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Old January 9th 08, 12:10 AM posted to rec.radio.amateur.dx
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Default Scientists DXing the Moon just outside 49 meters

"Public Affairs Office
Naval Research Laboratory
Washington, D.C.

Contact:
Janice Schultz, 202-767-2541

1/8/2008

NRL Press Release: 4-08r

Scientists Detect Lowest Frequency Radar Echo From the Moon

A team of scientists from the Naval Research Laboratory, the Air Force
Research Laboratory's (AFRL's) Research Vehicles Directorate, Kirtland Air
Force Base, N.M., and the University of New Mexico (UNM) has detected the
lowest frequency radar echo from the moon ever seen with earth-based
receivers.

In the lunar echo experiment (more properly called a lunar bistatic radar
experiment), the Air Force/Navy High Frequency Active Auroral Research
Program (HAARP) high power transmitter, located near Gakona, Alaska,
launched high power radio waves toward the moon. The reflected signal,
weakened because of the long distance to the moon and back, was detected by
receiving antennas in New Mexico.

NRL consultant scientist Dr. Paul Rodriguez, of NRL's Information Technology
Division, who conceived and proposed the experiment explains, "Analysis of
the echo gives information on the properties of the lunar sub-surface
topography, because the low frequency radar waves propagate to varying
depths below the visible surface of the moon. It is somewhat like sonar,
except that we are using electromagnetic waves rather than sound waves. The
experiment also allows us to study the interaction of the echo signal with
the earth's ionosphere along its return path, because the ionosphere is only
partially transparent at low frequencies."

During the experiment, which was carried out on Oct. 28 and 29, 2007, the
radar signals from HAARP were at 7.4075 MHz and 9.4075 MHz. Both the
transmitted signal and the echo from the moon were detected by NRL Remote
Sensing Division scientist, Dr. Kenneth Stewart, and NRL engineer Brian
Hicks with antennas built for the Long Wavelength Array (LWA). LWA is a
radio interferometer being built in the desert west of Socorro, N.M., by
UNM, NRL, the Applied Research Laboratories at the University of Texas at
Austin, Virginia Tech, and Los Alamos National Laboratory, for studies of
space physics and astrophysics.

The LWA is intended to work below the 88 MHz edge of the FM band, but to get
down to the HAARP signal frequencies, the antennas were equipped with
digital receivers and specially designed matching networks developed by
Stewart, Hicks, and engineer Nagini Paravastu at NRL. "Detecting the very
weak radio signals after their round trip to the moon and back was
challenging and required careful modification of the LWA antennas to improve
their performance at these frequencies," says Stewart. NRL LWA Project
Scientist Dr. Namir Kassim notes, "One of the successful goals of this
experiment was to demonstrate that the LWA can work with instruments like
HAARP at lower frequencies than its nominal design."

The HAARP radar antenna array was "phased" to point about 45 degrees away
from the zenith, in order to track and directly illuminate the moon. Its
full total power capability, about 3.6 MW, was used to transmit pulses two
seconds in length every five seconds over a period of two hours each day,
one hour at each frequency. Using such a pulse pattern makes the echo, which
arrives back from the moon 2.4 seconds later, immediately recognizable,
allowing the scientists to distinguish the moon's echo signal from the HAARP
signal. The HAARP signal reached the receiving antennas in New Mexico by
reflecting off the underside of the ionosphere, the region of the Earth's
atmosphere from 50 to 400 km in altitude that is partially ionized by solar
radiation.

The lunar echo measurements at 7.4075 MHZ are believed to be the lowest
frequency (longest wavelength) at which bistatic radar measurements have
been conducted. "Even though lunar echoes have been detected before at
higher frequencies, it was really exciting to see them arrive in real time
out under the full moon in the New Mexico desert," says NRL's Hicks.

The team members involved in the HAARP-LWA lunar radar experiment a
Dr.Paul Rodriguez, Dr. Kenneth Stewart, Brian Hicks, Dr. Nagini Paravastu;
and Edward Kennedy of NRL; Dr. Paul Kossey of AFRL's Research Vehicles
Directorate; and Dr. Lee J Rickard of UNM.

Significant help in conducting the experiment was provided by HAARP Program
Managers Paul Kossey (Air Force) and Edward Kennedy (Navy); Mike McCarrick
of BAE Systems-Advanced Technologies, which operates the HAARP facility, and
by Clinton Janes (UNM); Gerald O'Connell (National Radio Astronomy
Observatory); and Patrick Crane (NRL).

IMAGE CAPTION:
[http://www.nrl.navy.mil/PressRelease...raph-4-08r.jpg (29KB)]
7.4075 Mhz signals from HAARP received by LWA on October 28, 2007, 09:00
UTC. This figure shows the ionospheric reflections and the lunar echos of
three of the more than 1400 HAARP pulses received by one of the LWA antennas
in New Mexico."
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