Wasn\'t this impossible ?...

[Ricketty C]

On Saturday, August 22, 2020 at 3:04:21 PM UTC-4, upsid...@downunder.com wrote:

On Sat, 22 Aug 2020 08:41:34 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:

On Saturday, August 22, 2020 at 4:19:44 AM UTC-4, Martin Brown wrote:
On 22/08/2020 02:10, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first. The
farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have
a very hard time seeing anything other than stars because other
objects are too dim. I haven\'t done the math, but the data rate
would have to be microscopic to successfully send and receive a radio
signal from such distances. 0.1 light year is 6324 AUs. The Voyager
probes are about 141 AU so about 40 times closer. They now are
transmitting at 160 bps. Doing the math I get about 3 years to
transmit a MB of data.

It is slightly amazing that the Voyagers can be received at all now. The
transmitters on the probes are fixed 1970\'s space approved technology
with limited power and quite crude by modern communications standards.
The error correction was very sophisticated for the time though.

The base station receivers have improved so much since the probes were
launched that they can still follow Voyager out to the heliopause.

Data rates for a future deep space probe should be about the same order
of magnitude as the recent probe to Pluto managed but downgraded by the
increase in distance effects on signal to noise.

Yes, that is the problem. The distance hugely weakens the signals in both directions.

Only -6 dB for each doubling of the distance.

\"Only\" is a four letter word!

And how is the data rate impacted by a -17 dB adjustment to signal strength? You have to consider they are pushing the limit of what they can do working at 160 bps presently. We have done a lot to improve the ground stations, but they can\'t keep increasing their transmit power ad infinitum. As I said, it will take years, maybe decades to transmit a high resolution image from a space craft that far away. While larger antenna in general produce a more collimated beam, there are limits to what you can do given the precision of the antenna shape and the frequency you transmit on.

--

Rick C.

+- Get 1,000 miles of free Supercharging
+- Tesla referral code - https://ts.la/richard11209

 

[John S]

On 8/21/2020 8:10 PM, Ricketty C wrote:

On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T

Seems there are in fact billions of the damn things.

Be \"... an awful waste of space \" if Earth is the only one with life forms.

Above quote from the SF movie \"Contact\".



..... Phil



I\'m probably remembering the exact figures incorrectly but if you could
push a space telescope out to about a tenth of a light-year from Earth,
it could leverage gravitational lensing to make an equivalent lens of
enormous size.

It could then search for evidence of life in a large volume of space by
imaging planetary surfaces around other star systems directly, it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be... astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any image compression, but lossless of course. With the image mostly the star, I suppose they could do a fair bit of compression. Still, they would want to transmit and awful lot of MB, so it will take lots of time, still years.

Imagine what it would take to manage the cameras and other devices. Over a month just to send any message no matter how short.

 

[Ricketty C]

On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:

On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T

Seems there are in fact billions of the damn things.

Be \"... an awful waste of space \" if Earth is the only one with life forms.

Above quote from the SF movie \"Contact\".



..... Phil



I\'m probably remembering the exact figures incorrectly but if you could
push a space telescope out to about a tenth of a light-year from Earth,
it could leverage gravitational lensing to make an equivalent lens of
enormous size.

It could then search for evidence of life in a large volume of space by
imaging planetary surfaces around other star systems directly, it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be... astronomical..

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any image compression, but lossless of course. With the image mostly the star, I suppose they could do a fair bit of compression. Still, they would want to transmit and awful lot of MB, so it will take lots of time, still years.

Imagine what it would take to manage the cameras and other devices. Over a month just to send any message no matter how short.

160 bps is what they have now, not from 0.1 light years away. Apply the -17 dB factor and recalculate... I think the distance ratio is actually 45. Opps, I think I made a mistake. It should be -33 dB, no? I used 10log instead of 20log. So yeah, years.

I suppose they could just pop in a power source 2,000 times more powerful. How many kW would that be? Or is it MW? Not MW, they are currently using 23 watt transmitters, so 45 kW instead, only slightly less than WWVB. Can we launch WWVB into space?

--

Rick C.

++ Get 1,000 miles of free Supercharging
++ Tesla referral code - https://ts.la/richard11209

 

[server]

On Fri, 21 Aug 2020 18:10:35 -0700 (PDT), Ricketty C
<gnuarm.deletethisbit@gmail.com> wrote:

You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

160 bps is a quite decent speed. Mariner IV sent the first pictures
from Mars at 8.33 bps, which proved that there are no canals on Mars.
..

 

[bitrex]

On 8/23/2020 1:15 PM, Ricketty C wrote:

On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T

Seems there are in fact billions of the damn things.

Be \"... an awful waste of space \" if Earth is the only one with life forms.

Above quote from the SF movie \"Contact\".



..... Phil



I\'m probably remembering the exact figures incorrectly but if you could
push a space telescope out to about a tenth of a light-year from Earth,
it could leverage gravitational lensing to make an equivalent lens of
enormous size.

It could then search for evidence of life in a large volume of space by
imaging planetary surfaces around other star systems directly, it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be... astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any image compression, but lossless of course. With the image mostly the star, I suppose they could do a fair bit of compression. Still, they would want to transmit and awful lot of MB, so it will take lots of time, still years.

Imagine what it would take to manage the cameras and other devices. Over a month just to send any message no matter how short.


160 bps is what they have now, not from 0.1 light years away. Apply the -17 dB factor and recalculate... I think the distance ratio is actually 45. Opps, I think I made a mistake. It should be -33 dB, no? I used 10log instead of 20log. So yeah, years.

I suppose they could just pop in a power source 2,000 times more powerful. How many kW would that be? Or is it MW? Not MW, they are currently using 23 watt transmitters, so 45 kW instead, only slightly less than WWVB. Can we launch WWVB into space?

You\'d use a laser of some type, probably. One megawatt laser through 40
meter optics should be at least detectable by similar optics up to
20,000 light-years away:

<https://iopscience.iop.org/article/10.3847/1538-4357/aae380>

At a thousand AU you\'d need more than 25 watts, but likely not
megawatts. I don\'t think a radioisotope-thermal source would cut it but
small fission reactor might work.

 

[bitrex]

On 8/23/2020 3:25 PM, bitrex wrote:

On 8/23/2020 1:15 PM, Ricketty C wrote:
On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly
observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a
very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T


Seems there are in fact billions of the damn things.

Be \"...  an awful waste of space \" if Earth is the only one with
life forms.

Above quote from the SF movie \"Contact\".



.....  Phil



I\'m probably remembering the exact figures incorrectly but if you
could
push a space telescope out to about a tenth of a light-year from
Earth,
it could leverage gravitational lensing to make an equivalent
lens of
enormous size.

It could then search for evidence of life in a large volume of
space by
imaging planetary surfaces around other star systems directly, it
could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand.  I\'m referring to the RF link analysis.  They
have a very hard time seeing anything other than stars because other
objects are too dim.  I haven\'t done the math, but the data rate
would have to be microscopic to successfully send and receive a
radio signal from such distances.  0.1 light year is 6324 AUs.  The
Voyager probes are about 141 AU so about 40 times closer.  They now
are transmitting at 160 bps.  Doing the math I get about 3 years to
transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any
image compression, but lossless of course.  With the image mostly
the star, I suppose they could do a fair bit of compression.  Still,
they would want to transmit and awful lot of MB, so it will take
lots of time, still years.

Imagine what it would take to manage the cameras and other devices.
Over a month just to send any message no matter how short.


160 bps is what they have now, not from 0.1 light years away.  Apply
the -17 dB factor and recalculate...  I think the distance ratio is
actually 45.  Opps, I think I made a mistake.  It should be -33 dB,
no?  I used 10log instead of 20log.  So yeah, years.

I suppose they could just pop in a power source 2,000 times more
powerful.  How many kW would that be?  Or is it MW?  Not MW, they are
currently using 23 watt transmitters, so 45 kW instead, only slightly
less than WWVB.  Can we launch WWVB into space?


You\'d use a laser of some type, probably. One megawatt laser through 40
meter optics should be at least detectable by similar optics up to
20,000 light-years away:

https://iopscience.iop.org/article/10.3847/1538-4357/aae380

At a thousand AU you\'d need more than 25 watts, but likely not
megawatts. I don\'t think a radioisotope-thermal source would cut it but
small fission reactor might work.

Optical nuclear-electric battery seems like a plausible power source,
better power-to-weight than radioisotope thermal, less complexity than
something with circulating coolant

<https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery#:~:text=An%20opto%2Delectric%20nuclear%20battery,constituting%20a%20%22dust%20plasma%22.>

 

[bitrex]

On 8/23/2020 3:29 PM, bitrex wrote:

On 8/23/2020 3:25 PM, bitrex wrote:
On 8/23/2020 1:15 PM, Ricketty C wrote:
On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly
observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a
very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T


Seems there are in fact billions of the damn things.

Be \"...  an awful waste of space \" if Earth is the only one
with life forms.

Above quote from the SF movie \"Contact\".



.....  Phil



I\'m probably remembering the exact figures incorrectly but if
you could
push a space telescope out to about a tenth of a light-year from
Earth,
it could leverage gravitational lensing to make an equivalent
lens of
enormous size.

It could then search for evidence of life in a large volume of
space by
imaging planetary surfaces around other star systems directly,
it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand.  I\'m referring to the RF link analysis.  They
have a very hard time seeing anything other than stars because
other objects are too dim.  I haven\'t done the math, but the data
rate would have to be microscopic to successfully send and receive
a radio signal from such distances.  0.1 light year is 6324 AUs.
The Voyager probes are about 141 AU so about 40 times closer.  They
now are transmitting at 160 bps.  Doing the math I get about 3
years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any
image compression, but lossless of course.  With the image mostly
the star, I suppose they could do a fair bit of compression.
Still, they would want to transmit and awful lot of MB, so it will
take lots of time, still years.

Imagine what it would take to manage the cameras and other devices.
Over a month just to send any message no matter how short.


160 bps is what they have now, not from 0.1 light years away.  Apply
the -17 dB factor and recalculate...  I think the distance ratio is
actually 45.  Opps, I think I made a mistake.  It should be -33 dB,
no?  I used 10log instead of 20log.  So yeah, years.

I suppose they could just pop in a power source 2,000 times more
powerful.  How many kW would that be?  Or is it MW?  Not MW, they are
currently using 23 watt transmitters, so 45 kW instead, only slightly
less than WWVB.  Can we launch WWVB into space?


You\'d use a laser of some type, probably. One megawatt laser through
40 meter optics should be at least detectable by similar optics up to
20,000 light-years away:

https://iopscience.iop.org/article/10.3847/1538-4357/aae380

At a thousand AU you\'d need more than 25 watts, but likely not
megawatts. I don\'t think a radioisotope-thermal source would cut it
but small fission reactor might work.

Optical nuclear-electric battery seems like a plausible power source,
better power-to-weight than radioisotope thermal, less complexity than
something with circulating coolant

https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery#:~:text=An%20opto%2Delectric%20nuclear%20battery,constituting%20a%20%22dust%20plasma%22.

Or you could just have the whole power-generation system on Earth for a
relatively (heh) short distance like that. A huge-ass 100 megawatt laser
beams power to the spacecraft\'s solar panels and uses the electric power
to run its ion drive to accelerate it up and slow it down, and at 1000
AU there\'s enough received power from the huge-ass laser on Earth to run
a downlink laser back. Flight time would be about 20 years

 

[bitrex]

On 8/23/2020 2:50 PM, upsidedown@downunder.com wrote:

On Fri, 21 Aug 2020 18:10:35 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:


You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

160 bps is a quite decent speed. Mariner IV sent the first pictures
from Mars at 8.33 bps, which proved that there are no canals on Mars.
.

Your ideal out-of-the-Solar-system probe would be about 90% propulsion
system, 9% downlink optics, and 1% instruments by weight I think

 

[bitrex]

On 8/23/2020 3:48 PM, bitrex wrote:

On 8/23/2020 2:50 PM, upsidedown@downunder.com wrote:
On Fri, 21 Aug 2020 18:10:35 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:


You misunderstand.  I\'m referring to the RF link analysis.  They have
a very hard time seeing anything other than stars because other
objects are too dim.  I haven\'t done the math, but the data rate
would have to be microscopic to successfully send and receive a radio
signal from such distances.  0.1 light year is 6324 AUs.  The Voyager
probes are about 141 AU so about 40 times closer.  They now are
transmitting at 160 bps.  Doing the math I get about 3 years to
transmit a MB of data.

160 bps is a quite decent speed. Mariner IV sent the first pictures
from Mars at 8.33 bps, which proved that there are no canals on Mars.
.


Your ideal out-of-the-Solar-system probe would be about 90% propulsion
system, 9% downlink optics, and 1% instruments by weight I think

Downlink optics and instrumentation optics might be a dual-use kind of thing

 

[bitrex]

On 8/22/2020 11:34 PM, Ricketty C wrote:

On Saturday, August 22, 2020 at 3:04:21 PM UTC-4, upsid...@downunder.com wrote:
On Sat, 22 Aug 2020 08:41:34 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:

On Saturday, August 22, 2020 at 4:19:44 AM UTC-4, Martin Brown wrote:
On 22/08/2020 02:10, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first. The
farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have
a very hard time seeing anything other than stars because other
objects are too dim. I haven\'t done the math, but the data rate
would have to be microscopic to successfully send and receive a radio
signal from such distances. 0.1 light year is 6324 AUs. The Voyager
probes are about 141 AU so about 40 times closer. They now are
transmitting at 160 bps. Doing the math I get about 3 years to
transmit a MB of data.

It is slightly amazing that the Voyagers can be received at all now. The
transmitters on the probes are fixed 1970\'s space approved technology
with limited power and quite crude by modern communications standards.
The error correction was very sophisticated for the time though.

The base station receivers have improved so much since the probes were
launched that they can still follow Voyager out to the heliopause.

Data rates for a future deep space probe should be about the same order
of magnitude as the recent probe to Pluto managed but downgraded by the
increase in distance effects on signal to noise.

Yes, that is the problem. The distance hugely weakens the signals in both directions.

Only -6 dB for each doubling of the distance.

\"Only\" is a four letter word!

And how is the data rate impacted by a -17 dB adjustment to signal strength? You have to consider they are pushing the limit of what they can do working at 160 bps presently. We have done a lot to improve the ground stations, but they can\'t keep increasing their transmit power ad infinitum. As I said, it will take years, maybe decades to transmit a high resolution image from a space craft that far away. While larger antenna in general produce a more collimated beam, there are limits to what you can do given the precision of the antenna shape and the frequency you transmit on.

Cheapest bang-for-the-buck per-unit mission profile I think is keep the
power supply on Earth, a large laser, or array of lasers. Keep the
spacecraft as lightweight as possible. Fire it out into interstellar
space towards 1000 AU fast as it can go, using its instruments/optics to
take in all the data it can on the way, big sail of solar panels feeding
the ion/plasma drive or whatever from the laser beam.

Then at some point when received power is insufficient to run everything
flip it around and shut down everything but the downlink laser and use
the optics in reverse to beam the data back. Send as much as it can
before it goes out of range completely.

Send a number of probes and have them work in tandem if the data rate of
one alone is too low. When you don\'t have to put a power source on board
that keeps the cost down.

 

[bitrex]

On 8/23/2020 4:09 PM, bitrex wrote:

On 8/22/2020 11:34 PM, Ricketty C wrote:
On Saturday, August 22, 2020 at 3:04:21 PM UTC-4,
upsid...@downunder.com wrote:
On Sat, 22 Aug 2020 08:41:34 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:

On Saturday, August 22, 2020 at 4:19:44 AM UTC-4, Martin Brown wrote:
On 22/08/2020 02:10, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first. The
farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand.  I\'m referring to the RF link analysis.  They have
a very hard time seeing anything other than stars because other
objects are too dim.  I haven\'t done the math, but the data rate
would have to be microscopic to successfully send and receive a radio
signal from such distances.  0.1 light year is 6324 AUs.  The Voyager
probes are about 141 AU so about 40 times closer.  They now are
transmitting at 160 bps.  Doing the math I get about 3 years to
transmit a MB of data.

It is slightly amazing that the Voyagers can be received at all
now. The
transmitters on the probes are fixed 1970\'s space approved technology
with limited power and quite crude by modern communications standards.
The error correction was very sophisticated for the time though.

The base station receivers have improved so much since the probes were
launched that they can still follow Voyager out to the heliopause.

Data rates for a future deep space probe should be about the same
order
of magnitude as the recent probe to Pluto managed but downgraded by
the
increase in distance effects on signal to noise.

Yes, that is the problem.  The distance hugely weakens the signals
in both directions.

Only -6 dB for each doubling of the distance.

\"Only\" is a four letter word!

And how is the data rate impacted by a -17 dB adjustment to signal
strength?  You have to consider they are pushing the limit of what
they can do working at 160 bps presently.  We have done a lot to
improve the ground stations, but they can\'t keep increasing their
transmit power ad infinitum.  As I said, it will take years, maybe
decades to transmit a high resolution image from a space craft that
far away.  While larger antenna in general produce a more collimated
beam, there are limits to what you can do given the precision of the
antenna shape and the frequency you transmit on.


Cheapest bang-for-the-buck per-unit mission profile I think is keep the
power supply on Earth, a large laser, or array of lasers. Keep the
spacecraft as lightweight as possible. Fire it out into interstellar
space towards 1000 AU fast as it can go, using its instruments/optics to
take in all the data it can on the way, big sail of solar panels feeding
the ion/plasma drive or whatever from the laser beam.

Then at some point when received power is insufficient to run everything
flip it around and shut down everything but the downlink laser and use
the optics in reverse to beam the data back. Send as much as it can
before it goes out of range completely.

Send a number of probes and have them work in tandem if the data rate of
one alone is too low. When you don\'t have to put a power source on board
that keeps the cost down.

Why have one when you can have two at twice the price

 

[Pimpom]

On 8/23/2020 10:45 PM, Ricketty C wrote:

On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T

Seems there are in fact billions of the damn things.

Be \"... an awful waste of space \" if Earth is the only one with life forms.

Above quote from the SF movie \"Contact\".



..... Phil



I\'m probably remembering the exact figures incorrectly but if you could
push a space telescope out to about a tenth of a light-year from Earth,
it could leverage gravitational lensing to make an equivalent lens of
enormous size.

It could then search for evidence of life in a large volume of space by
imaging planetary surfaces around other star systems directly, it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be... astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Let\'s fantasize a bit. By the time we have the technology to send
a spacecraft to 0.1 LY within a reasonable period of time - say a
decade or so, communications technology should have advanced
quite a bit too. So, if NASA is currently able to receive data
sent from a 40-year-old technology at 160 bps, it\'s not
unreasonable to expect that they\'ll be able to achieve *at least*
the same data rate from much farther away at some point in the
imaginable future.

>>> Not as bad as I thought, but I suppose they would highly value any image compression, but lossless of course. With the image mostly the star, I suppose they could do a fair bit of compression. Still, they would want to transmit and awful lot of MB, so it will take lots of time, still years.

With a predominantly black background, the image could be
compressed quite a bit even in a lossless format like PNG. I dug
up some photos of the moon that I took with my old 8MP
point-and-shoot camera over 10 years ago. The file size is much
smaller than those of complex terrestrial scenes. Here\'s one
closely cropped image:
https://www.dropbox.com/s/7flugrs9vsar2xj/Moon%201.jpg?dl=0

Imagine what it would take to manage the cameras and other devices. Over a month just to send any message no matter how short.

That reminds me of one of Isaac Asimov\'s short stories in which
astronauts sent to Ganymede had somehow gone much farther and
reached Pluto. They seemed to be in an emergency situation but
Earth scientists were hampered by the 12-hour round trip time of
any radio communication. The chief physicist\'s mother, \"who
couldn\'t even read a thermometer\" provided the solution: Just
keep talking and listening on both sides. Chances were that
they\'d get all they needed without the usual ask-and-wait process.

 

[Tom Del Rosso]

On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:

I\'m probably remembering the exact figures incorrectly but if you
could push a space telescope out to about a tenth of a light-year
from Earth, it could leverage gravitational lensing to make an
equivalent lens of enormous size.

Perhaps you could make an enormous virtual lens with a large array of
Hubbles.

 

[bitrex]

On 8/23/2020 6:46 PM, Tom Del Rosso wrote:

On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:

I\'m probably remembering the exact figures incorrectly but if you
could push a space telescope out to about a tenth of a light-year
from Earth, it could leverage gravitational lensing to make an
equivalent lens of enormous size.

Perhaps you could make an enormous virtual lens with a large array of
Hubbles.

At infrared or optical wavelengths it\'s hard to keep the light coherent
between members of the array separated by large distances, aperture
synthesis is a lot easier with radio astronomy I think

 

[Ricketty C]

On Sunday, August 23, 2020 at 3:25:11 PM UTC-4, bitrex wrote:

On 8/23/2020 1:15 PM, Ricketty C wrote:
On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T

Seems there are in fact billions of the damn things.

Be \"... an awful waste of space \" if Earth is the only one with life forms.

Above quote from the SF movie \"Contact\".



..... Phil



I\'m probably remembering the exact figures incorrectly but if you could
push a space telescope out to about a tenth of a light-year from Earth,
it could leverage gravitational lensing to make an equivalent lens of
enormous size.

It could then search for evidence of life in a large volume of space by
imaging planetary surfaces around other star systems directly, it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be... astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any image compression, but lossless of course. With the image mostly the star, I suppose they could do a fair bit of compression. Still, they would want to transmit and awful lot of MB, so it will take lots of time, still years.

Imagine what it would take to manage the cameras and other devices. Over a month just to send any message no matter how short.


160 bps is what they have now, not from 0.1 light years away. Apply the -17 dB factor and recalculate... I think the distance ratio is actually 45. Opps, I think I made a mistake. It should be -33 dB, no? I used 10log instead of 20log. So yeah, years.

I suppose they could just pop in a power source 2,000 times more powerful. How many kW would that be? Or is it MW? Not MW, they are currently using 23 watt transmitters, so 45 kW instead, only slightly less than WWVB. Can we launch WWVB into space?


You\'d use a laser of some type, probably. One megawatt laser through 40
meter optics should be at least detectable by similar optics up to
20,000 light-years away:

https://iopscience.iop.org/article/10.3847/1538-4357/aae380

At a thousand AU you\'d need more than 25 watts, but likely not
megawatts. I don\'t think a radioisotope-thermal source would cut it but
small fission reactor might work.

What exactly does it mean to use 40 meter optics on a laser beam? Are you suggesting the optics need to be far enough away from the laser that the inherent limitation of the coherence of the laser beam create a 40 meter wide beam? That would be a pretty big distance. One huge antenna array!

Perhaps I don\'t understand the meaning of 40 meter optics in this context?

A MW is a bit more than 23 watts. A \"small\" fission reactor indeed. I realize they don\'t need to power it up until it is safely away from people, but the electronics need to operate in this environment. Can that be done in a weight that is practical to leave Earth orbit?

--

Rick C.

--- Get 1,000 miles of free Supercharging
--- Tesla referral code - https://ts.la/richard11209

 

[bitrex]

On 8/23/2020 7:17 PM, bitrex wrote:

On 8/23/2020 6:46 PM, Tom Del Rosso wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:

I\'m probably remembering the exact figures incorrectly but if you
could push a space telescope out to about a tenth of a light-year
from Earth, it could leverage gravitational lensing to make an
equivalent lens of enormous size.

Perhaps you could make an enormous virtual lens with a large array of
Hubbles.




At infrared or optical wavelengths it\'s hard to keep the light coherent
between members of the array separated by large distances, aperture
synthesis is a lot easier with radio astronomy I think

Then again building a propulsion system to get a space probe out to
500-1000 AU in reasonable time and figuring how to get the data back at
a reasonable rate isn\'t exactly an engineering cakewalk, either

 

[Ricketty C]

On Sunday, August 23, 2020 at 3:39:30 PM UTC-4, bitrex wrote:

On 8/23/2020 3:29 PM, bitrex wrote:
On 8/23/2020 3:25 PM, bitrex wrote:
On 8/23/2020 1:15 PM, Ricketty C wrote:
On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly
observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a
very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T


Seems there are in fact billions of the damn things.

Be \"...  an awful waste of space \" if Earth is the only one
with life forms.

Above quote from the SF movie \"Contact\".



.....  Phil



I\'m probably remembering the exact figures incorrectly but if
you could
push a space telescope out to about a tenth of a light-year from
Earth,
it could leverage gravitational lensing to make an equivalent
lens of
enormous size.

It could then search for evidence of life in a large volume of
space by
imaging planetary surfaces around other star systems directly,
it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand.  I\'m referring to the RF link analysis.  They
have a very hard time seeing anything other than stars because
other objects are too dim.  I haven\'t done the math, but the data
rate would have to be microscopic to successfully send and receive
a radio signal from such distances.  0.1 light year is 6324 AUs.
The Voyager probes are about 141 AU so about 40 times closer.  They
now are transmitting at 160 bps.  Doing the math I get about 3
years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any
image compression, but lossless of course.  With the image mostly
the star, I suppose they could do a fair bit of compression.
Still, they would want to transmit and awful lot of MB, so it will
take lots of time, still years.

Imagine what it would take to manage the cameras and other devices.
Over a month just to send any message no matter how short.


160 bps is what they have now, not from 0.1 light years away.  Apply
the -17 dB factor and recalculate...  I think the distance ratio is
actually 45.  Opps, I think I made a mistake.  It should be -33 dB,
no?  I used 10log instead of 20log.  So yeah, years.

I suppose they could just pop in a power source 2,000 times more
powerful.  How many kW would that be?  Or is it MW?  Not MW, they are
currently using 23 watt transmitters, so 45 kW instead, only slightly
less than WWVB.  Can we launch WWVB into space?


You\'d use a laser of some type, probably. One megawatt laser through
40 meter optics should be at least detectable by similar optics up to
20,000 light-years away:

https://iopscience.iop.org/article/10.3847/1538-4357/aae380

At a thousand AU you\'d need more than 25 watts, but likely not
megawatts. I don\'t think a radioisotope-thermal source would cut it
but small fission reactor might work.

Optical nuclear-electric battery seems like a plausible power source,
better power-to-weight than radioisotope thermal, less complexity than
something with circulating coolant

https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery#:~:text=An%20opto%2Delectric%20nuclear%20battery,constituting%20a%20%22dust%20plasma%22.


Or you could just have the whole power-generation system on Earth for a
relatively (heh) short distance like that. A huge-ass 100 megawatt laser
beams power to the spacecraft\'s solar panels and uses the electric power
to run its ion drive to accelerate it up and slow it down, and at 1000
AU there\'s enough received power from the huge-ass laser on Earth to run
a downlink laser back. Flight time would be about 20 years

What speed could be achieved? 1000 AU is still 6 times closer than 0.1 light year.

--

Rick C.

--+ Get 1,000 miles of free Supercharging
--+ Tesla referral code - https://ts.la/richard11209

 

[Ricketty C]

On Sunday, August 23, 2020 at 4:09:51 PM UTC-4, bitrex wrote:

On 8/22/2020 11:34 PM, Ricketty C wrote:
On Saturday, August 22, 2020 at 3:04:21 PM UTC-4, upsid...@downunder.com wrote:
On Sat, 22 Aug 2020 08:41:34 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> wrote:

On Saturday, August 22, 2020 at 4:19:44 AM UTC-4, Martin Brown wrote:
On 22/08/2020 02:10, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first. The
farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have
a very hard time seeing anything other than stars because other
objects are too dim. I haven\'t done the math, but the data rate
would have to be microscopic to successfully send and receive a radio
signal from such distances. 0.1 light year is 6324 AUs. The Voyager
probes are about 141 AU so about 40 times closer. They now are
transmitting at 160 bps. Doing the math I get about 3 years to
transmit a MB of data.

It is slightly amazing that the Voyagers can be received at all now. The
transmitters on the probes are fixed 1970\'s space approved technology
with limited power and quite crude by modern communications standards.
The error correction was very sophisticated for the time though.

The base station receivers have improved so much since the probes were
launched that they can still follow Voyager out to the heliopause.

Data rates for a future deep space probe should be about the same order
of magnitude as the recent probe to Pluto managed but downgraded by the
increase in distance effects on signal to noise.

Yes, that is the problem. The distance hugely weakens the signals in both directions.

Only -6 dB for each doubling of the distance.

\"Only\" is a four letter word!

And how is the data rate impacted by a -17 dB adjustment to signal strength? You have to consider they are pushing the limit of what they can do working at 160 bps presently. We have done a lot to improve the ground stations, but they can\'t keep increasing their transmit power ad infinitum. As I said, it will take years, maybe decades to transmit a high resolution image from a space craft that far away. While larger antenna in general produce a more collimated beam, there are limits to what you can do given the precision of the antenna shape and the frequency you transmit on.


Cheapest bang-for-the-buck per-unit mission profile I think is keep the
power supply on Earth, a large laser, or array of lasers. Keep the
spacecraft as lightweight as possible. Fire it out into interstellar
space towards 1000 AU fast as it can go, using its instruments/optics to
take in all the data it can on the way, big sail of solar panels feeding
the ion/plasma drive or whatever from the laser beam.

Then at some point when received power is insufficient to run everything
flip it around and shut down everything but the downlink laser and use
the optics in reverse to beam the data back. Send as much as it can
before it goes out of range completely.

And how far would that be with this laser?

--

Rick C.

-+- Get 1,000 miles of free Supercharging
-+- Tesla referral code - https://ts.la/richard11209

 

[bitrex]

On 8/23/2020 7:19 PM, Ricketty C wrote:

On Sunday, August 23, 2020 at 3:25:11 PM UTC-4, bitrex wrote:
On 8/23/2020 1:15 PM, Ricketty C wrote:
On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T

Seems there are in fact billions of the damn things.

Be \"... an awful waste of space \" if Earth is the only one with life forms.

Above quote from the SF movie \"Contact\".



..... Phil



I\'m probably remembering the exact figures incorrectly but if you could
push a space telescope out to about a tenth of a light-year from Earth,
it could leverage gravitational lensing to make an equivalent lens of
enormous size.

It could then search for evidence of life in a large volume of space by
imaging planetary surfaces around other star systems directly, it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be... astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand. I\'m referring to the RF link analysis. They have a very hard time seeing anything other than stars because other objects are too dim. I haven\'t done the math, but the data rate would have to be microscopic to successfully send and receive a radio signal from such distances. 0.1 light year is 6324 AUs. The Voyager probes are about 141 AU so about 40 times closer. They now are transmitting at 160 bps. Doing the math I get about 3 years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any image compression, but lossless of course. With the image mostly the star, I suppose they could do a fair bit of compression. Still, they would want to transmit and awful lot of MB, so it will take lots of time, still years.

Imagine what it would take to manage the cameras and other devices. Over a month just to send any message no matter how short.


160 bps is what they have now, not from 0.1 light years away. Apply the -17 dB factor and recalculate... I think the distance ratio is actually 45. Opps, I think I made a mistake. It should be -33 dB, no? I used 10log instead of 20log. So yeah, years.

I suppose they could just pop in a power source 2,000 times more powerful. How many kW would that be? Or is it MW? Not MW, they are currently using 23 watt transmitters, so 45 kW instead, only slightly less than WWVB. Can we launch WWVB into space?


You\'d use a laser of some type, probably. One megawatt laser through 40
meter optics should be at least detectable by similar optics up to
20,000 light-years away:

https://iopscience.iop.org/article/10.3847/1538-4357/aae380

At a thousand AU you\'d need more than 25 watts, but likely not
megawatts. I don\'t think a radioisotope-thermal source would cut it but
small fission reactor might work.

What exactly does it mean to use 40 meter optics on a laser beam? Are you suggesting the optics need to be far enough away from the laser that the inherent limitation of the coherence of the laser beam create a 40 meter wide beam? That would be a pretty big distance. One huge antenna array!

Perhaps I don\'t understand the meaning of 40 meter optics in this context?

I believe it means you use a lens or mirror of that scale to
focus/collimate the beam from your emitter. Like telescope but in reverse.

A MW is a bit more than 23 watts. A \"small\" fission reactor indeed. I realize they don\'t need to power it up until it is safely away from people, but the electronics need to operate in this environment. Can that be done in a weight that is practical to leave Earth orbit?

Yeah they\'ve flown fission reactors in space:

<https://en.wikipedia.org/wiki/TOPAZ_nuclear_reactor>

\"The first TOPAZ reactor operated for 1,300 hours and then was shut down
for detailed examination. It was capable of delivering 5 kW of power for
3–5 years from 12 kg (26 lb) of fuel. Reactor mass was ~ 320 kg (710 lb).\"

But you\'re going to need some more juice than that if you want to power
your ion/plasma drive that\'s going to take your probe out that far in
less than a human lifetime. Might as well power the communication laser
off the drive reactor or whatever power source if you\'re going to put
the propulsion energy source on board too.

 

[bitrex]

On 8/23/2020 7:23 PM, Ricketty C wrote:

On Sunday, August 23, 2020 at 3:39:30 PM UTC-4, bitrex wrote:
On 8/23/2020 3:29 PM, bitrex wrote:
On 8/23/2020 3:25 PM, bitrex wrote:
On 8/23/2020 1:15 PM, Ricketty C wrote:
On Sunday, August 23, 2020 at 8:11:26 AM UTC-4, John S wrote:
On 8/21/2020 8:10 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 3:49:41 PM UTC-4, Pimpom wrote:
On 8/21/2020 10:54 PM, Ricketty C wrote:
On Friday, August 21, 2020 at 11:55:30 AM UTC-4, bitrex wrote:
On 8/21/2020 6:38 AM, Phil Allison wrote:

Hi,

Recently it has become normal for astronomers to directly
observe planets around nearby stars in an optical telescope.

Couple of months ago, they found two in circular orbit around a
very new star.

https://www.businessinsider.com.au/first-ever-photo-shows-2-planets-orbiting-sun-like-star-2020-7?r=US&IR=T


Seems there are in fact billions of the damn things.

Be \"...  an awful waste of space \" if Earth is the only one
with life forms.

Above quote from the SF movie \"Contact\".



.....  Phil



I\'m probably remembering the exact figures incorrectly but if
you could
push a space telescope out to about a tenth of a light-year from
Earth,
it could leverage gravitational lensing to make an equivalent
lens of
enormous size.

It could then search for evidence of life in a large volume of
space by
imaging planetary surfaces around other star systems directly,
it could
resolve stuff like oceans, plants, or structures.

But the time required to return those images would be...
astronomical.

Sending back digital images over a distance of a tenth of a light
year by radio wave would take, well, just one-tenth of a year, or
about five weeks. No problem.

The big problem is to reach that 0.1 light year distance first.
The farthest man-made objects are now travelling at ~15 km/s
(Wikipedia). At that speed, it would take over 2000 years. :-(

You misunderstand.  I\'m referring to the RF link analysis.  They
have a very hard time seeing anything other than stars because
other objects are too dim.  I haven\'t done the math, but the data
rate would have to be microscopic to successfully send and receive
a radio signal from such distances.  0.1 light year is 6324 AUs.
The Voyager probes are about 141 AU so about 40 times closer.  They
now are transmitting at 160 bps.  Doing the math I get about 3
years to transmit a MB of data.

? 10Mb/160bps = 62.5k seconds = 17.4 hours. What am I doing wrong?

Not as bad as I thought, but I suppose they would highly value any
image compression, but lossless of course.  With the image mostly
the star, I suppose they could do a fair bit of compression.
Still, they would want to transmit and awful lot of MB, so it will
take lots of time, still years.

Imagine what it would take to manage the cameras and other devices.
Over a month just to send any message no matter how short.


160 bps is what they have now, not from 0.1 light years away.  Apply
the -17 dB factor and recalculate...  I think the distance ratio is
actually 45.  Opps, I think I made a mistake.  It should be -33 dB,
no?  I used 10log instead of 20log.  So yeah, years.

I suppose they could just pop in a power source 2,000 times more
powerful.  How many kW would that be?  Or is it MW?  Not MW, they are
currently using 23 watt transmitters, so 45 kW instead, only slightly
less than WWVB.  Can we launch WWVB into space?


You\'d use a laser of some type, probably. One megawatt laser through
40 meter optics should be at least detectable by similar optics up to
20,000 light-years away:

https://iopscience.iop.org/article/10.3847/1538-4357/aae380

At a thousand AU you\'d need more than 25 watts, but likely not
megawatts. I don\'t think a radioisotope-thermal source would cut it
but small fission reactor might work.

Optical nuclear-electric battery seems like a plausible power source,
better power-to-weight than radioisotope thermal, less complexity than
something with circulating coolant

https://en.wikipedia.org/wiki/Optoelectric_nuclear_battery#:~:text=An%20opto%2Delectric%20nuclear%20battery,constituting%20a%20%22dust%20plasma%22.


Or you could just have the whole power-generation system on Earth for a
relatively (heh) short distance like that. A huge-ass 100 megawatt laser
beams power to the spacecraft\'s solar panels and uses the electric power
to run its ion drive to accelerate it up and slow it down, and at 1000
AU there\'s enough received power from the huge-ass laser on Earth to run
a downlink laser back. Flight time would be about 20 years

What speed could be achieved? 1000 AU is still 6 times closer than 0.1 light year.

When I first typed up my post I overstated the distance to get a
gravitational-lens effect off the Sun\'s own gravity well. 500-1000 AU
should be enough. Nuclear thermal rocket, specific impulse ~1000 seconds
could do 1000 AU with basically current technology well within a human
lifetime. Ion/plasma drive, specific impulse 50,000 seconds, cuts it
down to 10 years maybe.

To go faster than in reasonable time that you need something far beyond
near-future tech. Fusion ramjet cuts it down to 3 months or so I think,
but you might as well send it on to the nearest star at that speed.