Space based SETI ...

Today I recieved a letter from The Planetary Society asking for
donations to their SETI Fund, and telling of new efforts being planned
for Space Based SETI. Space Based SETI involves putting SETI equipment
in orbit around Earth and in space. Good idea as it would be the first
attempts to isolate SETI antennas from Earth RFI/EMI and it would allow
looking at frequencies not possible with the Earth based SETI antennas.

One project idea was to use the NASA Terrestrial Planet Finder (TPF)
optics to search for infrared nanosecond pulses (this would be an
extension of the Optical SETI currently done at Harvard and Berkeley and
Princeton). It turns out that this (I don't know exactly how) would be
an easy thing to do and The Planetary Society might just succeed and
make it happen.
Al

Wow ! Cool !
That is my first reaction. Space based search definitely has advantages as you say : reduced RFI, but mostly : we could search in
vast and the interesting (advanced civilization?) region between 50Ghz to deep infrared which is mostly absorbed in the atmosphere.

But what is the benefit of doing Optical SETI in space ?
There is no RFI in ns pulses, and the atmosphere is very transparent for infrared.
Are ns pulses dispersed in the atmosphere or so ?
Is there some other effect that makes space-based OSETI advantageous w.r.t. an earth-based system ?

Rob


"Alfred A. Aburto Jr." wrote in message m...
Today I recieved a letter from The Planetary Society asking for
donations to their SETI Fund, and telling of new efforts being planned
for Space Based SETI. Space Based SETI involves putting SETI equipment
in orbit around Earth and in space. Good idea as it would be the first
attempts to isolate SETI antennas from Earth RFI/EMI and it would allow
looking at frequencies not possible with the Earth based SETI antennas.

One project idea was to use the NASA Terrestrial Planet Finder (TPF)
optics to search for infrared nanosecond pulses (this would be an
extension of the Optical SETI currently done at Harvard and Berkeley and
Princeton). It turns out that this (I don't know exactly how) would be
an easy thing to do and The Planetary Society might just succeed and
make it happen.
Al

Rob Dekker wrote:
Wow ! Cool !
That is my first reaction. Space based search definitely has advantages as you say : reduced RFI, but mostly : we could search in
vast and the interesting (advanced civilization?) region between 50Ghz to deep infrared which is mostly absorbed in the atmosphere.

But what is the benefit of doing Optical SETI in space ?
There is no RFI in ns pulses, and the atmosphere is very transparent for infrared.
Are ns pulses dispersed in the atmosphere or so ?
Is there some other effect that makes space-based OSETI advantageous w.r.t. an earth-based system ?

The main thing about the infrared, with respect to the TPF, is to move
away from the heat of the Sun so that the sensitivity of the instrument
can be significantly increased ...


Rob


"Alfred A. Aburto Jr." wrote in message m...

Today I recieved a letter from The Planetary Society asking for
donations to their SETI Fund, and telling of new efforts being planned
for Space Based SETI. Space Based SETI involves putting SETI equipment
in orbit around Earth and in space. Good idea as it would be the first
attempts to isolate SETI antennas from Earth RFI/EMI and it would allow
looking at frequencies not possible with the Earth based SETI antennas.

One project idea was to use the NASA Terrestrial Planet Finder (TPF)
optics to search for infrared nanosecond pulses (this would be an
extension of the Optical SETI currently done at Harvard and Berkeley and
Princeton). It turns out that this (I don't know exactly how) would be
an easy thing to do and The Planetary Society might just succeed and
make it happen.
Al

Rob Dekker wrote:
Wow ! Cool !
That is my first reaction. Space based search definitely has advantages as you say : reduced RFI, but mostly : we could search in
vast and the interesting (advanced civilization?) region between 50Ghz to deep infrared which is mostly absorbed in the atmosphere.

But what is the benefit of doing Optical SETI in space ?
There is no RFI in ns pulses, and the atmosphere is very transparent for infrared.

Rob,
The atmosphere is transparent to infrared at the small wavelengths
otherwise most of the infrared is blocked I believe ...

See the following web site:
http://www.ipac.caltech.edu/Outreach...irwindows.html


Are ns pulses dispersed in the atmosphere or so ?

Perhaps, but I don't think that is a critical factor being considered.

Is there some other effect that makes space-based OSETI advantageous w.r.t. an earth-based system ?

In the infrared region (1 to 500 micrometer wavelengths?)the sensitivity
of a telescope is improved by moving out away from the proximity of the
Sun (as the Sun tends to overwhelm in the infrared). For that reason the
TPF mission will be deployed out around 5 AU from the Sun (somewhere out
near the orbit of Jupiter (as I recall)).
Al


Rob


"Alfred A. Aburto Jr." wrote in message m...

Today I recieved a letter from The Planetary Society asking for
donations to their SETI Fund, and telling of new efforts being planned
for Space Based SETI. Space Based SETI involves putting SETI equipment
in orbit around Earth and in space. Good idea as it would be the first
attempts to isolate SETI antennas from Earth RFI/EMI and it would allow
looking at frequencies not possible with the Earth based SETI antennas.

One project idea was to use the NASA Terrestrial Planet Finder (TPF)
optics to search for infrared nanosecond pulses (this would be an
extension of the Optical SETI currently done at Harvard and Berkeley and
Princeton). It turns out that this (I don't know exactly how) would be
an easy thing to do and The Planetary Society might just succeed and
make it happen.
Al

For radio SETI in space, the antenna system needs to be out well beyond
geosynchronous orbit to get any benefit from reduced RFI. The lunar
farside would be a great place for SETI, but a space antenna orbiting
an Earth-Moon, or better an Earth-Sun, Lagrange point would have litle
interference from the Earth or satellites.

For radio SETI in space, the antenna system needs to be out well beyond
geosynchronous orbit to get any benefit from reduced RFI. The lunar
farside would be a great place for SETI, but a space antenna orbiting
an Earth-Moon, or better an Earth-Sun, Lagrange point would have litle
interference from the Earth or satellites.

(Sorry if this gets posted twice. There was an error on the first
attempt.)

In article ,
Rob Dekker wrote:
[ ... ]
But what is the benefit of doing Optical SETI in space ?
There is no RFI in ns pulses, and the atmosphere is very transparent for
infrared.
Are ns pulses dispersed in the atmosphere or so ?
Is there some other effect that makes space-based OSETI advantageous
w.r.t. an earth-based system ?
[ ... ]

In space, there are no clouds, at least not as dense as the ones
in our atmosphere.


Gary

--
Gary Heston

"Sept. 11, 2001, already a day of immeasurable tragedy, cannot be
the day liberty perished in this country." Judge Gerald Tjoflat

wrote:
For radio SETI in space, the antenna system needs to be out well beyond
geosynchronous orbit to get any benefit from reduced RFI. The lunar
farside would be a great place for SETI, but a space antenna orbiting
an Earth-Moon, or better an Earth-Sun, Lagrange point would have litle
interference from the Earth or satellites.

What would be great too at a Lagrange point would be to monitor the
broadband (and narrowband) emission from Earth. Then one would know
abosolutely about the possibilities of detecting Earth from some distant
place in the Galaxy. Make for a nice paper for a grad or undergrad
student perhaps ...

I remember seeing a plot of the broadband emissions from Earth (I
believe it was in a book by Tobias Owen) done in the early 70's I think.
It was intersting because it showed that the broadband EM power emitted
from Earth was periodic. It was periodic because it turned out that most
of the powerful transmitters were located along the coastal regions of
the continents (resulting in periodic EM blips as the Earth turned once
per day). Earth is like a micro miniscule pulsar beeping away to the
universe ...

Gary Heston wrote:
In article ,
Rob Dekker wrote:
[ ... ]

But what is the benefit of doing Optical SETI in space ?
There is no RFI in ns pulses, and the atmosphere is very transparent for
infrared.
Are ns pulses dispersed in the atmosphere or so ?
Is there some other effect that makes space-based OSETI advantageous
w.r.t. an earth-based system ?

[ ... ]

In space, there are no clouds, at least not as dense as the ones
in our atmosphere.


Gary

Wrong. We cannot even see the center of our own galaxy as a result of
dust clouds.

Chuck

In message , Chuck_Sterling
writes
Gary Heston wrote:
In article ,
Rob Dekker wrote:
[ ... ]

But what is the benefit of doing Optical SETI in space ?
There is no RFI in ns pulses, and the atmosphere is very transparent for
infrared.
Are ns pulses dispersed in the atmosphere or so ?
Is there some other effect that makes space-based OSETI advantageous
w.r.t. an earth-based system ?
[ ... ]
In space, there are no clouds, at least not as dense as the ones
in our atmosphere.
Gary

Wrong. We cannot even see the center of our own galaxy as a result of
dust clouds.

Only in visible light. Infrared and other wavelengths (some only
accessible in space) can penetrate to the centre of the galaxy.
--
What have they got to hide? Release the ESA Beagle 2 report.
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