

--
Bill Sloman, Sydney

 

[Jan Panteltje]

On a sunny day (Fri, 08 Sep 2023 04:18:05 -0700) it happened John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote in
<ok0mfi1nqgat1hghk8v8co0u9m8fgv7ne0@4ax.com>:

On Fri, 08 Sep 2023 06:18:35 GMT, Jan Panteltje <alien@comet.invalid
wrote:

On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.

Aim a laser pointer at the wall. Then try the equivalent with RF.

You do not get it, see:
https://www.quora.com/How-much-do-laser-beams-grow-in-diameter-over-distance
The thing will be at 2 or more earth-sun distances from receiver/transmitter
scroll down for Paul Manhart calculation example and do the math for a distance
2 * 149,597,871 kilometres for beam width.

So for the spacecraft some sort of dish (like James Webb has) or like used for RF (Voyagers have a dish) should
work better than a \'telescope\' (with lenses).
For transmission a lens system is cool, although lasers already have a narrow beam by default?
Searching finds this:

https://www.jpl.nasa.gov/news/nasas-deep-space-communications-to-get-a-laser-boost#carousel-27fdb231-a68f-434e-ad7e-5e92f104b2f1-1
you can enlarge the photo inset, shows a small mirror.
I sure hope they get enough signal.
Very small compared to the radio dish.
Now one could argue about the IR wavelength being much shorter
so for waves per square surface area more for IR..
But with such a small mirror back in a long tube, pointing becomes critical.
?
Seems sort of \'tucked on\'?

 

[John Larkin]

On Fri, 08 Sep 2023 12:27:33 GMT, Jan Panteltje <alien@comet.invalid>
wrote:

On a sunny day (Fri, 08 Sep 2023 04:18:05 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
ok0mfi1nqgat1hghk8v8co0u9m8fgv7ne0@4ax.com>:

On Fri, 08 Sep 2023 06:18:35 GMT, Jan Panteltje <alien@comet.invalid
wrote:

On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.

Aim a laser pointer at the wall. Then try the equivalent with RF.

You do not get it, see:
https://www.quora.com/How-much-do-laser-beams-grow-in-diameter-over-distance
The thing will be at 2 or more earth-sun distances from receiver/transmitter
scroll down for Paul Manhart calculation example and do the math for a distance
2 * 149,597,871 kilometres for beam width.

That\'s a laser pointer, costs a dollar, and its beam width is about
0.05 degrees. A 2-meter diameter satellite dish is about 3 degrees.

A decent laser typically has a divergence under an arc-second. Make a
microwave antenna like that.

Given a giant microwave dish, I wonder what fraction of the incoming
RF power (power density times dish area) is delivered to the receiver.
An optical system can be close to 100%.

So for the spacecraft some sort of dish (like James Webb has) or like used for RF (Voyagers have a dish) should
work better than a \'telescope\' (with lenses).
For transmission a lens system is cool, although lasers already have a narrow beam by default?
Searching finds this:

https://www.jpl.nasa.gov/news/nasas-deep-space-communications-to-get-a-laser-boost#carousel-27fdb231-a68f-434e-ad7e-5e92f104b2f1-1
you can enlarge the photo inset, shows a small mirror.
I sure hope they get enough signal.
Very small compared to the radio dish.
Now one could argue about the IR wavelength being much shorter
so for waves per square surface area more for IR..
But with such a small mirror back in a long tube, pointing becomes critical.
?
Seems sort of \'tucked on\'?

 

[jeroen]

On 2023-09-08 08:18, Jan Panteltje wrote:

On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.
So for the spacecraft some sort of dish (like James Webb has) or like used for RF (Voyagers have a dish) should
work better than a \'telescope\' (with lenses).
For transmission a lens system is cool, although lasers already have a narrow beam by default?
Searching finds this:
https://www.jpl.nasa.gov/news/nasas-deep-space-communications-to-get-a-laser-boost#carousel-27fdb231-a68f-434e-ad7e-5e92f104b2f1-1
you can enlarge the photo inset, shows a small mirror.
I sure hope they get enough signal.
Very small compared to the radio dish.
Now one could argue about the IR wavelength being much shorter
so for waves per square surface area more for IR..
But with such a small mirror back in a long tube, pointing becomes critical.
?
Seems sort of \'tucked on\'?

I have no doubt all telescopes involved in this project are some
variant of Newtonian telescopes, i.e., they user mirrors, not lenses.

I found some more information: The laser on the probe is 4W at 1.55um
wavelength. I don\'t know about the transmitter optics.

The ground station uses a 5kW laser at 1.064um, focused by a 1m aperture
telescope. That should give us a clue as to the EIRP. Hold on...

The probe receiver uses a 22cm aperture telescope.

The ground receiver uses the 5m Hale telescope at the Palomar observatory.

I still didn\'t find the link budget, but we\'re getting closer to making
one up ourselves.

Jeroen Belleman

 

[jeroen]

On 2023-09-08 13:18, John Larkin wrote:

On Fri, 08 Sep 2023 06:18:35 GMT, Jan Panteltje <alien@comet.invalid
wrote:

On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.

Aim a laser pointer at the wall. Then try the equivalent with RF.

There is no doubt whatsoever that at that distance, the diameter of the
laser beam will be much greater than the aperture of the telescope.

Jeroen Belleman

 

[Jan Panteltje]

On a sunny day (Fri, 08 Sep 2023 08:19:31 -0700) it happened John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote in
<mmdmfid4gap036ccj434juqc8rafshim15@4ax.com>:

On Fri, 08 Sep 2023 12:27:33 GMT, Jan Panteltje <alien@comet.invalid
wrote:

On a sunny day (Fri, 08 Sep 2023 04:18:05 -0700) it happened John Larkin
jlarkin@highlandSNIPMEtechnology.com> wrote in
ok0mfi1nqgat1hghk8v8co0u9m8fgv7ne0@4ax.com>:

On Fri, 08 Sep 2023 06:18:35 GMT, Jan Panteltje <alien@comet.invalid
wrote:

On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.

Aim a laser pointer at the wall. Then try the equivalent with RF.

You do not get it, see:
https://www.quora.com/How-much-do-laser-beams-grow-in-diameter-over-distance
The thing will be at 2 or more earth-sun distances from receiver/transmitter
scroll down for Paul Manhart calculation example and do the math for a distance
2 * 149,597,871 kilometres for beam width.




That\'s a laser pointer, costs a dollar, and its beam width is about
0.05 degrees. A 2-meter diameter satellite dish is about 3 degrees.

You mentioned a laser pointer so..

A decent laser typically has a divergence under an arc-second. Make a
microwave antenna like that.

I would like to see a drawing of that system they are sending into space,
also if there are any lenses in that tube.

But still, we can hardly make out an object the size of that spacecraft at 300 million km with optical telescopes.
and for sending data towards earth the beam will be wider than earth at the receive point,
suffer interference from the atmosphere (clouds etc,) but big dishes can be used.
The other way around: pointing accuracy to something you cannot even see...
In 2029 it is supposed to arrive at its destination and the experiment will be done,
But then with WW3 in 2024 an glowball worming killing everybody who is going to listen for the signal?

Given a giant microwave dish, I wonder what fraction of the incoming
RF power (power density times dish area) is delivered to the receiver.
An optical system can be close to 100%.

Even if you had a laser beam that was only a few meters wide when arriving at earth,
pointing to the observatory dish/receiver would requires an impossible precision in arc-seconds for the servo.
Earth is moving and rotating so does the spacecraft...

I have tried modulating a laser diode and receiving the signal, you can use it to listen
to conversations by using the reflection from windows too, here a simple one:
https://hackaday.com/2010/09/25/laser-mic-makes-eavesdropping-remarkably-simple/

So for the spacecraft some sort of dish (like James Webb has) or like used for RF (Voyagers have a dish) should
work better than a \'telescope\' (with lenses).
For transmission a lens system is cool, although lasers already have a narrow beam by default?
Searching finds this:


https://www.jpl.nasa.gov/news/nasas-deep-space-communications-to-get-a-laser-boost#carousel-27fdb231-a68f-434e-ad7e-5e92f104b2f1-1
you can enlarge the photo inset, shows a small mirror.
I sure hope they get enough signal.
Very small compared to the radio dish.
Now one could argue about the IR wavelength being much shorter
so for waves per square surface area more for IR..
But with such a small mirror back in a long tube, pointing becomes critical.
?
Seems sort of \'tucked on\'?

 

[Jan Panteltje]

On a sunny day (Fri, 08 Sep 2023 20:43:33 +0200) it happened jeroen
<jeroen@nospam.please> wrote in <udfq0q$3jt92$1@dont-email.me>:

On 2023-09-08 08:18, Jan Panteltje wrote:
On a sunny day (Fri, 08 Sep 2023 00:06:59 +0200) it happened jeroen
jeroen@nospam.please> wrote in <uddhi4$34vlh$1@dont-email.me>:

I\'ve been trying to find something about the link budget. I had
one for the Voyager or Pioneer probes somewhere, but I can\'t seem
to find it again. IIRC, factors going into it were transmitter power,
antenna gains, path loss, receiver S/N and bandwidth. It shouldn\'t
be much different for IR EM waves, although receiver S/N would here
be limited by shot noise rather than Johnson (thermal) noise.

The \'antennas\' here are telescopes, of course.

Maybe I am seeing his wrong,
but for a receive antenna to collect as much signal as possible,
a focussing dish surface catches a lot more light than a telescope aperture.
So for the spacecraft some sort of dish (like James Webb has) or like used for RF (Voyagers have a dish) should
work better than a \'telescope\' (with lenses).
For transmission a lens system is cool, although lasers already have a narrow beam by default?
Searching finds this:

https://www.jpl.nasa.gov/news/nasas-deep-space-communications-to-get-a-laser-boost#carousel-27fdb231-a68f-434e-ad7e-5e92f104b2f1-1
you can enlarge the photo inset, shows a small mirror.
I sure hope they get enough signal.
Very small compared to the radio dish.
Now one could argue about the IR wavelength being much shorter
so for waves per square surface area more for IR..
But with such a small mirror back in a long tube, pointing becomes critical.
?
Seems sort of \'tucked on\'?


I have no doubt all telescopes involved in this project are some
variant of Newtonian telescopes, i.e., they user mirrors, not lenses.

I found some more information: The laser on the probe is 4W at 1.55um
wavelength. I don\'t know about the transmitter optics.

That is not much power really...
Looks like a normal cheap ebay laser diode ;-)
pick your color:
https://www.ebay.com/itm/295894369961?hash=item44e4adc6a9:gVIAAOSw0RFk5Hnj

My blue one:
https://panteltje.nl/pub/1_1_2021_blue_laser_1.gif

The experiments one does....
https://panteltje.nl/pub/laser_propulsion_test_1_IXIMG_0856.JPG
no propulsion but burned a hole in the cardboard box..

The ground station uses a 5kW laser at 1.064um, focused by a 1m aperture
telescope. That should give us a clue as to the EIRP. Hold on...

That is a lot better already!


>The probe receiver uses a 22cm aperture telescope.

Yes that must be that tube.

The ground receiver uses the 5m Hale telescope at the Palomar observatory.

I still didn\'t find the link budget, but we\'re getting closer to making
one up ourselves.

Jeroen Belleman

Let us know if you find out, I am curious !