Wasn\'t this impossible ?...

[Phil Allison]

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

 

[Chris Jones]

On 21/08/2020 20:38, 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\".

I\'m more inclined to quote last line of the monty python song.

 

[Martin Brown]

On 21/08/2020 11:38, Phil Allison wrote:

Hi,

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

Most of the time they are inferring it from spectroscopy. But as the
instrumental methods and apertures have improved a select few can be
imaged directly. This one is certainly a tour de force.

They have become incredibly good at nulling out the glare from the
central star. It is a distinctly non-trivial observational technique!
The planets are *very* faint compared to the star they are orbiting.

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.

I\'m inclined to the view that where you have all three phases of water
there will eventually be life. Though most of it may just be coloured
single cell slimes matched to the peak emissions of their nearest star
or local geochemistry.

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

The Drake equation is your friend. It does seem now that planets are
relatively common. And also supports the conjecture that gas giants
formed much further out in the solar system then we observe them today.

It will be even more interesting when the Webb telescope is up in space.

--
Regards,
Martin Brown

 

[bitrex]

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.

 

[Martin Brown]

On 21/08/2020 16:55, 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 is a recognised method of finding exoplanets and is interesting
because it finds a slightly different subset of them to the more usual
spectroscopic methods.

https://lco.global/education/resources/articles/what-microlensing-event/

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.

I\'m afraid that is a bit fanciful. There a few gravitational lenses
based on galaxy clusters that let us see further than in other
directions with some distortions like Einstein rings. Here is a
particularly pretty example in a Hubble image:

https://www.nasa.gov/image-feature/goddard/2018/hubble-finds-an-einstein-ring


--
Regards,
Martin Brown

 

[bitrex]

On 8/21/2020 12:11 PM, Martin Brown wrote:

On 21/08/2020 16:55, 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 is a recognised method of finding exoplanets and is interesting
because it finds a slightly different subset of them to the more usual
spectroscopic methods.

https://lco.global/education/resources/articles/what-microlensing-event/

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.

I\'m afraid that is a bit fanciful. There a few gravitational lenses
based on galaxy clusters that let us see further than in other
directions with some distortions like Einstein rings. Here is a
particularly pretty example in a Hubble image:

https://www.nasa.gov/image-feature/goddard/2018/hubble-finds-an-einstein-ring

I mean NASA seems to take the idea seriously:

<https://www.nasa.gov/directorates/spacetech/niac/2020_Phase_I_Phase_II/Direct_Multipixel_Imaging_and_Spectroscopy_of_an_Exoplanet/>

\"Under a Phase II NIAC program, we confirmed that a mission to the
strong interference region of the SGL (beyond 547.6 AU) carrying a
meter-class telescope with a solar coronagraph would directly image a
habitable Earth-like exoplanet within our stellar neighborhood. For an
exo-Earth at 30 pc, the telescope could measure the brightness of the
Einstein ring formed by the exoplanet’s light around the Sun. Even in
the presence of the solar corona, the SNR is high enough that in 6
months of integration time one can reconstruct the exoplanet image with
~25 km-scale surface resolution, enough to see surface features and
signs of habitability.\"

 

[Ricketty C]

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.

Maybe the probe could orbit another star to obtain energy?

--

Rick C.

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

 

[Jeff Layman]

On 21/08/2020 18:24, 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.

I\'ve probably worked it out wrongly, but something over 76 hours from
the source to Earth when around 550AU out (see Bitrex\'s second post).
And how many bits of information could such a radio or laser beam carry?
The problem of getting any information back to Earth wasn\'t covered in
that NASA article.

> Maybe the probe could orbit another star to obtain energy?

How long would it take to get to another star using current or even
proposed technology?

--

Jeff

 

[Ricketty C]

On Friday, August 21, 2020 at 1:51:58 PM UTC-4, Jeff Layman wrote:

On 21/08/2020 18:24, 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.

I\'ve probably worked it out wrongly, but something over 76 hours from
the source to Earth when around 550AU out (see Bitrex\'s second post).
And how many bits of information could such a radio or laser beam carry?
The problem of getting any information back to Earth wasn\'t covered in
that NASA article.

Maybe the probe could orbit another star to obtain energy?

How long would it take to get to another star using current or even
proposed technology?

So make a new star where you want it to be. Hey! Put the star where you want it and keep the probe local! That solves all the problems while creating one other one. So one problem instead of several.

Can largish planets be used for gravitational lensing? What if we moved Jupiter to a perfect position, what distance would that be?

--

Rick C.

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

 

[Pimpom]

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. :-(

 

[Joe Gwinn]

On Sat, 22 Aug 2020 01:19:29 +0530, Pimpom <nobody@nowhere.com> 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. :-(

And to reach that far would take a very large laser. Maybe Phil
should count the photons, just to be sure?

And then there is the small matter of laser power and cooling, far
from anything solid.

Joe Gwinn

 

[Ricketty C]

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.

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.

--

Rick C.

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

 

[Phil Allison]

Martin Brown wrote:

===================

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

Most of the time they are inferring it from spectroscopy.

** Which does not inform the innocent.

Astronomers actually use good old Doppler shift to infer that planets exists. Ultra fine analysis of light spectra reveals tiny shifts in both senses if large planets are revolving about a star - cos the star moves a bit too.

Dimming of a star\'s brightness is the other method, but only works if planets traverse the star from our viewpoint.

Direst observation from a ground telescope is way cooler.


...... Phil

 

[Bill Sloman]

On Saturday, August 22, 2020 at 1:12:54 PM UTC+10, palli...@gmail.com wrote:

Martin Brown wrote:

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

Most of the time they are inferring it from spectroscopy.

** Which does not inform the innocent.

Astronomers actually use good old Doppler shift to infer that planets exists. Ultra fine analysis of light spectra reveals tiny shifts in both senses if large planets are revolving about a star - cos the star moves a bit too.

And even odder application is of Doppler shift detection astroseismology

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

Apparently the observatories that do it have optical filters that are filled with potassium vapour. The doppler shift on the narrow potassium emission lines from the moving surface of the star is apparently big enough to produce detectable amplitude modulation on the star-light that gets through the filter.

I imagine they\'d have narrow band interference filters to block out everything outside the narrow potassium emission lines.

It\'s not mentioned directly in the Wikipedia write-up, but an astroseismologist I once talked to mentioned the filters.

Dimming of a star\'s brightness is the other method, but only works if planets traverse the star from our viewpoint.

Direct observation from a ground telescope is way cooler.

It\'s lot cheaper.

--
Bill Sloman, Sydney

 

[server]

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

The problem with Voyagers and other early probes is the relatively low
frequencies (6-8 GHz) used, thus with a few meter transmitter antenna,
the beam is quite broad beamwidth illuminating the whole Earth.

Using say a 40 times higher frequency (240-320 GHz) the beam would be
40 times narrower, illuminating only a small part of the Earth, thus a
much higher power density and hence data rate would be available. Of
course, this requires better pointing accuracy. Going further, using a
HST size (2.5 m) optical telescope and a laser would produce a even
narrower beam.

The Voyager primary mission was to investigate the big planets in a
few decades, thus a radioisotope with a half life of a few decades was
selected for the RTG. After a few half lives, the electric output from
the RTG has dropped significantly, reducing the power for the radio
transmitter, further reducing the data rate,

For very long distance missions an isotope with longer half life would
be selected or alternatively a true nuclear reactor using a chain
reaction.

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.

 

[Martin Brown]

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.

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.

They include very sophisticated error correction in the datastream so
that lossless compression of the raw data isn\'t that much of a gain in
reality. You seldom gain much in lossless compression unless the source
material is nice clean line art. Noise doesn\'t compress at all well.

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

You would just have to plan it\'s observing programmes a month or two
ahead - which is about the norm for any large telescope anyway. Though
usually the observation is programmed in the days just prior to
observation to allow for any last minute maintenance hitches.

--
Regards,
Martin Brown

 

[Ricketty C]

On Saturday, August 22, 2020 at 3:56:58 AM UTC-4, upsid...@downunder.com wrote:

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

The problem with Voyagers and other early probes is the relatively low
frequencies (6-8 GHz) used, thus with a few meter transmitter antenna,
the beam is quite broad beamwidth illuminating the whole Earth.

Using say a 40 times higher frequency (240-320 GHz) the beam would be
40 times narrower, illuminating only a small part of the Earth, thus a
much higher power density and hence data rate would be available. Of
course, this requires better pointing accuracy. Going further, using a
HST size (2.5 m) optical telescope and a laser would produce a even
narrower beam.

While a more narrow beam width would raise the energy received at the receiving antenna, are you seriously suggesting at the distance of 0.1 light year the antenna could be focused to a beam that only illuminates a portion of the earth??? What would the dimensional tolerances be on the transmitting antenna? I would think very tiny imperfections would make the antenna ineffective in forming such a narrow beam.

0.1 light year is 9.461e+14 meters. The Earth is 12,742,000 meters. The resulting angle is around 0.8 micro-degrees. Really???

The Voyager primary mission was to investigate the big planets in a
few decades, thus a radioisotope with a half life of a few decades was
selected for the RTG. After a few half lives, the electric output from
the RTG has dropped significantly, reducing the power for the radio
transmitter, further reducing the data rate,

For very long distance missions an isotope with longer half life would
be selected or alternatively a true nuclear reactor using a chain
reaction.

The problem is the power output required increases with distance to the Earth. Ditto the transmitting equipment.

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.

It would be interesting to see how an outfit like NASA would approach the problem.

--

Rick C.

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

 

[Ricketty C]

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.

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.

They include very sophisticated error correction in the datastream so
that lossless compression of the raw data isn\'t that much of a gain in
reality. You seldom gain much in lossless compression unless the source
material is nice clean line art. Noise doesn\'t compress at all well.

Random noise doesn\'t compress at all. Lossless compression works by removing the redundancies in the data stream and increasing the entropy. Random noise is already at a maximum of entropy, so it can\'t be compressed.

Good thing such an image as the gravitational lensing using a star is not very noise like.

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

You would just have to plan it\'s observing programmes a month or two
ahead - which is about the norm for any large telescope anyway. Though
usually the observation is programmed in the days just prior to
observation to allow for any last minute maintenance hitches.

If you need to take any measurements it\'s a two month round trip before you get your responses.

Then there is the issue of aiming the thing. The telescope is 0.1 light year away and in position to image one target. Now to relocate to image another target will take how many more years??? Considering there is no fuel left for that level of maneuvering it is a mission to image exactly one target. The Voyagers imaged all of the big planets.

--

Rick C.

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

 

[server]

On Sat, 22 Aug 2020 08:32:39 -0700 (PDT), Ricketty C
<gnuarm.deletethisbit@gmail.com> wrote:

On Saturday, August 22, 2020 at 3:56:58 AM UTC-4, upsid...@downunder.com wrote:
On Fri, 21 Aug 2020 18:10:35 -0700 (PDT), Ricketty C
gnuarm.deletethisbit@gmail.com> 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.

The problem with Voyagers and other early probes is the relatively low
frequencies (6-8 GHz) used, thus with a few meter transmitter antenna,
the beam is quite broad beamwidth illuminating the whole Earth.

Using say a 40 times higher frequency (240-320 GHz) the beam would be
40 times narrower, illuminating only a small part of the Earth, thus a
much higher power density and hence data rate would be available. Of
course, this requires better pointing accuracy. Going further, using a
HST size (2.5 m) optical telescope and a laser would produce a even
narrower beam.

While a more narrow beam width would raise the energy received at the receiving antenna, are you seriously suggesting at the distance of 0.1 light year the antenna could be focused to a beam that only illuminates a portion of the earth??? What would the dimensional tolerances be on the transmitting antenna? I would think very tiny imperfections would make the antenna ineffective in forming such a narrow beam.

0.1 light year is 9.461e+14 meters. The Earth is 12,742,000 meters. The resulting angle is around 0.8 micro-degrees. Really???

OK, 320 GHz is a too low frequency for that.

The beam that would illuminate the whole Earth is 13 nanoradians.

The beamwidth from an antenna is about lambda / aperture_diameter
expressed in radians. A UV laser at 250 nm beamed through 2.5 m (HST)
mirror would provide a 100 nanoradian beam, so not much wider than the
Earth.

 

[server]

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.