Update: "Will amateur radio astronomers be the first to directly detect extrasolar planets?"

This news release reported on the creation of a "virtual telescope" to
combine the radio signals from widely separated radio telescopes in
real time over the internet:

Date Released: Friday, October 08, 2004
Source: Jodrell Bank Observatory
Astronomers Demonstrate a Global Internet Telescope
http://www.spaceref.com/news/viewpr.html?pid=15251

Something like this would be required to implement the method of
detecting extrasolar planets from their radio emissions using very
many widely separated dipole arrays, as discussed below. The report
noted the data was transmitted over the high-speed internet networks
that most universities world-wide are connected to.
The idea would be for thousands of universities world-wide to set-up
dipole arrays with several thousand dipoles each. The dipoles are
quite cheap consisting simply copper wire, so there is no problem of
the cost of the arrays for each university, and any empty athletic
field would do to hold the arrays.



Bob Clark


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From: Robert Clark )
Subject: Will amateur radio astronomers be the first to directly
detect extrasolar planets?
Newsgroups: rec.radio.amateur.space, rec.radio.amateur.antenna,
sci.astro, sci.astro.seti, sci.space.policy
Date: 2001-05-23 11:15:07 PST


The existence of extrasolar planets has been inferred from the
wobbling seen in some stars. Their actual light still has not been
detected or distinguished from that of their parent stars.
The long wavelength radio bursts that emanate from Jupiter have led
to suggestions that extrasolar planets might be detected by searching
for such bursts in the vicinity of stars:

Opening a New Window on the Universe:
High Resolution, Long Wavelength Radio Astronomy,
2.5.2 Extrasolar Planets,
by Joseph Lazio
http://rsd-www.nrl.navy.mil/7213/laz...eb/node34.html

However, sensitive searches have so far failed to detect them. This
is undoubtedly due to distance attenuation for such planets
light-years away. The distance to Jupiter ranges up to 9 x 10^8 km. A
star 10 light-years away is at 9 x 10^13 km, a factor of 10^5 larger
than the Jupiter distance.
The Jovian radio bursts have been detected by amateurs with simple
dipole antennas:

Radio-Jupiter for Amateur Observers, By Jim Sky
[expired link: http://******.com/SAS/bulletin/Sas44....html#Jupiter]
try instead NASA Radio JOVE Project Home Page,
http://radiojove.gsfc.nasa.gov/

PROJECT P5-2. JUPITER-IO MAGNETOSPHERE RADIO NOISE
http://www.elmag5.com/jupiter-io.htm

With its Radio JOVE project NASA also distributes low-cost dipole
kits to schools:

How To Hear Radio Signals From Jupiter
http://www.spacetoday.org/SolSys/Jup...iterRadio.html

Radio JOVE
http://spacescience.com/headlines/y2...may_1.htm?list

The proposal is for amateur radio astronomers to set up arrays of
such low cost dipole antennas world-wide. The T-shaped dipoles have
the advantage of steerability, but the vertical dipoles have the
advantage of simplicity and low cost for setting up large arrays. An
example of a steerable dipole array is the one that first discovered
the Jovian decametric emissions:

The Discovery of Jupiter's Radio Emissions
How a chance discovery opened up the field of Jovian radio studies
http://radiojove.gsfc.nasa.gov/libra...discovery.html

The signals from the various arrays would be combined digitally to
form a world-wide radio telescope. The large-wavelengths being
detected simplify the task of combining the signals
interferometrically. GPS transmitters are now available that can give
locations to within inches:

NASA satellite technology goes down on the farm
http://www.spaceflightnow.com/news/n0105/11farm/

The clocks in such transmitters also provide timing at better than
nanosecond resolution.

The signal strength for Jupiter at 10 light-years would decrease as
the square of the distance, so would be smaller by a factor of 10^10.
However, the extrasolar Jovian planets detected so far have been close
in to their primaries and are expected to produce stronger radio
emissions than Jupiter, perhaps, 100 to 1000 times more intense. Using
the optimistic estimate of 1000 times greater intensity would require
100,000 separate arrays with 100 dipoles or 10,000 arrays with 1,000
dipoles to detect such emissions.



Bob Clark

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